EOS

Source: Geophysical Research Letters

This is an authorized translation of an Eos article. 本文是Eos文章的授权翻译。

土壤湿度是温度和湿度的关键调节器，易受气候变化的显著影响。尽管土壤湿度至关重要，但其建模工作涉及数十个约束不充分的参数，而且不同的模型对土壤湿度水平在全球变暖背景下的变化往往存在分歧。

Gallagher 和 McColl 采取了一种“极其简化”的方法，仅根据降水量和地表净辐射来模拟土壤湿度。该模型在使用欧洲中期天气预报中心第五代大气再分析数据(ERA5) 和第六次耦合模式比较计划(CMIP6) 气候数据集进行测试时，效果良好。

研究人员表示，这令人惊讶，因为这个简单的模型排除了近期许多文献关注的测量数据：水汽压差（空气能够容纳的水分量与实际容纳的水分量之间的差值）和大气二氧化碳 (CO2) 水平。预计这两者都将随着温室气体排放的增加而上升。

研究人员认为，他们的模型之所以仍然有效，是因为水汽压差无法准确衡量大气对水的需求；而模型中包含的地表净辐射才是更佳的衡量指标。关于二氧化碳，研究人员表示，之前的一些研究高估了这种气体的作用。

这个简单的模型为两个关于土壤湿度的基本问题提供了可能的答案：(1)为什么土壤湿度呈W型纵向剖面，赤道和两极的湿度高，两极之间的湿度低；(2)为什么土壤湿度在某些地区随温度升高而增加，而在另一些地区则降低？

W型分布可能是降水率和辐射强度共同作用的结果。赤道附近的高降水量在模型中占主导地位，并导致高土壤湿度。中纬度地区和两极地区的降水量都处于中等水平。但中纬度地区比两极地区接收到更强烈的辐射，导致中纬度地区的土壤相对干燥。

至于第二个问题，研究人员认为，气候变暖可能对土壤湿度有不同的影响，因为气候变暖既可能伴随降水增加（导致土壤湿度升高），也可能伴随地表净辐射增加（导致土壤湿度降低）。这两个变量在不同地区会以不同的程度相互抵消，这意味着气候变暖有时会提高土壤湿度，有时则会降低土壤湿度。(Geophysical Research Letters, https://doi.org/10.1029/2025GL115044, 2025)

—科学撰稿人Saima May Sidik (@saimamay.bsky.social)

This translation was made by Wiley. 本文翻译由Wiley提供。

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

The El Niño Southern Oscillation (ENSO) is a natural climate phenomenon driven by interactions between the ocean and atmosphere in the tropical Pacific. In recent decades, major advances in observing and modeling ENSO have greatly improved our understanding, yet important challenges remain.

A recent article in Reviews of Geophysics highlights the recharge oscillator (RO) conceptual model, a simple mathematical representation of ENSO fundamental mechanisms. Here, we asked the lead author to provide an overview of ENSO, discuss the strengths and limitations of the RO model, and outline key open questions.

Why is the El Niño Southern Oscillation (ENSO) important to understand? 

ENSO events typically last around a year and occur in two phases: El Niño, when the central and eastern Pacific Ocean becomes unusually warm, and La Niña, when it becomes cooler than normal. These temperature shifts disrupt wind patterns and rainfall, triggering anomalies such as droughts, floods, tropical cyclones, and marine or terrestrial heatwaves. These impacts strongly affect ecosystems, agriculture, and economies around the world.

Although ENSO originates in the tropical Pacific, its influence extends globally.

Although ENSO originates in the tropical Pacific, its influence extends globally through atmospheric “teleconnections.” Because of its widespread effects, understanding and predicting ENSO is essential. Today, coupled ocean–atmosphere models and statistical methods allow scientists to forecast ENSO events up to a year in advance, making ENSO a key pillar of global seasonal climate prediction.

Over the past few decades, what advances have been made in observing and modeling ENSO?

Two major breakthroughs in the 1990s greatly advanced our ability to observe and model ENSO. First, on the observational side, the TAO mooring array across the equatorial Pacific and satellite altimetry provided continuous measurements of surface meteorological and subsurface ocean conditions—key data for understanding ENSO dynamics. Second, modeling evolved from simplified “intermediate” coupled models of the 1980s to more sophisticated coupled general circulation models (CGCMs), which simulate the full complexity of ocean–atmosphere interactions.

These advances provided deeper insight into the mechanisms driving ENSO. Importantly, subsurface observations also became essential for initializing ENSO forecasts improving their accuracy. Together, these observational and modeling tools laid the groundwork for modern ENSO research and prediction systems.

What are the benefits of using conceptual models to understand ENSO compared to other modeling methods?

Conceptual models of ENSO are simple mathematical representations that distill the phenomenon into just a few key variables—such as sea surface temperature in the central Pacific or equatorial ocean heat content. These models use basic equations to capture the core dynamics of ENSO, including the Bjerknes feedback (a positive loop that amplifies temperature anomalies) and slower equatorial ocean adjustment processes that help shift ENSO from one phase to another.

Conceptual models offer clarity and insight that complement the realism of full-scale simulations.

Because they focus on essential mechanisms, conceptual models are powerful tools for teaching and for gaining physical intuition. They also allow researchers to test hypotheses about ENSO dynamics in a controlled, simplified setting. Despite their simplicity, they can make useful quantitative predictions about ENSO features like amplitude or period, and are often used to diagnose biases in more complex climate models. In short, conceptual models offer clarity and insight that complement the realism of full-scale simulations.

What is the “recharge oscillator” model and why did you choose to focus on it?

The Recharge Oscillator (RO) is a conceptual model of ENSO introduced in the mid-1990s by Fei-Fei Jin. Unlike earlier models, it includes an explicit equation for subsurface ocean heat content, capturing ENSO’s “memory.” Its flexible mathematical structure has allowed researchers to gradually increase its realism while preserving simplicity and interpretability.

In our review, we show that the RO can now reproduce key ENSO characteristics, including its amplitude, dominant period, seasonal synchronization, and the tendency for El Niño events to be stronger than La Niña events. Remarkably, recent studies show that it can even rival complex dynamical models in terms of forecast skill. Thanks to its clarity, predictive power, and widespread use in the research community, the Recharge Oscillator was a natural focus for a dedicated review.

How does the recharge oscillator model aid in understanding ENSO response to climate change?

Climate models generally project increased near-surface ocean stratification under climate change. Most predict a weakening of the equatorial Pacific trade winds, though some show a strengthening—closer to observed trends in recent decades. These shifts in the background mean state can significantly affect ENSO behavior.

The Recharge Oscillator (RO) helps explore these effects by providing quantitative links between the mean state and ENSO characteristics such as amplitude, period, and asymmetry. This makes the RO a useful tool for understanding how future changes in stratification or winds might influence ENSO—and why model projections sometimes disagree. However, using the RO to study climate change impacts is still a developing field, partly because the way mean state changes affect RO parameters is not yet fully understood. Addressing this gap is highlighted in our review as a key direction for future research.

What are the primary challenges or limitations of the recharge oscillator model?

Klaus Wyrtki famously noted that “no two El Niño events are alike.” This insight underpins the challenge of ENSO diversity—the fact that some events peak in the eastern Pacific, while others peak farther west, with differing global impacts. Capturing this diversity remains a key limitation of the RO. While recent studies have proposed promising ways to represent these variations within the RO framework, more work is needed to develop a community consensus on a physically consistent approach.

Overcoming these limitations will strengthen the Recharge Oscillator’s relevance for studying both ENSO diversity and its links to broader climate variability.

Another challenge lies in modeling two-way interactions between ENSO and other climate modes, such as the Indian Ocean Dipole or Atlantic variability, which can influence ENSO through atmospheric teleconnections. These interactions are not accounted for in the RO. However, recent work introducing an extended Recharge Oscillator (XRO) offers a promising path forward. Overcoming these limitations will strengthen the RO’s relevance for studying both ENSO diversity and its links to broader climate variability.

What are some of the remaining questions where additional modeling, data, or research efforts are needed? 

In our review, we highlight 10 open research questions—many of which are well-suited for PhD or postdoctoral projects—centered on improving the RO and using it to explore broader ENSO dynamics. These include previously mentioned challenges such as understanding ENSO behavior in a warming climate, accounting for ENSO diversity, and modeling interactions with other climate modes. Several of these topics are already being actively explored, reflecting the vitality of the field.

To support future research, we will soon release open-source Python and Matlab versions of the RO, accompanied by a technical article detailing its numerical implementation and parameter fitting methods. This will make it easier for researchers to use and extend the RO framework to address today’s pressing ENSO questions—ultimately helping bridge conceptual models and complex Earth system simulations.

—Jérôme Vialard (jerome.vialard@ird.fr, 0000-0001-6876-3766), LOCEAN-IPSL, IRD-CNRS-MNHN-Sorbonne Universités, France; with feedback provided by review co-authors.

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: Vialard, J. (2025), Two equations that unlock El Niño, Eos, 106, https://doi.org/10.1029/2025EO255018. Published on 5 June 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.

A recent Facebook post has highlighted a reasonably large slump landslide in a remote area of Alaska. Satellite images suggest that this occurred in late October or early November 2024.

Loyal reader Andrew McNown kindly highlighted a recent Facebook post that provided some images of a landslide that has partially blocked the Lakina River in Alaska. This is one of the images, posted by John Matthews:-

The landslide on the Lakina River in Alaska. Photograph posted to Facebook by John Matthews.

This image provides a more detailed view:-

The landslide on the Lakina River in Alaska. Photograph posted to Facebook by John Matthews.

A quick review of the Planet image catalogue suggests that the location of the landslide is [61.46578, -143.27085]:-

Satellite image of the landslide on the Lakina River in Alaska. Image copyright Planet, used with permission. Image dated 19 May 2025.

The landslide is about 350 m from crest to toe and 300 m wide, with a surface area of about 0.085 km2. From the images, it appears to be a rotational slump in fine-graimed (presumably) glacial materials. The event blocked the river but has breached; a small lake remains on the upstream side.

In terms of timing of the event, the landslide appears to be present on a Planet image dated 4 November 2024, but it appears to be absent on one dated 24 October 2024, so it occurred sometime in that window. The trigger is unclear – this seems to be an unusual time for a landslide of this type, but perhaps there was a rapid snowmelt event.

There is a large displaced rotational block in the images in which there is erosion of the toe. This provides some potential for a further valley-blocking landslide, although this is far from inevitable. Fortunately, there are few assets at risk in the immediate downstream area, but there could be some threat to groups using or camping beside the Lakina River.

Reference

Planet Team 2025. Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/

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

Mountain landscapes are as much a product of erosion as they are of uplift. It is certainly true that glaciers can carve uplifted regions, increasing their topographic relief.

Using numerical modeling that integrates both river and glacial erosion across a time span that includes glacial-interglacial cycles, Bernard et al. [2025] flip the script on how we think glaciers shape mountains. The authors show that a “glacial sheltering” effect can lead to the development of extensive low-relief surfaces at moderate elevations, and they review the existence of candidate surfaces in Scandinavia and other locations.

A key finding is that such surfaces can not only be preserved by glaciation, but they can also emerge from it, and at variable elevations that are a function of ice volume. This is significant not just because humans are inspired by mountains and their topography: flat or low-relief surfaces play a large role as a reference elevation in explaining landscape evolution and in tectonic studies of uplift that make assumptions about where, when, and how such surfaces originated.

Citation: Bernard, M., van der Beek, P. A., Pedersen, V. K., & Colleps, C. (2025). Production and preservation of elevated low-relief surfaces in mountainous landscapes by Pliocene-Quaternary glaciations. AGU Advances, 6, e2024AV001610.  https://doi.org/10.1029/2024AV001610

—Peter Zeitler, Editor, AGU Advances

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Source: AGU Advances

Shortly after President Joe Biden took office in 2021, he nominated Asmeret Asefaw Berhe, then a biogeochemist at the University of California, Merced, to oversee the Department of Energy’s (DOE) Office of Science. After a 15-month vetting process involving interviews, a mountain of paperwork, and, ultimately, a Senate confirmation, the AGU medalist became the first person of color and the first Earth scientist to hold the position. She served in the position for just under 2 years.

Now, with science and diversity programs under attack, she reflects on her path to leadership in a new commentary in AGU Advances. Berhe became familiar with DOE’s science program as a graduate student at the University of California, Berkeley. She later went on to receive DOE funding, collaborate with researchers from various national laboratories, and mentor scientists who went on to secure DOE positions. She says that combined with guidance from her mentors, these experiences helped her develop the skills she needed for her DOE appointment, not only in science but in managing, accounting, mediation, and ethical guidance.

Berhe, who was born in Eritrea and was one of only a few undergraduate women at Asmara University studying soil science, prioritized basic research, robust science communication, and promoting diversity in STEM (science, technology, engineering, and mathematics) in her DOE role. Providing opportunities in STEM for people from all walks of life starts with equalizing the distribution of funding, she writes. She cited an American Physical Society report that found, in 2018, 90% of federal research funding went to the top 22% of institutions, even though the vast majority of students—especially those from low-income backgrounds—attend other schools. Under Berhe’s tenure, the DOE began asking grant applicants to demonstrate plans for collaborating with schools less likely to receive funding, enabling scholars from diverse backgrounds to access DOE resources.

Berhe thinks recent efforts by some politicians to end diversity, equity, and inclusion (DEI) programs are partly because of a misconception around what DEI means. These programs are often misconstrued as serving only gender or racial minorities from urban environments, when, in fact, many are intended to serve a much wider range of Americans, she writes.

Today’s political climate sometimes leaves Berhe with feelings of despair. But she remains hopeful that with time, the next generation of scientists will benefit from opportunities like those she’s had. “Together, we will weather this storm,” she writes. (AGU Advances, https://doi.org/10.1029/2025AV001757, 2025)

—Saima May Sidik (@saimamay.bsky.social), Science Writer

Citation: Sidik, S. M. (2025), Former Department of Energy leader reflects on a changing landscape, Eos, 106, https://doi.org/10.1029/2025EO250211. Published on 4 June 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.

What’s Next for Science?

A 200,000 cubic metre rockslide in a remote area of Tibet on Sunday has left ten people dead or missing.

On 1 June 2025 a large rockslide occurred in Muta township in Chamdo (Qamdo) metropolitan area in Tibet. Note that Chinese media sources call this area Xizang Autonomous Region, but it is what most of us know as Tibet. Chinese media reports, which can be unreliable from Tibet, indicate that three people are confirmed to have been killed with a further seven reported to be missing. Two people were injured.

CGTN has a video online showing the landslide, which includes drone footage. The area has a dusting of snow, which makes interpretation difficult. CCTV also has the same footage posted to Youtube:-

This video includes imagery of the head scarp of the landslide:-

The head scarp of the 1 June 2025 rockslide at Muta in Tibet. Image from a video posted to Youtube by CCTV.

There is also a good image of the full length of the rockslide:-

The full extent of the 1 June 2025 rockslide at Muta in Tibet. Image from a video posted to Youtube by CCTV.

This landslide has a slightly unusual morphology, with much of the material from the upper portion of the slope stalled on the hillside. However, the mass of material in the valley floor is large, as this image shows:-

The lower portion of the 1 June 2025 rockslide at Muta in Tibet. Image from a video posted to Youtube by CCTV.

The landslide has blocked the valley and a small lake has started to develop. This will need to be managed. Note the run up of the landslide deposit on the opposite slope, which indicates that the mass was moving comparatively quickly. There are two people on the left of the image for scale.

The CGTN video suggests that the landslide was about 200,000 m3, which would be around 500,000 tonnes.

The precise location of this event is unclear to me. Chamdo is a large area centred on [31.1362, 97.2359]. A report by Xinhua suggests that the landslide occurred in Dengqen County (Dêngqên County), which is in the northwest of Chamdo, centred on [31.5396, 95.4156]. Wikidata indicates that Muta is located at [32.30957, 95.09376], and Google maps has this location as “Mutaxiang”, with “Muta town” a little to the west, so this is credible. We shall have to wait for a clear day to obtain satellite imagery to confirm this – given the limited loss of life, the landslide has probably not struck Muta itself.

As usual for China, especially when it comes to Tibet, the media footage includes lots of images of the response of the authorities to the disaster. Sadly, the likelihood of the missing people being recovered alive is very low.

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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.

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

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?”

“Thousands of people are currently accessing the Antarctic continent, and my conclusion is that wherever we humans go, we bring contaminants.”

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. Text © 2025. The authors. CC BY-NC-ND 3.0
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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.

En 2017, Paulo Tarso Oliveira, profesor de hidrología en la Universidad de São Paulo, se encontró con una noticia sobre una pequeña aldea a orillas del río São Francisco, uno de los principales ríos del noreste de Brasil. El artículo informaba que los habitantes estaban presentando tasas inusualmente altas de hipertensión arterial, y relacionaba esta anomalía con el clima seco de la región y el bajo caudal del río. A medida que el nivel freático descendía, el agua oceánica comenzaba a infiltrarse hacia el agua subterránea de la región, elevando los niveles de sal en el suministro y provocando problemas de salud entre la población.

“Muchas veces, la gente no se da cuenta, pero las aguas superficiales y subterráneas están conectadas y deben considerarse como un todo”.

Intrigado, Oliveira investigó más a fondo. Más adelante descubrió que el flujo del río estaba disminuyendo porque los pozos estaban extrayendo agua del acuífero subyacente. “Muchas veces, la gente no se da cuenta, pero las aguas superficiales y subterráneas están conectadas y deben considerarse como un todo”, señaló Oliveira.

En lugares donde el nivel freático se encuentra bajo el lecho de un río, el río puede filtrar agua hacia el acuífero subyacente. Este proceso, conocido como filtración del caudal fluvial, ocurre de forma natural dependiendo de las formaciones geológicas subyacentes y los niveles de agua subterránea. Sin embargo, la construcción de pozos que extraen agua en exceso de los acuíferos puede intensificar este fenómeno.

Oliveira y sus colegas descubrieron que la situación en la cuenca del São Francisco no es un caso aislado. Al evaluar pozos en todo Brasil, los investigadores encontraron que en más de la mitad de ellos el nivel del agua estaba por debajo del nivel de los arroyos cercanos.

Mapeo de pozos

En 2023, Oliveira y el estudiante de maestría José Gescilam Uchôa comenzaron a mapear los ríos de Brasil para identificar zonas en riesgo de pérdida de agua. Se basaron en datos públicos sobre niveles de ríos y ubicación de pozos, proporcionados por el Servicio Geológico de Brasil. Sin embargo, la mayoría de los pozos registrados carecían de información suficiente. Como resultado, se enfocaron en 18,000 pozos con datos completos, distribuidos a lo largo de miles de ríos en el país.

Los investigadores compararon el nivel del agua en cada pozo con la elevación del arroyo más cercano. En el 55 % de los casos, el nivel del agua en los pozos era inferior a la elevación de los arroyos vecinos.

José Uchôa realiza mediciones en un río de São Paulo. Crédito: Laboratorio de Hidráulica Computacional, Universidad de São Paulo

“Nuestros datos sugieren que el uso de aguas subterráneas está afectando significativamente el caudal de los ríos”, señaló Uchôa. “Este es, y seguirá siendo, un motivo de creciente preocupación para la gestión del agua en el país”.

El estudio, publicado en Nature Communications, también identificó regiones críticas, incluida la cuenca del São Francisco, donde más del 60 % de los ríos podrían estar perdiendo agua debido a la intensa extracción subterránea. Esta extracción se asocia principalmente con actividades de irrigación.

En la cuenca del Verde Grande, en el este de Brasil, donde la irrigación representa el 90 % del consumo de agua, el 74 % de los ríos podrían estar perdiendo agua hacia los acuíferos.

Oliveira considera que los resultados son conservadores y que la situación podría ser aún peor, ya que los investigadores no tomaron en cuenta los pozos ilegales. Un estudio realizado en 2021 por el geólogo Ricardo Hirata, de la Universidad de São Paulo, estimó que alrededor del 88 % de los 2.5 millones de pozos en Brasil son ilegales, al carecer de licencia o registro para operar.

Hirata, quien no participó en la nueva investigación, advirtió que el estudio se basó únicamente en el 5 % de los pozos existentes, ubicados principalmente en regiones donde la explotación de aguas subterráneas es más intensa.

“Quizá esto también esté ocurriendo en otras regiones del país con alta demanda de irrigación, y simplemente no lo sabemos por falta de datos”.

Hirata también subrayó que, aunque los investigadores identificaron ríos que potencialmente están perdiendo agua hacia los acuíferos, esos datos por sí solos no son suficientes para determinar si los ríos realmente se están secando. Para evaluar eso, se deben considerar otros factores, como la cantidad de agua extraída del acuífero en comparación con el caudal del río, el grado de conexión entre el acuífero y el río, y cuánta agua se extrae del acuífero en relación con las variaciones estacionales del caudal.

“El hecho de que el nivel de agua de un pozo esté por debajo del de un río cercano no necesariamente afecta al río o al acuífero”, explicó Hirata.

Las áreas identificadas como críticas por el estudio se ubican principalmente en regiones áridas, donde ya se esperaba que ocurriera filtración del caudal de manera natural, señaló André F. Rodrigues, hidrólogo de la Universidad Federal de Minas Gerais, quien no participó en la investigación.

El estudio es relevante porque resalta un problema creciente, dijo Rodrigues, pero se necesitan análisis más locales para obtener una imagen más detallada del problema y considerar, por ejemplo, los efectos del clima y los cambios estacionales. “Quizá esto también esté ocurriendo en otras regiones del país con alta demanda de irrigación, y simplemente no lo sabemos por falta de datos”, comentó.

Un problema en crecimiento

La expansión descontrolada de pozos y la extracción excesiva de agua subterránea no solo afectan la salud de las personas, el abastecimiento de agua y la agricultura, sino que también pueden desestabilizar el suelo, provocando hundimientos (subsistencia). Fenómenos similares se han observado en regiones de China, Estados Unidos e Irán.

El panorama no es nada alentador para Brasil. Es probable que la cantidad de pozos se multiplique, ya que se espera que las áreas de riego se incrementen en más del 50 % en los próximos 20 años, según la agencia nacional del agua de Brasil.

“Probablemente veremos un círculo vicioso de degradación, en el que la disminución en la cantidad y calidad del agua superficial, combinada con el aumento de los períodos de sequía, obligará a los agricultores a perforar más pozos para mantener la producción de alimentos, intensificando aún más la extracción de aguas subterráneas y agravando el problema”, advirtió Oliveira.

La sobreexplotación de aguas subterráneas es una preocupación a nivel mundial. La mayoría de los acuíferos han mostrado un descenso en lo que va del siglo XXI, y los estudios por modelado sugieren que la filtración de caudales será más común en las próximas décadas. Aun así, este problema ha sido en gran medida ignorado en regiones tropicales como Brasil, que alberga el 12 % de los recursos de agua dulce renovables del planeta.

Esta falta de atención se debe en parte al escaso financiamiento y vigilancia, y en parte a una creencia persistente de que en los países tropicales y húmedos los ríos suelen ganar agua de los acuíferos y no perderla, mencionó Oliveira. “Debemos actuar ahora si queremos evitar que regiones enteras queden devastadas en el futuro”.

Los investigadores hacen un llamado a realizar más estudios y establecer un monitoreo sistemático de los pozos para identificar las zonas más secas y evaluar el impacto de nuevos pozos sobre los ríos. Actualmente, Brasil solo cuenta con 500 pozos de observación monitoreados constantemente por el gobierno, en comparación con los 18,000 que existen en Estados Unidos, a pesar de que ambos países tienen extensiones territoriales similares. “La vigilancia es extremadamente importante y está tremendamente subestimada”, enfatizó Uchôa.

—Sofia Moutinho (@sofiamoutinho.bsky.social), Escritora de ciencia

This translation by Saúl A. Villafañe-Barajas (@villafanne) was made possible by a partnership with Planeteando and Geolatinas. Esta traducción fue posible gracias a una asociación con Planeteando y Geolatinas.

Text © 2025. The authors. CC BY-NC-ND 3.0
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Editors’ Vox is a blog from AGU’s Publications Department.

Rock glaciers are debris landforms found in many mountain ranges on Earth. They represent the movement of permanently frozen ground over long periods of time and can be used to understand how climate change is affecting permafrost.  

A new article in Reviews of Geophysics explores the use of “Rock Glacier Velocity” to measure how fast these landforms move each year, and its relationship with climatic factors. Here, we asked the authors to give an overview of Rock Glacier Velocity, how scientists measure it, and what questions remain.

What makes rock glaciers unique landforms? 

Rock glaciers primarily form where the ground temperature ranges from approximately -3 to 0°C. Generated by gravity-driven deformation of permafrost, rock glaciers exhibit distinct morphologies indicative of a cohesive flow. The motion mechanism, known as rock glacier creep, involves shearing in one or more layers (i.e., shear horizons) at depth within the permafrost and deformation of the frozen materials above. Changes in rock glacier creep rates depend primarily on changes in ground temperature. Rock glaciers provide a unique opportunity to indirectly document the evolution of permafrost temperatures in mountainous regions.

Remote sensing and field photos of rock glaciers. Credit: Hu et al. [2025], Figure 1

What is “Rock Glacier Velocity” and why is it important to measure? 

“Rock Glacier Velocity (RGV)” refers to the time series of annualized surface velocity reflecting the movement related to rock glacier creep. Since 2022, RGV has been accepted by the Global Climate Observing System (GCOS) as an Essential Climate Variable (ECV) Permafrost Quantity. An ECV is defined as “a physical, chemical, or biological variable (or group of linked variables) that is critical for characterizing the Earth’s climate.” An ECV Quantity is a measurable parameter necessary for characterizing an ECV. Rock Glacier Velocity is instrumental in assessing the state of permafrost under climate change, especially in places where direct monitoring is scarce. From a climate-oriented perspective, relative changes in Rock Glacier Velocity are significant.

What are the main factors that control Rock Glacier Velocity? 

Rock Glacier Velocity is collectively controlled by the geomorphologic features such as slope and landform geometry, as well as the thermo-mechanical properties of the frozen ground, such as ice content, subsurface structure, temperature, and the presence of unfrozen water under permafrost conditions. On a given rock glacier, relative changes in surface velocity over time usually reflect the climatic impacts, with temperature forcing being the dominant factor, especially when temperatures approach 0°C.

How do scientists observe and monitor Rock Glacier Velocity at different spatial scales? 

An illustration showing different survey methods for quantifying Rock Glacier Velocity. Credit: Hu et al. [2025], Figure 5a

Rock Glacier Velocity can be observed and monitored using in-situ and remote sensing methods. Global Navigation Satellite System (GNSS), theodolite, and total station surveys, provide point-based in-situ measurements. Regional-scale surveys typically employ remote sensing techniques, such as laser scanning, photogrammetry, radar interferometry, and radar offset tracking. In-situ RGV time series’ are rare and have mostly been provided from the European Alps, but they can be more than 20 years long. The goal is to leverage the experience gained from the systematic compilation of those in-situ time series to expand the RGV collection to regional-scale surveys using remote sensing techniques.

What kinds of patterns have been observed in Rock Glacier Velocity? 

According to the Rock Glacier Velocity data from across the European Alps, rock glaciers have generally accelerated alongside increasing air temperatures over the past three decades. At the interannual scale, RGV exhibits a regionally synchronous pattern with distinct acceleration phases (i.e., 2000–2004, 2008–2015, and 2018–2020) which are interrupted by deceleration or a steady kinematic state. However, systematic monitoring and documentation of Rock Glacier Velocity is currently lacking in many parts of the world.

How is climate change expected to influence Rock Glacier Velocity? 

Among the climatic factors, multi-annual air temperature changes primarily influence Rock Glacier Velocity by altering the ground thermal state of rock glaciers. Snow cover acts as an insulating layer whose development varies from year to year, causing the ground temperature to deviate from the air temperature on an interannual scale.

In general, warmer ground temperatures favor rock glacier movement. This pattern is expected to occur in many rock glaciers in the future as the climate continues to warm.  When the ground temperature reaches 0°C, some rock glaciers experience drastic acceleration. However, consequent thawing at the tipping point of 0°C causes the rock glacier creep to decline.

What are some of the remaining questions where additional modeling, data, or research efforts are needed? 

First, a standardized strategy for monitoring Rock Glacier Velocity using different methods is under development. We call for more systematic and consistent velocity measurements that can be used to generate Rock Glacier Velocity data products.

Second, the mechanisms linking climatic factors to Rock Glacier Velocity still need to be explored further, such as whether water infiltrates the partially frozen body of a rock glacier and how cold temperatures influence winter deceleration.

Additionally, an in-depth understanding of the relationship between Rock Glacier Velocity, environmental factors, and permafrost conditions requires observations combined with laboratory work and numerical modeling. This is necessary in order to incorporate rock glacier processes into land surface models and predict future changes in a warming climate.

—Yan Hu (huyan@link.cuhk.edu.hk, 0000-0001-8380-276X), University of Fribourg, Switzerland; and Reynald Delaloye (0000-0002-2037-2018), University of Fribourg, Switzerland

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: Hu, Y., and R. Delaloye (2025), Rock Glacier Velocity: monitoring permafrost amid climate change, Eos, 106, https://doi.org/10.1029/2025EO255017. Published on 3 June 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.

Nine people have been killed in a series of landslides, triggered by heavy rainfall, that have struck an army camp.

At about 7 pm local time on 1st June 2025, a series of landslides struck an army camp at Chaten in the Lachen District of Sikkim in India. It is believed that nine people have been killed, although at the time of writing six of these people were still missing, including an army officer, his wife and daughter.

Chaten is located at [27.7188, 85.5581]. This is a Google Earth image of the site, collected in March 2022:-

Google Earth image of the site of the 1 June 2025 landslide at Chaten in Sikkim, India.

The best imagery of the landslides that I have found is on a Youtube video posted by Excelsior News:-

This still captures the site well:-

The 1 June 2025 landslides at Chaten in Sikkim, India. Still from a video posted to Youtube by Excelsior News.

The image shows two main landslide complexes (plus one in the background). Each consists of a series of shallow slips on steep terrain – the one on the left has at least three initial failures, on the right there are also at least three). These have combined to create open hillslope landslides that have stripped the vegetation and surficial materials. Note the very steep lower slopes to the river.

These shallow landslide complexes are characteristic of extremely intense rainfall events, which saturate the soil and regolith from the boundary with the underlying bedrock. This causes a rapid loss of suction forces and a reduction in effective stress, triggering failure. The high water content of the soil then promotes mobility.

It is interesting to note that the natural vegetation has been removed from these slopes. It would be premature to assert that this was an underlying cause of the landslides, but it may have been a factor.

It appears that there has also been erosion of the riverside cliffs, which has left other parts of the camp in severe danger.

Sadly, given the terrain and the availability of people to participate in a rescue (which is one advantage of an event in an army camp), the prospects for those who are missing are not postive.

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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.

In a move that worried politicians and space scientists alike, President Trump announced on 31 May that he will withdraw his nomination of Jared Isaacman for the position of NASA administrator, according to Semafor. Isaacman’s nomination received bipartisan support and he was expected to easily pass a Senate confirmation vote in a few days.

 
Related

•  White House to pull NASA nominee Isaacman
•  Trump withdraws Jared Isaacman’s nomination as NASA administrator
• The Planetary Society reissues urgent call to reject disastrous budget proposal for NASA
• Get Involved: AGU Science Policy Action Center

This is seismic.Isaacman had clearly articulated a strong support for science, and the withdrawal of his nomination yet further imperils NASA's Science Mission Directorate.www.semafor.com/article/05/3…

— Paul Byrne (@theplanetaryguy.bsky.social) 2025-05-31T20:49:52.860Z

Trump cited a “thorough review of prior associations” as the reason for withdrawing the nomination. It was not immediately clear whether he was referring to Isaacman’s past donations to Democrats or his ongoing associations with former DOGE head and SpaceX CEO Elon Musk, who spent the weekend distancing himself from the president. Both of these associations were public at the time of Isaacman’s nomination.

Isaacman, a billionaire, private astronaut, and CEO of credit processing company Shift4 Payments, was questioned by the Senate Committee on Commerce, Science, and Transportation in a nomination hearing in April. Despite a few contentious moments regarding Isaacman’s association with Musk and some waffling over NASA’s Moon-to-Mars plan, the committee ultimately approved Isaacman’s nomination with strong bipartisan support.

When Trump announced Isaacman’s nomination in December 2024, very early for a NASA administrator, space scientists greeted the news with cautious optimism. Isaacman had vocally expressed support for the imperiled Chandra X-ray Observatory, and is a known space enthusiast.

Now, with the withdrawal of his nomination just days after a president’s budget request that would devastate Earth and space science, scientists fear for the future of NASA.

—Kimberly M. S. Cartier (@astrokimcartier.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: AGU Advances

In the southern flanks of the Indian Ocean and the central and eastern Pacific, just north of the Antarctic Circumpolar Current, lie the Subantarctic Mode Waters. As part of the global ocean conveyor belt, these large masses of seawater transfer substantial amounts of heat and carbon northward into the interiors of the Indian and Pacific Oceans. These waters hold about 20% of all anthropogenic carbon found in the ocean, and their warming accounted for about 36% of all ocean warming over the past 2 decades—making them critical players in Earth’s climate system.

Prior research has suggested Subantarctic Mode Waters form when seawater flowing from warm, shallow subtropical regions mixes with water flowing from cold, deep Antarctic regions. But the relative contributions of each source have long been debated.

Fernández Castro et al. used the Biogeochemical Southern Ocean State Estimate model to investigate how these water masses form. The model incorporates real-world physical and biogeochemical observations—including data from free-roaming floats—to simulate the flow and properties of seawater. The researchers used it to virtually track 100,000 simulated particles of water backward in time over multiple decades to determine where they came from before winding up in Subantarctic Mode Waters.

The particle-tracking experiment confirmed that subtropical and Antarctic waters indeed meet and mix in all areas where Subantarctic Mode Waters form but offered more insight into the journeys and roles of the two water sources.

In the Indian Ocean, the simulations suggest, Subantarctic Mode Waters come mainly from warm, shallow, subtropical waters to the north. In contrast, in the Pacific Ocean, Subantarctic Mode Waters originate primarily from a water mass to the south known as Circumpolar Deep Water.

Along their southward flow to the subantarctic, subtropical waters release heat into the atmosphere and become denser, while ocean mixing reduces their salinity. Meanwhile, the cooler Circumpolar Deep Water absorbs heat and becomes fresher and lighter as it upwells and flows northward from the Antarctic region to the subantarctic.

These findings suggest that Subantarctic Mode Waters affect Earth’s climate differently depending on whether they form in the Indian or Pacific Ocean—with potential implications for northward transport of carbon and nutrients. Further observations could help confirm and deepen understanding of these intricacies. (AGU Advances, https://doi.org/10.1029/2024AV001449, 2025)

—Sarah Stanley, Science Writer

Citation: Stanley, S. (2025), On the origins of Subantarctic Mode Waters, Eos, 106, https://doi.org/10.1029/2025EO250207. Published on 2 June 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.

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

On 30 May 2025, a rock slope major failure occurred at a quarry at Gunung Kuda, which is located on the edge of Cipanas Village in Dukupuntang District, Cirebon Regency, West Java, Indonesia. At the time of writing, it has been confirmed that 19 people were killed in the accident, with a further six people remaining missing. Four people were injured.

The location of the failure is [-6.7754, 108.4022]. This is the site in Google Earth:-

Google Earth image of the site of the 30 May 2025 landslide at Gunung Kuda mine.

Universitas Siber Asia has a good article about the event, in Indonesian but it translates well. There is also some Youtube footage of the site immediately after the failure:-

There are other videos circulating of a dramatic rock slope failure, but the ones that I have seen are not this event.

There is also some very clear drone footage of the site after the failure:-

This includes this view of the landslide:-

Drone footage of the site of the 30 May 2025 landslide at Gunung Kuda mine. Still from a video posted to Youtube by Andrea Ramadhan.

The geological structure of this quarry is very complex, with many joints being visible in the above image that would promote instability.

The Universitas Siber Asia article describes a site with a very poor history regarding instability:-

“The Geological Agency said the mine location was in a zone of high soil movement vulnerability, with a probability of landslide of more than 50%. The Head of the West Java Energy and Mineral Resources Office, Bambang Tirto Mulyono, stated that the main cause was the wrong mining method, namely digging from under the cliff, making the soil structure fragile. Repeated warnings from the Energy and Mineral Resources and police lines since February 2025 have been ignored by mine managers. As a result, the West Java Provincial Government revoked the mining permit that was supposed to be valid until October 2025 and closed the site permanently.”

Interestingly, the quarrying was licensed, albeit with substantial safety concerns. Detik Jabar describes the long term worries about the site:–

“…the Head of the West Java Energy and Mineral Resources Office, Bambang Tirto Mulyono, stated that the incident was caused by a faulty mining method carried out by the mine management. Warnings have been conveyed many times by the Energy and Mineral Resources department, and even preventive measures have been taken by the police.”

“We have repeatedly warned the mining authorities, even in a loud tone. The Cirebon Police have also installed a police line at the location since February because the mining methods carried out are not in accordance with safety standards. Mining should have been done from above, not from below,” said Bambang when met at the scene.“

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The textbook explanation of how hailstones grow goes something like this: Nuclei collect frozen layers as they are repeatedly lofted up and fall through clouds. But scientists have had hints that this up-down cycle doesn’t always reflect real hailstones’ journeys. Now researchers have revived an old technique to track dozens of hailstones. The new results, published in Advances in Atmospheric Sciences, suggest that many hailstones take simpler paths.

The idea that hailstones grow as they repeatedly rise and fall on repeat arose as a way to explain stones’ alternating layers of different transparencies, said Xiangyu Lin, an atmospheric scientist at Peking University in Beijing and an author on the new study. But scientists don’t have any direct observations of individual hailstones’ paths in clouds because the severe storms that produce hail are difficult, even dangerous, to observe.

“The vast majority of our understanding of how hail grows has come from numerical modeling,” said Matthew Kumjian, an atmospheric scientist at Pennsylvania State University who wasn’t part of the study. The new research is “a nice piece of experimental evidence” to validate those models, he said.

“Over the past 8 years, we have collected more than 3,000 hailstones.”

At a seminar at Peking University in 2018, Kumjian showed a simple arcing trajectory—rather than a yo-yoing one—for simulated hailstones. Seeing those results, one of Lin’s colleagues at Peking University, atmospheric scientist Qinghong Zhang, wondered whether she could find real hailstones that followed a similar path. That year she started collecting hailstones, using social media to ask the public to save the icy orbs. “Over the past 8 years, we have collected more than 3,000 hailstones,” she said.

To trace the hailstones’ trajectories, the team turned to stable isotopes. At lower altitude, the ice that forms on hailstones tends to have a greater concentration of heavier isotopes of hydrogen and oxygen than the ice that forms higher up. Researchers can measure the ratio of heavy and light isotopes in a layer, providing a postmark of sorts for the altitude at which the ice originated.

The scientists analyzed 27 hailstones from nine different storms spread across eastern China. They sliced each stone in half to reveal its layers. Then they cut the hailstones down layer by layer, so they could melt each layer and measure its isotopes. To find the link between isotope concentrations and height in a storm cloud, the team used temperature, humidity, and pressure data from weather balloons that floated through the atmosphere near each storm.

Hailing from Where?

The isotopes showed that of the hailstones they analyzed, only one had more than one upward flight segment. A few hailstones grew at a relatively constant altitude, and 16 either rose or fell steadily as they grew.

Eight hailstones ascended once before falling to the ground. These eight hailstones were significantly larger than the other stones, Lin said. Hailstones primarily grew between −10°C and −30°C, the team found. With their up-and-down path, these eight stones seem to have spent more time in that zone, causing them to grow larger than others.

Many hailstones are not perfect spheres. Credit: Xiangyu Lin

Scientists used stable isotope analysis on hailstones some 50 years ago, but the technique fell out of favor, Kumjian said. Many of those early studies analyzed a small number of stones from few storms or sometimes a single storm. The new study is “bringing back this old type of analysis with modern methods,” he said.

But the analysis required assumptions that might cloud results. For instance, updrafts can mix air from different altitudes, Kumjian said. That can affect the isotopes in a hailstone’s layers.

Scientists are still exploring questions about hail across a range of scales from stone to storm. Though researchers know what sorts of storms can produce damaging hail, it’s hard to predict which will rain down baseball-sized stones or where exactly hail will fall. Meanwhile, the physics of hailstones’ growth is tricky. Researchers typically model stones as perfect spheres—a far cry from the bumpy lumps that fall from the sky. But those shapes affect how fast hail falls and the damage it can produce, Kumjian said.

“It’s a very exciting time in the hail world. We’re going to learn a lot in the coming years.”

Researchers are using modeling, radar observations, and isotope studies such as this one to improve forecasts. Hail can knock out crops, damage structures, and shatter solar panels. Even 10 minutes of warning is enough for people to move cars and prevent damage, Zhang said.

Kumjian is part of a team that is launching instrumented Styrofoam spheres into clouds that could provide insights on actual paths taken by stones. Zhang’s team is continuing to study isotopes in layers, now looking at larger stones that formed in storms over Italy. “It’s a very exciting time in the hail world,” Kumjian said. “We’re going to learn a lot in the coming years.”

—Carolyn Wilke (@CarolynMWilke), Science Writer

Citation: Wilke, C. (2025), Isotopes map hailstones’ paths through clouds, Eos, 106, https://doi.org/10.1029/2025EO250206. Published on 30 May 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
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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
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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
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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
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