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Sixty-seven extreme heat events have occurred since May 2024. All of these events—including a deadly Mediterranean heat wave in July 2024, an unprecedented March 2025 heat wave in central Asia, and extreme heat in South Sudan in February 2025—broke temperature records, caused major harm to people or property, or did both.

According to a new analysis, each of these extreme events was made more likely by climate change. The number of days with extreme heat is now at least double what it would have been without climate change in 195 countries and territories. Climate change added at least an extra month of extreme heat in the past year for 4 billion people—half the world’s population. 

“The numbers are staggering.”

“There’s really no corner of the globe that has been untouched by climate-driven extreme heat,” said Kristina Dahl, a climate researcher at the climate change research and communication nonprofit Climate Central who was part of the report team. “Half the world’s population is experiencing an extra month of extreme heat. The numbers are staggering.”

The authors of the report say it serves as a stark reminder of the dangers of climate change and the urgent need for better early-warning systems, heat action plans, and long-term planning for heat events across the globe. 

The report was created by scientists at Climate Central; World Weather Attribution, a climate research group; and the Red Cross Climate Centre. 

More Frequent Heat

In the new report, scientists calculated the number of days between 1 May 2024 and 1 May 2025 in which temperatures in a country or territory were above 90% of the historical temperatures from 1991 to 2020. Then, they analyzed how many of these extreme heat days were made more likely by climate change using the climate shift index, a methodology developed by Climate Central that compares actual temperatures to a simulated world without human-caused climate change. 

The team found that climate change made extreme heat events more likely in every country.

Over all the countries and territories, climate change added the greatest number of extreme heat days to the Federated States of Micronesia (57 days), and Aruba had the most extreme heat days in total over the past year, 187 days. The report’s authors estimate that in a world without climate change, Aruba would have experienced just 45 days of extreme heat.

Other Caribbean and Oceanic islands were among the countries and territories most strongly affected by climate change. People in the United States experienced 46 days of extreme heat, 24 of which were added by climate change. 

The authors of the report calculated the number of extreme heat days added by climate change in the past year. Credit: World Weather Attribution, Climate Central, and Red Cross Red Crescent Climate Centre

Of the 67 extreme heat events that occurred in the past year, the one most influenced by climate change was a heat wave that struck Pacific islands in May 2024. Researchers estimated the event was made at least 69 times more likely by climate change. 

The findings are not a surprise to Nick Leach, a climate scientist at the University of Oxford who was not involved in the report. “We’ve understood the impact of climate change on temperature and extreme heat for quite some time…[including] how it’s increasing the frequency and intensity of extreme heat,” he said. Research has consistently shown that heat events on Earth are made more likely, more intense, and longer lasting as a result of climate change. 

“Only comprehensive mitigation, through phasing out fossil fuels, will limit the severity of future heat-related harms.”

Leach said the new report gives a good overview of how climate change is influencing heat waves worldwide. However, defining extreme heat as temperatures above the 1991–2020 90th percentile creates a relatively broad analysis, he said. Studies using a more extreme definition of extreme heat may be more relevant to the impacts of extreme heat, and studies estimating those impacts are typically more policy relevant, he said.

The report’s authors chose the 90% threshold because heat-related illness and mortality begin to increase at those temperatures, Dahl said. 

Taking Action on Heat Waves

For rising global temperatures, “the causes are well known,” the report’s authors wrote. Burning of fossil fuels such as coal, oil, and gas has released enough greenhouse gases to warm the planet by 1.3°C (2.34°F; calculated as a 5-year average); 2024 marked the first year with average global temperatures exceeding 1.5°C (2.7°F) above preindustrial temperatures.

“Only comprehensive mitigation, through phasing out fossil fuels, will limit the severity of future heat-related harms,” the authors wrote.

Extreme heat puts strain on the human body as it tries to cool itself. This strain can worsen chronic conditions such as cardiovascular problems, mental health problems, and diabetes and can cause heat exhaustion and heat stroke, which can be deadly. Extreme heat is particularly dangerous for already-vulnerable populations, including those with preexisting health conditions, low-income populations lacking access to cool shelter, and outdoor workers. 

Heat Action Day on 2 June, hosted by the International Federation of Red Cross and Red Crescent Societies, raises awareness of heat risks across the globe. This year, the day of action will focus on how to recognize signs of heat exhaustion and heat stroke. Dahl recommends using the Centers for Disease Control and Prevention tips on heat and health to stay safe. “Most heat-related illness and death is preventable,” she said.

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

Citation: van Deelen, G. (2025), Climate change made extreme heat days more likely, Eos, 106, https://doi.org/10.1029/2025EO250208. Published on 30 May 2025. Text © 2025. AGU. 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.

SummaryWe revisit the budget of 20th century true polar wander (∼1°/Myr in the direction of 70°W) using a state-of-the-art adjoint-based reconstruction of mantle convective flow and predictions of ongoing glacial isostatic adjustment that adopt two independent models of Pleistocene ice history. Both calculations are based on a mantle viscosity profile that simultaneously fits a suite of data sets related to glacial isostatic adjustment (Fennoscandian Relaxation Spectrum, post-glacial decay times) and a set of present-day observations associated with mantle convection (long-wavelength gravity-anomalies, plate motions, excess ellipticity of the core-mantle boundary). Our predictions reconcile both the magnitude and direction of the observed true polar wander rate, with convection and glacial isostatic adjustment contributing signals that are 25-30% and ∼75% of the observed rate, respectively. The former assumes that large-scale seismic velocity heterogeneities are purely thermal in origin, and we argue that our estimate of the convection signal likely represents an upper bound due to the neglect of hypothesized compositional variations within the large low shear velocity provinces in the deep mantle.

In the remote and hostile realm of the Amundsen Sea Embayment, West Antarctica, powerful winds known as low-level jets (LLJs) race over its coastal regions, including both the Thwaites and Pine Island ice shelves and the open ocean. These previously unknown atmospheric forces could hold the key to understanding—and predicting—the alarming melt of two critical glaciers: Pine Island and Thwaites, the latter ominously called the "Doomsday Glacier" for its potential to unleash catastrophic sea-level rise.

Several key moments in Earth's history help us humans answer the question "How did we get here?" These moments also shed light on the question "Where are we going?" and offer scientists deeper insight into how organisms adapt to physical and chemical changes in their environment.

During the final week of summer in 2021, Hurricane Ida emerged from the Gulf of Mexico, turned almost directly northeast and swept through the South en route to Pennsylvania, New York, New Jersey and Connecticut.

A new study with ETH Zurich finds that if global warming exceeds the Paris Climate Agreement targets, the non-polar glacier mass will diminish significantly. However, if warming is limited to 1.5°C, at least 54% could be preserved—more than twice as much ice as in a 2.7°C scenario.

The Atlantic Meridional Overturning Circulation (AMOC) serves as the Atlantic Ocean's conveyor belt, transporting warm water north toward the Arctic Circle and returning cold, dense water back to the tropics. Nearshore areas off Greenland are critical sites in AMOC, influencing the redistribution of heat and nutrients around the world.

Earthquakes create ripple effects in Earth's upper atmosphere that can disrupt satellite communications and navigation systems we rely on. Nagoya University scientists and their collaborators have used Japan's extensive network of Global Navigation Satellite System (GNSS) receivers to create the first 3D images of atmospheric disturbances caused by the 2024 Noto Peninsula Earthquake.

The Atlantic meridional overturning circulation, commonly referred to as the "AMOC," is a system of ocean currents confined to the Atlantic basin that plays a crucial role in regulating Earth's climate by transporting heat from the Southern to the Northern Hemisphere. The AMOC also modulates regional weather, from the mild summers in Europe to the monsoon seasons in Africa and India.

Replanting forests can help cool the planet even more than some scientists once believed, especially in the tropics. But even if every tree lost since the mid-19th century is replanted, the total effect won't cancel out human-generated warming. Cutting emissions remains essential.

A research team utilized teleseismic double-difference tomography technology to uncover the morphological changes of the Pacific subducting slab in the mantle transition zone beneath Northeast China.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: AGU Advances

The relationship between phytoplankton production and dissolved iron affects the net annual air-sea exchange of carbon dioxide and impacts the ability of the subantarctic Southern Ocean to act as a carbon sink.

Traill et al. [2025] combine 27 years of monitoring data from a time series site in the subantarctic Southern Ocean south of Australia with ship-based observations to develop a composite seasonal cycle of productivity and dissolved iron. The seasonal cycle shows three phases that are defined by controls on production by light and multiple iron sources (Phase 1), iron limitation (Phase 2), and biomass decline from a shift to net heterotrophy and recycled nutrients (Phase 3). The seasonal cycle of coupling between dissolved iron and productivity provides validation of ocean biogeochemical models and informs understanding of variability associated with changing Southern Ocean iron supply mechanisms. 

Citation: Traill, C. D., Rohr, T., Shadwick, E., Schallenberg, C., Ellwood, M., & Bowie, A. (2025). Coupling between the subantarctic seasonal iron cycle and productivity at the Southern Ocean Time Series (SOTS). AGU Advances, 6, e2024AV001599.  https://doi.org/10.1029/2024AV001599

—Eileen Hofmann, Editor, AGU Advances  

Text © 2025. The authors. CC BY-NC-ND 3.0
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body {background-color: #D2D1D5;} Research & Developments is a blog for brief updates that provide context for the flurry of news regarding law and policy changes that impact science and scientists today.

On 27 May, the United States Supreme Court declined to hear arguments from a group of Apache leaders challenging a copper mine that would damage land that tribe members consider sacred, according to the Los Angeles Times. 

The mine is planned to be built beneath Oak Flat, a 4,600-acre area in southeastern Arizona. The site sits within the state’s “Copper Triangle,” an area home to one of the largest clusters of copper deposits in the world. Magma intrusions and subsequent subsurface movement of high-pressure, metal-rich fluids about 65 million years ago created high-grade copper deposits.

According to mining company Resolution Copper, a joint venture of two other mining companies, Rio Tinto and BHP, the deposit at Oak Flat is particularly high grade, at 1.5% copper, making the site attractive for industrial activity.

Members of Apache Stronghold, a tribal advocacy group, traveled on a two month pilgrimage last year to Washington, D.C., to present an appeal to the Supreme Court, asking them to review a decision on their case, Apache Stronghold v. United States of America, by the 9th U.S. Circuit Court of Appeals that had ruled narrowly in favor of moving the mine project forward.

In the case, Apache Stronghold argued that the development of the copper mine would violate the First Amendment rights of Indigenous community members who consider Oak Flat an important religious site. 

 
Related

•  Here’s Why Resolution Copper Wants to Mine Oak Flat
•  Supreme Court Clears Way for Massive Copper Mine on Apache Sacred Land
•  Supreme Court Refuses to Hear Oak Flat Case, Clearing a Roadblock for Huge Copper Mine
•  Get Involved: AGU Science Policy Action Center
 

The Supreme Court’s decision not to hear arguments from Apache Stronghold means the U.S. Forest Service is now allowed to move forward with plans to create a final environmental impact report and solicit a final round of public comments before deciding whether to transfer the land to Resolution Copper. 

Justices Neil Gorsuch and Clarence Thomas dissented from the denial of the appeal. Gorsuch wrote that the decision not to hear the arguments was a “grievous mistake—one with consequences that threaten to reverberate for generations.”

“Faced with the government’s plan to destroy an ancient site of tribal worship, we owe the Apaches no less,” Gorsuch wrote. “They may live far from Washington, D.C., and their history and religious practices may be unfamiliar to many. But that should make no difference.”

“We are pleased that the Ninth Circuit’s decision will stand,” said Vicky Peacey, Resolution Copper’s general manager, in a statement. “The Resolution Copper mine is vital to securing America’s energy future, infrastructure needs, and national defense.”

“We will never stop fighting—nothing will deter us from protecting Oak Flat from destruction,” said Wendsler Nosie Sr., leader of Apache Stronghold, in a statement.

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

These updates are made possible through information from the scientific community. Do you have a story about how changes in law or policy are affecting scientists or research? Send us a tip at eos@agu.org. Text © 2025. AGU. CC BY-NC-ND 3.0
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Source: Journal of Geophysical Research: Oceans

The Atlantic Meridional Overturning Circulation (AMOC) serves as the Atlantic Ocean’s conveyor belt, transporting warm water north toward the Arctic Circle and returning cold, dense water back to the tropics. Nearshore areas off Greenland are critical sites in AMOC, influencing the redistribution of heat and nutrients around the world.

The continental shelf along Greenland’s coast is marked by deep grooves called glacial troughs that extend from the mouths of glacially carved fjords to the open ocean. Research in Antarctica suggests glacial troughs there enhance the mixing of cold and warm waters, but few observations have been collected to determine whether the same is true of Greenland’s troughs.

Aboard R/V Neil Armstrong in late summer 2022, as part of an Overturning in the Subpolar North Atlantic Program cruise funded by the National Science Foundation, Nelson et al. explored how troughs influence ocean circulation around Greenland. They collected data in southwestern Greenland at the Narsaq Trough, which is 30 kilometers wide at its mouth and reaches 600 meters at its deepest point—about 4 times deeper than the average surrounding continental shelf. Gathering measurements along multiple ship tracks allowed the researchers to compare water mass properties in and outside the trough, describe flows in and around it, and estimate the mixing of waters with different temperatures and nutrient concentrations.

The results showed that the Narsaq Trough provides a pathway for warm, salty Atlantic Water to intrude onto the continental shelf and mix with cold, fresh polar waters. Consequently, waters in the trough are fresher, richer in oxygen, less rich in nutrients, and sometimes colder than nearby offshore waters. These changes in water conditions may slightly limit melting of glacial ice in the adjacent fjord. Furthermore, the trough creates subsurface circulation that likely exports the modified water from the trough, which may increase stratification and decrease deepwater formation off the continental shelf.

The study offers new insights into Greenland’s understudied glacial troughs and their role in modulating the climate system, the authors say. They note, however, that more work is needed to establish the troughs’ cumulative effects on global ocean circulation. (Journal of Geophysical Research: Oceans, https://doi.org/10.1029/2024JC022246, 2025)

—Aaron Sidder, Science Writer

Citation: Sidder, A. (2025), How Greenland’s glacial troughs influence ocean circulation, Eos, 106, https://doi.org/10.1029/2025EO250205. Published on 29 May 2025. Text © 2025. AGU. 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.

“Everyone benefits from more accurate [orbital tracking] of the asteroids, from missions that are going there to observers on the ground that want to look at them from various telescopes.”

Data from the spacecraft that created the most accurate map of the Milky Way are being used to study objects in our own solar system. Information provided by the European Space Agency’s Gaia satellite have now enabled astronomers to measure the masses of hundreds of asteroids, allowing for improved orbital calculations.

“Everyone benefits from more accurate [orbital tracking] of the asteroids, from missions that are going there to observers on the ground that want to look at them from various telescopes,” said Oscar Fuentes-Muñoz, a NASA postdoctoral fellow at the Jet Propulsion Laboratory in California. Fuentes-Muñoz presented the masses of 231 asteroids he and his colleagues determined using Gaia last month at the Lunar and Planetary Sciences Conference in Houston.

The new research more than doubles the number of known asteroid masses, and the results are only the beginning.

“This work…is really pushing for high precision with novel techniques,” said Kevin Walsh, a solar system dynamicist who studies asteroids at the Southwest Research Institute in Colorado. Walsh was not part of the study.

Gravity Assist Asteroids

The new research relied on a familiar staple of Newtonian physics, taught in high schools everywhere: When two objects interact, each mass exerts a gravitational force on the other. The result is often negligible—the gravitational force of your phone isn’t going to pull you across the room.

But if the objects are moving and the mass difference is large enough, the more massive object will change, or perturb, the path of the less massive one. Fuentes-Muñoz called the phenomenon a “gravitational assist” and compared the relationship between massive and less massive asteroids to the way Earth’s mass perturbs the orbit of a satellite. “The mass of the satellite doesn’t affect the motion of the Earth,” he explained, but the path of the satellite can be dramatically altered.

Although they were not part of its primary mission, the star mapper Gaia was developed with solar system observations in mind and was able to tease out such interactions in incredible detail before being decommissioned in March. According to Gaia team member Mikael Granvik of the University of Helsinki, the telescope’s precision was comparable to observing a 2-euro coin on the Moon while standing on Earth.

As asteroids interacted, Gaia captured how their orbits shifted over 66 months. Fuentes-Muñoz and his colleagues used that information to determine the gravitational mass of the larger objects. Gravitational mass is a way to measure an object’s mass on the basis of how it moves in gravity, rather than calculating the object’s absolute mass in kilograms, for example. This type of measurement is commonly used to estimate the masses of solar system bodies as well as Earth-orbiting satellites and spacecraft.

Most of the 1.4 million known asteroids are too small to have their masses measured, however. “We can estimate things that are maybe…a thousand times smaller than Ceres, but not a million times,” Fuentes-Muñoz said.

Of the more than 1,000 large asteroids they observed, the researchers were able to more precisely calculate the gravitational masses of nearly 300 previously discovered objects. This calculation significantly increases the precision of asteroid orbits.

The dwarf planet Ceres is the largest object in the asteroid belt, and Fuentes-Muñoz calculated its gravitational mass, providing “ground truth” to previous measurements. The new research puts Ceres’s gravitational mass at 62.650 cubic kilometers per square second, which closely matches previous estimates and demonstrates the accuracy of the researchers’ technique. (For comparison, Earth’s gravitational mass is 398,600 cubic kilometers per square second.)

Gaia Is the Gift That Keeps Giving

Gaia wrapped up its mission after more than a decade in space, but new results continue to pour in. That’s due in part to the strict scrutiny the Gaia team uses before releasing data publicly.

Fuentes-Muñoz used the focus product release (FPR), sort of a halfway step between Gaia’s data release (DR) 3, released in 2022, and DR4. DR4 will be released no sooner than this summer, and DR5 won’t be released before the end of 2030.

“It was interesting to see that they got so many accurate masses already from just the FPR,” said Granvik, who reported the first observations of asteroid mass using Gaia in 2022.

“It’s a significant change overall. We’re going to get hundreds of asteroid masses.”

Granvik said Gaia will eventually provide “up to a tenfold increase in the sheer number of objects that we have masses” for.

Walsh said increased precision “will just really help nail down masses and the perturbative effects down to smaller and smaller asteroids.”

“It’s a significant change overall,” Fuentes-Muñoz said. “We’re going to get hundreds of asteroid masses.”

—Nola Taylor Tillman (@astrowriter.bsky.social), Science Writer

Citation: Tillman, N. T. (2025), The late, great Gaia helps reveal asteroid masses, Eos, 106, https://doi.org/10.1029/2025EO250204. Published on 29 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.

Editors’ Vox is a blog from AGU’s Publications Department.

Healthy soils are vital for sustaining life on Earth. They are essential for ecosystems, agricultural production, and clean water, and even help to regulate climate.

A new article in Reviews of Geophysics explores the latest scientific methods for monitoring soil health, including innovative tools like digital twins and satellite-enabled programs, while highlighting persistent gaps in linking indicators to soil functions across scales. Here, we asked the authors to give an overview of the topic.

What is soil health, and how is it different from soil quality?

A healthy soil is a thriving ecosystem: it feeds plants, filters water, stores carbon, and supports worms, microbes, and other tiny lifeforms.

Think of soil health as the soil’s ability to “stay alive” and do its job. A healthy soil is a thriving ecosystem: it feeds plants, filters water, stores carbon, and supports worms, microbes, and other tiny lifeforms. Soil quality, on the other hand, usually refers to how good soil is for growing crops. Soil health is the bigger picture—it’s about keeping soil thriving not just for farms, but for nature and our planet.

Why does soil health matter?

Healthy soil is a multifunctional linchpin of terrestrial ecosystems. It secures food production by nurturing crops, acts as a natural water filter by retaining pollutants, and serves as a massive carbon sink, sequestering atmospheric CO₂ to mitigate climate change—a process monitored at continental scale through EU’s initiatives such as LUCAS, which tracks soil carbon through satellite and field data. Simultaneously, it harbors diverse subterranean communities, from bacteria to earthworms, that drive nutrient cycling and enhance ecosystem resilience against droughts, floods, and pathogens.

How do we measure soil health?

Scientists assess three core dimensions:

1. Physical properties: Structure (e.g., root penetration, water retention).
2. Chemical properties: Nutrient availability and pH balance.
3. Biological properties: Microbial and macrofaunal activity (e.g., decomposition rates).

Emerging tools, such as satellite spectral imaging and AI-driven digital twins, integrate landscape-scale data (e.g., erosion patterns, vegetation cover) to contextualize field measurements. However, challenges persist in scaling microscale processes (e.g., nutrient cycling) to predict landscape-level outcomes.

Why are soil microbes so important?

Soil microbial communities (bacteria, fungi, archaea) are indispensable biogeochemical agents. They decompose organic matter, recycle nutrients, and secrete substances that stabilize soil aggregates, reducing erosion. Microbial communities also suppress plant pathogens and form symbiotic relationships with roots, enhancing crop resilience. Their absence leads to soil degradation, compromising biophysical integrity and triggering cascading declines in ecosystem functionality.

How does water affect soil health?

Water is the lifeblood of soil ecosystems.

Water is the lifeblood of soil ecosystems. Optimal moisture sustains plant hydration and microbial activity. Excess water, however, induces hypoxia, impairing root respiration and promoting anaerobic processes like methanogenesis. Prolonged drought destabilizes soil structure, increasing erosion risks. Healthy soils counteract these extremes through stable aggregates and organic matter, acting like sponges to store water during droughts and absorb rainfall during floods.

Can satellites truly monitor soil health?

Yes. Programs like the EU’s LUCAS integrate satellite data (e.g., Copernicus Sentinel-2’s multispectral imaging for organic carbon) with ground surveys—more than 100,000 soil samples collected between 2009 and 2022 for physical, chemical, and biological analysis. This hybrid approach identifies degraded zones, evaluates restoration efforts, and scales localized data (e.g., nutrient cycles) to landscape processes. These datasets also feed into digital twins, enabling predictive models that inform policies like the EU Soil Monitoring Law.

What’s a “digital twin” for the soil-plant system?

A digital twin is a dynamic, computer-based replica of a physical system – in this case, the soil-plant-environment continuum. It simulates critical processes like water, nutrient, and energy flows (e.g., using models like STEMMUS-SCOPE) and continuously improves its accuracy by assimilating real-time sensor data. This creates a virtual laboratory where we can test responses to challenges like drought or pollution without risking real ecosystems. While the concept originated in aerospace, digital twins now drive major initiatives like the EU’s Destination Earth for modeling climate extremes. Leveraging recent advances in AI and satellite data, we can now perform continent-scale soil health monitoring and scenario modeling, optimizing and transforming land management practices.

What critical gaps remain in our understanding of soil health?

Safeguarding soil health is not just an ecological imperative but a cornerstone of humanity’s future.

Key unknowns include feedback loops between soil structure and microbial communities, scaling microscale processes (e.g., nutrient cycling) to landscapes, and predicting climate impacts on soil carbon and microbial symbioses. Practical hurdles include fragmented global datasets, limited integration of microbial traits in models, and cost-effective tools for farmers. Collaborative platforms like the EU Soil Observatory bridge research and policy, but challenges like modeling root-water-nutrient dynamics in heterogeneous soils or fusing satellite-ground data persist. Addressing these gaps requires interdisciplinary innovation—an urgent task, as safeguarding soil health is not just an ecological imperative but a cornerstone of humanity’s future.

—Yijian Zeng (y.zeng@utwente.nl, 0000-0002-2166-5314), University of Twente, Enschede, The Netherlands; and Bob Su (0000-0003-2096-1733), University of Twente, Enschede, The Netherlands

Editor’s Note: It is the policy of AGU Publications to invite the authors of articles published in Reviews of Geophysics to write a summary for Eos Editors’ Vox.

Citation: Zeng, Y., and B. Su (2025), Keeping soil healthy: why it matters and how science can help, Eos, 106, https://doi.org/10.1029/2025EO255016. Published on 29 May 2025. This article does not represent the opinion of AGU, Eos, or any of its affiliates. It is solely the opinion of the author(s). 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.

The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.

Over the course of the last few days, I have been blogging about the evolving situation on the slopes above Blatten in Switzerland. I documented that attention slowly transitioned from worries about the stability of the slope on Kleine Nesthorn (Petit Nesthorn in French) to concerns about the stability of the Birch Glacier due to increased loading from the rockslide debris. Yesterday, I outlined three scenarios and emphasised that we were in unknown territory.

On 28 May 2025, the Birch Glacier catastrophically collapsed, generating the massive landslide that had been the source of concern. The move by the authorities to evacuate the village proved to be the correct call, but tragically a 64 year old resident appears to have been buried in the landslide. Assuming that he was indeed in the area, their prospects are bleak.

Others have covered the failure event better that can I, and once again I recommend two Bluesky accounts that have provided amazing insights. First, there is Melaine Le Roy, who has posted this for example:-

https://bsky.app/profile/subfossilguy.bsky.social/post/3lqaup44u6k2l

And second is Jan Beutel, who is new to Bluesky (a well timed introduction, sir!), who has posted this before and after comparison that is simply awesome:-

Birchgletscher collapse, before and after.

— Jan Beutel (@janbeutel.bsky.social) 2025-05-28T15:29:58.028Z

These two scientists will be really good sources of information over the coming days. Reuters also has a nice summary news video of the events:-

So, was the final collapse my scenario 1 (a further failure of Kleine Nesthorn that triggered failure of the Birch Glacier) or scenario 2 (a catastrophic failure of the glacier itself)? At this stage, I am not sure. The seismic data will reveal all in due course – this event will have been extremely well captured in this dataset. Jan Beutel posted seismic record soon after the failure – look at the scale of the signal that the landslide generated:-

What an inaugural post on bsky.app. A (the) major glacier collapse at Bichgletscher/Kleines Nesthorn.

— Jan Beutel (@janbeutel.bsky.social) 2025-05-28T13:43:41.174Z

I am certainly no expert in analysing this data, so I can only speculate, but it is interesting that there was an elevated signal in the two minutes or so before the catastrophic failure began. What was this? Was movement starting to occur in the Birch Glacier, or was there an event on the slope above (or am I misreading the signal)?

So, for now, attention will focus on three things:

First, the valley of the Lonza river is dammed and a substantial lake is starting to develop. This has the potential to inundate the remaining properties in Blatten and, of course, to release a major flood. Two further communities downstream have been evacuated. There is a good Youtube video of this situation:

This will need to be addressed with urgency, but Switzerland is well placed in terms of expertise and resource to mitigate the threat.

Second, attention will need to be paid to the Birch Glacier and the slopes on the Kleine Nesthorn. Is there the potential for a further failure? Massive though this collapse has been, it is unlikely to have included all of the mass on the slope. What is the state of the remaining material? This will be a critical question in terms of the safety of those charged with managing the flood hazard.

And finally, many people have lost their homes, and more may do so in the coming days. This is a devastating event for them, and they will need considerable help.

As a final comment, I have to pay tribute to those individuals who have managed this hazard. The situation was immensely unpredictable, but they acted quickly and decisively. Whilst it is a tragedy that someone is missing, their actions saved many lives.

In due course, I’m sure that there will be a series of papers about this remarkable event. There are many lessons to be learnt from an absolutely amazing case study. As always, please remember that my posts here are provisional and speculative – the definitive analyses comes from the on site experts and from rigorous scientific study in due course.

Return to The Landslide Blog homepage Text © 2023. The authors. CC BY-NC-ND 3.0
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The butterfly effect suggests that small changes in a system can have a large impact on eventual outcomes. One metaphor used to illustrate this concept is a butterfly flapping its wings only to cause a hurricane across the ocean. While meteorologists' current cause-and-effect understanding of weather isn't this granular, researchers are actively investigating how changes in temperature, rainfall, wind patterns, etc. can impact weather phenomena halfway across the world.

A recent study led by Prof. Chen Yaning from the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences has released the Tianshan watershed streamflow (TSWS) dataset (1901–2019). The dataset compiles daily streamflow data for 56 watersheds and monthly data for 89 watersheds in the Tianshan Mountains.

The 120-mile Tijuana River flows from Baja California into the United States and discharges millions of gallons of wastewater—including sewage, industrial waste and runoff—into the Pacific Ocean every day, making it the dominant source of coastal pollution in the region.