Antarctica is Earth’s most remote continent, barely touched by human activities.

It is, however, not immune to the kind of environmental damage that plagues more populated parts of the world. In a new study, researchers found chemicals originating from everyday personal care products (PCPs), such as cosmetics, detergents, pharmaceuticals, and deodorants, in Antarctic snow.

Contaminants in PCPs—loosely defined as semivolatile organic compounds that are industrially produced at a global scale, used in large volumes, and relatively persistent in the environment—are increasingly being recognized as pollutants. Both the Arctic Monitoring and Assessment Programme and the Scientific Committee on Antarctic Research have encouraged further research on PCP ingredients and the creation of monitoring plans for tracking their presence at the poles.

Looking for these pollutants, researchers collected 23 surface snow samples from 18 sites along the Ross Sea coast during the Antarctic summer of 2021–2022. Though some sampling locations were near areas with human activity, including Italy’s seasonally occupied Mario Zucchelli research station, the majority were situated hundreds of kilometers from human settlements.

The scientists reached these remote locations by piggybacking on helicopter rides transporting other teams maintaining weather stations or deploying scientific instruments. “This way we halved the impact of our sampling, because they needed to go there in any case,” said Marco Vecchiato, an analytical chemist at Ca’ Foscari University in Venice, Italy, who led the study.

Back in Italy, Vecchiato and his colleagues analyzed the snow samples under clean-room conditions to prevent contamination.

They found PCP chemicals in every sample, with varying chemical concentrations suggesting different capacities for atmospheric transport. Of the 21 chemicals analyzed, three compound families were particularly notable. Salicylates, commonly used as preservatives in cosmetics (including lotions, shampoos, and conditioners) and pharmaceutical products, were the most prevalent, followed by UV filters associated with sunscreens. Fragrances such as musks were also detected.

Most of these substances were dissolved in the snow. The UV filter octocrylene, however, which has been associated with coral reef damage and banned in places like the U.S. Virgin Islands and Palau, was found bound to solid particles within the snow.

The researchers observed an unexpected seasonal variation in the amount of PCPs within the samples: Samples collected later in the summer had about 10 times higher PCP levels than those collected earlier in the season, though the relative proportions of each pollutant within a sample remained consistent.

Seasonal fluctuation suggests that Antarctic summer air circulation plays a role in transporting pollutants from distant sources to the continent’s interior. During summer, oceanic winds blowing inland dominate over winds originating from the polar plateau, which are stronger during the rest of the year. That shift may push pollutants far inland.

“This very different behavior during the season means that [PCPs] are very sensitive to the environmental conditions,” Vecchiato said.

One of the researchers presented the team’s preliminary findings at the European Geosciences Union General Assembly in May, and the scientists have a more comprehensive analysis currently underway, according to Vecchiato.

A Local or Distant Source

Finding organic pollutants in seemingly pristine polar environments isn’t surprising. In the 1960s, scientists found large concentrations of persistent organic pollutants (POPs), including the widely used pesticide DDT (dichlorodiphenyltrichloroethane), in Antarctica. POPs don’t degrade naturally and travel thousands of kilometers through the atmosphere, with some eventually getting trapped in snow and ice. Permanently frozen places such as glaciers and polar regions become natural traps. Starting in the early 2000s, the United Nations’ Stockholm Convention on Persistent Organic Pollutants established international cooperative efforts to eliminate or restrict the production and use of POPs.

Though they might travel by a mechanism similar to that used by persistent organic pollutants, unlike POPs, PCPs “do break down in the environment,” said Alan Kolok, a professor of ecotoxicology at the University of Idaho. However, “if those fragrances are not coming from the [research] stations themselves,” he asked, “where are they coming from?”

To rule out a local origin for the PCP pollutants, researchers analyzed sewage from the Mario Zucchelli research station. The outpost did contribute some pollution, but the relative abundance of each compound in the sewage differed from that found in the snow, suggesting that the PCPs detected in the broader Antarctic environment likely originated from more distant sources.

“My suspicion is that for these types of compounds—personal care products, pharmaceutical products—there must be a local source,” said Ricardo Barra Ríos, an environmental scientist at the Universidad de Concepción in Chile who has analyzed PCP pollution in Antarctic coastal waters related to research stations. “Thousands of people are currently accessing the Antarctic continent, and my conclusion is that wherever we humans go, we bring contaminants.”

Vecchiato disagreed. In a separate study published earlier this year, he and other colleagues found PCPs, including fragrances and UV filters, in the snows of the Svalbard archipelago in the Arctic. In that study, the researchers linked the presence of these compounds to atmospheric patterns that carried pollution from northern Europe and the northwestern coast of Russia.

“Most of these contaminants should have a limited mobility, but actually, we found them in remote regions,” Vecchiato said. “Does that mean that the models are wrong or that our analysis is wrong?” he asked. “No, probably we are missing a piece [of the puzzle], or maybe the use of these contaminants is so huge that we still have a relevant concentration in remote areas, even if they should not be prone to this kind of transport.”

—Javier Barbuzano (@javibar.bsky.social), Science Writer

Citation: Barbuzano, J. (2025), Is your shampoo washing up in Antarctica?, Eos, 106, https://doi.org/10.1029/2025EO250209. Published on 3 June 2025.

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Pine Hollow Arboretum’s founder, John W. Abbuhl, began planting trees around his Albany, N.Y., home in the 1960s. He planted species native to surrounding ecosystems but also made ambitious choices—bald cypresses, magnolias, pawpaws, sweetgums—that were more climatically suited to the southeastern United States.

Now, those very trees are thriving, said Dave Plummer, a horticulturalist at Pine Hollow. 

Other Pine Hollow trees, such as balsam firs native to New York, have struggled with this century’s warming winters. “We’re noticing they’re not doing as well as they were maybe 5 to 10 years ago,” Plummer said. “These are trees that are just meant to be in more northern climates where the winters are harsher, and we just don’t have those winters [anymore].”

Pine Hollow Arboretum is one of many botanical gardens rethinking their planting strategies as the climate warms. These strategies range from testing out new, warmth-loving plants to putting more resources toward pest and invasive species management. 

Planting Zones Shift North

The U.S. Department of Agriculture recognizes 13 plant hardiness zones based on a region’s coldest annual temperatures, averaged over a period of 30 years. These zones guide gardeners’ planting decisions by advising which species of plants, especially perennials, are most likely to thrive in a specific zone.

A new report from Climate Central, a climate change research and communication nonprofit, lays out stark changes to these zones.

Scientists compared 30-year coldest temperature averages from the past (1951–1980) and present (1995–2024) at 247 locations across the United States using NOAA’s Applied Climate Information System dataset. They found that 67% of locations have shifted to warmer zones since the 1951–1980 period.

They also used the most recently released phase of the Coupled Model Intercomparison Project (CMIP) to simulate how planting zones might shift by mid-century. In the CMIP6 scenario they used, carbon emissions decline but do not stay under Paris Agreement limits, a framework consistent with the Shared Socioeconomic Pathway 2-4.5 “middle of the road” scenario.

The models predict that the mid-century average annual coldest temperatures during the 2036–2065 time period will warm in 100% of the country by an average of 3.1°C (5.6°F). Coldest annual temperatures in the Upper Midwest, Alaska, the Northern Rockies and Plains, and the Northeast and Ohio Valley were projected to warm the most. 

Longer Seasons, Looming Threats

The results match what staff at Pine Hollow and Mount Auburn Cemetery in Cambridge, Mass., have seen. At the cemetery (which is also a botanical garden), staff have begun to test whether plants that traditionally couldn’t survive cold Massachusetts winters can now thrive. For example, staff there have begun testing crepe myrtles and paperbush, two flowering shrubs that have survived recent winters.

In Minnesota, plant hardiness zones have shifted by about half a zone since 1951–1980.

Laura Irish-Hanson, an educator and horticulturist at the University of Minnesota, tells students and local gardeners to pay attention to the hardiness map when shopping for perennials and to consider planting species more adapted to warmer climates. “Don’t just look at things that, 200-300 years ago, were native to Minnesota,” she said. “Try things that, historically, maybe are native to Iowa, or Illinois, or parts of Wisconsin that are warmer.”

Mount Auburn is also taking the long view. “The effects of a changing climate on plants and plant communities will be significant and, unfortunately, without precedent,” said Ronnit Bendavid-Val, vice president of horticulture and landscape at Mount Auburn Cemetery, in an email. “We can make informed guesses about a certain plant’s resiliency and toughness based on what is known about its adaptability to extremes in the habitats where its species evolved over millennia. However, horticulturally speaking, ‘plant hardiness’ and fitness can be a vexing subject.”

Anchorage, Alaska, is among the cities that have experienced the largest increase in average annual coldest temperatures, according to the Climate Central report, jumping from −29.8°C (−21.6°F) during 1951–1980 to −24.8°C (−12.6°F) during 1995–2024. 

At the Alaska Botanical Garden in Anchorage, hardiness zone changes aren’t the sole climate consequence affecting plants. Will Criner has been gardening there for 12 years as the garden and facilities manager. In that time, he’s noticed the growing season lengthen and, in turn, the time between the first and last frosts dwindle. “We’re definitely seeing a season extension,” he said. 

While warming temperatures could expand growing ranges for some specialty, high-value crops like oranges, almonds, and kiwis, they could also expand the ranges of pests. In Alaska, for instance, warmer winters have made it easier for the spruce beetle, a native insect capable of decimating entire tree stands, to thrive, Criner said. And Plummer expects that the spotted lanternfly, an invasive species that threatens fruit and hardwood trees in particular, will become a problem in Albany as its range expands northward. 

Warmer temperatures may also make it easier for invasive plant species to establish themselves because they would be able to spread their seeds earlier in the year. Non-native species planted intentionally in gardens may more easily grow out of control, too.

Such non-native species could outcompete other garden plants for water, sunlight, and nutrients, forcing gardeners to change their planting strategies. “I could imagine, as we get longer seasons, that some of these [non-native] plants would have to be removed from our database and deaccessioned” for other plants to thrive, Criner said.

Planting for Precipitation

As the climate warms, gardeners and horticulturists across the country have begun to think about how to better protect their plots. 

In the Midwest, gardeners increasingly face oscillating weather conditions—extreme drought and extreme flooding—that can damage and drown plants. That makes gardening even more of a challenge, Irish-Hanson said. For areas facing intensifying rainstorms, water-loving plants can help mitigate damage to a garden, she said, but they must be planted in low-lying spots to receive adequate water.

Plummer, who grew up in Albany, said he’s seen less snow and more ice and wind storms than when he was a child. Those storms can damage plants—a March 2024 ice and wind storm at Pine Hollow Arboretum felled multiple trees, which harmed other specimens. Moving forward, the facility may begin planting species more suited to a warmer climate.

Irish-Hanson recommends gardeners adapt their mindset along with their planting decisions. “Even if we do everything perfectly right and choose the right plant for our environment, it can still die,” she said. “We can be so frustrated, but then [we should] think of it as an opportunity to try something else, to do something new with that space, and not try to fight with the environment.”

Criner has similar advice: “[We should] try to be mindful of the plant choices we make and how plants interact with the surrounding environment, not just if they look pretty or not.”

—Grace van Deelen (@gvd.bsky.social), Staff Writer

Citation: van Deelen, G. (2025), As climate changes, so do gardens across the United States, Eos, 106, https://doi.org/10.1029/2025EO250203. Published on 28 May 2025.

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Historic wildfires broke out in South Korea in late March 2025, killing 32 people, injuring 45, and displacing about 37,000. In total, the fires burned more than 100,000 hectares (about 247,000 acres), nearly quadruple the area that burned in the country’s previous worst recorded fire season in 2000. (In comparison, the January 2025 Palisades and Eaton Fires in Southern California burned about 91,000 hectares, or 37,000 acres.)

A new study by scientists with World Weather Attribution (WWA) suggests that atmospheric warming—caused primarily by fossil fuel burning—made the hot, dry, and windy conditions that drove the South Korean fires about twice as likely and 15% more intense.

About 5,000 buildings burned, including homes, industrial structures, farms, and cultural heritage sites such as the Gounsa Temple in Uiseong, which was originally built in 618 CE.

“The scale and speed of the fires were unlike anything we’ve ever experienced in South Korea,” said June-Yi Lee, an atmospheric scientist at Pusan National University and the Institute for Basic Science, in a statement. “This study adds to a growing body of science showing how climate change is making weather conditions more favorable to dangerous wildfires.”

Hot, Dry, and Windy

WWA researchers examined the Hot-Dry-Windy Index (HDWI) across the entire country for the month of March. This metric calculates fire risk from temperature, humidity, and wind speed observations.

The combination of high temperatures, low humidity, and high wind speeds that occurred from 22 to 26 March were unusual, even for today’s climate, the researchers found. Such conditions are expected to occur in March only once every 340 years. But this combination of conditions would have been even rarer in a preindustrial climate, occurring only once every 744 years.

The study suggests that the trend in the HDWI was driven primarily by unseasonably high temperatures.

“From March 22–26, the daily maximum average temperature in southeastern Korea averaged around 25°C, which was 10°C higher than the normal March average,” Lee said in a press briefing. Little rain fell in the region this winter, which, combined with high temperatures, led to drier, more flammable fuels. Relative humidity was around 20% at the time of the fires, not unusual for March. Wind speeds on 25 March reached up to 25 meters per second, a short-lived spike that helped the fires spread quickly.

The WWA team also calculated that if the climate warms by another 1.3°C by 2100, the HDWI will continue to increase, with the conditions behind such fires growing another 2 times as likely.

The nature of WWA’s rapid response studies means they are not peer reviewed, but they have published peer-reviewed studies on the methodology they use in all of their analyses. The study marks the World Weather Attribution’s 100th rapid analysis since the organization formed in 2014. It is the sixth to focus on a wildfire.

A Strong Case

ClimaMeter, another project that examines how extreme weather events may have been affected by a changing climate, released a study about South Korea’s wildfires on 25 March. (As with the WWA study, it was not peer reviewed but used peer-reviewed methods.)

ClimaMeter uses a different methodology than WWA does but had similar findings, reporting that the meteorological conditions leading up to the fires were about 2°C hotter, 30% drier, and 10% windier compared with similar past events.

Davide Faranda, a physicist with the French National Centre for Scientific Research and coordinator of ClimaMeter, pointed out that their study showed climate change strengthened the meteorological conditions conducive to fires, not necessarily that climate change caused the fires. He was not involved with the WWA study but noted that the two groups’ rapid response studies often arrive at similar or complementary findings.

“For the moment, it’s more difficult to prove that climate change did not affect an event,” he said.

“A decade ago, the influence of climate change on events was less clear. But now it’s undeniable. The wildfires in South Korea are a case in point,” said Friederike Otto, WWA colead and a climatologist at Imperial College London, in a statement.

—Emily Dieckman (@emfurd.bsky.social), Associate Editor

Citation: Dieckman, E. (2025), Climate change heightened conditions of South Korean fires, Eos, 106, https://doi.org/10.1029/2025EO250170. Published on 30 April 2025.

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Each year in early March, when summer turns to fall in the Southern Hemisphere, New Zealand glaciologists gather at an airfield in Queenstown to embark on a predawn flight along the spine of the Southern Alps.

For hours, they twist in the Cessna’s narrow seats to train cameras on glaciers clinging to mountaintops. The images capture the glaciers’ vanishing contours and the shifting snowline—the demarcation between the remains of the winter snowpack and exposed glacial ice.

“It’s like a bank account,” said Andrew Lorrey, a climate scientist at the National Institute of Water and Atmospheric Research who has been coordinating the surveys for 16 years. “If we put in the same amount of snow in winter as we’re taking out in summer, the glacier would be in balance, melting at its terminus but advancing downhill due to gravity and replenishing the ice that’s lost.”

But the surveys, which have been running since 1977, show that summer melt now far exceeds winter snowfall and “we’re seeing the glaciers’ terminus and sides, the whole body, diminishing.”

New Zealand has lost more than a third of its glacial ice and the archipelago ranks third globally—after central Europe and the Caucasus—in the proportion of ice lost to rising temperatures, according to findings published in Nature by the first comprehensive global Glacier Mass Balance Intercomparison Exercise (GlaMBIE).

Global Assessment of Glacial Retreat

The project assessed observations from 35 international teams, with a goal of reconciling all methods used to track glacial mass changes. These methodologies range from in situ measurements (in which scientists stud individual glaciers with ablation stakes to record their shrinkage) to various satellite-borne sensors (which use optical, radar, laser, and gravimetry technologies to track changes in glacial surface elevation).

Bringing all these methodologies together, the GlaMBIE team produced a time series of global glacial mass change between 2000 and 2023, showing that collectively, the world’s glaciers lost 5% of their total volume. “This may not seem much,” said Michael Zemp, GlaMBIE project leader and director of the World Glacier Monitoring Service at the University of Zürich. But it means an annual global loss of 273 billion tonnes (301 billion tons) of ice.

“To put this in perspective,” Zemp said, “the ice lost each year amounts to the water intake of the entire global population in 30 years, assuming 3 liters per person a day.”

Andrew Shepherd, an Earth scientist at Northumbria University who was not involved in this project but has led a similar assessment of mass loss from polar ice sheets, welcomed the authoritative standardized framework provided by GlaMBIE.

Reconciling the different methodologies is important because “climate change isn’t smooth,” Shepherd said. Short-term in situ measurements can deliver contrasting results and each satellite technique has its strengths and weaknesses, but “bringing all methods together leads to a clearer picture of total ice loss,” he noted.

Although all areas experienced ice loss, the GlaMBIE results show significant differences between regions, ranging from 1.5% ice loss in the Antarctic to 39% in central Europe.

The largest overall contribution to ice loss (22%) comes from Alaska, said Caitlyn Florentine, a research physical scientist with the U.S. Geological Survey in Bozeman, Mont., and a GlaMBIE member.

Alaska, like the Canadian Arctic and Greenland, has enormous volumes of ice. But the relatively low elevation and latitude of Alaskan glaciers meant that these ice fields “were the biggest contributor to sea level rise [from glaciers] in the first 2 decades of this century and are projected to continue [to be] until 2100,” Florentine explained.

The GlaMBIE results also revealed clear evidence of increasing melt rates, with a 36% jump during the second half of the study period, from 2012 to 2023. Mountain glaciers hold enough water to raise sea level by 32 centimeters if all were to melt. The ice that has already been lost from the world’s mountains has contributed 18% more to sea level rise than the loss from the Greenland Ice Sheet and more than twice the loss from the Antarctic Ice Sheet.

“Even small amounts of sea level rise matter, because it leads to more frequent coastal flooding,” Shepherd said. “Every centimeter of sea level rise exposes another 2 million people to annual flooding somewhere on our planet.”

Zemp hopes to focus future work on assessing how glacier melt affects seasonal runoff, and that requires ongoing access to satellite data and higher-resolution remote sensing techniques. As some satellites and sensors approach the end of their missions, he’s concerned about continuing the study. “If we are left without open access to high-resolution stereo imaging missions with a global coverage, we’d be blind to these changes,” he said.

Gone This Century

In addition to the ice sheets in Antarctica and Greenland, there are more than 275,000 glaciers—or crystal cones, as Zemp calls them—in mountain ranges from the tropics to the polar regions. Only about 500 are monitored up close.

One is Brewster Glacier in New Zealand, which Te Herenga Waka–Victoria University of Wellington glaciologist Lauren Vargo visits regularly. She drills ablation stakes into the ice in spring and retrieves their exposed parts in fall. In the 8 years between 2016 and 2024, she’s helped document that the glacier has shrunk by 24% and lost 17 meters in height.

The retreat made Vargo’s latest visit, in March, physically taxing, she said. “The more melt that happens, the more stakes you have to collect,” she explained. “I don’t think I could have carried any more stakes.”

Many glaciers will not survive this century, Zemp said. Among these is one of his favorites, Oberaargletscher at Grimselpass in Switzerland, which Zemp has studied for almost a quarter of a century and, more recently, began visiting with his sons.

Oberaargletscher will be gone by 2050, regardless of any cuts to carbon emissions, Zemp said. While the retreat is “interesting to witness as a scientist,” he continued, “I am deeply sad that my sons and their generation will lose this fantastic glacier.”

—Veronika Meduna (@veronikameduna.bsky.social), Science Writer

Citation: Meduna, V. (2025), First global comparison of glacier mass change: They’re all melting, and fast, Eos, 106, https://doi.org/10.1029/2025EO250141. Published on 15 April 2025.

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On 6 February 2023, a pair of powerful earthquakes—magnitudes 7.8 and 7.5—struck southern Türkiye and northwestern Syria 9 hours apart, killing 59,000 people and causing catastrophic damage.

While in the area mapping earthquake-triggered landslides the following month, Istanbul Technical University geomorphologist Tolga Görüm and his team noticed an atmospheric river approaching the disaster zone. They found this worrying, because an earthquake can weaken surrounding slopes for months and possibly years, making them vulnerable to heavy rainfall.

In a recent Communications Earth & Environment study, Görüm and colleagues documented the atmospheric river’s characteristics and how it caused flooding, landslides, and, tragically, further loss of life in the already devastated region. According to the team, the case study demonstrates a need for updated hazard models that better integrate various atmospheric and seismic hazards, particularly as climate change is expected to intensify atmospheric rivers in some regions.

A Once-in-20-Year Storm

For the study, the scientists analyzed global climate data from the European Centre for Medium-Range Weather Forecasts’ Reanalysis v5 (ERA5). The data revealed that the atmospheric river, originating over the Red Sea, carried more moisture than did 99.99% of all such events recorded in the region. When that moisture hit southern Türkiye’s Taurus Mountains on 14 and 15 March 2023, the resulting upward airflow along the slopes produced extreme rainfall.

“This was the heaviest rainfall event in the area in the last 20 years,” Görüm said. In the Turkish town of Tut, the storm delivered up to 183 millimeters (7.2 inches) of rain within 20 hours. In addition, warm temperatures had caused snowmelt in the mountains just before the atmospheric river arrived, leaving the soil saturated with water and further reducing its stability.

By analyzing the strength of shaking, the steepness of the terrain, and the position of the slopes, the scientists estimated that the shear strength of hillsides—the ability of soil and rock to resist sliding when subjected to a force—in the Tut region was weakened by 52%–77%.

The consequences were severe. “The atmospheric river hit the area, triggered significant sediment movement, and killed more than 20 people,” Görüm said. Twelve of those deaths were within the study area. The resulting landslides, debris flows, and flooding also disrupted ongoing recovery efforts from the earthquake.

The catastrophe was the result of unfortunate timing. Using a computational model, the scientists ran simulations for earthquakes occurring in different seasons and tracked landslide probability over 5 years. They found that had the earthquakes occurred during summer or fall instead of winter, the recovery period wouldn’t have coincided with peak atmospheric river season, and the landslide hazard would have been significantly reduced.

Ben Leshchinsky, a civil engineer at Oregon State University who has studied cascading hazards but wasn’t involved in the research, said this study “highlights the importance of remembering there is a legacy to hazards. It’s incredibly important to keep following what happens so we can make sure we recover more quickly and plan for recovery in a smarter, more resilient way.”

Anticipating the Worst

Preparing for contemporaneous disasters might become increasingly relevant. Using 40 years of data, the researchers showed that Türkiye has experienced a significant increase in atmospheric river frequency and intensity, likely driven by climate change.

This trend extends beyond Türkiye to other seismically active regions worldwide. “On the Pacific coast [of the United States], the frequency and magnitude of atmospheric rivers is even higher than our area,” Görüm noted, adding that Southern California is seismically similar to Türkiye. These parallels suggest that lessons learned from Türkiye’s experience could help vulnerable communities around the globe develop more comprehensive disaster preparedness plans.

Bruce Malamud, a geophysicist at Durham University who wasn’t involved in the study, noted that it can be dangerous when multiple hazards coincide, because government agencies focusing on different hazards work independently, so their disaster responses aren’t coordinated. “What’s important about this paper is that it reinforces the argument that we need to be thinking about these coincident hazards,” he said.

Having spent time in the disaster zone following the 2023 earthquakes, Görüm saw damaged cities and the struggles of response crews to rescue people; he understands more than most the need to warn communities of additional hazards. “It was like a nightmare,” he said.

It’s taxing to work in those conditions, he said, “but at the same time it’s quite important. You have to learn from this type of event.”

—Andrew Chapman (@andrewchapman.bsky.social), Science Writer

Citation: Chapman, A. (2025), An atmospheric river exacerbated Türkiye’s 2023 earthquake crisis, Eos, 106, https://doi.org/10.1029/2025EO250132. Published on 8 April 2025.

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Source: Journal of Geophysical Research: Oceans

The vast Antarctic Ice Sheet holds more than half of Earth’s freshwater. In several places around the continent, the ice extends over the ocean, where it forms large floating shelves. Observations suggest many of these ice shelves are thinning as they melt from below, with implications for ocean dynamics, global sea level, and Earth’s climate.

For now, the Filchner-Ronne Ice Shelf—one of Antarctica’s biggest, extending over the Weddell Sea—appears to be relatively stable, thanks to near-freezing currents circulating over the continental shelf beneath it. However, climate models predict that shifting ocean currents may bring warmer water to the continental shelf in the future.

To gain a clearer picture of the Filchner-Ronne Ice Shelf’s future, Steiger et al. analyzed water temperature and velocity data from 2017 to 2021. The data were captured by sensors attached to bottom moorings along the seafloor and subsurface floats near the ice shelf.

Prior research had already shown that during summer, relatively warm seawater rises from middle depths in the nearby ocean up to the continental shelf, then along the undersea Filchner Trough toward the edge of the ice shelf. However, most of these observations have been limited to single-site or single-year data.

In this study, researchers found that the summertime flow of warm water occurs not just along the Filchner Trough but also along a second, smaller trough to the east and that the relative importance of each path varies from year to year. During warmer-than-average years, the warm water flows more rapidly across the continental shelf.

The analysis also highlights two summers, 2017 and 2018, when both anomalously warm inflows and anomalously low amounts of floating sea ice occurred. The researchers suggest that scant ice cover alters ocean dynamics, causing warm water to rise and more readily surge onto the continental shelf.

It is not clear whether the warmer flows of 2017 and 2018 actually reached the edge of the Filchner-Ronne Ice Shelf itself. However, researchers did observe warmer waters meeting the ice in summer 2013, and previous research suggested this warm water movement was associated with wind patterns. Ongoing observation could help clarify the precise drivers of year-to-year differences in this warm water flow. (Journal of Geophysical Research: Oceans, https://doi.org/10.1029/2023JC020700, 2024)

—Sarah Stanley, Science Writer

Citation: Stanley, S. (2025), Warm seawater encroaches on major Antarctic ice shelf, Eos, 106, https://doi.org/10.1029/2025EO250011. Published on 8 January 2025.

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Source: AGU Advances

Over the past several decades, summer jet streams (or west to east wind flow) and weather systems in the Northern Hemisphere have weakened. Projections suggest the trend will continue, which could make extreme heat events more likely and affect air quality.

Some studies have hypothesized that the weakening is related to Arctic amplification, or the way the Arctic is warming more quickly than the rest of the planet, because this phenomenon reduces the temperature difference between the equator and the North Pole. But others have suggested that anthropogenic emissions of aerosols, which lead to a similarly weakened gradient, may be more directly to blame.

Using Detection and Attribution Model Intercomparison Project (DAMIP) data, Kang et al. studied how anthropogenic factors may have influenced summertime circulation patterns between 1980 and 2020. They found that aerosols play just as big a role as greenhouse gases in the slowdown of wind patterns and atmospheric flow during the summer months. Changes in aerosol emissions can influence the strength of the weather systems by altering the flow of energy between land and ocean.

A reduction in aerosol emissions in North America and Europe during this period meant more sunlight reaching the surface, causing a greater energy contrast between these land surfaces and the ocean. This caused energy export to the air over the ocean. As a result, the energy converged over the higher-latitude ocean (40°N–70°N), weakening the gradient between the poles and the equator, as well as the weather systems. This effect is about twice as pronounced over the Pacific because aerosol emissions were reduced more in Eurasia than in North America.

Increased aerosol pollution from South and East Asia had the same weather-weakening effect, but through the opposite process: The increased pollution decreased the amount of solar energy that reached the surface and reduced the energy transport between land and the lower-latitude (25°N–40°N) Pacific Ocean. Ultimately, less energy converged over the lower-latitude Pacific, further weakening the energy gradient and the weather systems.

Because aerosols have shaped summertime circulation patterns over the past 40 years, it will be important to continue research on how they may shape future summer climate trends, the researchers write. (AGU Advances, https://doi.org/10.1029/2024AV001318, 2024)

—Rebecca Owen (@beccapox), Science Writer

Citation: Owen, R. (2024), Aerosols could be weakening summertime circulation, Eos, 105, https://doi.org/10.1029/2024EO240556. Published on 18 December 2024.

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This weekend, people all across the United States will be enjoying the last hurrah of summer, perhaps with a trip to the nearest swimming hole. But an influx of bathers, tubers, and paddle boarders could significantly change the composition of freshwater streams, according to new research published in ACS ES&T Water.

“People are exposed to other chemicals based on the choices of their fellow swimmers. And you’re all swimming around in it like a soup,” said Carsten Prasse, an environmental chemist at Johns Hopkins University and an author on the study, in a statement.

Not-So-Clear Creek

Most research studying how recreation affects water bodies has focused on oceans and tested for specific compounds rather than attempting to identify the array of organic, inorganic, and microbial elements present. Prasse and his colleagues took the latter approach, using multiple mass spectrometry methods and gene sequencing to determine as many components of the stream as possible.

The team collected water samples upstream and downstream of a section of Clear Creek in Golden, Colo., a popular river tubing destination, during Labor Day weekend in 2022 as well as on the morning of the following Tuesday, when there was no tubing activity.

Downstream of weekend tubing, the stream’s composition changed significantly. The water contained a very different array of organic compounds, mostly from personal care products such as lotions, shampoos, and makeup. The research team also identified compounds that originate in plastic products, such as phthalates, and compounds known to be toxic to fish, including oxybenzone (an ultraviolet filter used in sunscreens). Traces of pharmaceuticals and illicit drugs, including acetaminophen and cocaine, were also present.

The microbial community in the river shifted, too, containing more species associated with the human gut.

By the following Tuesday, most of the compounds and microorganisms were no longer detectable, showing that the changes to the stream were short-lived.

The team expected to see a change in the occurrence of metals such as titanium and zinc because of mineral sunscreens washing off into the water, Prasse told Eos. But sediment in Clear Creek already has naturally high concentrations of metals, and recreational activity suspends this sediment in the water. “The background signal was basically too high to distinguish any additional metal particles from sunscreens.”

Recreation Risks

“The new angle here is that…everyday activities leave a water quality fingerprint that we can now detect with all these cutting-edge tools,” said Sujay Kaushal, a biogeochemist at the University of Maryland who was not involved in the study. Capturing a holistic picture of the composition of a stream, as this study did, can help to make future water management strategies more effective because managers can consider how all components in the stream are transported together and interact, he said. “They discovered a new chemical cocktail.”

The next step is to determine the impacts this cocktail of chemicals and microbes has on surrounding ecosystems or people, Prasse said. But scientists know very little about the environmental health impacts of many of the compounds detected in Clear Creek. The team also didn’t measure the concentrations of the compounds in the water, so it’s hard to tell what the magnitude of the environmental impacts may be, he said. 

Prasse emphasized that his team’s findings don’t mean people should stay out of water bodies this weekend, but they should be more aware of the substances they’re introducing into the environment. Using mineral sunscreens instead of those containing oxybenzone is one place to start, he said.

—Grace van Deelen (@GVD__), Staff Writer

Citation: van Deelen, G. (2024), Labor Day dips alter stream composition, Eos, 105, https://doi.org/10.1029/2024EO240397. Published on 30 August 2024.

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Forested areas absorb billions of tons of carbon dioxide each year—and new research suggests trees could also be sequestering another important greenhouse gas: methane.

Microbes that live on trees take up between 25 million and 50 million metric tons of methane each year, according to a study published in Nature. The findings suggest that certain forests could serve as net methane sinks and that reforestation could have greater benefits than expected.

“I think it’s very exciting research,” said Luke Jeffrey, an aquatic biogeochemist at Southern Cross University in Lismore, Australia, who was not involved in the new study. “It just shows us there’s so very little we know about the role of trees within the global methane cycle.”

Methane is the second-most abundant greenhouse gas emitted by human activity, after carbon dioxide (CO₂). It enters the atmosphere through sources such as agriculture, mining, and the decomposition of waste in landfills. Though methane is some 200 times less prevalent than CO₂ in the atmosphere, it traps heat more effectively.

Methane also finds its way into the air through natural sources, such as trees. The phenomenon is particularly prevalent in areas where the water table is high, such as the Amazon basin.

Previous research has indicated that naturally occurring microbes can curb these emissions. A 2021 study, for instance, found methane-eating microbes living in the bark of the Australian paperbark tree (Melaleuca quinquenervia). These microbes offset methane emissions of swamp-dwelling paperbarks by about a third.

In the new study, researchers led by Vincent Gauci, an environmental scientist at the University of Birmingham in the United Kingdom, measured methane uptake and emissions in trees around the world.

Top, Down, and All Around

In addition to studying trees in different types of forests—tropical, temperate, and hemiboreal—Gauci and his colleagues documented the methane uptake and output at different heights on the trees.

In line with previous results, the researchers found that trees in tropical zones emit methane during wet periods. But in the dry season, tropical trees behave more like their temperate and hemiboreal counterparts: They continue to emit methane at the ground-level base of their trunks, but just a few tens of centimeters above the ground, the emission rate slows so much that other processes outcompete and trees actually behave as methane sinks.

“It’s quite interesting, because you don’t expect to find a [methane] sink,” Gauci said.

Gauci explained the results by describing the role of trees in the methane cycle. Tree roots take up methane from the soil around them. That methane diffuses back out to the atmosphere through bark. But the effect diminishes farther up from the soil, especially during dry periods when the water table is meters below the soil surface. At the same time, microbes in the bark metabolize methane from the air all along the trunk. Eventually, the rate at which these microbes absorb methane from the atmosphere outpaces the rate that the gas diffuses out from the tree.

Terrestrial Laser Scanning

As part of their research, the team estimated the area of Earth’s surface covered by trees and woody plants by using a technique called terrestrial laser scanning. They set up a laser scanning instrument to bounce light off surfaces and constructed a 3D image of forested areas in different biomes. They then extrapolated the findings to global woody surface area. The technique is “like the sorts of laser scans that you find in front of these new cars that prevent crashes,” Gauci said.

The surface area of trees around the world covers 143 million square kilometers—about the size of all the land area on Earth. Few prior estimates of global bark surface area exist, Jeffrey said, so “this is a great advancement in the literature, to have this new global surface area that we can work with.”

On the basis of their surface area estimate and methane measurements, the researchers determined that microbes on trees around the world could capture between 25 million and 50 million metric tons of methane each year. Such methane sequestration could have as much climate impact as sequestering between 197 million and 399 million metric tons of CO₂, according to the researchers.

The newly discovered methane sink means that planting more trees could offer an additional 10% benefit to the climate on top of what’s already predicted from reforestation efforts, according to the team’s calculations.

“We know we need to reduce our emissions,” Gauci said. “But this also tells us that if deforestation is diminishing the sink, that’s not going to help either.”

—Skyler Ware (@skylerdware), Science Writer

Citation: Ware, S. (2024), Microbes in tree bark absorb millions of tons of methane each year, Eos, 105, https://doi.org/10.1029/2024EO240376. Published on 23 August 2024.

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In 2023, a marine heat wave gripped the oceans, and coral reefs around the world bleached, turning ghostly white. NOAA estimates that since 1 January 2023, more than 72% of reef area worldwide could have been affected.

When stressed, corals bleach—they expel the symbiotic algae that lend them their vibrant colors and their main source of food. Reefs can sometimes recover from bleaching. But sufficiently long, extreme, or frequent heat waves can kill. In the Florida Keys, where NOAA is investing nearly $100 million in coral restoration, record-breaking temperatures killed more than one third of planted staghorn corals and up to 95% of planted elkhorn corals.

Bleaching typically begins in late summer, when water temperatures peak. But as oceans warm, many reefs could begin to bleach in spring by 2080, according to a new study. Along the equator, some reefs may be at high risk of bleaching year-round.

Warming seas threaten reefs worldwide, but scientists are still working to understand when and where bleaching will be most severe.

On the basis of two different climate projections, a group of scientists assessed bleaching risk around the world. The analysis, published in a paper in Science Advances, compared a future scenario with high greenhouse gas emissions (Shared Socioeconomic Pathway (SSP) 5-8.5) to a medium-emissions scenario (SSP2-4.5) that reflects the world as it would be if countries stick to their existing pledges to limit emissions.

“It’s important for us to predict how different reef sites across the globe will fare,” said coral reef ecologist Miguel Mies of the University of São Paulo in Brazil. “It’s very difficult to predict,” he added, because heat stress is just one of many relevant factors. “But for their metric, they did a really good job.”

The researchers divided a map of the world’s reefs into tens of thousands of square pixels, each about 50 kilometers on a side. Then, using the Coupled Model Intercomparison Project Phase 6 (CMIP6) projections for day-to-day sea surface temperature, they assessed multiple factors associated with bleaching risk, including the severity, duration, and timing of heat stress.

“The innovation of our paper is that we didn’t just look at how severe it will be, but also how long it would last during the year,” said quantitative biologist Camille Mellin of the University of Adelaide.

Mellin and her colleagues tuned their model by comparing its predictions to real records of sea surface temperature and coral bleaching from 1985 to 2014, then tested the two different climate scenarios for the future. The calculation took some serious computational heft—the team needed a supercomputer to get the job done.

Comparing the two emissions scenarios revealed regions where cutting greenhouse gas emissions could benefit reefs most. Coastal Venezuela and Colombia, for instance, are expected to experience lower bleaching risk than the rest of the Caribbean thanks to upwellings of cool, deep water. But in some large regions, especially those right along the equator, reducing emissions didn’t reduce bleaching much.

Some regions, including parts of the Pacific Coral Triangle and Micronesia, as well as waters off the Pacific coasts of Panama, Colombia, and Ecuador, will begin bleaching in spring instead of summer even in the medium-emissions scenario. In the high-emissions scenario reefs off Hawaii’s coasts would begin bleaching in spring, too. By 2080, reefs in the most vulnerable spots along the equator, such as the eastern Coral Triangle, the Marshall Islands, and central Polynesia, could bleach year-round.

Nothing Left to Save

Even that grim projection could be “almost misleading,” said Maria Beger of the University of Leeds, who was not involved in the work. “The reefs don’t have time, you know, reefs are being degraded now, reefs are dying now.” By some estimates, more than half of the reefs alive in 1950 have already died. “In 2080—we don’t care, nothing will be left if nothing happens now,” she said.

Tom Goreau, the president of the Global Coral Reef Alliance, likewise stressed the urgency of reducing emissions and protecting reefs now. Generations of his family have documented reefs for almost a century. “What we’ve learned is they’re disappearing much faster than anyone who makes models can realize.”

James Guest, a coral reef ecologist at Newcastle University who was not involved in the study, pointed out that this study doesn’t account for corals’ ability to adapt to changing conditions—a limitation the study authors acknowledged. For now, there just weren’t enough data to include adaptation in the model, Mellin said. “Future research should really focus on that.”

“We’ve lost 55% of what we had. And we still losing a lot,” Mies said. Adaptation won’t change that, he said—most reefs will not be able to cope with how fast the climate is changing. “But some, a small portion of that, will adapt. And that’s what’s going to survive.”

—Elise Cutts (@elisecutts), Science Writer

Citation: Cutts, E. (2024), Some reefs could bleach year-round by 2080, Eos, 105, https://doi.org/10.1029/2024EO240354. Published on [DAY MONTH] 2024.

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Climate simulations created by the United Nations’ Intergovernmental Panel on Climate Change (IPCC) indicate that the planet could warm roughly 3°C by the end of the century under intermediate carbon emissions scenarios. But how such a rise might manifest in seasonal and regional temperature changes can be difficult to test.

Focusing on western Europe, a group of researchers looked back 3.3 million years ago, when Earth was about as warm as it is predicted to be in the year 2100, for clues. Fossilized shells from the time give a season-by-season account of regional temperatures and show that summer and winter may not warm at the same rate. The new study was published in Science Advances.

A Blurry Picture

Temperature projections can be tested on multiyear scales relatively easily. Paleoclimatologists often turn to sediment deposits to search for buried fossils or certain isotopes that can indicate temperature conditions. These deposits can show changes over a long period of time because sediment buildup can take “literally ages,” said Niels de Winter, a paleoclimatologist at Vrije Universiteit Amsterdam and first author on the study.

“But what’s really impactful for us as humans is to see the impacts of two or three degrees warming on extreme weather events in our seasons,” said de Winter. Smaller-scale fluctuations in temperature such as these can be harder to predict.

Shorter records, such as from the rings of a tree, may be used to tease out seasonal conditions, but trees don’t preserve well over millions of years. Fossilized shells, however, do.

While living, some marine critters record the seasonal temperature changes around them in each new ringed growth of their calcium carbonate shell. “They record environmental change on a very short timescale,” de Winter said. “And so we’re able to do a snapshot of the climate in this warm period [3.3 million years ago].”

Shells are also abundant. De Winter and his colleagues analyzed fossil mollusk shells from the collection of the Royal Belgian Institute of Natural Sciences in Brussels. They chose shells gathered from harbor excavations in Antwerp, Belgium, near the North Sea.

The researchers measured oxygen and carbon isotopes along cross sections of the shells. To what degree the heavier isotopes of oxygen and carbon are bonded together rather than to other lighter isotopes is dependent on the temperature of the water in which each part of the shell grew. From this, a technique known as clumped isotope thermometry, the researchers could pull out seasonal temperature differences.

“This is an elegant and unique method of data-model comparison,” wrote Harry Dowsett, a research geologist with the U.S. Geological Survey who was not involved with the study, in an email.

The fossilized shells recorded winters that were about 2.5°C warmer than current sea surface temperatures and summers that were about 4.3°C warmer. The findings corroborate the general IPCC climate simulations and suggest that in the future, as average temperatures rise by roughly 3°C, the summers could warm much more than winters will.

“This is a pretty worrisome prediction,” de Winter said. These numbers suggest that Europe may face prolonged heat in the summer in the coming decades—conditions the area is already struggling to deal with. A record heat wave affected the region in July 2023, topping the heat waves in 2022 that caused 60,000 reported deaths.

“This work is an excellent example of how deep-time paleoclimate research has a direct bearing on our understanding and preparing for future climate change,” Dowsett said.

Clouds and Insulation

Scientists are still trying to understand why summers may warm faster than winters. The reason could, in part, be clouds—simulations show a reduction in cloud cover in northwestern Europe during the summer as westerly winds decrease, which may increase warming. Conversely, winter cloud cover did not significantly change.

Sea ice may also play a factor, de Winter said. “It insulates the winter.” Arctic ice cools the ocean, making heat transfer from the ocean into the atmosphere less efficient and keeping air temperatures relatively low in the winters.

In the future, de Winter plans on expanding the project to analyze shells all over northwestern Europe to further understand how the region will experience a warmer climate.

—Sierra Bouchér, Science Writer

Citation: Bouchér, S. (2024), Fossilized shells reveal the seasonality of a warmer climate, Eos, 105, https://doi.org/10.1029/2024EO240315. Published on 26 July 2024.

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Western disturbances describe a system of winds that bring snow and rainfall to northern India during winter months. They originate west of the Hindu Kush and the Himalaya mountains, sometimes as far away as the Mediterranean Sea, and are vital for ensuring water security across states in northern India.

A new study published in the journal Weather and Climate Dynamics found a seasonal shift in western disturbances: They are now occurring more frequently in summer months, when they were once rare. Western disturbances have become twice as common in June in the past 20 years than during the previous 50 years.

Typically, western disturbances occur between December and March. That timing benefits farmers and boosts water security, because the heavy precipitation recharges mountain glaciers and snowpack that lose mass in the warmer summer months.

“Winter precipitation is important for livelihoods [in northern Indian Himalayan states] because it ensures water availability in the subsequent spring season,” said A. P. Dimri, a climate scientist at Jawaharlal Nehru University who was not affiliated with the study.

The snow and ice associated with western disturbances melt in the spring, making up a large proportion of runoff in the Indus-Ganges river system—an artery that provides water for irrigation, hydropower, and household use for the roughly half a billion people living in its plains.

But 70 years of storm track data from a climate hindcast (European Centre for Medium-Range Weather Forecasts Reanalysis version 5; ERA5) show that the western disturbance season has gotten longer. It now stretches into May, June, and July, when the weather pattern can sometimes interact with the summer monsoon, which begins in June. The result is worse flooding.

“In the winter, the atmosphere is drier because it’s colder. So western disturbances have to draw their own water from the Arabian Sea, and typically, they do not cause floods,” said Kieran Hunt, the author of the study and a meteorologist at the University of Reading. A lot of the precipitation falls as snow, which melts slowly through the spring. But an overlap between western disturbances and monsoons—which carry about 6–7 times more moisture—can be catastrophic.

“We had anecdotal evidence of western disturbances interacting with the monsoon, but now we have been able to show the trend [in shifting patterns] more clearly,” Hunt said. Flash floods in 2013 in the Himalayan state of Uttarakhand claimed around 6,000 lives. They happened in June, when western disturbances struck during the summer monsoon. The same happened in July 2023, leading to floods in many northern Indian states, including in the capital, New Delhi.

The changing pattern of western disturbances is “very concerning,” especially because it has the potential to result in weather extremes, said Rajib Chattopadhyay, a meteorologist at the Indian Institute of Tropical Meteorology.

The Climate Link

Western disturbances are steered by the subtropical jet stream, a high-altitude air current.

Climate change has altered the jet stream’s movement: Polar regions have become warmer, reducing the temperature gradient between them and the tropical regions to the south. The force that used to draw the jet stream northward before the monsoon season is therefore weaker, extending the time storms pass over India.

The weakening temperature gradient also means that the jet stream is more susceptible to local factors. One dominant local factor, according to Hunt, is the rapid warming of the Tibetan Plateau. Studies have previously shown that the region is warming at rates almost twice the global average. This makes the plateau warmer than surrounding regions, resulting in a temperature gradient that strengthens the jet stream, intensifying western disturbances and making them more frequent.

Another local factor, according to Hunt, may be the reduction in aerosols over northern India due to air pollution control measures, which has made the local atmosphere warmer and the temperature gradient stronger, also strengthening the jet stream.

“We need to give more attention to western disturbance forecasts,” Chattopadhyay said, adding that “it is useful to get some first-order outlook on impending disasters of flash flood, cloudbursts, etc., during monsoon and cold wave or snowfall during other seasons.”

—Rishika Pardikar (@rishpardikar), Science Writer

2 May 2024: This article was updated to clarify water use in the basin.

Citation: Pardikar, R. (2024), Shifting winter storms bring more flooding to India, Eos, 105, https://doi.org/10.1029/2024EO240192. Published on 1 May 2024.

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This is an authorized translation of an Eos article. Esta es una traducción al español autorizada de un artículo de Eos.

Según un nuevo análisis publicado en Scientific Reports, el evento de El Niño en curso probablemente causará un rompimiento de récords en las temperaturas promedio superficiales del aire en varias partes del mundo antes de empezar a decaer este verano.

Los investigadores mencionan que existe un 90% de probabilidad de que las temperaturas superficiales medias globales desde julio de 2023 hasta junio de 2024 sean las más altas jamás registradas. Es probable que partes del sudeste asiático, Alaska, el mar Caribe y la región amazónica sean las más propensas a experimentar este efecto.

“Conocer que estas son regiones con riesgo potencial en algún momento de este año nos otorga una ventaja al momento de preparar un plan sobre cómo proteger vidas, propiedades y los recursos marinos vivos”, dijo Michael McPhaden, coautor del estudio y científico climático en el Laboratorio Ambiental Marino del Pacífico de la NOAA.

El Niño persiste

El Niño Oscilación del Sur, o ENOS, hace referencia a un patrón climático que determina cómo se almacena el calor en los océanos del mundo.

ENOS incluye una fase cálida (El Niño), en la cual los débiles vientos alisios del este dejan aguas cálidas frente a la costa oeste de las Américas, y una fase fría (La Niña), durante la cual estos vientos son más fuertes, conduciendo agua superficial cálida hacia el oeste y causando el ascenso de aguas más frías y profundas.

Estas fases cambian aproximadamente cada dos a siete años. Durante las condiciones de El Niño, el calor almacenado en el océano se libera a la atmósfera, calentando el aire en los trópicos y más allá de ellos.

La Tierra ha estado experimentando condiciones de El Niño desde junio de 2023, por lo cual, los científicos lo han ligado a las altas temperaturas jamás registradas.

Usando datos de las condiciones actuales del ENOS, concentraciones de gases de efecto invernadero en la atmósfera, concentraciones de aerosoles, y las anomalías de temperatura existentes, los investigadores modelaron los efectos del actual El Niño en las temperaturas promedio globales del aire en la superficie. El modelo utilizó datos desde el inicio actual del ENOS en junio de 2023 hasta su probable transición a un estado neutral para julio de 2024.

El equipo estimó la intensidad de los escenarios de El Niño en función de las temperaturas superficiales del mar previstas dentro de un área del Pacífico central que es particularmente sensible a las fluctuaciones del ENOS, conocida como la región El Niño 3.4. En sus proyecciones, las condiciones de El Niño moderadas se definen como aquellas con desviaciones de temperatura superficial del mar de 1°C a 1.5°C (1.8°F a 2.7°F) durante un mínimo de tres meses, y las condiciones de El Niño fuertes se refieren a desviaciones mayores a 1.5°C (2.7°F) durante un mínimo de tres meses.

El Niño actual se considera fuerte, ya que el aumento de la temperatura superficial del mar ha superado los 1.5°C (2.7°F) desde agosto. El evento probablemente estará entre los cinco más fuertes jamás registrados, según McPhaden y Marybeth Arcodia, una científica climática de la Universidad Estatal de Colorado que no participó en la investigación.

Los investigadores encontraron que si las condiciones actuales continúan, hay un 90% de probabilidad de que las temperaturas promedio globales del aire en la superficie sigan rompiendo récords históricos. La Bahía de Bengala, Filipinas, el mar de China Meridional, el mar Caribe, el Amazonas y Alaska están en particular riesgo.

Riesgos futuros debido al calor

Predicciones como las realizadas en el nuevo artículo ayudan a brindar a las comunidades de las áreas afectadas tiempo para prepararse ante los riesgos relacionados con el calor, menciona Arcodia. En el Sureste de Asia, por ejemplo, las altas temperaturas podrían conducir una prolongada ola de calor marino, afectando negativamente ecosistemas marinos y generando consecuencias económicas para las comunidades costeras, según los autores.

El calentamiento en Alaska, escriben, podrían resultar en un incremento en los índices de retraso de los glaciares, el deshielo del permafrost, y erosión costera, mientras que temperaturas más altas en el Amazonas aumentarían la probabilidad de fenómenos meteorológicos extremos, incendios forestales y sequías.

Las condiciones actuales de El Niño están exacerbando el aumento de las temperaturas que ya están ocurriendo como resultado del cambio climático causado por el ser humano, dijo McPhaden. “Aunque las temperaturas globales están aumentando debido a los gases de efecto invernadero, se puede presentar gran pico porque hay un impulso adicional de El Niño al liberar calor del océano hacia la atmósfera.”

Aunque el presente evento de El niño es extremadamente fuerte y duradero, sus efectos continúan siendo temporales, dijo: los científicos predicen que las condiciones del ENOS cambiarán hacia La Niña para finales del verano 2024, lo que probablemente conducirá a temperaturas globales más frías.

Pero a medida que el clima se calienta, es probable que El Niño siga batiendo récords de calor en el futuro, según McPhaden. “La escalera mecánica del cambio climático no hace más que subir. La próxima vez que llegue El Niño, veremos aún más extremos”.

—Grace van Deelen (@GVD__), Escritora de ciencia

This translation by Ana Karina Mariano-Reyes (@akrinamr) was made possible by a partnership with Planeteando y GeoLatinas. Esta traducción fue posible gracias a una asociación con Planeteando y GeoLatinas.

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Source: Journal of Geophysical Research: Biogeosciences

Snow plays a vital role in northern and high-elevation ecosystems. It protects soil and vegetation from extreme cold and keeps the land surface cool by reflecting incoming solar energy. In the spring, snowmelt feeds rivers and replenishes groundwater. Yet springtime snow cover across the Northern Hemisphere has decreased by about 2% each decade since the 1960s. This slow but steady loss threatens the ecology, hydrology, and economies of many historically snowed-in locales.

One such place is the Marcell Experimental Forest in north central Minnesota, part of the Chippewa National Forest administered by the U.S. Forest Service’s Northern Research Station. Situated at the southern margin of a boreal peatland forest, the ecosystem is considered especially vulnerable to climate change. It is therefore a strategic location for the Spruce and Peatland Responses Under Changing Environments (SPRUCE) whole-ecosystem experiment, operated by the Terrestrial Ecosystem Science Scientific Focus Area of Oak Ridge National Laboratory’s Climate Change Program. This experiment subjects environments to a range of elevated temperature and carbon dioxide conditions to elicit biogeochemical responses.

SPRUCE comprises 10 open-topped octagonal enclosures in a forested bog dominated by black spruce. Each hydrologically isolated enclosure stands 40 feet wide × 26 feet tall. The enclosures feature forced-air blowers that warm plot temperatures to between 4.05°F (2.25°C) and 16.2°F (9°C) above ambient air temperatures. In each plot, digital cameras continuously monitor vegetation and watch as snow piles up and disappears throughout the seasons.

Using SPRUCE digital camera imagery from 2015 to 2021, Richardson et al. researched the relationship between warming temperatures and changes to snow duration, depth, and cover. The study evaluated the snow’s response to experimental warming treatments in the enclosures, which were superimposed on natural climate fluctuations.

The results showed that snow presence, depth, and coverage were extremely sensitive to warming, especially as temperatures crested at 8°F (4.5°C) higher than the ambient air temperature. But even warming of 3.6°F (2°C) cut in half the number of days with at least 2 inches (5 centimeters) of snow cover. The reduction in snow cover resulted in higher surface temperatures, as shrub-covered ground reflected less solar energy than snow. The plots also experienced more frequent freeze-thaw cycles.

The findings indicated that at best, climate change will have a negative but linear effect: Warmer temperatures will, of course, lead to less snow and its accompanying consequences. However, the results revealed other plausible scenarios in which snow will behave nonlinearly, with steep and immediate loss of snow cover in response to any warming beyond current conditions. (Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2023JG007833, 2024)

—Aaron Sidder, Science Writer

Citation: Sidder, A. (2024), Warming experiment explores consequences of diminished snow, Eos, 105, https://doi.org/10.1029/2024EO240153. Published on 1 April 2024.

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Drip by drip, steady ice loss in the Arctic and sub-Arctic is injecting enormous quantities of meltwater into the North Atlantic Ocean. Researchers have now shown how all that fresh water ultimately drives more extreme summer weather over Europe. These results might enable better long-term weather predictions in Europe, the team concluded.

Every year, the Arctic and sub-Arctic lose several hundred cubic kilometers, on average, of both sea ice and glacial ice due to rising temperatures. The fresh water liberated by all that melting eventually enters the North Atlantic, where it aggregates into so-called freshwater anomalies. Those structures, which tend to lurk on the surface of the ocean because of their relatively low density, can measure thousands of kilometers in extent and several tens of meters deep in winter.

First Fresh Water, Then Heat Waves

Freshwater anomalies in the North Atlantic have been shown to precede European heat waves. However, the mechanism—or mechanisms—behind that linkage has long remained unknown, said Marilena Oltmanns, an ocean and climate scientist at the National Oceanography Centre in the United Kingdom. That question is increasingly relevant given rapidly warming temperatures in the Arctic and recent weather extremes—such as heat waves and droughts—that have occurred in Europe, Oltmanns and her colleagues suggested.

To track the presence of freshwater anomalies, the team used satellite-derived sea surface temperature data available since 1979. That technique worked, said Oltmanns, because temperature and salinity were strongly correlated. The researchers opted not to use salinity data to trace freshwater anomalies because such data have been available over large areas only since 2009. Furthermore, many of those measurements are known to be biased, Oltmanns said. “The biases are about the same order of magnitude as the interannual variability.”

The researchers also combined data on the ocean’s temperature, salinity, and currents with atmospheric data tracing winds, pressure, temperature, and precipitation.

Gushing from Greenland

Oltmanns and her collaborators inferred that some of the freshwater anomalies they observed were caused by runoff from Greenland. The seasonal signals that they noted were consistent with melting in the summer and then propagation of that meltwater south, via ocean currents, the following winter. Freshwater anomalies have a pronounced effect at latitudes between 25°N and 65°N, the team showed.

By virtue of residing in the uppermost layer of the ocean, freshwater anomalies function somewhat like a barrier, Oltmanns said. “The fresh water inhibits heat exchange between the deeper ocean and the air.” Thanks to their relative thermal isolation, freshwater anomalies also cool more quickly in the autumn and winter than surrounding water masses, the researchers found.

That situation sets up sharp north–south gradients in sea surface temperature, which in turn promote the development of stormy weather and a preponderance of westerly winds along a freshwater anomaly’s southern boundary, the team showed.

Eddies Go North

Those winds then drive pressure changes that form eddies that same winter, Oltmanns and her colleagues found. Those swirling bodies of water stretch in a band across the Atlantic, and their presence can shift the North Atlantic Current—an eastward-flowing extension of the warm Gulf Stream—to the north by several hundred kilometers, the team showed. “It’s at an anomalously northward location,” said Oltmanns.

When westerly winds blow the following summer, they follow the temperature front between the now-shifted North Atlantic Current and colder subpolar waters. “The location of the freshwater anomaly in winter has a lot of implications for the location of the winds in subsequent summers,” Oltmanns said. And those same winds are deflected even farther north when they make landfall over Europe, the researchers found. All that northward deflection forms atmospheric anomalies associated with high-pressure systems, which are in turn linked to warmer and drier weather patterns.

When Oltmanns and her colleagues focused on the 10 warmest and coldest summers in Europe over the past 4 decades, they found that warmer summers tended to follow winters characterized by larger freshwater anomalies, colder freshwater anomalies, and stronger northward deflection of westerly winds. These results were published in Weather and Climate Dynamics.

Given that rates of melting in the Arctic and sub-Arctic are likely to increase in the future, it makes sense that warmer conditions in Europe will also be on the rise, Oltmanns said. That’ll be particularly true in more southerly regions, she added. “Southern Europe will become warmer and drier, no question.”

The Lure of Predictability

These findings offer an important way forward when it comes to predicting weather in Europe, Oltmanns said. Because the drivers of conditions in June, July, and August in cities such as Barcelona, Spain, and London are set in motion many months prior, it should be possible to make long-term weather forecasts, she said. “European summer weather is predictable at least a winter in advance.”

“These results can help us understand some of the impacts of future climate change,” said Melissa Gervais, a climate dynamicist at Pennsylvania State University who was not involved in the research. And there’s incredible utility to such weather predictions, she added. “If I’m a farmer and I know I’m going to be experiencing heat and drought, I might change what crops I have,” she said. “I might think about my irrigation strategy.”

Oltmanns and her colleagues hope to expand their analysis to freshwater anomalies that occur in the North Pacific. Similar weather forcing might also be occurring over parts of the United States and Canada, she said. “There are so many open questions.”

—Katherine Kornei (@KatherineKornei), Science Writer

Citation: Kornei, K. (2024), Melting ice in the polar north drives weather in Europe, Eos, 105, https://doi.org/10.1029/2024EO240139. Published on 28 March 2024.

Text © 2024. The authors. CC BY-NC-ND 3.0
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