The Arctic is experiencing the most rapid climate change on Earth as average temperatures there rise up to 4 times faster than on the rest of the planet. Among the many environmental effects of this warming, the Arctic Ocean, critically, is moving toward a “blue” state, meaning it is increasingly becoming ice free during the summer months.

This shift raises significant concerns about the region’s future. Arctic Indigenous peoples, for instance, heavily rely on stable ice conditions for traditional hunting, fishing, and travel. As ice disappears, these activities become more dangerous or impossible, threatening food security, cultural practices, and the transmission of Traditional Knowledge. Global geopolitical and economic pressures will also rise as new shipping routes open, previously inaccessible resources become available for extraction, and international competition over these resources rises.

Currently, however, scientists struggle to predict how an ice-free Arctic will react to and amplify a warmer global climate. The lack of clear climate projections for the region is largely due to a shortage of key geological data describing former climatic conditions and how the Arctic has responded to past changes, as well as to difficulties interpreting the records we do have. Making sense of these data is essential for understanding how the Arctic will evolve in the coming decades.

Deep-sea sediment cores provide some of the best available archives from the Arctic Ocean. These cores, drilled and collected from sites around the region, contain sediments deposited over hundreds of thousands of years that offer clues about past ocean temperatures, sea ice and ice sheets, and ocean circulation changes. To gain insights specifically into how the Arctic may respond to future warming—and the broader implications for the planet—scientists focus on past “greenhouse” states, when Earth’s climate was warmer than it is today, such as the Last Interglacial, about 130,000 years ago.

However, reconstructing past warm climates from deep-sea core records is challenging, particularly because the chronology of Arctic Ocean sediments has been difficult to establish. The lack of biological remains and the dissolution of calcium carbonate in these sediments complicate efforts to determine their ages (i.e., their chronostratigraphy). Furthermore, the use of different dating methods and uncertainties about sedimentation rates have led to conflicting interpretations of core records and hindered the development of a solid timeline for Arctic climate history [e.g., Stein et al., 2025].

Recent advances in research have raised questions about the accuracy of prior published ages of Arctic Ocean sediments. These developments have also highlighted ongoing uncertainties and the need to understand the abilities and limitations of different dating tools. Without this understanding, it will be difficult to identify and detail past greenhouse climates with confidence, which in turn, will limit our ability to apply knowledge of these past conditions to inform climate models.

The Arctic Ocean Stratigraphic Toolbox

In fall 2024, more than 40 scientists gathered at the ArcSTRAT conference in Tromsø, Norway, to discuss the latest research and how available methods can best be used to develop a reliable chronostratigraphic framework, or age model, for Arctic sediments. Additional goals were to foster shared understanding of the region’s climate history and to improve our ability to provide accurate data to climate modelers.

A key challenge in studying Arctic paleoclimate is that oceanic sedimentation rates are typically low across the region. In fact, the central Arctic Ocean is one of the slowest accumulating marine sedimentary environments globally because of limited sediment sources and biological productivity, suppression of sediment transport by sea ice, and sediment trapping on broad circum-Arctic continental shelves.

The slow sediment accumulation results in thin sediment layers that can make it difficult to obtain clear chronological data. Dissolution of calcium carbonate from deposited sediments, which can occur where deep seawater is undersaturated with respect to the mineral, further reduces the possibility of finding datable microfossils in the sedimentary record.

In some areas, biostratigraphy (the distribution of ancient life in sedimentary rocks) and stable isotope geochronology (which compares ratios of nonradioactive isotopes of, e.g., carbon or oxygen) can be used to refine age models. In other areas, alternative methods are needed to provide age constraints. Such methods include magnetostratigraphy, which dates sediment layers by correlating their magnetism to the record of Earth’s magnetic field reversals; amino acid racemization, which measures the time-dependent breakdown of proteins in fossils too old for radiocarbon dating; luminescence dating, which measures radiation that builds up in materials as they age; and radionuclide dating.

Recent breakthroughs, particularly in applying radionuclide methods, have shown promise in improving the accuracy of Arctic Ocean sediment age models (Figure 1). For example, novel applications of uranium series isotopes (e.g., thorium-230 and protactinium-231) have been used to propose new age constraints for marine sediment sequences from important topographic regions, such as the Mendeleev-Alpha and Lomonosov Ridges, where low sedimentation and poor preservation of fossil material have hampered previous attempts to date these sequences [Hillaire-Marcel et al., 2017]. These isotopes decay predictably over time, allowing scientists to date past interglacial periods more confidently, including the Last Interglacial and others occurring around 200,000 years ago.

These new radionuclide-based age constraints are supported in part by recent applications of more traditional dating methods like biostratigraphy. Specifically, a newly revised Arctic sediment chronology for the late Pleistocene (400,000–10,000 years ago) established on the basis of analyses of calcareous nanoplankton, although not perfectly aligned, showed less uncertainty in the identification of interglacial periods in the central Arctic Ocean [Razmjooei et al., 2023]. Tracking changes in the concentration of cosmogenic radionuclides, like beryllium-10, in Arctic sediments has also provided new insights into the timing of interglacials [Spielhagen et al., 1997].

The Need for a Multimethod Approach

The generally low sedimentation rates across the Arctic Ocean produce thin sediment layers that require precise sampling and, because not every dating method works well everywhere, careful selection of analytical methods. Some methods are better suited than others for studying sediments from given locations because environmental conditions across the Arctic differ, contributing to variable sedimentation rates, variable preservation of fossils, and disturbances like erosion and bioturbation (the reworking of sediment layers by living organisms).

Whereas relying on a single method to study sediments from across the Arctic Ocean may lead to inaccuracies and gaps in understanding, different methods can complement each other, providing a fuller, more robust picture of the past. Discussions during the ArcSTRAT conference highlighted the importance of using a multimethod approach, combining the various available stratigraphic and isotopic dating methods.

The challenge lies in carefully selecting appropriate methods to study cores from different regions to minimize errors and uncertainties and provide a reliable reconstruction of past Arctic environments. In areas where calcium carbonate is well preserved (e.g., topographic highs), for example, biostratigraphy and isotope geochronology are extremely useful. In areas where it is not (e.g., deep basins), litho- and magnetostratigraphy combined with radionuclide dating might be better options.

The past few decades have seen the development and application of a veritable toolbox of different techniques for dating Arctic Ocean sediments. These tools must now be integrated and applied to study newly collected sediment archives.

New Arctic Archives

Alongside methodological developments, new Arctic sediment cores have been retrieved recently, including during the International Ocean Discovery Program’s Expedition 403. In 2024, this campaign successfully drilled more than 5 kilometers of sediment cores from the Fram Strait west of Svalbard that offer a high-resolution record of past Arctic climates [Lucchi et al., 2024].

The scientific aim of this drilling was to better understand the ocean system and cryosphere during past warm intervals and how they relate to high insolation (exposure to sunlight) and atmospheric carbon dioxide levels. This information is essential for comprehending the climatic evolution of the Northern Hemisphere and the dynamics of ice sheets, sea ice, and ocean circulation. Data from these cores will be invaluable for studying the mechanisms that lead to ice-free Arctic summers and for understanding the effects of these conditions within and beyond the Arctic.

In 2025, the European Research Council’s (ERC) Synergy Grant–funded “Into The Blue” (i2B) Arctic expedition aboard R/V Kronprins Haakon will focus on recovering additional unique sediment archives from the central Arctic Ocean. The plan is to use a combination of classical and cutting-edge techniques to explore the Arctic’s climate history as completely as possible, matching the methods to the demands of each core. Together with stratigraphic methods, these techniques include analyses of molecular biomarkers, palynology (the study of preserved pollen grains and spores), ancient DNA, radionuclides, and stable isotopes to reconstruct past sea ice conditions, ocean heat transport, and cryosphere variability during warmer-than-present climate states such as the Last Interglacial.

A Promising Start to the Work Ahead

The ArcSTRAT conference made clear that the work ahead is challenging but promising. The outcomes and consensus about coordinating multimethod approaches will provide a crucial framework for analyzing new cores from the i2B expedition and, hopefully, additional future expeditions. The meeting also helped to establish a forum for continued collaboration and knowledge exchange among Arctic stratigraphy experts—an important step toward resolving continuing disparities among dating methods and developing a robust Arctic Ocean chronostratigraphy.

As the Arctic continues changing at an unprecedented rate and advancing toward blue summers, understanding its past is more critical than ever. By piecing together the climatic history of past greenhouse states, scientists are building the foundation for more accurate climate models, which are essential for informing accurate global climate assessments that, in turn, guide policy decisions in countries and communities around the world.

With ongoing advances in the toolbox of techniques for studying ocean sediment stratigraphy, as well as the collection of new sediment records, we will be better positioned to predict how the Arctic will respond to further warming and what the far-reaching consequences of this response will be.

Acknowledgments

We thank the participants in the 2024 ArcSTRAT conference in Tromsø, Norway, especially keynote speakers Ruediger Stein, Anne de Vernal, Renata Lucchi, Jutta Wollenburg, and Stijn De Schepper. The conference was funded by the Research Council of Norway, as well as by ERC through the Synergy Grant “i2B–Into The Blue” (grant 101118519).

References

Hillaire-Marcel, C., et al. (2017), A new chronology of late Quaternary sequences from the central Arctic Ocean based on “extinction ages” of their excesses in ²³¹Pa and ²³⁰Th, Geochem. Geophys. Geosyst., 18(12), 4,573–4,585, https://doi.org/10.1002/2017GC007050.

Lisiecki, L. E., and M. E. Raymo (2005), A Pliocene‐Pleistocene stack of 57 globally distributed benthic δ¹⁸O records, Paleoceanography, 20(1), PA1003, https://doi.org/10.1029/2004PA001071.

Lucchi, R. G., et al. (2024), Expedition 403 preliminary report: Eastern Fram Strait paleo-archive, Int. Ocean Discovery Program, https://doi.org/10.14379/iodp.pr.403.2024.

Razmjooei, M. J., et al. (2023), Revision of the Quaternary calcareous nannofossil biochronology of Arctic Ocean sediments, Quat. Sci. Rev., 321, 108382, https://doi.org/10.1016/j.quascirev.2023.108382.

Spielhagen, R. F., et al. (1997), Arctic Ocean evidence for late Quaternary initiation of northern Eurasian ice sheets, Geology, 25(9), 783–786, https://doi.org/10.1130/0091-7613(1997)025%3C0783:AOEFLQ%3E2.3.CO;2.

Stein, R., et al. (2025), A 430 kyr record of ice-sheet dynamics and organic-carbon burial in the central Eurasian Arctic Ocean, Nat. Commun., 16, 3822, https://doi.org/10.1038/s41467-025-59112-7.

West, G., et al. (2023), Amino acid racemization in Neogloboquadrina pachyderma and Cibicidoides wuellerstorfi from the Arctic Ocean and its implications for age models, Geochronology, 5(1), 285–299, https://doi.org/10.5194/gchron-5-285-2023.

Author Information

Jochen Knies (Jochen.Knies@uit.no), UiT The Arctic University of Norway, Tromsø; Matt O’Regan, Stockholm University, Sweden; and Claude Hillaire Marcel, Université du Québec à Montréal, Montreal, Canada

Citation: Knies, J., M. O’Regan, and C. H. Marcel (2025), Finding consensus on Arctic Ocean climate history, Eos, 106, https://doi.org/10.1029/2025EO250230. Published on 25 June 2025.

Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Coral reefs are vital ecosystems supporting marine life, ecotourism, and coastal protection. They also hold something valuable under their surface: records of the ocean’s past. Beneath the living outer layer of massive corals are dense, rocklike skeletal structures containing annual bands, similar to tree rings. Scientists can study the conditions at the time these bands formed by drilling, retrieving, and analyzing cores, some of which represent centuries of coral growth.

Since the 1970s, studies of coral cores to determine past growth patterns, a field known as coral sclerochronology, have produced notable scientific discoveries. Knutson et al. [1972] found that annual bands comprise alternating high- and low-density bands that reflect seasonal growth patterns. Hudson [1981] found that typically, high-density bands form during slower winter growth and low-density bands form during faster summer growth and that long-term coral growth variations are influenced by water quality and the effects of coastal development. Some cores also contain high-density “stress bands” formed because of coral bleaching events or other environmental challenges [Lough, 2008]. Together, this banding provides insights into coral growth history, enabling scientists to construct reliable age models of past oceanic and climatic conditions.

Today, methods used to investigate coral cores have advanced considerably. Alongside other methods such as stable isotope and elemental ratio analyses, computed tomography (CT) scanning plays a major role in yielding data that help to reveal coral growth parameters. Scientists can use 2D X-ray and 3D CT scanning to examine the internal structure of coral cores, including their annual density bands [Knutson et al., 1972; Hudson, 1981; Lough, 2008; DeCarlo et al., 2025]. In some cases, such analysis even involves a scientist visiting a local hospital to use its CT machine—an unexpected patient for the radiology technician.

However, there has been no systematic archiving of coral core imagery data, partly because of the lack of a suitable repository. This gap presents risks of losing valuable images and prevents streamlined, transparent sharing of scientific interpretations from these images. Therefore, a centralized, virtual, open-access repository of coral core imagery is crucial for fostering transparent science and preserving these resources for future research.

An App for Organizing an Archive

The CoralCT application was developed to consolidate and organize coral core scans in a virtual repository that enables digital archiving and image analysis [DeCarlo et al., 2025]. The repository currently contains scans of more than 1,000 cores collected from a wide range of coral reef regions, including the Great Barrier Reef, the Caribbean, and the Red Sea. These core scans have been contributed by individuals and agencies, including the U.S. Geological Survey (USGS) and NOAA.

Coral researchers upload X-ray or CT scans to CoralCT and, when they are ready, can make their data publicly available to anyone with a computer and internet connection. This approach to transparency fosters collaborations among coral core researchers, who can view the app’s core directory and see who else has collected cores from their areas of interest. It also helps avoid unnecessary duplication of research efforts, which is especially important given the need to reduce sampling impacts on corals, many of which are endangered species.

Using the application’s analytical tools, observers can map annual density bands in coral cores to extract data on growth rates and skeletal density. As in tree ring studies, this sort of analysis offers insights into past environmental conditions because coral growth can respond sensitively to climate variability.

For example, Barkley et al. [2018] used CoralCT to visualize high-density stress bands and reconstruct the history of coral bleaching over 6 decades on a remote reef in the equatorial Pacific Ocean where monitoring data were sparse. Rodgers et al. [2021] measured annual growth rates in CoralCT to track the recovery of corals off Kaua‘i, Hawaii, in the 15 years after a damaging flood event. More recently, DeCarlo et al. [2024] leveraged the breadth of cores in CoralCT to reconstruct coral growth trends over recent decades to centuries across thousands of kilometers of the Indo-Pacific.

Rescuing Old Records and Gathering New Ones

Archiving valuable data that might otherwise be lost is a foundational purpose of CoralCT. A standout example of how it’s serving this purpose involves the rescue and digitization of X-ray images of more than 20 cores collected across the Pacific Ocean between the 1980s and early 2000s. The X-ray films, previously stored by a retiring scientist, are now archived and available for analysis on CoralCT.

In a similar effort, USGS recently CT scanned coral cores dating back to the late 1960s, some of the earliest cores ever collected [Hudson et al., 1976]. These scans are being added to the repository so they can be reanalyzed by researchers now and into the future. Older collections like these can provide valuable insights into coral growth before environmental disturbances, such as mass bleaching from heat stress, began to affect them.

Alongside these historical contributions, CoralCT’s repository continues to grow with the addition of new data. One such recent contribution includes scans of reef cores collected from offshore Hawai‘i in 2023 during the International Ocean Discovery Program’s Expedition 389. Reef cores differ from coral cores in composition and structure but are also critical for understanding ocean history and environmental change. During Expedition 389, cores were collected from drowned reefs that once grew near the ocean surface but stopped calcifying as they were submerged in deeper water. These reef cores contain fragmented coral, coralline algae, microbialites, and other reef-building materials whose compositions enable scientists to look millennia into the past and uncover valuable records of sea level and climate change.

Repeatable Analyses, Verifiable Results

When raw, unprocessed coral core images are not archived, the value of growth measurements and other analyses is limited because other scientists cannot readily and independently verify them. This is problematic because science fundamentally relies on the ability to repeat experiments and verify results, especially considering individual researchers can introduce subjectivity and potential biases into even highly systematic and rigorous interpretations of data. As datasets grow larger, more intricate, and more numerous, maintaining transparency is increasingly important but also increasingly difficult.

CoralCT addresses these challenges by ensuring that all information and context about a core is fully documented, accessible, and downloadable. This information includes essential metadata such as the core’s origin, ownership details, collection date, depth, and species identifications. Most important, CoralCT archives the user-defined maps of annual banding used to derive growth rate data [DeCarlo et al., 2025], ensuring that these data and interpretations are fully reproducible and open to verification by others.

This transparency is also shared among observers within the application. When a user is mapping the bands of a core, they can add notes and screenshots that other users can view when they’re analyzing that core. Furthermore, when a user finishes mapping the bands of a core and processes the data, this information is saved and made downloadable for other scientists to view. This ability enables scientists to conduct multiobserver studies, which can reduce potential biases introduced by individual observation.

Despite these advantages, a challenge encountered in our efforts to broaden CoralCT has been the hesitancy of some researchers and programs to share data because of concerns about intellectual property infringements and the “scooping” of prepublication data. This hesitancy, which is understandable considering the lack of transparency and protections for data owners in prior data management practices, can unfortunately limit scientific advancements and collaborations that might help address climate change, coral reef degradation, and other complex challenges.

To address these concerns, CoralCT offers privacy controls to core owners that they can use to restrict access to their scans and the derived output data. These controls are particularly useful when cores are part of ongoing research that has not yet been published or are subject to a postcruise moratorium, ensuring that sensitive data remain protected until the research is ready to be shared. In addition, each core is tagged with a data owner, acknowledgments, and relevant citations.

Advancing Accessibility and Collaboration

CoralCT also represents a path to making science more inclusive and accessible. The application is designed with an easy-to-use interface and includes resources such as video tutorials and a step-by-step user guide to help introduce its features to a wide audience. K–12 lesson plans that guide students through mapping coral core bands in the app were also recently created, offering approachable ways to explore marine science.

The app’s educational potential was demonstrated during recent outreach events. Using virtual reality technology, middle school students in New Orleans viewed 3D coral core scans from CoralCT and practiced identifying annual density bands. At a similar event, sixth grade students in Hawaii interacted with 3D holographic coral cores, learning how scientists retrieve and study them to understand growth patterns over time. The positive experiences of students and teachers during these events demonstrated how CoralCT provides an opportunity to engage hands-on with real scientific data.

Looking forward, there is potential to integrate artificial intelligence (AI) into CoralCT for automated identification of coral banding patterns. If an AI system were trained on existing human interpretations, it could automatically suggest band markings that users could review and verify. This advancement offers the potential for more accurate and efficient coral core analyses while maintaining human oversight. Integration of AI could also, importantly, make it easier for all users to contribute to coral core analysis, regardless of their academic background or field experience. Each new contribution or analysis of a core enhances the CoralCT database and extends our knowledge of coral reefs and past ocean conditions.

Coral sclerochronology is vital for understanding environmental changes in coral reef ecosystems and the impacts these changes have wrought. Through this research, we gain insights into the ocean’s past and advance our understanding of coral reefs today. As threats to reefs intensify, large open-access datasets are increasingly essential for monitoring reef health and predicting future impacts.

CoralCT thus plays an important role in preserving valuable records of coral growth and environmental history while promoting collaborative, accessible, and transparent data sharing. In making coral reef science available to researchers and the public alike, it is connecting data, ideas, and people to address critical questions about our changing world.

Acknowledgments

CoralCT was developed with support from National Science Foundation award OCE-2444864. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. government. We thank the IODP 389 Expedition Science Party, ECORD Science Operator (ESO) support staff, benthic drilling team, MMA surveyors, and the captain and crew of the MMA Valour. International Ocean Discovery Program (IODP) Expedition 389 was supported by funding from the various national funding agencies of the participating IODP countries. We also thank all data contributors to date, including Giulia Braz, Jessica Carilli, Leticia Cavole, Ben Chomitz, Travis Courtney, Ian Enochs, Thomas Felis, Ke Lin, Malcolm McCulloch, Haojia Ren, Riccardo Rodolfo-Metalpa, Natan Pereira, and the U.S. Geological Survey Coastal and Marine Hazards Resources Program.

References

Barkley, H. C., et al. (2018), Repeat bleaching of a central Pacific coral reef over the past six decades (1960–2016), Commun. Biol., 1, 177, https://doi.org/10.1038/s42003-018-0183-7.

DeCarlo, T. M., et al. (2024), Calcification trends in long-lived corals across the Indo-Pacific during the industrial era, Commun. Earth Environ., 5, 756, https://doi.org/10.1038/s43247-024-01904-8.

DeCarlo, T. M., et al. (2025), CoralCT: A platform for transparent and collaborative analyses of growth parameters in coral skeletal cores, Limnol. Oceanogr. Methods, 23(2), 97–116, https://doi.org/10.1002/lom3.10661.

Hudson, J. H. (1981), Growth rates in Montastraea annularis: A record of environmental change in Key Largo Coral Reef Marine Sanctuary, Florida, Bull. Mar. Sci., 31(2), 444–459, www.ingentaconnect.com/content/umrsmas/bullmar/1981/00000031/00000002/art00014.

Hudson, J. H., et al. (1976), Sclerochronology: A tool for interpreting past environments, Geology, 4(6), 361–364, https://doi.org/10.1130/0091-7613(1976)4<361:SATFIP>2.0.CO;2.

Knutson, D. W., et al. (1972), Coral chronometers: Seasonal growth bands in reef corals, Science, 177(4045), 270–272, https://doi.org/10.1126/science.177.4045.270.

Lough, J. M. (2008), Coral calcification from skeletal records revisited, Mar. Ecol. Prog. Ser., 373, 257–264, https://doi.org/10.3354/meps07398.

Rodgers, K. S., et al. (2021), Rebounds, regresses, and recovery: A 15-year study of the coral reef community at Pila‘a, Kaua‘i after decades of natural and anthropogenic stress events, Mar. Pollut. Bull., 171, 112306, https://doi.org/10.1016/j.marpolbul.2021.112306.

Author Information

Avi Strange and Oliwia Jasnos, Tulane University, New Orleans, La.; Lauren T. Toth, St. Petersburg Coastal and Marine Science Center, U.S. Geological Survey, Fla.; Nancy G. Prouty, Pacific Coastal and Marine Science Center, U.S. Geological Survey, Santa Cruz, Calif.; and Thomas M. DeCarlo (tdecarlo@tulane.edu), Tulane University, New Orleans, La.

Citation: Strange, A., O. Jasnos, L. T. Toth, N. G. Prouty, and T. M. DeCarlo (2025), A coral core archive designed for transparency and accessibility, Eos, 106, https://doi.org/10.1029/2025EO250226. Published on 20 June 2025.

Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

On 10–11 May 2024, the strongest solar storm since 2003 hit Earth. The storm caused spectacular aurorae around the world, including as far south as Kansas in the midwestern United States. Unfortunately, it also had negative effects, such as days-long disruptions in GPS signals needed by farm tractors that, in turn, caused delays in planting operations at a critical time in the spring.

Solar storms, which throw torrents of protons, neutrons, and other particles at our planet, have had severe effects in decades past. A massive storm in May 1967, for example, significantly disrupted military communications (and ultimately led the United States to strengthen its space weather capacity) [Knipp et al., 2016]. Another, in March 1989, disabled power grids, hitting Quebec, Canada, especially hard [Boteler, 2019].

The biggest recorded modern event took place in February 1956. Were it to be repeated today, such an event could disrupt aircraft electronics and expose passengers to substantially elevated radiation doses.

The largest known solar event in history, 50–100 times larger than the one that happened in 1956, occurred in 774 CE [Miyake et al., 2012]. An event on par with the 774 storm is considered a worst-case scenario for modern aviation [Mishev et al., 2023].

With the 11-year solar cycle approaching its maximum in 2025, we are in a time of heightened potential for such events to disrupt daily life.

Fortunately, technology for observing solar storms and the particle showers they rain down on Earth has developed significantly over the past several decades. Both ground-based and satellite observations are critical for measuring solar storms and their effects [National Academies of Sciences, Engineering, and Medicine, 2024] and for generating space weather forecasts (e.g., by NOAA’s Space Weather Prediction Center (SWPC)). The global aviation sector, for example, uses these forecasts to predict solar radiation storm warning levels and radiation dosage levels to help keep flights safe.

Good predictions rely on the availability of high-quality and comprehensive data. However, the small number of high-energy neutron monitoring stations currently used to observe the effects of solar events at Earth’s surface limits data availability and thus the accuracy and spatial resolution of forecasts. But solutions are within reach.

In addition to space weather scientists, hydrologists use data from these monitoring stations, albeit for a different purpose: They rely on the high-energy neutron detections to calibrate the low-energy neutron detectors they use as one way to collect snow cover and soil moisture measurements that are important for hydrological modeling and agricultural applications. Recent studies showed that the larger networks of low-energy neutron detectors used by hydrologists can supplement and effectively increase the coverage of the smaller network of high-energy neutron monitors [Baird, 2024]. Now, scientists are devising a strategy to combine forces for their mutual benefit.

Wanted: Better Observational Capabilities

Massive lead-lined neutron monitors (NMs) are typically used to monitor the arrival of cosmic ray particles at Earth’s surface. These particles include high-energy secondary neutrons (carrying energies of ~50–100 megaelectron volts) that are generated by collisions of primary solar and galactic cosmic rays with other particles in the atmosphere, a process that can be reconstructed using NM data and numerical models [Mishev et al., 2014].

Satellites, including those in the GOES (Geostationary Operational Environmental Satellite) system, also provide operational data about primary cosmic rays in real time, but they cannot resolve particle energies in the detail required for estimating radiation doses affecting aviation or for modeling solar particle energy spectra [National Academies of Sciences, Engineering, and Medicine, 2024].

A global network of NMs, each run by different universities or other entities, has been in operation for the past 7 decades [Väisänen et al., 2021]. Unfortunately, today, only 20 NM sites around the globe provide real-time data; another roughly 30 NMs have been shut down because of a lack of long-term funding to maintain them. Geopolitical factors and closed data policies in some parts of the world additionally limit data quality and access internationally.

The U.S. Senate’s 2020 Space Weather Research and Forecasting Act emphasized the need for better observational capabilities to address this crisis of critical infrastructure. The 2020 PROSWIFT Act and the most recent National Academies’ solar and space physics decadal survey [National Academies of Sciences, Engineering, and Medicine, 2024] further underscored the challenges and need for supporting long-term operational NM networks.

Hydrologists Have Their Own Networks

Applying methods developed beginning several decades ago [e.g., Kodama et al., 1979], hydrologists have, in the past 15 years, deployed networks of detectors similar to NMs to measure snow and soil moisture [Zreda et al., 2012]. These cosmic ray neutron sensors (CRNSs) are, however, much smaller than NMs, and they are sensitive to much lower neutron energies (~0.025 to 100 kiloelectron volts).

At these lower energies, the number of detected neutrons depends not only on incoming secondary cosmic rays but also on the abundance of hydrogen in the surrounding environment (e.g., in the form of snow or soil moisture). In soil, for example, cosmic ray neutrons collide with hydrogen atoms, lose energy in the process, and become thermalized (i.e., they slow down). CRNSs are designed to count these water-sensitive neutrons.

The sensors can measure these low-energy neutrons within a roughly 20-hectare circular area and up to about 30 centimeters above the ground surface, an extraordinarily large volume relative to their size. Figure 1 shows how example CRNS measurements of neutron counts and soil water content from central Nebraska clearly respond to rainfall, as measured by the local Mesonet station, and match potential evapotranspiration data well.

Area-averaged estimates of snow and soil moisture like this match scales relevant for hydrological modeling and agricultural management (e.g., irrigation and fertilizer application, crop yield prediction), providing a big advantage compared with estimates from point-scale measurements, given the high spatial variability that naturally exists from one meter to another. CRNS detectors offer other benefits as well. Their measurements, collected roughly hourly, are nondestructive; they have extremely low maintenance costs; and they can be deployed outdoors for long-term environmental monitoring.

Today, more than 300 CRNS instruments are operating across all seven continents, with networks in Australia, China, Europe, India, South Africa, the United Kingdom, and the United States. These networks have led to exciting advances in hydrology.

For example, CRNSs have been shown to be excellent sources of ground validation data for remote sensing soil moisture data products like SMAP (Soil Moisture Active Passive) and SMOS (Soil Moisture and Ocean Salinity) that support weather and agricultural forecasting efforts, among other applications [Montzka et al., 2017]. CRNS data have also been shown to significantly improve predictions of streamflow by catchment models by improving estimates of near-surface water storage [Dimitrova-Petrova et al., 2020]. Mobile CRNSs have also been deployed on commuter trains in Europe, providing soil moisture and snow observations across unprecedented scales [Schrön et al., 2021].

Despite their clear utility, CRNS networks, like the global NM network, often lack long-term funding. Moreover, in the United States, no single federal agency is mandated to monitor soil moisture, a void that hinders the development of a national coordinated soil moisture monitoring network.

An Exciting Opportunity

The CRNS research community has been highly dependent on the NM network because real-time reference data are required to correct CRNS measurements for variations in incoming cosmic radiation. In a recent advance bridging the two neutron monitoring communities, Baird [2024] showed that potential benefits also extend in the other direction.

He used 50 CRNS stations in the United Kingdom to investigate whether they can inform space weather monitoring, concluding that they “can identify persistent space weather periodicities, transient space weather periodicities, and transient aperiodic space weather signals” and that these capabilities are “largely unaffected by the influence of soil moisture in the data.” Although these identifications are not as reliable as those from neutron monitors, the much larger number of CRNSs compared with NMs offers promise for expanding data collection.

Baird also found that the CRNS data recorded some medium to large solar events, such as Forbush decreases (FDs), which are decreases in galactic cosmic rays reaching Earth following solar coronal mass ejections. The CRNSs detected 4 out of 28 FDs that had been identified by NMs between 2014 and 2022.

CRNS data have also been used to simulate ground level enhancements (GLEs) of radiation levels at Earth’s surface caused by bombardments of intense solar cosmic rays. These emitted particles, primarily protons, are accelerated to high energies during solar flares or coronal mass ejections. GLEs are rarer than FDs, occurring once per year on average, but are more detrimental to humans and aviation. GLEs are also nearly impossible to predict and prepare for because they arrive at Earth only minutes after a solar flare or coronal mass ejection occurs, whereas FDs take several days to arrive.

Given the newfound connection between low-energy neutron observations and space weather phenomena, an exciting opportunity exists to use CRNS networks globally to augment the roughly 20-station NM network. This ability would offer an unprecedented number of ground monitors to help researchers understand and analyze larger FD and GLE events and their impacts all around Earth.

Two Communities Join Forces

The hydrology and space weather communities have worked together informally since the 2010 launch of the Cosmic-Ray Soil Moisture Observing System in the United States [Zreda et al., 2012]. But the need for additional collaboration has been identified in the literature and during joint sessions at AGU and European Geoscience Union meetings.

In response to this increased interest, the first Coordinated Cosmic-Ray Observation System Conference was held in October 2024 at the University of Nebraska–Lincoln. The hybrid event gathered 50 experts from academia, government, and industry to explore both the scientific potential of ground-based neutron monitoring across energy spectra and opportunities for productive cross-disciplinary partnerships.

Conference participants produced a concept paper identifying key issues on which the participating communities can work together. These issues involve critical needs for improved infrastructure and enhanced data accessibility.

Documenting soil moisture conditions more comprehensively and meeting data needs for environmental modeling and operational products, for example, require the deployment of additional CRNS stations globally—ideally, 30 stations per 1 million square kilometers. In the United States, this level of coverage equates to about 250 stations spread across the country’s roughly 8 million square kilometers.

With respect to space weather, NOAA’s SWPC has stated a need for real-time NM data (1-minute resolution with 5-minute latency) and additional NM monitoring sites to improve the spatial resolution of aviation forecasts. More NM sites are also needed to better understand the anisotropy (uneven distribution) of incoming cosmic ray particles globally, particularly during GLEs and other perturbed geomagnetic conditions, and how it may influence space weather impacts experienced around the planet.

By collaboratively addressing these and other gaps in the neutron-detecting networks used for space weather and soil moisture monitoring, we can advance scientific understanding of critical environmental and planetary processes and better serve the needs of operational systems designed to foster safety and prosperity.

References

Baird, F. (2024), The potential use of hydrological neutron sensor networks for space weather monitoring, Ph.D. thesis, University of Surrey, Guildford, U.K., https://doi.org/10.15126/thesis.901065.

Boteler, D. H. (2019), A 21st century view of the March 1989 magnetic storm, Space Weather, 17(10), 1,427–1,441, https://doi.org/10.1029/2019SW002278.

Dimitrova-Petrova, K., et al. (2020), Opportunities and challenges in using catchment-scale storage estimates from cosmic ray neutron sensors for rainfall-runoff modelling, J. Hydrol., 586, 124878, https://doi.org/10.1016/j.jhydrol.2020.124878.

Knipp, D. J., et al. (2016), The May 1967 great storm and radio disruption event: Extreme space weather and extraordinary responses, Space Weather, 14(9), 614–633, https://doi.org/10.1002/2016SW001423.

Kodama, M., et al. (1979), An application of cosmic-ray neutron measurements to the determination of the snow-water equivalent, J. Hydrol., 41(1–2), 85–92, https://doi.org/10.1016/0022-1694(79)90107-0.

Mishev, A. L., L. G. Kocharov, and I. G. Usoskin (2014), Analysis of the ground level enhancement on 17 May 2012 using data from the global neutron monitor network, J. Geophys. Res. Space Phys., 119(2), 670–679, https://doi.org/10.1002/2013JA019253.

Mishev, A., S. Panovska, and I. Usoskin (2023), Assessment of the radiation risk at flight altitudes for an extreme solar particle storm of 774 AD, J. Space Weather Space Clim., 13, 22, https://doi.org/10.1051/swsc/2023020.

Miyake, F., et al. (2012), A signature of cosmic-ray increase in AD 774–775 from tree rings in Japan, Nature, 486, 240–242, https://doi.org/10.1038/nature11123.

Montzka, C., et al. (2017), Validation of spaceborne and modelled surface soil moisture products with cosmic-ray neutron probes, Remote Sens., 9(2), 103, https://doi.org/10.3390/rs9020103.

National Academies of Sciences, Engineering, and Medicine (2024), The Next Decade of Discovery in Solar and Space Physics: Exploring and Safeguarding Humanity’s Home in Space, Natl. Acad. Press, Washington, D.C., https://doi.org/10.17226/27938.

Schrön, M., et al. (2021), Neutrons on rails: Transregional monitoring of soil moisture and snow water equivalent, Geophys. Res. Lett., 48(24), e2021GL093924, https://doi.org/10.1029/2021GL093924.

Väisänen, P., I. Usoskin, and K. Mursula (2021), Seven decades of neutron monitors (1951–2019): Overview and evaluation of data sources, J. Geophys. Res. Space Phys., 126(5), e2020JA028941, https://doi.org/10.1029/2020JA028941.

Zreda, M., et al. (2012), COSMOS: The Cosmic-ray Soil Moisture Observing System, Hydrol. Earth Syst. Sci., 16, 4,079–4,099, https://doi.org/10.5194/hess-16-4079-2012.

Author Information

Trenton Franz (tfranz2@unl.edu), School of Natural Resources, University of Nebraska–Lincoln; Darin Desilets, Hydroinnova LLC, Albuquerque, N.M.; Martin Schrön, Helmholtz Centre for Environmental Research UFZ, Leipzig, Germany; Fraser Baird, University of Surrey, Guildford, U.K.; and David McJannet, Commonwealth Scientific and Industrial Research Organisation, Canberra, Australia

Citation: Franz, T., D. Desilets, M. Schrön, F. Baird, and D. McJannet (2025), Two neutron-monitoring networks are better than one, Eos, 106, https://doi.org/10.1029/2025EO250212. Published on 6 June 2025.

Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Over the past few years, hurricanes in the Gulf of Mexico have broken records for their intensity and the speed at which they have evolved from tropical storms into major cyclones. Hurricane Beryl, for example, strengthened quickly in early July 2024 to become the earliest category 5 hurricane on record. A few months later, in October, Hurricane Milton set a record for intensifying from a tropical depression to a category 5 hurricane in a little over 2 days.

A wealth of scientific research has implicated anomalously warm seas as the primary cause for intensifying storms in the region [e.g., Liu et al., 2025]. Ocean currents that circulate warm water, including the Loop Current, which transports water from the tropics to latitudes farther north, are also well-documented contributors to conditions around the Gulf today.

But how these currents have behaved in the past and how they are responding to climate change, which may have significant implications for coastal and inland communities adversely affected by cyclones, are not entirely clear. An interdisciplinary group of scientists from Mexico and the United States has been collaborating in recent years to find out.

Why the Loop Current Matters

The Loop Current (Figure 1), which enters the Gulf of Mexico from the Caribbean by way of the Yucatán Channel between the Campeche Peninsula and Cuba, is a major pathway for water flowing from the tropics to the high-latitude North Atlantic. It is a key component of global thermohaline circulation (currents driven by differences in temperature and salinity), providing roughly 85% of the Gulf Stream as it flows through the Straits of Florida, up the U.S. East Coast, and across the North Atlantic. This warm, salty water substantially influences the Gulf’s hydrography, as well as North American and European climate.

Recent research has shed light on concerning trends in the Gulf, the Loop Current, and the broader system of ocean currents. For example, warming upper layer waters in the Gulf appear to be exacerbating rising sea levels there [Thirion et al., 2024], and warm-core eddies shed from the Loop Current have been shown to be an important factor in the rapid intensification of recent Gulf hurricanes [Liu et al., 2025] (Figure 1).

The Loop Current and Gulf Stream together also form an important part of the Atlantic Meridional Overturning Circulation (AMOC). The AMOC is a fundamental component of Earth’s climate system, circulating water north and south through the Atlantic—and from the surface to ocean depths—while also distributing heat and nutrients. With the recently documented slowing of the Gulf Stream [Piecuch and Beal, 2023], concern is growing that a similar change in AMOC, perhaps in response to a warming planet, will upset the global heat balance in the Northern Hemisphere. This sort of change could have far-reaching consequences—from cooling temperatures in northern Europe to rapidly rising sea levels along the U.S. East Coast—for the habitability and sustainability of communities all around the Atlantic.

Since 2017, researchers at the University of Texas Institute for Geophysics (UTIG) and Universidad Nacional Autónoma de México (UNAM) have been collaborating to study the paleoceanographic (i.e., deep-time) history of the Loop Current. Among its activities, this team has gone to sea to acquire high-resolution subseafloor seismic images [Lowery et al., 2024] (Figure 2), generate high-precision seafloor maps, and collect samples from the seafloor.

A broad international effort is also ongoing to understand the Loop Current’s modern complexity [National Academies of Sciences, Engineering, and Medicine (NASEM), 2018], using data from moored instruments, glider measurements across multiple transects in the Yucatán Channel, and modeling (Figure 3). This effort has focused primarily on characterizing today’s Loop Current in the region between eastern Mexico and Cuba, where historical data are limited.

Delving into the Current’s History

A current has been flowing through the Gulf of Mexico since at least the Late Cretaceous (~100 million years ago), and like ocean circulation generally, that current has probably strengthened gradually since then. However, hypotheses about when a current of roughly the size and strength of the modern Loop Current first developed are still debated. Understanding this timing is important because it will implicate either a climatic or nonclimatic (i.e., tectonic) driver for its onset and could therefore inform ideas about whether and how the current will respond to climate change. Whereas this region is now relatively stable tectonically, the state of climate is changing rapidly.

Building on previous seismic and coring expeditions, the U.S.-Mexico team collected high-frequency, multichannel seismic profiles, multibeam bathymetry, and surficial seafloor sediments (i.e., grab samples) in the Yucatán Channel in 2022 and 2024 (Figure 2) while aboard the UNAM vessel Justo Sierra. The primary imaging target was a series of offlapping sediment drift deposits laid down by the interaction of the Loop Current with the seafloor over millions of years.

Drift deposits are lens-shaped accumulations elongated along the axis of prominent boundary flows like the Loop Current and are promising archives for precision samplings (i.e., piston coring and drilling) and dating. Their fine-grained compositions and rich concentrations of microfossil skeletal remains of benthic (bottom-dwelling) and calcareous planktonic (floating) foraminifera provide valuable chronological markers and proxy records of ocean temperature and salinity, important for reconstructing past oceanographic and climatic conditions. Preliminary observations from samples collected confirm that these skeletal remains are diverse and excellently preserved.

The at-sea data acquisition in the Gulf led to two follow-on workshops. The first, held in Mexico City in August 2023, brought together international investigators to examine the new seismic data from the Yucatán Channel and begin to identify potential sites to propose for future drilling (Figure 2). The second, held in Austin, Texas, in September 2024, focused on integrating the paleoceanographic perspectives of the Loop Current with knowledge of its modern physical oceanography.

As illuminated during discussions at the Austin workshop, physical oceanographic measurements collected across the Yucatán Channel from 2012 to 2016 using moored instrument arrays (Figure 2) established the modern Loop Current’s temporal complexity for the first time [Candela et al., 2019]. The current varied, both spatially and in strength, across that 4-year observation period. Tides play an important role in influencing the current, with both semidiurnal and diurnal components; the strength of transport in the current varies by 5%–10%.

This work has led to a multiyear set of studies of the Yucatán Channel, coordinated by the U.S. National Academies of Sciences, Engineering, and Medicine [NASEM, 2018], to characterize further modern conditions in the Loop Current. The 2024 portion of this study, called the Mini-Adaptive Sampling Test Run (MASTR), applied enhanced observation capacities, combining near-real-time surface and subsurface data from a simultaneous deployment of instrumented gliders and drifters with background observations from Argo floats and modeling. MASTR observations confirmed the Loop Current’s short-term complexity over short timescales, and they improved the performance of numerical models, including NOAA’s Real-Time Ocean Forecast System, in representing the current’s vertical hydrographic structure [DiMarco et al., 2024] (Figure 3).

Linking the Loop’s Past to Its Present

A key overlap, as revealed by recent research [Lowery et al., 2024], between modern and ancient oceanography in this region involves the seafloor. Current strength plays a vital role in our knowledge of past and present Loop Current conditions because it moves the grains that eventually become the current’s sedimentary archive. Seafloor topography also drives turbulent mixing of seawater in the Gulf, influencing both current flow and eddy formation. It is clear that more work and collaboration are needed to link our understanding of the long-term evolution of the Yucatán Channel seafloor with the Loop Current and its history.

An important, and thus far understudied, question is how the Loop Current responded to past warm climate events, such as the Middle Miocene Climatic Optimum (~17.5–14.5 million years ago) [e.g., Steinthorsdottir et al., 2021]. Thoroughly addressing that question will require scientific ocean drilling to sample and date key buried sediment layers (i.e., seismic reflectors) in the Yucatán Channel to build a picture of Loop Current history. Planning for this work is underway, with support potentially coming from the U.S. National Science Foundation (NSF), the Scientific Ocean Drilling Coordination Office (which NSF has just established), and the current International Ocean Discovery Programme (IODP³), a partnership among Japan, Europe, and Australia and New Zealand.

Another issue on the minds of researchers studying the Loop Current is how anthropogenically driven changes in the current might negatively affect coastal resiliency and estuarine health along the entire Gulf Coast. Emerging problems include risks from sea level rise [Thirion et al., 2024] and strengthening hurricanes, both of which are directly affected by Loop Current flow.

Community organizations such as the Galveston Bay Foundation in Texas are leading efforts to adapt to changes in coastal environments brought by storms and sea level rise by, for example, building terraces and bulkheads, developing “living shorelines,” and restoring coastal prairie and by communicating with the public. As the global climate continues to warm, more effort is required to enhance coastal resilience. Scientists must partner with community organizations to build public awareness of ongoing, human-induced climate change and to train students, the future leaders in environmental mitigation efforts.

In addition to coastal ecosystems, millions of people around the Gulf region are affected by the Loop Current and its influences on weather and sea level rise. Studying these effects requires active participation and collaboration among researchers and various entities in Mexico and the United States. Indeed, the studies noted here could not have been attempted or completed without such participation—and continued collaboration is essential to continuing to collect crucial data. Unfortunately, despite ongoing efforts from all parties to involve representatives from Cuba in these initiatives, meaningful engagement has yet to be achieved.

Our long-term goal is to continue the tradition of international collaboration in the study of the Loop Current, which demands intensified, sustained scrutiny, considering the enormous stakes as human-induced climate change continues.

Acknowledgments

The August 2023 workshop was funded by the U.S. Science Support Program of the International Ocean Discovery Program. The September 2024 workshop was funded by the Jackson School of Geosciences and the Teresa Lozano Long Institute for Latin American Studies, both at the University of Texas at Austin. We also thank the officers and crew of the Justo Sierra.

References

Candela, J., et al. (2019), The flow through the Gulf of Mexico, J. Phys. Oceanogr., 49(6), 1,381–1,401, https://doi.org/10.1175/JPO-D-18-0189.1.

DiMarco, S. F., et al. (2024), Results of the Mini-Adaptive Sampling Test Run (MASTR) experiment: Autonomous vehicles, drifters, floats, ROCIS, and HF-radar, to improve Loop Current system dynamics and forecasts in the deepwater Gulf of México, paper presented at the Offshore Technology Conference, Houston, Texas, 6–9 May, https://doi.org/10.4043/35072-MS.

Liu, Y., et al. (2025), Rapid intensification of Hurricane Ian in relation to anomalously warm subsurface water on the wide continental shelf, Geophys. Res. Lett., 52(1), e2024GL113192, https://doi.org/10.1029/2024GL113192.

Lowery, C. M., et al. (2024), Seismic stratigraphy of contourite drift deposits associated with the Loop Current on the eastern Campeche Bank, Gulf of Mexico, Paleoceanogr. Paleoclimatol., 39(3), e2023PA004701, https://doi.org/10.1029/2023PA004701.

National Academies of Sciences, Engineering, and Medicine (NASEM) (2018), Understanding and Predicting the Gulf of Mexico Loop Current: Critical Gaps and Recommendations, 116 pp., Natl. Acad. Press, Washington, D.C., https://doi.org/10.17226/24823.

Piecuch, C. G., and L. M. Beal (2023), Robust weakening of the Gulf Stream during the past four decades observed in the Florida Straits, Geophys. Res. Lett., 50(18), e2023GL105170, https://doi.org/10.1029/2023GL105170.

Steinthorsdottir, M., et al. (2021), The Miocene: The future of the past, Paleoceanogr. Paleoclimatol., 36(4), e2020PA004037, https://doi.org/10.1029/2020PA004037.

Thirion, G., F. Birol, and J. Jouanno (2024), Loop Current eddies as a possible cause of the rapid sea level rise in the Gulf of Mexico, J. Geophys. Res. Oceans, 129(3), e2023JC019764, https://doi.org/10.1029/2023JC019764.

Author Information

James A. Austin Jr. (jamie@ig.utexas.edu) and Christopher Lowery, Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin; Ligia Pérez-Cruz and Jaime Urrutia-Fucugauchi, Universidad Nacional Autónoma de México, Mexico City; and Anthony H. Knap, Geochemical and Environmental Research Group, Texas A&M University, College Station

Citation: Austin, J. A., Jr., C. Lowery, L. Pérez-Cruz, J. Urrutia-Fucugauchi, and A. H. Knap (2025), Ocean current affairs in the Gulf of Mexico, Eos, 106, https://doi.org/10.1029/2025EO250190. Published on 19 May 2025.

Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

You can’t teach an old dog new tricks, but can you teach the current generation of Earth scientists about emerging artificial intelligence and machine learning (AI/ML) methods relevant to their research? From our experience helping run a program intended to do just that at the U.S. Department of Energy’s (DOE) Pacific Northwest National Laboratory (PNNL), the answer is yes.

Earth scientists, from those focused on the atmosphere or ocean to those studying the continents or deep subsurface, often work with extremely large—sometimes global—datasets, trying to find patterns among noisy real-world observations. AI/ML is well suited for such tasks.

AI/ML approaches have recently been used, for example, to replace slow, numerical representations of rainfall in a global general circulation model [Gettelman et al., 2021]. Similarly, AI/ML image detection techniques have been used with weather radar datasets to better predict short-term rainfall [Ji and Xu, 2024]. Yet relatively few domain scientists in the field have been trained in these methods, meaning unfulfilled opportunities exist to learn from the growing volumes of Earth science data available.

Several hundred data scientists work at PNNL, and for more than a decade, the lab has developed AI/ML approaches to address critical challenges in scientific discovery, energy resilience, and national security. Recent advancements in computational techniques and methodologies have sparked renewed interest in applying AI/ML across various disciplines. However, connecting the expertise of PNNL’s data scientists to Earth science research at the lab—encompassing atmospheric, hydrological, and environmental sciences—has been a challenge.

Beginning in 2022, researchers at PNNL implemented a two-step approach—a boot camp followed by a hackathon—to prepare their colleagues to incorporate AI/ML into their research effectively. Eighty percent of those who participated in both events are now using ML techniques in their research, and the experience has boosted collaboration between the lab’s data scientists and Earth scientists. The program has also led to innovative new projects, and its initial success suggests it may be a useful model for other organizations.

Boot Camp

Prior to PNNL initiating the program, many of the lab’s Earth scientists expressed interest in learning more about AI/ML and exploring its applicability for addressing a wide variety of science questions.

Atmospheric science in particular offers ideal ground for teaching and applying ML methods because these methods are conducive to tackling many common tasks in the field. For example, they can help fill patchy datasets, such as in time series of satellite imagery [Appel, 2024]; correct biases in gridded data (e.g., overestimations of solar radiation reaching Earth in reanalysis products) [Chakraborty and Lee, 2021]; merge measurements of atmospheric properties into numerical models [Krasnopolsky, 2023]; and iteratively improve models [Irrgang et al., 2021]. Furthermore, the field is ripe with the sort of very large, high-quality datasets that are necessary for applying modern ML methods.

The staff’s interest and the clear relevance of AI/ML for their work motivated development of an initial 10-week boot camp, held in fall 2022, with weekly hybrid (online and in-person) sessions attended by 30–50 people. We enlisted 10 in-house data scientists to design lessons, hands-on tutorials, and activities covering a range of AI/ML methods and tools.

The first four sessions introduced participants to the basics of ML, with each session building upon the previous one and focusing on more state-of-the-art approaches. The remaining sessions covered popular deep learning techniques such as convolutional neural networks (CNNs), generative adversarial networks, transformers, and recurrent neural networks. They also covered topics such as how to use the ML libraries Keras and PyTorch, which offer the tools to run these models and other useful resources.

To connect the lessons to the participants’ research interests, each one featured an Earth science–relevant activity, such as using maps of monthly sea surface temperature anomaly data from NOAA satellites with unsupervised learning algorithms to detect the phases of the El Niño–Southern Oscillation (i.e., El Niño and La Niña). The instructors developed and guided participants through virtual notebook environments that included fundamental information (with references) about the topic of the activity and heavily commented model code that could be run interactively. Time was also allotted for participants to better familiarize themselves with the models by running them in parallel on their own research computing environments.

As a result of the boot camp approach, participants gained understanding and appreciation of data curation for AI/ML and the full gamut of AI/ML methods they could use in their research. One remarked that they were impressed by the diversity of applications for ML and said, “I can tell if I continue to work on this skill, it will open a lot of doors and funding opportunities in the future for me.” Another commented, “By the end, I felt my programming skills had improved as well.”

Together with colleagues, one scientist at the lab who took part in the training applied knowledge and code directly from the boot camp material in research exploring stochasticity in aerosol-cloud interactions using field campaign data [Li et al., 2024].

The instructors also reported that participating in the boot camp was worthwhile for several reasons. Each of their lessons and student demonstrations were reviewed by the other instructors, which fostered connections among peers knowledgeable in ML. According to one instructor, teaching their fellow staff also “helped provide context of how valuable my expertise is here at the lab.”

In addition, creating and presenting the weekly lesson plans to an audience with limited knowledge about AI/ML offered opportunities for instructors to improve their teaching skills. Furthermore, the adaptability of the instructional materials to other domain sciences supports the materials’ value, longevity, and easy reuse in future trainings and research.

One year after the boot camp, participant responses to a questionnaire indicated that though many had gained literacy in ML, most had not taken the next step to start incorporating ML methods into their research. The results also showed that additional hands-on opportunities were necessary to bridge the gap between learning ML and putting it into practice. So we organized a second learning opportunity—this time a hackathon—focused on pairing ML experts and data scientists with domain scientists who share common research interests.

The Hackathon

Twenty-five domain and data scientists, many of whom had participated in the boot camp, took part in the 6-week hackathon, which began in January 2024. The domain scientists involved work in various areas of Earth science and as part of DOE projects such as the Atmospheric Radiation Measurement user facility and the PNNL-led Addressing Challenges in Energy: Floating Wind in a Changing Climate (a DOE Energy Earthshot research center), as well as NASA’s Aerosol Cloud Meteorology Interactions over the western Atlantic Experiment project.

In preparing for the course, we discovered that these scientists often had trouble formulating research questions suited to ML methods and selecting which ML method to use. Prehackathon brainstorming sessions proved critical to success. During the first prehackathon meeting, the organizing committee gathered participants virtually to group the domain scientists by their topics of interest—vegetation-atmosphere interactions, clouds and precipitation, aerosols and aerosol-cloud interactions, hydrology, and wind energy—and to brainstorm potential research questions to address.

Each of the five groups then pitched project ideas to the participating ML experts and data scientists, who selected which team to join. With the teams assembled, each further workshopped a research question within their topic focus area—as well as which ML methods to use—that they could address within the duration of the hackathon. For example, one team chose to use a CNN model to identify open- versus closed-cell atmospheric convection in radar data, which helps explain distributions of clouds and rainfall.

During the hackathon, all the teams met weekly to discuss progress and exchange ideas for continuing work. This assessment method allowed the domain scientists to engage further with experts in the PNNL ML community, who provided feedback and answers to follow-up questions, such as how to prepare data for use in the ML models. Data preparation proved to be the most time-consuming step for the domain scientists because of the challenges of correctly formatting time series and gridded atmospheric datasets (e.g., temperature, relative humidity, and pressure) before they were fed into the models.

At the end of the 6 weeks, four of the five project groups had successfully processed their data and run them through their models to achieve results related to their initial questions. The fifth group, upon reflection, agreed that selecting an overly broad research question hindered progress on their project. Their experience underscored the importance of clearly defining a focused research question—and an appropriate ML approach—with cross-disciplinary consultation among scientists.

Soon after the hackathon concluded, a representative from each team presented their project during a seminar. A postseminar Q&A about the projects with staff who had not participated in the hackathon was positive and engaging, indicating a base level understanding of AI/ML methods within the division that was not present before the boot camp.

Fostering an AI-Literate Workforce

With growing datasets of Earth observations and ongoing computing advancements, AI/ML is an increasingly useful tool to aid in skillfully assessing conditions and processes in the Earth system.

At PNNL, more than 20% of the research workforce is advancing AI and its applications in science. The initial goal of the recent training activities was to further grow ML expertise and implementation specifically within the lab’s Atmospheric, Climate, and Earth Sciences (ACES) division. The lessons and successes of these activities suggest that other organizations similarly seeking to expand their use of AI/ML may benefit from the model of PNNL’s approach.

The boot camp created a long-term, structured environment for a large number of staff to better understand the increasingly complex ML landscape, whereas the follow-up hackathon allowed a smaller group of eager staff to be coached in a faster-paced environment to produce deliverables. The different approaches of the boot camp and the hackathon allowed instructors to meet participants at their preferred comfort level and cater to different learning styles.

The results demonstrate that although learning new skills in AI/ML takes time, the effort is worthwhile and a collaborative, cross-disciplinary environment accelerates such learning. Staff self-reported that work done during the boot camp and hackathon had resulted in three conference presentations, including at the HydroML 2024 Symposium, and two publications (another is still in preparation).

Furthermore, PNNL reported an uptick in proposals from its Earth scientists for various internal funding opportunities focused on leveraging AI/ML methods. More proposals means more competition for funding, which should drive innovation and ultimately lead to stronger projects moving forward.

Another lesson from our experience was that sourcing instructors from within PNNL (i.e., ML experts who are already colleagues of Earth scientists in the ACES division) facilitated future collaborations between data and domain scientists and new research opportunities that wouldn’t have been possible previously. One of the participating AI/ML experts noted to us that “after the hackathon, many lab scientists reached out to me for help in implementing ML/AI algorithms into their work,” leading to multiple collaborations.

Hackathon participant Sha Feng’s comments offer additional, anecdotal evidence of the success of PNNL’s program: “Participating in the hackathon has been a transformative experience,” Feng said. “By bridging the gap between atmospheric science and data science, we have created a foundation for future projects that leverage the strengths of both fields.”

We plan to continue to bridge such gaps at PNNL—and we support other organizations doing the same—to advance applications of AI/ML to address crucial questions about our planet, from the atmosphere to the ocean to the solid Earth.

Acknowledgments

We acknowledge the instructors who took part in the boot camp and hackathon: Peishi Jiang, Tirthankar “TC” Chakraborty, Andrew Geiss, Sing-Chun “Sally” Wang, Robert Hetland, Rachel Hu and Danielle Robinson from Amazon Web Services, Erol Cromwell, Maruti Mudunuru, Robin Cosbey, Samuel Dixon, and Melissa Swift. We also acknowledge the work of colleagues who contributed to this article and supported these efforts: Sing-Chun “Sally” Wang, Court Corley, Larry Berg, Timothy Scheibe, Ian Kraucunas, and Rita Steyn.

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Ji, C., and Y. Xu (2024), trajPredRNN+: A new approach for precipitation nowcasting with weather radar echo images based on deep learning, Heliyon, 10(18), e36134, https://doi.org/10.1016/j.heliyon.2024.e36134.

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Li, X.-Y., et al. (2024), On the prediction of aerosol-cloud interactions within a data-driven framework, Geophys. Res. Lett., 51, e2024GL110757, https://doi.org/10.1029/2024GL110757.

Author Information

Lexie Goldberger, Peishi Jiang, Tirthankar “TC” Chakraborty, Andrew Geiss, and Xingyuan Chen (xingyuan.chen@pnnl.gov), Pacific Northwest National Laboratory, Richland, Wash.

Citation: Goldberger, L., P. Jiang, T. Chakraborty, A. Geiss, and X. Chen (2025), A two-step approach to training Earth scientists in AI, Eos, 106, https://doi.org/10.1029/2025EO250160. Published on 29 April 2025.

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Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Neutron stars, supernova explosions, and other extremely energetic phenomena across the universe produce gamma rays, the highest-energy radiation in the electromagnetic spectrum. Closer to home, the Sun also emits gamma rays, and here on Earth, gamma ray sources include nuclear explosions, radioactive decay of certain materials (sometimes applied for medical uses), and—as we’ve known for about 30 years—lightning.

Many details of lightning-generated gamma rays, however, including how common they are, have remained uncertain over the past few decades since they were discovered. Every day, more than 3 million lightning strikes occur in thunderstorms around the planet. How many of these lightning bolts emit gamma radiation?

Such information is important for improving our understanding of the chemistry and dynamics of thunderclouds and other features, which feeds into our ability to forecast weather, including potentially hazardous conditions, more accurately.

With recent observations and research, scientists are revealing new insights into the mysteries of Earth’s atmospheric gamma rays, including that thunderclouds act as huge particle accelerators, emitting gamma rays far more often than previously thought.

Early Observations of Terrestrial Gamma Rays

In the early 1990s, the first observations of gamma rays in thunderstorms revealed a phenomenon known as terrestrial gamma ray flashes (TGFs). The discovery, made by the Compton Gamma Ray Observatory (CGRO), a space observatory built to study gamma rays originating in space, came as a big surprise for the scientific community. The scientists involved were clearly amazed to find that such a gamma ray source existed in their own backyard, writing that “detectors aboard the CGRO have observed an unexplained terrestrial phenomenon: brief, intense flashes of gamma rays” [Fishman et al., 1994].

The find immediately set the stage for the next 3 decades of research in the field of atmospheric electricity, with researchers intensely scrutinizing terrestrial gamma rays. However, in retrospect, it is evident that for much of this time, exploration and measurements of gamma rays were hampered by the available instrumentation. The only workable detectors for gamma ray detection at the time had been developed to study processes other than TGFs. These detectors included the Burst and Transient Source Experiment (BATSE) on CGRO and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and, more recently, the Astro Rivelatore Gamma a Immagini Leggero and the Fermi Gamma-ray Burst Monitor.

BATSE, for example, was designed to study gamma ray bursts from the universe, but because it had difficulty capturing very short (~1 millisecond) TGFs, the BATSE measurements were heavily biased toward the most intense events. Meanwhile, RHESSI measurements sometimes combined detections of TGF photons from two events into one [Grefenstette et al., 2008].

A Purpose-Built Mission

A few years before the discovery of TGFs, in 1989, the first documented cases of unexpected lightning above thunderclouds were observed. Several phenomena, collectively referred to as transient luminous events (TLEs), were characterized and given mythical names like blue jets, elves, and red sprites.

Early this century, researchers began developing a plan to study these newly identified atmospheric events from the International Space Station (ISS). With scientists at the University of Valencia in Spain and the University of Bergen (UiB) in Norway, Torsten Neubert from the Technical University of Denmark initiated the Atmosphere-Space Interactions Monitor (ASIM) project. While Neubert and his team took the lead on TLE studies, Nikolai Østgaard and his group at UiB developed an instrument specifically designed for TGF studies called the Modular X- and Gamma-ray Sensor (MXGS) as part of ASIM.

In 2018, the ASIM payload was finally launched into space and mounted on the ISS’s Columbus module. From this vantage, more than 400 kilometers above the ground, ASIM would have a view from above of the drama unfolding during thunderstorms. Over the next few years, the scientists reported several groundbreaking observations.

For example, Østgaard et al. [2019] found that TGFs observed from space actually occur before or simultaneously with the optical (visible light) pulses of lightning. Østgaard et al. [2021] then found that the delay of the optical pulse in those cases was explained well by the scattering of light through clouds. This finding, that TGFs happen before the visible flashes of lightning, was crucial for establishing a theoretical framework for the sequence of events in thunderstorms. It means that electrons are accelerated to relativistic energies in electric fields associated with long conductive leaders and that the optical pulse we see from space is a signature of the leader discharge that follows.

In another study, Neubert et al. [2019] reported the first simultaneous observation of TGFs and TLEs known as elves (emissions of light and very low frequency perturbations), confirming previous theoretical predictions of their co-occurrence.

ALOFT Changes the Game

ASIM observations provided great insights into TGFs, but the question remained whether a significant population of TGFs that are too weak to observe from space existed. That question, addressed and discussed by Østgaard et al. [2012], motivated the Airborne Lightning Observatory for FEGS and TGFs (ALOFT) flight campaign, a collaboration between UiB and NASA, in summer 2023.

Building on their experience developing MXGS, the UiB scientists came up with a new instrument, called UiB-BGO, to measure gamma rays from NASA’s ER-2 aircraft. Although the detector and front-end electronics were similar to those in MXGS, the system used on ASIM to trigger gamma ray measurements was replaced with a data acquisition and storage system that enabled continuous data recording during flights.

Ten ALOFT flights were conducted, with NASA operating the ER-2 out of MacDill Air Force Base in Florida. The aircraft visited tropical thunderstorms around the Gulf of Mexico, Central America, and the Caribbean, flying just above the thunderclouds at heights of about 20 kilometers and bringing the UiB-BGO as close as possible to the spectacular events unfolding.

Real-time telemetry of gamma ray count rates allowed scientists to recognize immediately whether the plane was flying over a gamma ray–producing storm. They could then instruct the pilot to turn and scan an area again to maximize gamma ray detections. The ER-2’s instrument payload also included lightning sensors and microwave sensors, which provided data on thundercloud characteristics.

The results from ALOFT have turned out to be game-changing. Prior to the flight campaign, terrestrial gamma rays were considered rare, and only two types—microsecond bursts of TGFs and gamma ray glows that lasted minutes at a time—had been observed. That prior understanding has now been updated significantly.

Flickering Flashes and Boiling Glows

Observations of ample gamma ray events from the ALOFT campaign suggest that TGFs occur up to 100 times more frequently than previously believed [Østgaard et al., 2024; Marisaldi et al., 2024; Bjørge-Engeland et al., 2024]. It turns out that a substantial population of TGFs is, indeed, too weak to observe from space, showing that earlier detection efforts from space had just scratched the tip of the iceberg. Further, unlike previous flight campaigns that circulated around the outskirts of thunderclouds, the ALOFT ER-2 flew directly above thunderclouds, enabling it to detect the weak TGF population.

Data from ALOFT also allowed identification of a third, previously undetected terrestrial gamma ray phenomenon named flickering gamma ray flashes (FGFs), which seem to combine characteristics of both TGFs and gamma ray glows [Østgaard et al., 2024]. FGFs begin as glows before intensifying into pulsed sequences of gamma ray emissions resembling TGFs, except that the pulses last longer (~2 milliseconds) and the sequences overall last tens to hundreds of milliseconds. As with gamma glows, but unlike TGFs, initiation of FGFs is not associated with detectable optical or radio signals, including lightning discharges.

The old picture of minutes-long gamma ray glows must be revisited too. The recent observations show that thunderclouds can actually emit gamma rays for hours and that these emissions can take place over many thousands of square kilometers. They also seem to be highly dynamic in space and time, with gamma glows popping up for 1–10 seconds at a time in different locations within the most highly convective cores of a cloud system, resembling bubbles in a boiling pot [Marisaldi et al., 2024].

Reconsidering the Role of Atmospheric Gamma Rays

The groundbreaking results from the ALOFT campaign suggest a revised view of the role of gamma rays in the atmosphere and that we need to reconsider existing frameworks describing gamma ray phenomena. Thunderclouds are, indeed, huge particle accelerators, and gamma ray emissions, hardly a rarity, are an intrinsic part of highly convective systems.

Assessing the implications of this new knowledge will motivate additional questions and continued study of atmospheric electricity. It’s possible, for example, that gamma ray generation contributes importantly to lightning initiation, at least for a large fraction of lightning.

Considering that about 2,000 thunderstorms are active on the planet at any given moment and about 3 million lightning strikes occur each day globally, further discerning the effects of gamma ray production and propagation on thundercloud dynamics is a fundamental need for improving our understanding of and ability to forecast the planet’s weather and atmospheric environment.

References

Bjørge-Engeland, I., et al. (2024), Evidence of a new population of weak terrestrial gamma-ray flashes observed from aircraft altitude, Geophys. Res. Lett., 51(17), e2024GL110395, https://doi.org/10.1029/2024GL110395.

Fishman, G. J., et al. (1994), Discovery of intense gamma-ray flashes of atmospheric origin, Science, 264, 1,313–1,316, https://doi.org/10.1126/science.264.5163.1313.

Grefenstette, B. W., et al. (2008), Time evolution of terrestrial gamma ray flashes, Geophys. Res. Lett., 35(6), L06802, https://doi.org/10.1029/2007GL032922.

Marisaldi, M., et al. (2024), Highly dynamic gamma-ray emissions are common in tropical thunderclouds, Nature, 634, 57–60, https://doi.org/10.1038/s41586-024-07936-6.

Neubert, T., et al. (2019), A terrestrial gamma-ray flash and ionospheric ultraviolet emissions powered by lightning, Science, 367, 183–186, https://doi.org/10.1126/science.aax3872.

Østgaard, N., et al. (2012), The true fluence distribution of terrestrial gamma flashes at satellite altitude, J. Geophys. Res. Space Phys., 117, A03327, https://doi.org/10.1029/2011JA017365.

Østgaard, N., et al. (2019), First 10 months of TGF observations by ASIM, J. Geophys. Res. Atmos., 124(24), 14,024–14,036, https://doi.org/10.1029/2019JD031214.

Østgaard, N., et al. (2021), Simultaneous observations of EIP, TGF, Elve, and optical lightning, J. Geophys. Res. Atmos., 126(11), e2020JD033921, https://doi.org/10.1029/2020JD033921.

Østgaard, N., et al. (2024), Flickering gamma-ray flashes, the missing link between gamma glows and TGFs, Nature, 634, 53–56, https://doi.org/10.1038/s41586-024-07893-0.

Author Information

Arve Aksnes (Arve.Aksnes@vlfk.no), Nikolai Østgaard, Martino Marisaldi, and Ingrid Bjørge-Engeland, University of Bergen, Bergen, Norway

Citation: Aksnes, A., N. Østgaard, M. Marisaldi, and I. Bjørge-Engeland (2025), A new view of gamma rays from thunderclouds, Eos, 106, https://doi.org/10.1029/2025EO250156. Published on 25 April 2025.

Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Many instructors in Earth sciences and other scientific disciplines wish to engage students with the latest advances in their fields, teach cutting-edge skills, and adopt more equitable and inclusive teaching practices. The latter is an especially pressing need in the Earth sciences, which remain among the least diverse of all science, technology, engineering, and mathematics (STEM) fields [Bernard and Cooperdock, 2018].

However, achieving these goals while balancing other requirements of careers in science and science education is extraordinarily challenging. It is simply impossible to be an expert in everything. Instructional models that significantly reduce barriers to providing innovative teaching may thus be highly valuable for scientist-instructors, saving them time and increasing their effectiveness in engaging a diversity of students.

The comprehensive, evidence-based approach of Observing Earth from Above offers such a model, tailored for teaching students how to access, visualize, and communicate satellite remote sensing data focused on the environment. First piloted in 2023, we developed Observing Earth from Above to provide equitable and inclusive pedagogy and content that transforms students’ knowledge, skills, and attitudes toward science and to create an environment where all students can be successful.

We applied the principles of project-based learning (PBL), in which students engage in projects as a foundational part of the curriculum. Seven principles guide the PBL approach:

• Start with a challenging problem or question
• Be subject to sustained inquiry
• Have authenticity
• Incorporate student voice and choice
• Provide opportunity for reflection
• Include critique and revision
• Conclude with a public-facing end product

The active learning that this approach engenders lends itself to equitable and inclusive teaching practices [Theobald et al., 2020]. It also supports our goal to empower students and increase their interest in science, their science identity, and their sense of self-efficacy, which are keys to enhancing diversity in STEM [Ballen et al., 2017a].

A Range of Resources

The materials developed for Observing Earth from Above focus on NASA’s Ecosystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) mission [Fisher et al., 2020]. ECOSTRESS, launched in 2018, provides high spatial resolution observations of land surface temperatures globally, with revisit times of every 3–5 days. These land surface temperatures are then used to derive additional data products related to evapotranspiration, water use efficiency, and evaporative stress index.

At the heart of the resources provided by Observing Earth from Above is a series of follow-along tutorials in which students learn how to access ECOSTRESS data using the free NASA AppEEARS (Application for Extracting and Exploring Analysis Ready Samples) interface, visualize those data using free and open-source geographic information system (GIS) software (Figure 1), and then effectively communicate their findings. A key goal is for students to repeatedly practice accessing and visualizing data over the span of the tutorials, creating familiarity through repetition while gradually introducing new and increasingly sophisticated skills and data products. However, each tutorial is also designed to stand alone and to require only about 30 minutes to complete, which increases the flexibility of their use.

We complement the tutorials with video lectures that introduce the ECOSTRESS mission, provide comprehensive overviews of the theory and algorithms for each data product, discuss current applications of these products, and consider best practices in data visualization and science communication. The slide decks used for each lecture are available for instructors to modify and adopt as needed.

Resources also include short video interviews with individuals of diverse identities who have different careers connected to remote sensing. For example, students can learn how a college student found himself in graduate school using satellite remote sensing to detect crop disease or how an air pollution specialist uses satellite remote sensing to track air quality.

Together these resources form the basis of a course with learning outcomes aligned to core competencies, including the abilities to apply the process of science, use quantitative reasoning, understand the interdisciplinary nature of science, communicate and collaborate with others, and understand how science relates to society. In addition, we provide sample syllabi, assignments, and even grading rubrics, each of which can be particularly helpful for early-career faculty developing new classes while balancing research and service demands.

Pedagogy and Curriculum in Practice

We have now taught the Observing Earth from Above materials twice to undergraduate students at Chapman University in Orange, Calif. The course spans disciplines including environmental science, remote sensing, GIS, data science, science communication, environmental justice, and others. As such, it draws students from across majors—from philosophy and business to science and engineering—engaging them in interdisciplinary thinking grounded in science. Such an approach, connecting STEM to other disciplines, can improve students’ ability to contribute to the STEM workforce [Tytler, 2020].

During twice-weekly class sessions, students first learn about a given topic through a lecture; then they work through a tutorial on that topic. Weekly homework assignments prompt students to engage further by producing a new satellite remote sensing data visualization related to the topic.

For example, students may practice working with land surface temperature data by drawing a polygon around their hometown on a map, downloading corresponding ECOSTRESS data, and producing a visualization of the hottest or coldest local surface temperatures. This “hometown temperature competition” exercise begins to connect satellite remote sensing to issues of personal relevance, which is an important motivational factor for student learning and may provide inspiration for career paths [Priniski et al., 2018]. Having students work on a series of low-stakes assignments through the course ensures that they are making progress and that they have opportunities to demonstrate what they have learned in a way that minimizes the undue stress and anxiety that often accompany high-stakes midterm and final exams [Ballen et al., 2017b].

After learning to gather and visualize land surface temperature data, students turn their attention to producing visualizations of evapotranspiration and water use efficiency in different environments, for example, comparing a field with a neighboring forest. They ultimately tackle a final project of their choosing, often using ECOSTRESS data to characterize a recent environmental event such as a heat wave or wildfire, which offers a sense of timeliness and relevance. Final projects have ranged from a study of how cooling water from power plants affects lake surface temperatures to how dam removal affects rates of evapotranspiration on neighboring riverbanks.

One student studied the surface temperatures of the school grounds in her hometown of Brea, Calif., for her final project (Figure 2). Increasing temperatures at schools represent a growing problem that has implications for students’ physical and mental health. She and another student have since expanded this work to consider every K–12 public school across Orange County, California, and are studying how school ground temperatures correlate with neighborhood demographics. This work drew interest from city government officials, who are using the information to help decide where to prioritize limited resources for repairing and renovating school grounds.

Students have expressed excitement and a sense of accomplishment at seeing the societal impacts of their work. In addition to the interest in the school temperatures project, other student projects are now featured on NASA’s ECOSTRESS image gallery, where they contribute to the mission’s public-facing communication efforts. Following participation in the Observing Earth from Above course, some students have focused on transitioning their class projects into publishable science, helping to advance their careers and expanding the value of the ECOSTRESS mission.

Encouraging Outcomes

The 47 students in our first two cohorts reported increases in their interest in remote sensing and science, in their sense of science identity, and in their self-efficacy to participate in science (Figure 3). One possible explanation for the reported increases may be the success of project-based learning; in semistructured interviews, students repeatedly mentioned the course’s “real-world” approach (in contrast to typical problem sets and exams):

• “The projects connected classroom theories to real-world environmental issues, which made the learning process incredibly relevant and engaging.”
• “Tackling real-world problems through projects developed my ability to analyze complex datasets and think critically about potential solutions.”
• “The hands-on GIS component was unlike anything offered in my other courses, providing not just insight but real-world skills.”

More equivocal were students’ responses about their interest in pursuing a career in science, which did not change significantly after participating in the course. A possible explanation is that about half the students across the two classes were already pursuing majors outside the natural sciences and may have been envisioning careers related to those majors.

Still, the videos featuring individuals from various careers in remote sensing were well received by many of the students, according to their interview responses. We are as content with the idea that a journalism student, for example, could engage with satellite remote sensing as part of their reporting as we are with the idea of a student changing career paths because of their participation in the course. Ultimately, the course helps build marketable skills for internships and career opportunities across disciplines—indeed, some students have subsequently been accepted for internships at NASA and other institutions.

Earth Sciences for Everyone

Through word of mouth and conference presentations, we are engaging broader networks of educators and expanding the use of Observing Earth from Above’s learning materials to colleges and universities across the country. In these efforts, we are emphasizing empowering early-career instructors at institutions that predominantly serve students from identities that have historically been underrepresented in the geosciences.

The materials, revised on the basis of initial evaluations and assessments, are now being used by instructors at the University of California, Riverside; Murray State University; California State University, Northridge; Northern Arizona University; Wesleyan University; Colorado State University; New Jersey Institute of Technology; and Texas A&M Corpus Christi, many of which are minority-serving institutions.

This expansion has not been without challenges: Different schools have different academic calendars, curricular requirements, and class structures (e.g., with different meeting durations). And because adding new classes to course catalogs can be difficult and time-consuming, many instructors must blend our materials with other materials that they have to teach.

Highly modular, evidence-based materials that help address unmet needs are more flexible and likely of greater value for a broader range of educational settings than, for example, a full semester-long curriculum. Thus, we designed our lecture and tutorial content for application in 30-minute blocks to facilitate their widespread use.

Analytics data from fall 2024, the first semester that the materials were publicly available, indicate robust use. Nearly 400 users engaged with the website more than 1,500 times, and more than half of the visits were to the tutorials. Ongoing evaluation and assessment will help us understand how students with diverse identities and their instructors interact with the materials—and thus how they can be improved in the future.

Broadening diversity in the Earth sciences and expanding the relevance of the discipline in addressing environmental and societal challenges require transformative, evidence-based approaches that create equitable and inclusive opportunities for people of all identities to contribute. NASA, the U.S. Geological Survey, and other institutions have expressed strong interest in the pedagogical framework of Observing Earth from Above as one such approach and in applying it to other missions beyond ECOSTRESS. And we welcome additional interest from other programs.

We are confident that Observing Earth from Above can become a model for creating accessible educational experiences designed around Earth science missions and applications that can be used widely across classrooms to engage a new generation of students.

Acknowledgment

Observing Earth from Above was developed with support from NASA ECOSTRESS mission grant 80NSSC23K0309.

References

Ballen, C. J., et al. (2017a), Enhancing diversity in undergraduate science: Self-efficacy drives performance gains with active learning, CBE Life Sci. Educ., 16(4), ar56, https://doi.org/10.1187/cbe.16-12-0344.

Ballen, C. J., S. Salehi, and S. Cotner (2017b), Exams disadvantage women in introductory biology, PLOS One, 12(10), e0186419, https://doi.org/10.1371/journal.pone.0186419.

Bernard, R. E., and E. H. G. Cooperdock (2018), No progress on diversity in 40 years, Nat. Geosci., 11(5), 292–295, https://doi.org/10.1038/s41561-018-0116-6.

Fisher, J. B., et al. (2020), ECOSTRESS: NASA’s next generation mission to measure evapotranspiration from the International Space Station, Water Resour. Res., 56(4), e2019WR026058, https://doi.org/10.1029/2019WR026058.

Priniski, S. J., C. A. Hecht, and J. M. Harackiewicz (2018), Making learning personally meaningful: A new framework for relevance research, J. Exp. Educ., 86(1), 11–29, https://doi.org/10.1080/00220973.2017.1380589.

Theobald, E. J., et al. (2020), Active learning narrows achievement gaps for underrepresented students in undergraduate science, technology, engineering, and math, Proc. Natl. Acad. Sci. U. S. A., 117(12), 6,476–6,483, https://doi.org/10.1073/pnas.1916903117.

Tytler, R. (2020), STEM education for the twenty-first century, in Integrated Approaches to STEM Education: An International Perspective, edited by J. Anderson and Y. Li, pp. 21–43, Springer, Cham, Switzerland, https://doi.org/10.1007/978-3-030-52229-2_3.

Author Information

Gregory R. Goldsmith (goldsmit@chapman.edu), Schmid College of Science and Technology, Chapman University, Orange, Calif.; Monae Verbeke, Institute for Learning Innovation, Beaverton, Ore.; Jeremy Forsythe, Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff; and Joshua B. Fisher, Schmid College of Science and Technology, Chapman University, Orange, Calif.

Citation: Goldsmith, G. R., M. Verbeke, J. Forsythe, and J. B. Fisher (2025), A diverse new generation of scientists observes Earth from above, Eos, 106, https://doi.org/10.1029/2025EO250111. Published on 16 April 2025.

Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Cycles of ice sheet growth (glacials) and intervening warmth (interglacials) in Earth’s past—largely triggered by shifts in the amount of solar radiation (insolation) reaching the planet—have been characterized by major changes in global atmospheric carbon dioxide (CO₂) levels, sea levels, and temperatures. Around the time of the Last Glacial Maximum 20,000 years ago, for example, average global temperatures were roughly 6°C (11°F) colder, and sea levels were more than 120 meters (400 feet) lower than today, whereas ice covered about a quarter of Earth’s land surface.

Such changes have had profound effects on ecosystems, particularly coastal ecosystems, including coral reefs. And as CO₂ levels, temperatures, and sea levels rise rapidly around the world today, modern ecosystems—humans included—will likely continue to experience major impacts as well.

Yet many unknowns remain about the mechanisms that control climate transitions, particularly during past episodes of rapid warming. These unknowns raise critical questions about present and future warming as well: Are predictions of catastrophic sea level rise—up to several meters—resulting from ice sheet collapse valid? Will the behavior and effects of annual to interannual climate phenomena, such as the El Niño–Southern Oscillation and seasonal rainfall, change as the average global climate changes?

Also uncertain is how coral reefs and coasts will respond to associated environmental stresses. Coral reef systems are highly sensitive to sea level and climate, and fossil reefs preserve reliable records of past variations. Yet our understanding of these variations is severely limited because we lack continuous fossil coral records, particularly from periods of abrupt climate instability. Such records are exceptionally rare given the specific conditions required to build and preserve fossil reef sequences over extended periods and the difficulty of sampling them where they do occur.

In fall 2023, scientists and crew on the International Ocean Discovery Program’s (IODP) Expedition 389 (X389) employed an advanced, remotely operated seabed drilling system to access the interiors of submerged, or “drowned,” fossil reefs off the island of Hawai‘i for the first time (Figure 1). The reef sequences there contain globally unique records of sea level and climate change—and their impacts on reef ecosystems—over the past 500,000 years [Webster et al., 2025].

Hawai‘i’s Unique Reef Records

Hawai‘i is geologically special. Located over an active volcanic hot spot, it has been—and continues to be—built up by successive eruptions. As the underlying mantle compensates for the increasing weight of the island, the ocean crust has experienced nearly constant subsidence over the past 500,000 years. This subsidence creates space that accommodates growth and vertical expansions of reefs, which, as they accumulate and fossilize, capture conditions through glacial-interglacial intervals in great detail (Figures 1b and 2). These reefs ring the island, forming a spectacular sequence of increasingly older terraces between 100 and 1,500 meters below present sea level (Figure 1a).

The reefs have been the subject of 4 decades of data collection and study involving multiple methods of seafloor imaging (bathymetric, backscatter, and seismic) and sampling (with dredges, submersibles, and remotely operated vehicles), as well as geochronologic methods and numerical modeling [Webster et al., 2009]. These prior data underpin our knowledge of fossil reef development and motivated the scientific rationale and drilling strategy of X389.

As Hawai‘i subsides at a rate of 2.5 millimeters per year, space below the ocean surface is created for reef growth in the near term (Figure 2). But how do large and longer-term sea level changes occurring through glacial-interglacial intervals affect reefs?

Reef growth initiates during sea level highstands and continues during glaciation as sea levels slowly drop. If sea level falls quickly, outpacing the island’s subsidence rate, the living part of the reef dies as it is exposed above the waves. If, on the other hand, sea level rises too quickly and new reef growth—which requires the sunlight available near the ocean surface—fails to keep up, the reef will deepen and ultimately drown.

Rapid sea level rises linked to catastrophic ice sheet collapse and abrupt meltwater pulse events during deglaciations thus cause reef drowning [Sanborn et al., 2017]. Then, during the subsequent warm high sea level stand, a new reef is initiated upslope, and the cycle starts again.

Numerical models of reef growth and demise, forced by changes in sea level, predict that the Hawaiian terraces comprise thicker sequences of fossilized reef—100–150 meters per glacial cycle—compared with those built on stable margins such as the Great Barrier Reef. As such, the Hawaiian expanded sequences hold great promise for providing sea level and climate records of unprecedented resolution and detail.

To sample these Hawaiian reefs across a range of water depths and challenging lithologies (they commonly fragment and break), researchers required a novel drilling system—unavailable to the scientific community until recently—that could penetrate the reef interior rather than just scratch its surface.

The Core of the Matter

The X389 team found the needed technology in Benthic’s fifth-generation portable remotely operated drill (PROD5). This commercial, tethered device can be guided to and secured at seafloor targets as deep as several kilometers, where its automated capabilities allow it to collect long sample cores (up to 73 meters below the seafloor in the case of X389). A major advantage of seafloor drills over ship-based systems is that they’re stationary, which makes it easier to keep constant weight on the drill bit and improves recovery of continuous core segments.

Sailing aboard the MMA Valour, the expedition used PROD5 to obtain reef material from roughly the past 500,000 years to address four major objectives: (1) measuring the extents of past sea level variations, (2) investigating seasonal to millennial climate and oceanic change, (3) assessing coral reef ecosystem responses to abrupt sea level and climate changes, and (4) improving knowledge of the growth and subsidence of Hawai‘i over time.

Over the course of 2 months in fall 2023, we deployed the drill at 16 drowned reef sites offshore Hawai‘i, coring 35 holes at water depths ranging from 132 to 1,242 meters (Figure 1a). A total of 425 meters of core were recovered, comprising both reef (83%) and volcanic (17%) materials. Core recoveries averaged 66%, and numerous intervals of well-preserved reef samples exhibited recoveries greater than 90%, significant achievements compared with recoveries from prior expeditions. For example, core recoveries averaged 27% using a ship-based drilling system during Expedition 325 to the Great Barrier Reef in 2010 [Webster et al., 2011].

The deployments were largely successful, but the expedition was not all smooth sailing. Technical issues with the drill, including mechanical breakdowns and difficulties penetrating heterogeneous coral reef material, limited our ability to reach all target depths.

Moreover, the expedition did not adequately engage with community members about the plans and purpose of its research or about concerns it may have posed. This regrettable oversight alienated members of the local and Native Hawaiian communities, some of whom expressed frustration at not being informed or consulted prior to the Valour’s arrival offshore and voiced uncertainties over possible environmental harms.

In addition to damaging the expedition’s relationship with local communities, the lack of timely and vital engagement directly affected the science we could pursue. The concerns raised by community members contributed to the denial of a permit to drill in state waters—a decision received after X389 was already at sea—meaning that we could not sample at some young, science-critical reef sites as originally planned.

Consequently, we pivoted our approach to add more sites in federal waters where we could sample other young reef sequences and to drill transects of shorter, but high-quality, cores to capture small sea level oscillations. Since the research cruise, expedition members have sought to redouble community engagement efforts to redress the offenses and concerns caused by the expedition.

Ancient Anatomy Lessons

Analysis of the hundreds of meters of core collected during X389 will reveal, for the first time, the complex internal anatomy and composition of Hawai‘i’s extensive reef packages through the past half million years. Preliminary visual observations have already offered glimpses of exquisite new details, including drowning reef sequences formed during the terminations of glacial periods [Webster et al., 2025]. The building blocks of these drowning reefs include branching, columnar, and massive shallow corals; several types of microbialite; thick crustose coralline algae (Figure 3); lithified and unlithified sediments; and a diversity of volcanic flows and associated sediments.

Observations so far also suggest that our sampling captured distinct shallow, intermediate, and deep reef communities and depositional settings, as well as the first evidence of major lithologic boundaries indicating repeated reef initiation and demise, as predicted by models and previous seafloor observations [Webster et al., 2009] (Figure 2). Furthermore, substantial differences in sedimentary contributions to the reefs between the dry and wet sides of Hawai‘i highlight that variations in precipitation, sediments, and nutrient input might influence reef evolution (Figure 3).

Early analyses of the cores have been done using a suite of nondestructive imaging techniques (Figure 4). X-ray computed tomography is providing 3D reconstructions of massive Porites coral specimens, which often provide accurate records of past ocean conditions. In addition, traditional high-resolution line scans integrated with high-resolution hyperspectral scanning of the cores are revealing carbonate and other minerals (e.g., aragonite, calcite, clay, and iron), helping to guide sampling and more detailed analyses of the cores.

Windows into the Past and Future

The material recovered during X389 is between 10,000 and 500,000 years old and includes hundreds of well-preserved samples. These samples will be used to reconstruct the first absolute dating of sea level changes during portions of this time window. Putting absolute dates to these changes will have profound implications for testing theories about the drivers and triggers of past glacial-interglacial cycles and for validating climate and ice sheet models that are critically important for predicting sea level changes resulting from current and future global warming.

Further, the X389 cores include more than 300 Porites coral specimens with annual banding that will provide the first estimates of seasonal to millennial paleoclimate variability in the region. Geochemical analyses can be used to estimate monthly oceanographic variability with respect to temperature, precipitation, nutrient dynamics, carbon chemistry, and pH.

Assessing the nature of variability at different temporal scales will help answer critical questions. For example, were the occurrence and seasonality of extreme climate events in the past dependent on the background average climate state at times when global temperature, Pacific storm tracks positions, solar insolation, and atmospheric CO₂ levels were different? The state dependency of high-frequency temperature and hydroclimate variability is a key question today as Earth warms.

The sequences of reef lithologies recovered during X389, including volcanic flows and the diverse variety and shapes of reef-building organisms, will be interpreted to reveal a story of ecosystem response to geological processes and paleoclimatic variations in sea level and oceanographic conditions. This interpretation will inform broader understanding of the factors that control reef growth, reef health, and coastal resilience in subsiding island settings in the face of future changes in hydroclimate, ocean temperature, nutrient availability, sediment supply, and ocean pH.

The X389 science party is working together to continue studying the collected cores in greater detail to address the project’s scientific goals. And we welcome contributions from external scientists as well: Careful sampling of the cores has left much of the material intact, and as of late February 2025, anyone can request X389 samples from the IODP core repository at Texas A&M University. With concerted and collaborative efforts, we can continue the flexible and inclusive approach of IODP—even as the Sun sets over its current phase—to advance knowledge of the paleoclimate over the past 500,000 years and understanding of what conditions Earth may experience in the future.

Acknowledgments

We thank the entire IODP 389 Expedition Science Party, ECORD Science Operator (ESO) support staff, Benthic drilling team, MMA surveyors, and the captain and crew of the MMA Valour for their outstanding work on the offshore and onshore phases of the expedition. IODP Expedition 389 was supported by funding from the various national funding agencies of the participating IODP countries.

References

Elderfield, H., et al. (2012), Evolution of ocean temperature and ice volume through the mid-Pleistocene climate transition, Science, 337(6095), 704–709, https://doi.org/10.1126/science.1221294.

Lambeck, K., et al. (2014), Sea level and global ice volumes from the Last Glacial Maximum to the Holocene, Proc. Natl. Acad. Sci U. S. A., 111(43) 15,296–15,303, https://doi.org/10.1073/pnas.1411762111.

Rohling, E. J., et al. (2009), Antarctic temperature and global sea level closely coupled over the past five glacial cycles, Nat. Geosci., 2(7), 500–504, https://doi.org/10.1038/ngeo557.

Sanborn, K. L., et al. (2017), New evidence of Hawaiian coral reef drowning in response to meltwater pulse-1A, Quat. Sci. Rev., 175, 60–72, https://doi.org/10.1016/j.quascirev.2017.08.022.

Webster, J. M., et al. (2009), Coral reef evolution on rapidly subsiding margins, Global Planet. Change, 66(1–2), 129–148, https://doi.org/10.1016/j.gloplacha.2008.07.010.

Webster, J. M., et al. (2011), Great Barrier Reef environmental changes, Proc. Integrated Ocean Drill. Program, 325, https://doi.org/10.2204/iodp.proc.325.2011.

Webster, J. M., et al. (2025), Hawaiian drowned reefs, Proc. Int. Ocean Discovery Program, 389, https://doi.org/10.14379/iodp.proc.389.2025.

Author Information

Jody M. Webster (jody.webster@sydney.edu.au), School of Geosciences, Geocoastal Research Group, University of Sydney, Australia; and Christina Ravelo (acr@ucsc.edu), Ocean Sciences Department, Institute of Marine Sciences, University of California, Santa Cruz

Citation: Webster, J. M., and C. Ravelo (2025), Unlocking climate secrets of Hawai‘i’s drowned reefs, Eos, 106, https://doi.org/10.1029/2025EO250135. Published on 11 April 2025.

Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Tens or even hundreds of kilometers beneath Earth’s surface, magmas are born when water, carbon, heat, and pressure are present in the right proportions and minerals in the mantle begin to melt. This melting marks the beginning of a long journey, in which microscopic amounts of buoyant magma gradually make their way upward, migrating along crystal edges and forcing their way through fractures in the surrounding rock. As these tiny amounts of melt find each other, they merge into larger magma bodies that pry open jagged conduits through which they ascend further.

Mantle supply refers to the flux of these magmas (and to the volatile chemical species like water and carbon dioxide that they carry) from the mantle to magmatic systems that span the thickness of the crust. This supply is the essential driver of volcanism and volcanic hazards at the surface, from explosive eruptions and towering ash plumes to lava and debris flows and volcanic gas emissions.

Yet despite its fundamental importance, mantle supply is poorly understood because it is difficult to “see”—using geochemical and geophysical techniques—through shallower parts of magmatic systems to their roots in the mantle. Compounding this issue, different geoscientific disciplines determine mantle supply constraints (i.e., flow rates and volumes) by looking at processes over a wide range of temporal and spatial scales.

To better understand magma supplies deep beneath volcanoes in subduction zones and other tectonic settings, scientists must catalyze progress in research to address several grand challenges. These challenges, illuminated by 70 participating scientists during a June 2024 workshop, include improving modeling and geophysical imaging of mantle magma systems and reconciling knowledge of these systems across disciplines.

Making the needed progress will depend upon leveraging recent scientific advances in geophysics, gas geochemistry, petrology, and geodynamic modeling; developing interdisciplinary approaches to study mantle supply; and synthesizing new strategies to geophysically image magmatic systems from the mantle to the surface.

Mantle Magmatic Models

Over the past few decades, our understanding of volcanic systems has advanced in transformative ways. Scientists have adopted a new conceptual model of transcrustal magmatic systems underpinned by petrologic studies of erupted volcanic rocks. In this model, magma bodies, encased to different extents within crystal-rich mush zones, are interconnected across crustal depths [e.g., Cashman et al., 2017].

Extending this conceptual model to integrate the mantle is an important step toward addressing profound questions about the origins of and controls on magmatic systems (Figure 1). Such questions include how and why volcanoes emerge where they do and how mantle supply influences magma storage and transport in the crust and eruptions and hazards at the surface.

The lower crust is a key interface between the mantle and upper crustal portions of magmatic systems. Geochronologic studies of the ages of exhumed lower crustal magmatic rocks and petrologic studies of the compositions of crystals from primitive magmas from volcanic arc settings (e.g., the Andes, Cascades, and Central American arcs) offer the potential to elucidate how the lower crust controls magma supply to the upper crust and the initiation of eruptions. For example, diffusion timescales gleaned from primitive olivines from the Central American arc suggest rapid, subdecadal resupply of magmas from the mantle to transcrustal magmatic systems, with magmas then transiting the lower and middle crust at rates of tens of meters per day [Ruprecht and Plank, 2013].

Advances in geodynamics, which focuses on processes and properties controlling the movement of materials in Earth, are also crucial for developing robust mantle-to-surface magmatic models. Geodynamic models can break down at key interfaces between different regimes, such as the lithosphere-asthenosphere boundary and the Moho (the Mohorovičić discontinuity, which marks the boundary between Earth’s crust and mantle). Consequently, modeling the pathways followed by magma en route to the surface can be extremely challenging.

Likewise, treating aqueous fluids and magmas as generic fluids without any distinction between them, as is often done in models of fluid migration, also complicates geodynamic interpretations. In reality, aqueous fluids and magmas have distinct or hybrid properties. More accurate modeling of the complex interplay among melting, freezing (solidifying), and dissolution reactions that control fluid compositions and properties is likely critically important for tracking these fluids through mantle and crustal magmatic systems.

Imaging Beneath the Upper Crust

Geophysical techniques using gravity, seismic, and magnetotelluric data have captured increasingly complex snapshots of magmatic systems in the upper crust, for example, revealing the locations of upper crustal magma chambers (Figure 1). These methods are poised to play key roles in shedding light on the architecture and properties of deeper magmatic systems as well.

However, determining magmatic properties such as melt fraction, temperature, and porosity from geophysical images is not trivial because a given set of seismic or gravity data could result from multiple distinct combinations of values for these variables. Moreover, imaging deep portions of magmatic systems in the first place remains a pressing challenge, one that will require coordinated application of multiple methods, buttressed by modeling, field, and experimental data that will aid in the interpretation of imaging results.

A key first step is developing a geophysical model intercomparison project. In this project, conceptual models of transcrustal magmatic systems and geodynamic models of the mantle will be compared and combined to produce a more thermodynamically realistic understanding and physical models of mantle supply. Among the key properties considered in these models will be temperature, melt composition, melt fraction, and melt volatile content.

These synthetic mantle magmatic models will be used to investigate applications of different combinations of geophysical techniques—and different arrays of deployed instrumentation—to assess questions that can and cannot be addressed. The results of this intercomparison project will then guide the design of future geophysical deployments in the field, including those of the Subduction Zones in Four Dimensions (SZ4D) effort, a large-scale research community initiative to explore processes underlying subduction zone hazards.

Even within the relatively well studied upper crust, major questions about magma systems remain. For example, how quickly do magma reservoirs from the Moho to the upper crust change, and how quickly does magma move through them? The emerging use of time-lapse geophysical imaging that can capture changes in magmatic systems on human timescales offers especially exciting prospects for answering these questions.

Reconciling Mantle Supply Constraints

Accurately quantifying mantle supply from a single method is difficult, but comparing and reconciling magma supply constraints obtained from different methods are perhaps even more so. This difficulty arises because different methods suggest estimates of mantle supply over a wide range of temporal and spatial scales (Figure 2). Further, different disciplines constrain supply rates at different depths in different magmatic systems using different measurement units. For example, cubic kilometers per year is used for hot spot settings, individual plutons, and global estimates, whereas cubic kilometers per kilometer (of trench or ridge) per million years is commonly used to express supply per kilometer of trench in subduction zones or per kilometer of ridge at divergent boundaries.

Understanding the ratio of intrusive to extrusive rock in magmatic systems, which reflects the proportion of igneous rocks that have solidified in the crust (intrusive) to the proportion that erupted at the surface (extrusive), is especially important for reconciling different magma supply constraints because the eruptive flux likely represents only a fraction of the total magma supply.

Estimates of this ratio in volcanic arc settings vary widely, from <1:1 to 35:1 [White et al., 2006], but it is not clear whether this range is due to true natural variability or to differences in the approaches and data used to quantify the ratio. Eruption histories are sometimes used, for instance, but they record only magmas that reach the surface, whereas records of volcanic sulfur emissions also track shallow intrusive magmas that do not reach the surface (but still emit gas to the atmosphere) and records of noble gas emissions (e.g., helium) help constrain mantle-to-crust magma fluxes. At larger scales, geophysical estimates of net crustal growth relate to magma supply and inform intrusive-to-extrusive ratios, although processes that remove crust, such as delamination at the base of the crust and erosion, must also be accounted for.

Agreeing on consistent and robust magma supply constraints across scales will require interdisciplinary collaboration between gas geochemists, field geologists, geodynamicists, geochemists, geochronologists, and others. A sensible first step is to establish common units for these constraints. Ultimately, coordinating efforts to estimate mantle supply—and to develop novel indirect approaches that inform these estimates, such as tracking noble gas emissions or surface erosion rates—promises to bridge the gap between our understanding of deep magmatic processes and volcanic eruptions.

Building on Lessons Learned

The SZ4D initiative aims to compare subduction zone processes across the Cascades, Aleutian, and Chilean volcanic arcs. Understanding mantle supply, which links subducting tectonic plates with surface volcanism, is central to answering the scientific questions driving SZ4D’s investigation of subduction zone volcanic hazards (see the SZ4D Implementation Plan).

The well-studied Cascades arc has provided an excellent natural laboratory for examining connections between crustal structure and mantle-derived magma supply, and at the 2024 workshop, participants evaluated past and ongoing research across the Cascades arc as a template for coordinated research efforts elsewhere. For example, heat flow observations help constrain magmatic fluxes in the Cascades [e.g., Till et al., 2019], but this type of data is not available for all arcs.

Systematically tracking heat flow elsewhere (e.g., the Andes) could enable comparisons of magma supply among arcs globally, especially when this information is combined with other data, such as chemical measurements of gas emissions. Furthermore, new geophysical techniques pioneered in the Cascades, such as scattering of seismic waves by magma bodies, demonstrate the potential to image upper crustal magma reservoirs using only sparse instrumental arrays. These advances raise the exciting possibility of improved capabilities for comparing observations from many magmatic systems across different arc segments.

Work on the Cascades arc also highlights the challenges of studying mantle supply. For example, sulfur emissions from Cascades volcanoes are undetectable, precluding comparison to other arcs for which robust sulfur measurements are available. Consequently, using multiple overlapping methodologies at different arcs will be essential for scaling our understanding of magma supply from local to regional and global scales.

The key message that emerged from the workshop is that progress in understanding mantle supply across scales is needed to yield new insights into the life cycles and behaviors of magmatic systems. On long timescales of millions of years, mantle supply builds arcs and continental crust. On shorter timescales, mantle supply governs the tempo and style of volcanic eruptions and the hazards they cause at the surface. Yet many facets of how these processes play out remain mysterious.

Recent technological advances and new opportunities for interdisciplinary collaboration among geophysicists, geochemists, and geodynamicists promise to improve the accuracy of magma supply estimates and elucidate the deep-seated controls on Earth’s prolific volcanism.

Acknowledgments

The 3-day Workshop on Mantle Magma Supply and Imaging Magmatic Systems, held in June 2024 at the Lamont-Doherty Earth Observatory of Columbia University in New York, was sponsored by the National Science Foundation (NSF) and cosponsored by the SZ4D initiative. We thank Terry Plank for invaluable insights and logistical support, and we appreciate conversations with all the workshop participants. Support was provided by NSF grant EAR 2404913.

References

Cashman, K. V., R. S. J. Sparks, and J. D. Blundy (2017), Vertically extensive and unstable magmatic systems: A unified view of igneous processes, Science, 355, eaag3055, https://doi.org/10.1126/science.aag3055.

Ruprecht, P., and T. Plank (2013), Feeding andesitic eruptions with a high-speed connection from the mantle, Nature, 500, 68–72, https://doi.org/10.1038/nature12342.

Till, C. B., et al. (2019), The causes of spatiotemporal variations in erupted fluxes and compositions along a volcanic arc, Nat. Commun., 10(1), 1350, https://doi.org/10.1038/s41467-019-09113-0.

Ulberg, C. W., et al. (2020), Local source Vp and Vs tomography in the Mount St. Helens region with the iMUSH broadband array, Geochem. Geophys. Geosyst., 21(3), e2019GC008888, https://doi.org/10.1029/2019GC008888.

White, S. M., J. A. Crisp, and F. J. Spera (2006), Long‐term volumetric eruption rates and magma budgets, Geochem. Geophys. Geosyst., 7(3), Q03010, https://doi.org/10.1029/2005GC001002.

Author Information

Ben Black (bblack@eps.rutgers.edu), Department of Earth and Planetary Sciences, Rutgers University, Piscataway, N.J.; Samer Naif, School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta; Forrest Horton, Woods Hole Oceanographic Institution, Woods Hole, Mass.; and Andrea Goltz and Cian Wilson, Carnegie Institution for Science, Washington, D.C.

Citation: Black, B., S. Naif, F. Horton, A. Goltz, and C. Wilson (2025), The deep frontier of mantle magma supply, Eos, 106, https://doi.org/10.1029/2025EO250114. Published on 25 March 2025.

Text © 2025. The authors. CC BY 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

The volumes and varieties of data coming from all types of scientific instrumentation around the globe and beyond are rapidly growing. Appropriate curation and management of these data enable scientists to share and access them efficiently and to reuse and capitalize on them effectively.

Many scientists intuit that research data management (RDM) done well does not mean using dusty USB drives or aging laptops for storage. Yet the path to strong data management is not always clear. How is RDM done? Who does it? Bolstering cyberinfrastructure and human capacity to ensure that the data being collected are reusable by both humans and machines can help advance science.

Skills for RDM, which involves organizing, documenting, analyzing, preserving, and publishing data, are increasingly important for scientists today. These skills allow scientists to keep up with trends in data acquisition and complexity, as well as the opportunities and efficiencies afforded by advanced computing power and global information exchange.

Effective RDM underpins interdisciplinary scientific research by providing mechanisms for consistent sharing and translation of information across fields. For example, the 10-year, $500-million Gulf of Mexico Research Initiative investigated impacts of oil, dispersed oil, and dispersants on Gulf ecosystems following the Deepwater Horizon oil spill in 2010. Effective data management planning and use of established metadata standards resulted in successful stewardship of more than 3,000 datasets, representing more than 150 terabytes of data generated by more than 3,000 people. The resulting 1,700 scientific publications crossed multiple disciplines, including biology, oceanography, engineering, socioeconomics, and human health.

Powerful examples like this help explain why strategies for data management and sharing are increasingly required in scientific grant applications. For example, the U.S. National Institutes of Health and the National Science Foundation, among many other federal agencies, require applicants to include a data management plan in their proposals that lays out how data will be stored, curated, maintained, and shared. These requirements, developed partially in response to shifting public sentiment, as well as guidance to U.S. agencies from the White House Office of Science and Technology Policy, have trickled down to the wider scientific community.

Despite such requirements, instruction on RDM has not been integrated widely into curricula, and science students are rarely taught data management as part of their formal education [Strasser and Hampton, 2012; Aikat et al., 2017; Demchenko and Stoy, 2021]. As a result, students may enter the professional world ill-equipped to handle the data management requirements of contemporary science.

Students have reported frustration at this lack of instruction, and at times they have taken it upon themselves to learn data management skills and share knowledge with peers [Roberts-Pierel et al., 2021]. This individual approach is one option, but community-wide and systemic solutions may be a more efficient way to build a scientific workforce well-versed in RDM.

Many scientists worldwide have expressed increasing urgency to address a looming RDM skills gap in the geosciences workforce specifically, including community members in the Earth Science Information Partners (ESIP), an organization of data professionals and data scientists from government agencies, academia, and industry [Schuster et al., 2019; Donaldson and Koepke, 2022].

To respond to these concerns and plant seeds for action, we hosted a session at the ESIP Meeting July 2023 that drew dozens of participants from this community. The session engaged attendees in developing potential actions for individuals and programs to take to help close the gap in data management education at undergraduate and graduate levels.

Finding Fertile Ground

The ESIP community has been working for years to improve access to data management training for early-career researchers [Hoebelheinrich and Hou, 2016]. ESIP maintains a Data Management Training Clearinghouse that supports openly available training materials and multiple modes of delivering these trainings. Further, many of the data professionals involved work at research data repositories or institutional data archives and have firsthand experience building bridges and interfaces between researchers and such organizations [Bishop et al., 2021, 2023]. We ourselves have experience helping scientists contribute data to the Global Biodiversity Information Facility, the Ocean Biodiversity Information System, the CLIVAR and Carbon Hydrographic Data Office, and other repositories.

Outside ESIP, projects like the UNESCO Intergovernmental Oceanographic Commission’s OceanTeacher Global Academy (OTGA) are working toward similar objectives within the framework of the United Nations’ Sustainable Development Goals (SDG). OTGA offers courses covering various facets of RDM in support of SDG target 14.A, which aims to “develop research capacity.” However, the efforts and advances of ESIP and other groups appear not to have reached teaching paradigms in the broader academic communities of domain sciences.

As we have shared our experiences and ideas about integrating RDM further into higher science education with colleagues, our discussion seems to resonate with individuals serving in a wide range of roles in the Earth science and life science communities—from field, bench, and dry lab science to scientific society leadership. This resonance, which motivated our ESIP meeting session, highlights a need in the scientific community to advance such integration by acting across the spectrum from individuals to institutions.

From Seeds to Saplings

The session began with opening provocations from several speakers that provided a wide range of examples of formal and informal opportunities to learn about RDM and that primed participants to think about the topic from various perspectives (e.g., the data manager, the teacher, small versus large institutions).

Participant breakout groups then discussed the question, “If there were no resource limits or other restrictions, what concrete actions would you take to ensure undergraduate and graduate students graduated with the necessary data management skills?” Each group then submitted its top actions to a collaborative document, and we ranked the results as a full group.

The top five potential actions identified by the workshop participants—in descending order starting with the most popular—included the following (Figure 1):

• Integrate data skills across the curriculum: This recommendation likely offers the most comprehensive approach to building skills as students complete courses toward a degree.
• Incorporate data management into 101 courses: Teaching data management in introductory level undergraduate courses could help to ensure broad exposure. A suggestion was to include lessons on foundational data science skills such as those vetted by The Carpentries.
• Include data management plans as part of class projects focused on writing proposals: Graduate students are often first exposed to writing proposals as part of their coursework. Including a data management plan as a project requirement could offer students preparation for future grant proposals to the many agencies and foundations that now require such plans.
• Incorporate a data management lecture by a data professional into a core science course required for the degree.
• Establish workshops for incoming students to work through data management topics: Offering a data skills workshop as part of orientation programming, especially to introduce incoming graduate students to their institution’s data library and computing infrastructure, could help connect students early on to resources helpful in their new research.

Some of these actions may be straightforward for individuals to implement in their own courses with local coordination, whereas others are broader and may require coordination at the degree or program level. Moreover, some of these recommendations overlap, and pursuing any combination of them, or any of them individually, could support early-career scientists.

Other actions proposed by participants mapped to the top five. For example, a suggestion related to integrating data skills across curricula was to create sequential learning experiences in which students encounter data skills instruction in a series of courses that progress from general to more disciplinary. Related to including a data management lecture in a core science course was an appeal for data professionals to volunteer themselves as guest lecturers in courses where the professor may not be savvy about data management.

Spurring Growth from the Bottom Up and Top Down

Scientists have long pondered whether the computing efficiencies predicted by Moore’s law will result in proportional advances in science by allowing them to leverage computing power to synthesize and analyze massive amounts of data quickly [Wooley and Lin, 2005]. Implicit in this vision of accelerating scientific advances is the assumption that scientists have the skills necessary to collect, organize, and publish standardized, well-documented data as part of their normal workflows. Some experts have candidly critiqued how far we are from fulfilling this assumption, citing an absence of data management training as one reason we are “drowning in data” [MacFadyen et al., 2022].

Brainstorming actionable ideas for change—as our session participants did—is a step in support of data management training, but constraints and obstacles to implementing these ideas exist. Perhaps foremost is the systemic undervaluing of data management as an essential skill of modern scientists [Tenopir et al., 2020]. In addition, instructors and programs constrained by time and resources may have limited capacity to implement changes, especially when balancing these changes with competing instructional demands.

Integrating RDM training into existing courses and curricula thus presents a challenge, although techniques like using real data to teach concepts can help accomplish it [Bristol and Pfeiffer-Herbert, 2024]. Resistance to the changing expectations for how data are managed and shared is another potential obstacle. These challenges are significant but surmountable with solid guidance and effort.

Strengthening connections between data support disciplines and domain science fields such as the Earth sciences can help to ensure that competency with data management is a standard part of earning a science degree, and it can help to support continued competency. A one-size-fits-all solution for making these connections does not exist. However, the diverse professional roles that scientists fill allow ample opportunities to support, build, and participate in systems that involve such connections, and individuals can consider how best to fill knowledge gaps they encounter (Figure 2).

Knowledgeable professionals across domains can teach RDM skills within their own institutions, for example, through a growing number of cross-departmental data science programs. They can also participate in informal or formal offerings through cross-institutional programs such as iSchools, an academic consortium focused on promoting information science, to help teach broader groups of untrained scientists the basics of RDM. Beneficiaries of data-focused training can further participate in teaching peers and students through informal education initiatives like The Carpentries.

Data professionals working outside domain sciences often have little agency to effect change in the curricula and programs used for training and credentialing professional scientists. Like-minded partners within these science programs can help to support efforts toward meaningful change. The recommendations from the 2023 ESIP meeting session can help guide these efforts.

Support from organizations like ESIP and AGU may also influence education across a broader, top-down scale. These organizations and other scientific societies can be guiding lights for educational institutions—by, for example, recommending that scientists document and demonstrate FAIR (findable, accessible, interoperable, and reusable) practices and mature data management skills in publications and presentations—and can serve as counterpoints to those working from the bottom up.

A goal is that with both bottom-up and top-down efforts by individuals and institutions, the time will come when the requisite knowledge and tools for responsible RDM are part of the fundamental skill set of modern scientists. As this future approaches, members of the scientific community can join these efforts and explore ways to increase data management literacy in the spaces where they work.

Acknowledgments

We thank speaker Michael Gravina and the more than 40 participants at our working session at the ESIP Meeting July 2023, including Mathew Biddle, Natalie H. Raia, and Robert R. Downs, who provided additional comments for this article. The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the U.S. Fish and Wildlife Service. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. government.

References

Aikat, J., et al. (2017), Scientific training in the era of big data: A new pedagogy for graduate education, Big Data, 5, 12–18, https://doi.org/10.1089/big.2016.0014.

Bishop, B. W., A. M. Orehek, and H. R. Collier (2021), Job analyses of Earth science data librarians and data managers, Bull. Am. Meteorol. Soc., 102, E1,384–E1,393, https://doi.org/10.1175/bams-d-20-0163.1.

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Demchenko, Y., and L. Stoy (2021), Research data management and data stewardship competences in university curriculum, in 2021 IEEE Global Engineering Education Conference (EDUCON), pp. 1,717–1,726, Inst. of Electr. and Electron. Eng., Piscataway, N.J., https://doi.org/10.1109/educon46332.2021.9453956.

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Author Information

Abigail Benson, U.S. Fish and Wildlife Service, Palm Springs, Calif.; Stace E. Beaulieu, Woods Hole Oceanographic Institution, Woods Hole, Mass.; Bradley Wade Bishop, University of Tennessee, Knoxville; Stephen C. Diggs, University of California Office of the President, Oakland; and Stephen Formel (sformel@usgs.gov), U.S. Geological Survey, Lakewood, Colo.

Citation: Benson, A., S. E. Beaulieu, B. W. Bishop, S. C. Diggs, and S. Formel (2025), Planting seeds for thriving data management, Eos, 106, https://doi.org/10.1029/2025EO250109. Published on 24 March 2025.

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On 19–20 June 2024, less than 2 days after the Salt and South Fork Fires ignited near Ruidoso, N.M., monsoon thunderstorms triggered flash flooding across the same area. The rainfall helped to extinguish the fires, which together burned roughly 100 square kilometers and displaced thousands of residents, but it also caused the first of 10 postfire flooding and debris flow events that plagued Ruidoso over the following months. These events led to travel disruptions; numerous swift water rescues; and damage to homes, buildings, roads, bridges, and vehicles.

In similar fashion, on 12 August 2024, less than a month after the Easy Fire ignited in Washington’s Northern Cascades, a thunderstorm triggered a debris flow that blocked a highway and impeded firefighting operations.

When a wildfire ignites, the focus of response efforts is often on immediate effects from fire, including destruction of homes and property, smoke pollution, loss of ecosystems and habitats, and releases of toxins into the environment. Yet incidents of compounded hazards caused by postfire precipitation are becoming increasingly common across western North America—and around the world—leaving communities recently affected by wildfire racing to prepare for flood and debris flow impacts before the next rainstorm. Fire-enhanced runoff and erosion can lead to hazards ranging from flooding to rockfalls; however, fast-moving postfire debris flows (PFDFs) are particularly hazardous to life, property, and infrastructure [Lancaster et al., 2021].

Debris flows are mixtures of water, mud, boulders, wood, and other debris that can exceed velocities of 10 meters per second—similar to the speeds of the fastest human sprinters—and exert substantial forces on anything in their path. Apart from their obvious threats to public safety, they can also, for example, bury roads under meters of debris and push thousands of cubic meters of sediment into rivers, negatively affecting water quality, aquatic habitats, and flow capacities. Heightened potential for PFDFs begins immediately after a wildfire starts and can persist for several years [McGuire et al., 2024].

During the past 2 decades, areas at risk from PFDFs have increased as wildfires have become larger, more severe, and more frequent worldwide because of climate warming [Oakley, 2021] and as homes, businesses, and infrastructure have expanded into the wildland-urban interface. With this risk growing, a better understanding of PFDFs is becoming more critical.

Defining pressing research questions about processes driving PFDFs and about their effects on the built environment will help researchers develop and improve operationally useful metrics, such as rainfall thresholds. A rainfall threshold offers a critical characterization of rainfall intensity that, when exceeded, indicates a high likelihood of debris flow. These metrics and similar tools and resources support decisionmakers who issue public warnings about postfire hazards and who coordinate emergency and mitigation efforts with limited resources.

In May 2024, a group of 91 government, academic, and practitioner scientists and engineers gathered to address PFDF needs at the Establishing Directions in Postfire Debris Flow Science Conference. By identifying major research and operation hurdles and prioritizing research objectives to address those hurdles, participants identified critical future directions for PFDF science.

Altered Landscapes, Heightened Hazards

Wildfire alters landscapes in ways that substantially increase the likelihood of debris flows above background rates, creating an acute hazard in areas where these flows are otherwise infrequent. Fire consumes vegetation and ground cover and decreases soil infiltration capacity [Ebel and Martin, 2017], making soil more susceptible to erosion and increasing runoff during storms [Cannon, 2001]. High-intensity rainfall is particularly effective at generating the magnitude of runoff needed to kick-start debris flows [Kean et al., 2011]. Such rainfall can result from thunderstorms or convection embedded in midlatitude weather systems [e.g., Oakley et al., 2017].

In burned areas, runoff-generated PFDFs initiate when sediment is rapidly eroded by water flowing down steep hillslopes and channels [Rengers et al., 2021] (Figure 1, left). In contrast, in unburned areas or on slopes several years or more after fire, shallow landslides are the primary drivers of debris flows. Shallow landslides initiate when water saturates soil and sufficiently decreases the frictional forces holding it in place on a hillslope. Whereas debris flows mobilized by saturation-induced shallow landslides leave telltale scarps at their initiation locations (Figure 1, right), runoff-generated debris flows, which are made up of sediment eroded from across the landscape, rarely have a single initiation point [Kean et al., 2013] (Figure 1, left).

Different Regions, Different Triggers

The May 2024 gathering of postfire debris flow scientists, engineers, and practitioners was motivated by increased PFDF activity in recent decades in western North America. However, observations of PFDFs have been documented since the early 20th century, with some of the earliest—from Southern California—published 90 years ago [e.g., Eaton, 1936]. Starting a few decades ago, PFDF research accelerated, and the science has evolved rapidly to encompass many fields (Figure 2).

Much progress has been made in this research. For example, we have learned that PFDFs are commonly initiated by runoff from short bursts of high-intensity rainfall over steep, burned slopes. These results have allowed researchers to develop observation-based, or empirical, models to help identify hazard areas. In the western United States, for example, empirical models are used to predict PFDF likelihood and volume using terrain attributes, soil erosivity, soil burn severity, and rainfall intensity [e.g., Gartner et al., 2014; Staley et al., 2017]. Similar models have been developed for other fire-prone regions around the world, such as southeastern Australia [e.g., Nyman et al., 2015].

Although recent research has produced many insights into the mechanisms that influence the likelihood and magnitude of PFDF hazards, fundamental questions remain unanswered, further motivating the May 2024 conference. One question identified during the conference, for example, was how PFDF initiation mechanisms change across (and depend on) climatic, biotic, and geologic settings.

In recent years, drought has brought unusually large, high-severity wildfires to forested areas of western Canada and the U.S. Pacific Northwest. Growing evidence indicates that contrary to burn areas in semiarid regions, runoff from high-intensity rainfall may not be the main driver of PFDFs in that region. Rather, PFDFs may more commonly initiate from shallow landslides and gravity-driven failures of channel material resulting from long-duration rainfall or rain-on-snow and snowmelt events that saturate the soil.

Fire activity is also increasing in some of the drier regions of North America, with implications for PFDFs. In the Sonoran Desert, where invasive grasses have helped feed recent large wildfires, runoff from high-intensity rainfall is the main driver of PFDFs, although rainfall thresholds for debris flow initiation are greater relative to those of nearby forest and chaparral ecosystems.

Priorities for Postfire Debris Flow Science

Participants at the May 2024 meeting discussed the state of PFDF science and research. The group identified and voted on 10 priorities for advancing the field (Figure 3), then further discussed tangible products and activities to advance the top three of those.

The first of these consensus priorities is more research into how and why different processes drive PFDFs in different geographic and climatic regions. Identifying and understanding these different regional drivers are critical for developing generalizable models of PFDF hazards—or a suite of regionally appropriate models—as well as rainfall thresholds and related operational products such as models for rapidly assessing debris flow volume and runout. These products can, in turn, help guide efforts to raise PFDF hazard awareness, design effective mitigation strategies, and improve early-warning systems.

In situ monitoring of debris flows across a range of geographic and climatic regions, including areas where fire is emerging as a catalyst for debris flow activity, could help meet this research need. In the United States, the group consensus around this idea is supported by the National Landslide Preparedness Act, which was passed in 2021 and calls for an expansion of early-warning systems for PFDFs.

The second priority is to establish a centralized data hub to support research into PFDF processes and hazards. Currently, PFDF data are collected by individual agencies and research groups with their own protocols and stored in a variety of formats that may not be easily shared. Adopting standardized data collection procedures and formats in a centralized hub would provide reliable, consistent, and accessible data useful for gaining new insights and for developing and testing models, which could accelerate research across the range of priorities identified (Figure 3).

Next steps toward developing this data hub include creating a task force to work with potential contributors to establish protocols and to identify funding sources and potential hosts for the hub. Similar active data hubs that may serve as models include the National Centers for Environmental Information for global climate, terrestrial, and natural hazards data and EarthScope for seismic data.

Recognizing that the geographic areas subject to PFDF hazards are expanding, the third priority identified is improved communication, outreach, and education about these hazards by scientists. Such efforts can provide actionable information to decisionmakers and emergency managers regarding the triggers, potential effects, and mitigation strategies of PFDFs and will require relationship building by PFDF scientists to facilitate the two-way knowledge transfer. These efforts can also involve translating research findings into operational guidelines and products, providing plain language information to assist communities in hazard areas, and explaining the implications of research results for policy development and land management.

Collaboration Through Community Building

It will take a community of scientists, emergency management experts, policymakers, and community leaders to understand, address, and ensure safety from the expanding hazard of PFDFs across varying climatic, geographic, and ecological regions. Boundary organizations are well suited for bringing such groups together to establish a common understanding of complex issues and consensus around goals.

Boundary organizations such as the Joint Fire Science Program Fire Science Exchange Network (FSEN) help foster knowledge exchange and implementation of fire science information across agencies and disciplines. The California Fire Science Consortium (CFSC), one of 15 regional FSENs, facilitated the May conference, which laid the foundation for future collaborations, including the new Interagency Post-fire Integration Council.

Through its discussions, this group highlighted the highest-priority needs for PFDF science and established directions for ongoing research. By focusing on improving our understanding of regional PFDF drivers, creating a centralized data hub, fostering accessible and actionable science communication, and other identified priorities, we can reduce risks from PFDFs to communities in the Desert Southwest, the Pacific Northwest, and elsewhere around the world.

Acknowledgments

The authors gratefully acknowledge the U.S. Geological Survey for funding the conference described above, CFSC for its support in planning and running the conference, and the conference attendees for their participation. The authors also gratefully acknowledge fellow conference coconveners: Katanja Waldner of CFSC, Derek Cheung of the California Geological Survey, and Emily Wells of the Cooperative Institute for Research in the Atmosphere at Colorado State University and NOAA Global Systems Laboratory. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. government.

References

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Eaton, E. C. (1936), Flood and erosion control problems and their solution, Trans. Am. Soc. Civ. Eng., 101(1), 1,302–1,330, https://doi.org/10.1061/TACEAT.0004726.

Ebel, B. A., and D. A. Martin (2017), Meta-analysis of field-saturated hydraulic conductivity recovery following wildland fire: Applications for hydrologic model parameterization and resilience assessment, Hydrol. Processes, 31(21), 3,682–3,696, https://doi.org/10.1002/hyp.11288.

Gartner, J. E., S. H. Cannon, and P. M. Santi (2014), Empirical models for predicting volumes of sediment deposited by debris flows and sediment-laden floods in the transverse ranges of Southern California, Eng. Geol., 176, 45–56, https://doi.org/10.1016/j.enggeo.2014.04.008.

Kean, J. W., D. M. Staley, and S. H. Cannon (2011), In situ measurements of post-fire debris flows in Southern California: Comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions, J. Geophys. Res. Earth Surf., 116(F4), F04019, https://doi.org/10.1029/2011JF002005.

Kean, J. W., et al. (2013), Runoff-generated debris flows: Observations and modeling of surge initiation, magnitude, and frequency, J. Geophys. Res. Earth Surf., 118(4), 2,190–2,207, https://doi.org/10.1002/jgrf.20148.

Lancaster, J. T., et al. (2021), Observations and analyses of the 9 January 2018 debris-flow disaster, Santa Barbara County, California, Environ. Eng. Geosci., 27(1), 3–27, https://doi.org/10.2113/EEG-D-20-00015.

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Oakley, N. S. (2021), A warming climate adds complexity to post-fire hydrologic hazard planning, Earth’s Future, 9(7), e2021EF002149, https://doi.org/10.1029/2021EF002149.

Oakley, N. S., et al. (2017), Synoptic conditions associated with cool season post-fire debris flows in the Transverse Ranges of Southern California, Nat. Hazards, 88, 327–354, https://doi.org/10.1007/s11069-017-2867-6.

Rengers, F. K., et al. (2021), Movement of sediment through a burned landscape: Sediment volume observations and model comparisons in the San Gabriel Mountains, California, USA, J. Geophys. Res. Earth Surf., 126(7), e2020JF006053, https://doi.org/10.1029/2020JF006053.

Staley, D. M., et al. (2017), Prediction of spatially explicit rainfall intensity–duration thresholds for post-fire debris-flow generation in the western United States, Geomorphology, 278, 149–162, https://doi.org/10.1016/j.geomorph.2016.10.019.

Author Information

Ann M. Youberg (ayouberg@arizona.edu), Arizona Geological Survey, University of Arizona, Tucson; Luke A. McGuire, Department of Geosciences, University of Arizona, Tucson; Nina Oakley, California Geological Survey, Sacramento; Francis K. Rengers, Geologic Hazards Center, U.S. Geological Survey, Golden, Colo.; and Autym Shafer, California Fire Science Consortium, Berkeley

Citation: Youberg, A. M., L. A. McGuire, N. Oakley, F. K. Rengers, and A. Shafer (2025), Confronting debris flow hazards after wildfire, Eos, 106, https://doi.org/10.1029/2025EO250069. Published on 19 February 2025.

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Plant life plays crucial roles in absorbing carbon and supporting biodiversity. Yet plants in ecosystems worldwide are under increasing stress from their changing environments. Recent research suggests some may be approaching dangerous temperature thresholds.

A groundbreaking 2022 study, for example, revealed that forest canopies are often significantly warmer than the surrounding air, indicating that many forests are approaching temperatures at which photosynthesis may slow—reducing their ability to take up carbon. Even more concerning, a study in 2023 found that a small, but increasing, percentage of tropical forests has already surpassed these critical temperatures, threatening their health and resilience.

These findings were made possible because of the unique capabilities of thermal infrared (TIR) remote sensing, both from space and near Earth’s surface. This technology is unlocking new ways to study ecosystems, from individual leaves to entire landscapes. By passively measuring longwave (infrared) radiation that surfaces emit and reflect, TIR sensing provides data that can be used to estimate surface temperatures and infer surface-atmosphere energy exchanges (e.g., evapotranspiration). When paired with eddy covariance measurements—which track the flows of carbon, water, and energy between ecosystems and the atmosphere—near-surface TIR data offer deep insights into how these flows interact.

A Need for Consistency

Near-surface TIR remote sensing involves using in situ thermal sensors and cameras mounted on towers or platforms. The technique’s biggest strength is its ability to provide temporally and spatially high-resolution measurements at leaf, crown, and canopy scales. This ability bridges the gap between traditional ground-based tools, like thermocouples and infrared thermometers, and coarse-resolution satellite observations.

Despite TIR’s potential, concerns over its accuracy and reliability and the lack of standardized protocols for field deployment and data processing have slowed its integration by environmental researchers. These were major topics of discussion at the 2023 Linking Optical and Energy Fluxes Workshop, where it became evident that consistent approaches are crucial for integrating different near-surface remote sensing techniques. Such consistency enhances the ability to combine data from various sources and improves the reliability of ecosystem assessments, which is particularly important when evaluating climate change impacts.

To follow up on the discussion from the 2023 meeting, 40 scientists from more than 10 countries convened at the Great Thermal Bake-off in August 2024. This workshop aimed to enhance cross-disciplinary participation and work toward tackling challenges of standardization and accessibility of near-surface TIR methods and technology in ecological research.

The event fostered a collaborative environment among a diverse group of ecosystem ecologists, climate scientists, and remote sensing experts from a wide range of career stages. Together this group developed new deployment and data protocols, conducted a comprehensive camera comparison, and strengthened the near-surface thermal research community in the process.

Comparing Data with Confidence

Several key factors influence TIR temperature readings. For example, the farther a sensor is from its measurement target, the more that TIR radiation emitted by the target interacts with the surrounding air before reaching the sensor. Different materials in air, including water vapor, can absorb and scatter TIR signals, causing signal loss and affecting readings. So longer distances and higher relative humidities, if unaccounted for, can lead to potential inaccuracies.

In addition, different surfaces emit varying amounts of thermal radiation at a given temperature, a property known as emissivity, requiring corrections based on the material being measured. Sensors can also detect background radiation from the sky, introducing errors that must be adjusted for.

Without consistent procedures for deploying near-surface TIR sensors and processing TIR data, these factors make it difficult to draw meaningful conclusions or integrate findings from different studies. Standardization allows researchers to compare data confidently across locations and time periods, enhancing the accuracy and impact of ecosystem assessments.

These issues were the primary focus at the recent workshop, where participants also tested a novel data-processing package intended to streamline and cohere data processing across studies. Meeting participants provided feedback on the software that will help refine the package.

The group also began developing a comprehensive best practices document for deploying TIR, which will offer detailed guidelines for every aspect from the initial setup of instrumentation to final data interpretation. Specifically, the document will contain guidance and recommendations for the following topics:

• Lab testing to calibrate and assess instrument accuracy across a range of target (e.g., leaf) and ambient air temperatures prior to deployment
• Collecting required additional data like air temperature, relative humidity, and effective sky temperature
• Data quality assurance and uncertainty quantification in each step of the process, including implementations and protocols for reference panels (which provide known temperature and thermal emissivity values)
• Selecting regions of interest that minimize interference from nonvegetation surfaces and avoid the edges of the TIR camera’s view
• Key considerations for camera specifications, including power requirements, user control options, and optimal settings
• Postprocessing and interpretation to facilitate implementation of the new data-processing package

Each section of the document will offer tiered recommendations, providing baseline best practices as well as more comprehensive options. This approach will ensure that the protocols are accessible to a wide range of researchers, facilitating broader adoption and reliable use of thermal cameras in ecological studies.

Assessing Instruments in Person

A complexity in any near-surface remote sensing research is navigating the wide array of available cameras and sensors, each of which varies in accuracy, performance, cost, and ease of use. To address the effects of this diversity of instrumentation on near-surface TIR data, bake-off participants brought their own thermal cameras to the event—14 models in total, ranging from consumer-grade handheld models to research-oriented systems and drone-mounted cameras—and evaluated their performance.

The evaluation process began with controlled lab testing, in which attendees assessed cameras against standardized targets calibrated to a wide range of ecologically relevant temperatures. In addition, testing was conducted at two different ambient air temperatures to evaluate camera performance under different conditions. In total, the lab comparison assessed all 14 cameras in two ambient temperatures, with 12 target temperature values.

Following the lab tests, attendees moved to a field setting, where they tested the cameras at 40 and 20 meters from the targets (including a broadleaf tree canopy, tree bark, and grass) to simulate real-life field conditions. Data from several reference panels were crucial for calibrating the cameras and ensuring consistency across their measurements. When possible, cameras were also left to record data continuously for 24 hours, providing insights into their performance over extended periods and overnight.

These tests are important for determining whether data from different cameras can be reliably compared and whether certain cameras are better suited for specific environmental conditions. This work will be published in a forthcoming paper (separate from the best practices document) that suggests equipment standardization across sites and studies.

A Network of Cameras, a Community of Researchers

The 2024 Great Thermal Bake-off marked a pivotal moment in advancing near-surface TIR remote sensing for ecosystem studies, in part because of its focus on building and reinforcing a community of committed researchers. Structured small-group networking sessions during the workshop facilitated exchanges among participants from various career stages, geographies, and backgrounds (e.g., those with more technical interests in instrumentation and methods versus those whose work is driven by scientific questions).

These cross-disciplinary discussions resulted in ideas for collaborative projects and created lasting connections for future joint research. They also produced clear action items that fed into the codevelopment effort to establish standardized protocols. Combined with the live hands-on equipment testing, real-time feedback, and joint writing effort to craft best practices guidelines, the workshop’s collaborative and solution-oriented approach has strengthened the TIR community and its ability to support diverse research efforts.

The workshop also underscored the importance of expanding and sustaining collaborations beyond the event by, for example, joining the FLUXNET Canopy Thermal Imaging Committee. This working group provides a platform for ongoing communication and data sharing to ensure tangible, long-term connections in TIR research. Participants also made plans to engage other research networks with similar scientific focuses, such as the Integrated Carbon Observation System and the National Ecological Observatory Network, as well as with upcoming TIR satellite missions such as TRISHNA (Thermal Infrared Imaging Satellite for High-Resolution Natural Resource Assessment).

Building on the foundation established during the Great Thermal Bake-off, a growing and evolving Thermal Camera Network—akin to the phenology-focused PhenoCam Network—will be crucial for addressing many scientific questions, such as how plant temperatures deviate from air temperatures across ecosystems globally and whether these trends reveal broader climate patterns across spatial scales. The network will also enable researchers to track the impacts of extreme events like heat waves and droughts, as well as shifts in carbon, water, and energy fluxes.

Clearly, technology and methods for near-surface TIR remote sensing will remain hot topics for scientists investigating the current and future health of forests and other critical ecosystems.

Acknowledgments

This work benefited greatly from the insights and contributions of the following workshop participants and organizers: Adrian Rocha, Atefeh Hosseini, Chris Doughty, Chris Kibler, Christopher Still, Daphna Uni, David Trilling, Enrico Tomelleri, Eyal Rotenberg, Franklin Sullivan, George Koch, Jack Hastings, Jason Kelley, Jennifer Adams, John Lenters, Kai Begay, Li Ming Tan, Lindsey Bell, Mallory Barnes, Mark Irvine, Milagros Rodriguez-Caton, Mukund Palat Rao, Rae DeVan, Rui Cheng, Sandra Torres, Shannon Bayliss, Sophie Fauset, Sreenath Paleri, Stephanie Pau, Wen Zhang, William Hagan Brown, Xian Wang, Yujie Liu, and Zoe Pierrat. We acknowledge funding from the FLUXNET Co-op, the AmeriFlux Year of Remote Sensing, and Campbell Scientific, as well as from the following programs at Northern Arizona University: the T3 Option in Ecological and Environmental Informatics (supported by National Science Foundation award 1829075); the College of the Environment, Forestry, and Natural Sciences; the Department of Astronomy and Planetary Science; the School of Informatics, Computing, and Cyber Systems; the Center for Ecosystem Science and Society; and the Richardson Lab. This work was also supported by the National Science Foundation’s Accelerating Research through International Network-to-Network Collaborations (AccelNet) program under award 2113978. J.D. was supported by NASA under Future Investigators in NASA Earth and Space Science and Technology (FINESST) program award 80NSSC23K0138.

Author Information

Jen L. Diehl (jdiehl@nau.edu), School of Informatics, Computing, and Cyber Systems (SICCS) and Center for Ecosystem Science and Society (ECOSS), Northern Arizona University, Flagstaff; Benjamin C. Wiebe, SICCS, Northern Arizona University, Flagstaff; Mostafa Javadian, ECOSS, Northern Arizona University, Flagstaff; Stephanie Pau, Department of Geography, University of California, Berkeley; and Andrew D. Richardson, SICCS and ECOSS, Northern Arizona University, Flagstaff

Citation: Diehl, J. L., B. C. Wiebe, M. Javadian, S. Pau, and A. D. Richardson (2025), Sensing potential, scientists refine thermal imaging of ecosystems, Eos, 106, https://doi.org/10.1029/2025EO250051. Published on 7 February 2025.

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The deepest regions of Earth’s oceans, known as the abyssal and hadal zones, lie at least as far under the water’s surface as Mount Rainier’s peak rises above the land surface. These great depths of 4,000 or more meters make up one of Earth’s least explored frontiers and are home to some of its most extreme environments and habitats.

The conditions in these regions—immense pressures, cold temperatures, and the total lack of sunlight—shape the physical, chemical, and geological phenomena that occur there in ways both predictable and surprising [e.g., Marlow et al., 2021]. They also support unique life-forms that—far removed from the sunlit world above—thrive on alternative energy sources such as hydrothermal vents, seeps, and whale falls.

This part of the ocean remains largely unexplored because of the technical challenges of reaching such depths. However, potential discoveries within abyssal and hadal regions—such as dark oxygen, critical mineral resources, pressure-adapted extremophilic organisms, distinct ecosystems, archaeological sites (e.g., submerged human artifacts, including shipwrecks), and otherwise unknown landscapes—reinforce their allure. Remotely operated and autonomous vehicles offer valuable access to these regions, but there is no substitute for direct human observation: The situational awareness and targeted, delicate sampling that human-occupied vehicles (HOVs) enable are unique capabilities.

Yet the small number of vehicles capable of reaching abyssal and hadal depths—and the even smaller subset that can safely carry humans—limits the ability to explore them.

A key tool for this exploration is the deep submergence vehicle Alvin, the world’s longest-operating and most productive human-occupied deep-sea submersible, with more than 5,000 dives completed over 60 years of operation. Alvin recently underwent a significant upgrade, allowing it to reach depths of up to 6,500 meters—surpassing its previous limit of 4,500 meters.

The upgrade and a capstone science verification expedition (SVE) represent more than a decade of planning, scientific and engineering input, and technological development that have opened new possibilities for deep-sea research. With Alvin, researchers now have access to roughly 99% of the ocean floor (Figure 1), enabling in-person observations and data collection in regions that were previously unreachable by the submersible.

Exploring the Deep Ocean Directly

Direct exploration is crucial for understanding deep-ocean environments. Pilots and observers inside an HOV can see the area around them, intuitively perceive distances, and feel the movement of the thrusters and robotic arms when they collect samples. These sensory inputs help them understand spatial relationships among features as well as water currents and the condition of specimens as they are being collected.

In addition, because a human-occupied submersible is not connected to a surface ship by a cable, it is a versatile and nimble exploration tool. An HOV can change direction more quickly than a remotely operated vehicle, without requiring a ship move, and it can explore steeper, more complex areas without encountering the constraints of a tether and a surface vessel, albeit usually with shorter dive times.

Such exploration is especially needed, for example, to provide baseline information that allows us to evaluate whether—and, if so, how—human-induced global changes are affecting deep ecosystems at different depths. Such effects are already pronounced in most ocean environments closer to the surface.

Alvin is owned by the U.S. Navy and certified under the Navy’s Submarine Safety Program (SUBSAFE) protocol but is part of the National Science Foundation’s National Deep Submergence Facility (NDSF) hosted at the Woods Hole Oceanographic Institution (WHOI). Operated by WHOI since its commissioning in 1964 and used by many research organizations, Alvin has long been at the forefront of deep-sea exploration. It can conduct a variety of logistical and scientific tasks, notably, transporting observers to study sites, conducting mapping and photographic surveys, and collecting samples using its robotic arms.

Throughout its lifetime, Alvin has undergone numerous upgrades to remain a state-of-the-art research platform. The most recent upgrade included outfitting it with a new, larger personnel sphere with better ergonomics and improved visibility, as well as improved thrusters and a more advanced command-and-control system. New high-definition imaging systems and faster data acquisition capabilities were also installed, as were enhanced inertial navigation capabilities enabling very accurate tracking from the surface to seafloor, even at great depth, and a new science interface that enables rapid integration of routine and novel sensors for in-sub viewing.

The 2022 Science Verification Expedition

In summer 2022, a diverse team of scientists—led in part by researchers from WHOI and the University of Rhode Island Graduate School of Oceanography (URI-GSO)—put Alvin and its upgraded systems to the test in real-world conditions during its first SVE following the upgrade [Soule et al., 2022]. Team members represented a wide range of disciplines, career stages, and personal backgrounds, and the expedition included a major milestone in U.S. deep-sea science: Alvin’s first dives below 6,000 meters.

All told, the expedition involved six successful dives in the Puerto Rico Trench to nearly 6,400-meter depth and nine along the Mid-Cayman Rise to nearly 6,100-meter depth (Figure 2). These areas, chosen for their extreme depths and diverse conditions, provided rigorous proving grounds for Alvin’s new systems and offered opportunities to study underexplored regions.

During the dives, scientists explored various geological features, including fault lines, landslides, outcrops of ancient oceanic crust, young volcanic features, and active hydrothermal vent systems. The crew also deployed complementary tools, such as a CTD (conductivity, temperature, depth) profiler, as well as an autonomous sampling lander [Muir et al., 2021] that enhanced Alvin’s observational and sampling capabilities down to 8,000-meter depth.

The 2022 expedition yielded several significant scientific observations that have contributed to our understanding of Earth’s geological history and processes that shape the ocean floor. On the Mid-Cayman Rise, researchers aboard Alvin discovered the world’s deepest-known very young (<1–2 decades) submarine volcanic eruption site at 6,000 meters deep [Rubin et al., 2023], an important finding for understanding the effect of high ambient pressure and low temperature on eruption mechanisms.

These researchers also characterized high-grade metamorphic rocks in multiple locations and collected samples at the Von Damm and Beebe active hydrothermal vents [German et al., 2010], which have distinct faunal communities (Figure 3). In addition, the science team recovered the first samples of the active microbial communities living within the vent chimneys, offering insights into life in these extreme environments.

In the Puerto Rico Trench, Alvin’s dives uncovered well-preserved geological structures on steep rock faces, including samples of intrusive oceanic crust [e.g., Rubin et al., 2022] thought to be as much as 100 million years old [Klein et al., 2017]. The site is well suited for systematic follow-on studies of spatiotemporal variations that occur during crustal accretion and alteration at the slow-spreading Mid-Atlantic Ridge. The team also documented behavioral adaptations of deep-dwelling isopods in response to the recent appearance of Sargassum in the Caribbean Sea [Peoples et al., 2024], a remarkable adaptation in the deep ocean to a modern ecological change in the surface waters.

The scientists and Alvin operations team of pilots and engineers on the SVE, over the course of these dives, confirmed the upgraded Alvin’s readiness for abyssal and hadal explorations. Indeed, the submersible’s new capabilities, including enhanced imaging, improved maneuverability, and upgraded navigational tracking, proved essential for the success of the mission.

Since the SVE, Alvin has returned to its regular operational cadence, completing more than 100 dives per year. These dives have included expeditions back to long-term study sites on the East Pacific Rise—where researchers, aided by the autonomous underwater vehicle Sentry, discovered a new off-axis hydrothermal vent site (D. Fornari, personal communication, 2024)—and in the Guaymas Basin, where scientists found dramatically changed hydrothermal venting at a previously known site (M. Joye, personal communication, 2024). A subsequent series of deep science dives in 2024 reached nearly 5,000 meters in the Aleutian Trench, where polychaete-populated seeps were observed to provide habitat for a host of organisms such as hydroids, foraminifera, bacteria, and folliculinids, including possibly new species discoveries (L. Levin, personal communication, 2024).

Alvin’s Legacy and Future

The deep ocean is a place where high hydrostatic pressure influences biological adaptation, geological processes like volcanism, and chemical phenomena such as mineral and ore formation. Throughout its history, Alvin—the most active research submersible in the world and the only U.S. HOV capable of reaching such extreme depths—has contributed to numerous scientific discoveries related to these processes, as well as to explorations of shipwrecks and unknown deep-sea environs.

Alvin’s notable contributions to deep-sea exploration include, among many others, the first discoveries of submarine hydrothermal vents (on the Galapagos Spreading Center in 1977) and black smokers (at 21°N on the East Pacific Rise in 1979), the discovery of methane seeps along the Florida Escarpment in 1984, Bob Ballard’s famous 1986 dive to the Titanic, and the first exploration of the unique Lost City hydrothermal field in 2000.

Alvin has also supported U.S. leadership in deep-ocean exploration and motivated the work of more than 14,000 personnel. Continuing through the SVE in 2022, it has been a major part of each of our own dive histories, for example, contributing indelibly to our research and careers.

The SVE didn’t involve just established scientists, however. As part of an emphasis on equity, diversity, and inclusion within the scientific community, it also included 11 early-career scientists, most of whom were diving in Alvin for the first time. These scientists offered their expertise in geology, microbiology, biology, hydrothermal activity, and resource mapping, and they hailed from oceanographic institutions, large research universities, and smaller teaching colleges, as well as from the Cayman Islands government. The continuing focus on inclusivity in future expeditions will help to foster a welcoming environment for the next generation of researchers using Alvin to expand our understanding of deep-sea biological, geological, and chemical processes.

Alvin’s upgraded capabilities will offer these scientists opportunities to study such processes in greater detail, contributing to knowledge of how life and Earth itself have evolved under extreme conditions. They will also help to provide vital understanding and insights into how human activities are increasingly affecting environments, including deep-ocean ecosystems, supporting comprehensive assessments of global change and how we might manage these regions. As we continue to push the boundaries of human exploration ever deeper in the ocean, Alvin remains a critical tool and a symbol of enduring curiosity and commitment to understanding the world beneath the waves.

Acknowledgments

Alvin is a U.S. Navy–owned asset certified under the Navy’s SUBSAFE protocol with support from the Naval Sea Systems Command (NAVSEA). The recent Alvin upgrade was supported primarily by the National Science Foundation with additional support from the Office of Naval Research. K.H.R. is the associate dean of research at URI-GSO and has completed more than 30 HOV dives. A.P.M.M. is an associate scientist at WHOI and the current chief scientist of deep submergence at NDSF. S.A.S. is a professor of oceanography at URI-GSO, director of the Ocean Exploration Cooperative Institute, and former NDSF chief scientist.

References

German, C. R., et al. (2010), Diverse styles of submarine venting on the ultraslow spreading Mid-Cayman Rise, Proc. Natl. Acad. Sci. U. S. A., 107(32), 14,020—14,025, https://doi.org/10.1073/pnas.1009205107.

Klein, F., et al. (2017), Mid-ocean ridge serpentinite in the Puerto Rico Trench: From seafloor spreading to subduction, J. Petrol., 58(9), 1,729–1,754, https://doi.org/10.1093/petrology/egx071.

Marlow, J. J., et al. (2021), New opportunities and untapped scientific potential in the abyssal ocean, Front. Mar. Sci., 8, 798943, https://doi.org/10.3389/fmars.2021.798943.

Muir, L., et al. (2021), The Deep Autonomous Profiler (DAP), a platform for hadal profiling and water sample collection, J. Atmos. Oceanic Technol., 38(10), 1,833–1,845.

Peoples, L. M., et al. (2024), A deep-sea isopod that consumes Sargassum sinking from the ocean’s surface, Proc. R. Soc. B, 291(2030), 20240823, https://doi.org/10.1098/rspb.2024.0823.

Rubin, K., et al. (2022), Classic oceanic crustal section recovered by Alvin submersible divers from the Puerto Rico Trench north wall, Abstract OS25B-05 presented at 2022 Fall Meeting, AGU, Chicago, Ill., 12–16 Dec., https://doi.org/10.5281/zenodo.13930734.

Rubin, K., et al. (2023), Young submarine lava flow identified at 6 km depth on the Mid Cayman Rise, Abstract 928 presented at IAVCEI 2023 Scientific Assembly, Int. Assoc. of Volcanol. and Chem. of the Earth’s Inter., Rotorua, New Zealand, 30 Jan. to 3 Feb., zenodo.org/records/13930806.

Soule, S. A., A. Michel, and Alvin Science Verification Team (2022), An upgraded HOV Alvin for abyssal and hadal science, Abstract OS25B-04 presented at 2022 Fall Meeting, AGU, Chicago, Ill., 12–16 Dec.

Author Information

Kenna Harmony Rubin (kenna.rubin@uri.edu), Graduate School of Oceanography, University of Rhode Island, Narragansett; Anna P. M. Michel, Woods Hole Oceanographic Institution, Woods Hole, Mass.; and S. Adam Soule, Graduate School of Oceanography, University of Rhode Island, Narragansett

Citation: Rubin, K. H., A. P. M. Michel, and S. A. Soule (2025), An upgraded Alvin puts new ocean depths within reach, Eos, 106, https://doi.org/10.1029/2025EO250037. Published on 31 January 2025.

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Greenland’s natural resources—critical minerals and clean energy potential, in particular—have evolved into a cornerstone for renewable energy transitions and sustainability efforts elsewhere in the world. Unraveling the intricacies of Greenland’s subsurface, where these resources reside but which remains relatively unknown, could facilitate efficient exploration and responsible management of these natural resources.

Recently, the European Union signed a memorandum of understanding with the government of Greenland to develop sustainable raw material value chains, aiming to secure a diversified and steady supply of critical minerals essential for the green transition. The collaboration encompasses economic integration, infrastructure development, skill building, and joint research to ensure the sustainable use of these resources.

Similarly, the United States is making efforts to invest in Greenland’s mining sector to boost the supply of materials needed for clean energy technologies. U.S. officials have engaged with Greenlandic authorities and potential investors, highlighting Greenland’s potential to become the next mining frontier.

Both the European Union and the United States recognize the strategic importance of Greenland’s resources in meeting global demand for critical minerals vital for a sustainable future. As international interest grows, responsible exploration and development of Greenland’s resources are crucial to ensuring environmental protections and benefits for local communities.

Less obvious but equally important, our understanding of subsurface phenomena pivotally informs climate modeling and long-term forecasts of sea level rise, ocean currents, and climate change. The thermal structure deep beneath Greenland controls the geothermal energy release at the base of the ice sheet, directly influencing the rate at which the ice sheet melts. This melting not only contributes to rising sea levels but also alters the amount of fresh water entering the oceans, which affects currents and climate.

In March 2024, scientists from across Europe, the United States, and Canada who study Greenland’s lithosphere (comprising the crust and uppermost mantle) convened in Copenhagen for a landmark workshop. The purpose was to review the past and present state of knowledge about Greenland’s subsurface structure and dynamics in the context of climate change and resource exploration and to discuss collaborative steps to address outstanding scientific questions and challenges.

Everything’s Connected

How does Greenland’s lithosphere affect the climate above it? A rush of recent scientific studies has elucidated the impact of Greenland’s melting ice sheet on global ocean currents and climate patterns. This ice melting is heavily influenced by rising air temperatures and other conditions at the ice sheet surface, of course, but it is also closely linked to conditions beneath the ice, including geothermal heat flow and the mechanical properties of Earth’s interior.

This connection is easy to grasp when we consider how differences in lithospheric thickness influence a cascade of effects. For example, areas with thin lithosphere, such as the East African Rift, have elevated thermal gradients (i.e., the transition from subsurface to surface temperatures occurs over a shorter distance), leading to higher surface heat flow and mechanically weaker tectonic plates. In Greenland, high surface heat flow accelerates ice melting, and weaker sections of plate facilitate relatively rapid vertical movements of the surface as it rebounds in response to ice loss, a phenomenon known as glacial isostatic adjustment.

Against a backdrop of escalating concerns over the effects of climate change, the need for precise ice melting models and the corresponding imperative to grasp Greenland’s lithospheric structure, dynamics, and surface heat flow are becoming more critical.

Progress Toward a More Holistic Approach

The Copenhagen workshop focused on Greenland’s lithospheric structure and its connection to key natural resources and natural hazards while shedding light on the implications of subsurface dynamics for modeling of ice melting and climate. Participants presented, reviewed, and assessed a wealth of geoscientific data relevant to our understanding of Greenland’s subsurface composition, thermal structure, and dynamics from the top of the crust down to the deep upper mantle.

A major theme of the workshop was the reconciliation of disparate datasets and predictions regarding Greenland’s lithospheric structure. Ten years ago, conflicting models of important subsurface traits such as crustal density and lithospheric and crustal thickness stirred controversies and hindered consensus among researchers. For example, predictions of lithospheric thickness in different models differed by as much as 80%–120% in large portions of central and northern Greenland.

During the workshop, it became clear that at least part of the explanation for the model differences can be traced to the use of single-discipline or single–data type approaches (e.g., using only specific seismic data or gravity inversion data) to model the subsurface in a region that is poorly covered by land-based datasets. It is now well known in the geophysical community that many types of data, when considered on their own, have limited sensitivity to variations in properties like lithospheric thickness.

Therefore, when researchers reconstruct images of subsurface features using only a few observations from a single dataset, they must supplement these observations using modeling assumptions (e.g., about relationships between model parameters or maximum allowed variations in the model). These assumptions invariably add subjectivity and may result in different models of the same subsurface feature. By contrast, working with multiple datasets with complementary sensitivities tends to reduce ambiguity in models and in the images of the subsurface they produce.

Accordingly, a central focus of the workshop was to explore the opportunities and added value inherent in integrating new and diverse datasets (e.g., integrating gravity, seismic, and magnetic datasets) to construct more robust models, capitalizing on the different coverages and sensitivities offered by each dataset.

At the workshop, several groups showcased comprehensive models of Greenland’s lithosphere, each offering unique perspectives and nuances but collectively showing critical consistencies in fundamental features, such as patterns of lithospheric thickness, density anomalies, and temperature structure (Figure 1). This convergence marks a significant milestone in our understanding, indicating that past discrepancies are being ironed out and raising confidence in the validity and predictions of the models.

From Knowledge to Applications

This newfound confidence has key implications for exploration and management programs related to critical minerals, energy, and hazard mitigation. With a clearer understanding of Greenland’s lithospheric architecture and thermal structure, scientists are better positioned to advise local governments and inform exploration efforts aimed at revealing its abundant natural resources. From there, geothermal energy potential and critical mineral deposits could be targeted with greater precision, promoting more efficient and sustainable resource use and helping accelerate energy transitions.

Furthermore, with improved lithospheric models, glaciologists and scientists studying glacial isostatic adjustment have better constraints on heat flow at the base of the ice sheet, as well as on temperatures and compositions of the crust and mantle. With this knowledge, these researchers can refine model estimates of ice evolution, sea level change, and variations in land motion, gravity, and tectonic stress. These advances are vital for assessing the regional and global impacts of the response of the Greenland ice sheet to climate warming.

Charting a Way Forward

The workshop concluded with a resounding call for continued collaboration and interdisciplinary research to further refine understanding of Greenland’s natural systems. Indeed, plans are underway for future deployments of seismic instrumentation in critical regions by both U.S. and European research groups, as well as for multi-institution collaborative projects. In addition, the entire group of workshop attendees pledged to more closely integrate satellite and airborne datasets with seismic data, a commitment now being realized by workshop attendees.

These plans aim to leverage the newfound knowledge discussed at the March workshop in Copenhagen—and during a follow-up splinter meeting held in April at the European Geosciences Union General Assembly 2024—to address pressing scientific questions and challenges related to sustainable resource management, climate modeling, and resilience.

Of particular interest are new multidata methods and acquisition programs designed to better evaluate the thermal and lithological structure of the crust beneath retreating ice sheets. Evaluating such factors as the surface heat flux beneath central Greenland, mantle dynamics, and the rheological structure of the lithosphere is crucial for predicting relative sea level changes and the evolution of ice sheets. (A white paper discussing these sessions in more technical detail is currently being written.)

As Greenland’s significance in global discussions about natural resource use and climate change continues to grow, efforts like these serve as critical mechanisms for advancing scientific understanding, fostering international collaboration and engagement, and informing evidence-based decisionmaking.

Acknowledgments

We acknowledge the participants in the March 2024 workshop held at the headquarters of the Geological Survey of Denmark and Greenland, who include the following: John Hopper, Juan Carlos Afonso, Clint Conrad, Jörg Ebbing, Samantha Hansen, Judith Freienstein, Rene Forsberg, Biao Lu, Alexander Minakov, Derek Schutt, Rebekka Steffen, Kristoffer Szilas, Agnes Wansing, Zhirui Ray Wang, Bjørn Henning Heincke, Pierpaolo Guarnieri, Trine Dahl-Jensen, Thomas Funck, Carmen Gaina, Parviz Ajourlou, Sergei Lebedev, Glenn Milne, Fiona Darbyshire, Andrew Schaeffer, Giampiero Iaffaldano, Max Moorkamp, Glenn Jones, and Judith Bott.

Author Information

Juan C. Afonso (j.c.afonso@utwente.nl), Faculty of Geo-Information Science and Earth Observation, University of Twente, Enschede, Netherlands; Agnes Wansing, Institute of Geosciences, Kiel University, Kiel, Germany; Parviz Ajourlou, Department of Earth and Environmental Science, University of Ottawa, Ottawa, Ont., Canada; John Hopper, Department of Geophysics and Sedimentary Basins, Geological Survey of Denmark and Greenland, Copenhagen; and Jörg Ebbing, Institute of Geosciences, Kiel University, Kiel, Germany

Citation: Afonso, J. C., A. Wansing, P. Ajourlou, J. Hopper, and J. Ebbing (2025), Beneath Greenland, insights for energy transitions and climate models, Eos, 106, https://doi.org/10.1029/2025EO250019. Published on 15 January 2025.

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The world of academic workshops and conferences is changing. Constrained budgets for meeting organizers and attendees, postpandemic reluctance to travel, concerns about environmental footprints, and the need to be more inclusive are all motivating efforts, including in the sciences, to find workable alternatives to in-person gatherings [Kremser et al., 2024; Fraser and Mancl, 2024]. Meanwhile, widespread access to improved communication technology and the availability of an ever-growing set of online tools are increasingly making remote workshops more viable and effective than in the recent past.

Online events are particularly attractive for geographically dispersed groups of participants and—because there is no need to work out location-based logistics—for meeting organizers facing tight constraints on the lead time available for planning. Online events, though they have their own challenges, can also minimize the time commitment for attendees and can enable inclusion of a broader group of perspectives, including in multidisciplinary workshops bringing together experts from different fields.

We are a group of Earth scientists, including modelers and observationalists, interested in quantifying and understanding the impacts of the increasing volumes of meltwater flowing into the ocean from the Greenland and Antarctic ice sheets. This meltwater affects the ocean through sea level and density changes, which can have wider impacts on the climate through ocean temperatures and sea ice changes. Data on these fluxes will be an important input for climate models, such as those used in the Coupled Model Intercomparison Project (CMIP), a vital source of input for international and national climate assessments.

In late 2023, with a looming deadline for submitting input data for the next round of CMIP, we recognized the need for a rapid coordinated global effort to produce datasets characterizing historical freshwater fluxes to support these models. (The deadline was originally in April 2024, although it was subsequently pushed back.) In response, we organized a virtual workshop, held 11–13 February 2024, to gather contributions from a global group of experts. The novel format offered many benefits and was successful, although participant feedback pointed to possible improvements.

Topic, Scope, Format, and Scheduling

The scientific literature is increasingly mentioning effects of meltwater from the Greenland and Antarctic ice sheets. Accurately quantifying meltwater fluxes is important for matching observed and modeled surface temperature and sea ice trends in the Southern Ocean. These fluxes have also been implicated in changes in salinity and temperature in the North Atlantic and tropical east Pacific [Dukhovskoy et al., 2019; Dong et al., 2022].

Recent studies have suggested that these fluxes need to be represented in climate model simulations, either by including dynamic ice sheets or by adding freshwater as an external driver, to improve the models’ skill in reproducing observations [Pauling et al., 2016; Schmidt et al., 2023; Li et al., 2023; Roach et al., 2023].

To address this need, we set three goals for our recent workshop: to develop a community of observationalists and modelers to collate and document the required datasets, to recommend methods for implementing this freshwater flux in climate models, and to publish the methodology in time for it to be incorporated into the next round of CMIP simulations.

Given this scope and the short timeline we had to work with, we developed a virtual workshop format. In addition to simplifying planning (it took less than 4 months from conception to execution) and its flexibility for participants, this format had financial cost benefits because it eliminated travel expenses and used only preexisting resources.

The conference organizing committee canvassed for potential presenters across the range of topics to be discussed, from ice sheet observations to ocean modeling and preliminary results from coupled systems. We requested that speakers prerecord a focused talk of up to 15 minutes and upload their video and slides to a shared Google Drive folder at least a week before the conference. This format mitigated the usual limitations on speaking time at meetings, so invitations to speak were sent to all of the initially proposed presenters and to others suggested during the organizing process. Not all speakers had experience with self-recording talks, so we provided guidance on useful techniques and software alternatives.

In total, 30 recorded talks with accompanying slides were made available to workshop participants about a week before it started. Attendees who provided feedback after the meeting universally praised this aspect of the workshop, although some expressed frustration that not all speakers kept to the 15-minute limit. Other respondents said they would have preferred more lead time to view the talks in advance. Additional prompting by organizers to encourage participants to watch the talks ahead of the discussion sessions likely would have also helped.

To attract participants on short notice, we promoted the workshop heavily through standard approaches such as mailing lists, word of mouth, and advertising at other meetings. We also spread the word with frequent messaging on social media platforms widely used by scientists—notably X (formerly Twitter) and Bluesky—and we specifically targeted social media accounts that reach underrepresented communities (e.g., @BlkinGeoscience).

Approximately 160 people registered for the workshop. Registrants were based around the world, including in (starting at the International Date Line) New Zealand, Australia, Japan, China, India, eastern Europe, central Europe, the United Kingdom, locations across the contiguous United States, and Hawaii. Some were also on ships at sea or in field camps in Antarctica (and connected via Starlink). Using an online multitime zone meeting planner, we quickly assessed whic­h blocks of time were within (or close to) the working day for four representative zones: the Australian East Coast, central Europe, the U.S. East Coast, and the U.S. Pacific coast.

No time blocks were ideal for all participants, but we identified a 1-hour block (beginning at 20:00 UTC) that minimized the collective inconvenience. We thus chose that time block to host daily “global Zoom” sessions that covered welcoming remarks, summaries of prior sessions, and concluding statements. We also defined three or four 2-hour discussion blocks per day, each of which was convenient for participants in a subset of time zones. (For example, a block from 13:00 to 15:00 UTC was considered convenient for people in Europe and on the U.S. East Coast.) The whole workshop took place over 49 hours.

Immediately after the workshop, all participants were asked to provide feedback on any or all aspects of the format; 16% of the signed-up participants responded.

An Abundance of Information

Zoom sessions during the meeting were all recorded, and those recordings were posted to the shared Google Drive as soon as they were available. In addition, each session had a facilitator and rapporteur whose notes were visible (and editable) on the Google Drive in real time. (See the sidebar for more information on the tools used and other technical considerations for this meeting.)

Survey respondents mostly reported that they at least skimmed the notes from sessions they missed, but few felt they had enough time to review the Zoom session videos. In fact, 50% of respondents did not think the session recordings were useful, whereas 75% thought the notes were more useful. We realized in retrospect that the combination of trying to catch up on both relevant presentations and meeting discussions they’d missed was too much for many participants. (We return to this point below.)

Up to 60 participants at a time attended the regionally specific Zooms, which supported a rolling discussion of important topics, such as modeling strategies and sources of observational data. The rolling format, designed to keep conversations moving and effectively tap the collective intelligence of a large group, was successful overall and helped to foster the intensity and focus of an in-person workshop.

However, a limitation of this approach for our event was that in some sessions, few or none of the relevant experts on the particular topic of focus could attend because of inconvenient timing, which limited the depth of discussion slightly. Other criticisms of these sessions related to facilitators not adequately including all participants and an occasional lack of focus in discussions, but most respondents reported that they were able to engage in and follow the conversations.

For questions and answers on the talks and technical discussions, we set up a GitHub repository accessible to all participants with facilities for uploading data and code. The repository also featured flexible discussion boards [Braga et al., 2023] tailored to the session topics, technical issues such as dataset formats, and the broader philosophy of model coupling. Most of the survey respondents (74%) said they appreciated having the discussion boards, and even months later, the boards are still in use.

Feedback and Future Improvements

From our perspective as organizers, this global, virtual workshop developed on relatively short notice was a success. Fulfilling our first goal, it indeed brought together a community of researchers to focus on the representation of freshwater fluxes in climate models—and it did so with no dedicated funding and zero travel-related carbon emissions.

Large majorities of survey respondents reported that they were very or extremely satisfied with the format (72%) and that they would attend another similar event (84%). They appreciated the time, energy, and money they saved compared to attending an in-person event, and most said they would prefer this format over others, such as multiregion hub meetings or hybrid options for standard workshops.

An additional demonstration of the meeting’s success will come with the timely delivery of the new collated datasets, the guidance on implementing these fluxes in models that emerged from the meeting, and the paper documenting the implementation process, all of which are in progress.

Our experience running the recent meeting and the participant feedback we received offer useful lessons for future efforts. Suggestions for improving the experience focused on slowing things down. Specifically, people requested that the prerecorded talks be made available further in advance of the workshop. They also requested more time between sessions for breaks, to catch up on prior conversations, or to prepare for upcoming discussions.

We therefore recommend that organizers maximize the time available for attendees to view the uploaded videos beforehand; ideally, it should be at least 2 weeks. Also, considering that people cannot necessarily devote many hours a day to a remote workshop, such events should be spread over a longer period than would be normal for an in-person event. We recommend at least a week or possibly two, instead of just a few days. Further, although rolling discussions can work well, organizers should build in open time between sessions to allow people to catch up.

The format of our workshop fostered inclusivity of a geographically dispersed community, but organizers should also make sure that a broad range of voices and persons with relevant expertise participate in and are called upon in online sessions. In our case, prepolling to gauge attendance in each regional session and adjusting topics if needed would have been useful. Finally, many participants in this event were unfamiliar with some aspects of the tools being used, so offering training and advice before the event starts is likely to be worthwhile.

Given the benefits outlined above, we strongly encourage other workshop organizers to consider this online meeting format, albeit with some fine-tuning, for future events. Clearly, scientists no longer need to be tied to a specific place, time zone, or modality to foster community and advance important research.

References

Braga, P. H. P., et al. (2023), Not just for programmers: How GitHub can accelerate collaborative and reproducible research in ecology and evolution, Methods Ecol. Evol., 14(6), 1,364–1,380, https://doi.org/10.1111/2041-210X.14108.

Dong, Y., et al. (2022), Antarctic ice‐sheet meltwater reduces transient warming and climate sensitivity through the sea‐surface temperature pattern effect, Geophys. Res. Lett., 49(24), e2022GL101249, https://doi.org/10.1029/2022GL101249.

Dukhovskoy, D. S., et al. (2019), Role of Greenland freshwater anomaly in the recent freshening of the subpolar North Atlantic, J. Geophys. Res. Oceans, 124(5), 3,333–3,360, https://doi.org/10.1029/2018JC014686.

Fraser, S., and D. Mancl (2024), Virtual and the future of conferences, Commun. ACM, 67, 32–34, https://doi.org/10.1145/3624638.

Kremser, S., et al. (2024), Decarbonizing conference travel: Testing a multi-hub approach, Bull. Am. Meteorol. Soc., 105(1), E21–E31, https://doi.org/10.1175/BAMS-D-23-0160.1.

Li, Q., et al. (2023), Abyssal ocean overturning slowdown and warming driven by Antarctic meltwater, Nature, 615, 841–847, https://doi.org/10.1038/s41586-023-05762-w.

Pauling, A. G., et al. (2016), The response of the Southern Ocean and Antarctic sea ice to freshwater from ice shelves in an Earth system model, J. Clim., 29, 1,655–1,672, https://doi.org/10.1175/JCLI-D-15-0501.1.

Roach, L. A., et al. (2023), Winds and meltwater together lead to Southern Ocean surface cooling and sea ice expansion, Geophys. Res. Lett., 50(24), e2023GL105948, https://doi.org/10.1029/2023GL105948.

Schmidt, G. A., et al. (2023), Anomalous meltwater from ice sheets and ice shelves is a historical forcing, Geophys. Res. Lett., 50(24), e2023GL106530, https://doi.org/10.1029/2023GL106530.

Author Information

Gavin A. Schmidt (gavin.a.schmidt@nasa.gov), NASA Goddard Institute for Space Studies, New York; Julie Arblaster, Securing Antarctica’s Environmental Future, School of Earth, Atmosphere and Environment, Monash University, Melbourne, Vic., Australia; Kenneth D. Mankoff, Autonomic Integra LLC, New York; also at NASA Goddard Institute for Space Studies, New York; Andrew Pauling, University of Otago, Dunedin, New Zealand; and Qian Li, Massachusetts Institute of Technology, Cambridge

Citation: Schmidt, G. A., J. Arblaster, K. D. Mankoff, A. Pauling, and Q. Li (2024), Lessons learned from running a virtual global workshop, Eos, 105, https://doi.org/10.1029/2024EO240514. Published on 18 November 2024.

Text © 2024. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.