EOS

The solar system’s oddball planet has some pretty odd moons, too. The first infrared spectra of Uranus’s small inner moons, which will be presented on 18 December at the 2025 AGU Annual Meeting in New Orleans, have shown that their surfaces are much redder, much darker, and more water-poor than the larger moons orbiting far from the planet.

“We were trying to see how these properties varied across the rings and moons,” said Matt Hedman, a planetary scientist at the University of Idaho in Moscow and a coauthor on the research. “We didn’t have a lot of information about their spectra before because they’re hard to observe.”

The new observations also revealed that some moons were not quite where they should have been, highlighting how much more astronomers have to learn about the dynamics of the Uranian system.

Small, Dark, and Red

In 1986, Voyager 2 flew past Uranus in humanity’s only visit to the system. At that time, astronomers knew only of the planet’s five major moons and a handful of rings. Voyager 2 discovered 11 more moons and was able to roughly measure their sizes. Since then, scientists have used ground- and space-based telescopes to discover more than a dozen additional satellites, bringing Uranus’s moon total to 29.

Many of the more recently discovered moons are pretty tiny, from Sycorax at 150 kilometers across to Mab and Cupid at just 10 kilometers. Most of them also orbit within or just outside Uranus’s ring system, close to the much brighter planet.

All of these properties have made it tricky for astronomers to learn more about the smallest Uranian moons. That’s where the infrared powerhouse James Webb Space Telescope (JWST) comes in.

This diagram shows the orbital distances of Uranus’s inner moons and rings, to scale. Uranus is placed at the top of the diagram. Click image for larger version. Credit: Ruslik0/Wikimedia Commons, Public Domain

“Part of what makes JWST particularly good for this compared to, say, Hubble and other optical telescopes, is that in the infrared, Uranus is much fainter, so you can see the things orbiting it way more easily,” Hedman explained. What’s more, all of the spectral features the team was interested in, like water ice, occur at wavelengths that JWST can observe.

The researchers observed Uranus at several infrared wavelengths in February and got a deep look at the inner portions of the planetary system. They wanted to characterize the known small moons and search for new ones. They did discover a previously unknown moon, temporarily named S/2025 U1, orbiting just outside the epsilon ring.

Those observations also provided the first information on the infrared brightnesses of the smallest moons, many of which have remained elusive since the Voyager flyby.

“Most of the rings and inner moons show very similar properties,” Hedman said. They tend to be much redder, darker, and more water-poor when compared with the larger outer moons Miranda, Ariel, Umbriel, Titania, and Oberon.

“And then there’s Mab,” Hedman added.

The new spectra show that Mab’s surface is bluer and more water-rich than the other inner moons, said Jacob Herman, a physics graduate student at the University of Idaho and lead author on the research. In fact, its surface spectrum looks very similar to Miranda’s, the major moon that orbits closest to the rings and to Mab. Miranda’s jigsaw surface suggests a messy history.

“There is still much to be discovered about Uranus’s small inner moons, particularly regarding their origin, composition, and long-term orbital stability.”

Did the two moons encounter each other sometime during Uranus’s chaotic past? Could that encounter be related to Uranus’s mu ring, which is likely generated by material sloughing off Mab? Hedman hopes that future observations or a long-term mission to Uranus will provide those answers.

“These new measurements significantly expand our current knowledge, revealing, for instance, striking variations in the composition and reflectivity of the surfaces of moons such as Mab, Cupid, and Perdita,” said Jadilene Xavier, an astrophysicist at São Paulo State University in Guaratinguetá, Brazil, who was not involved with this research.

“There is still much to be discovered about Uranus’s small inner moons, particularly regarding their origin, composition, and long-term orbital stability,” Xavier said. “More precise data on their density, three-dimensional shape, and surface properties would be essential to determine whether these moons are fragments produced by collisions, captured objects, or primordial remnants associated with the formation of Uranus’s ring system.”

Just a Little Bit Off

Because Voyager 2 spent only a short time visiting Uranus, it could provide only limited information about the small moons’ orbital periods and distances, sometimes with large uncertainties. When the researchers compared the moons’ current positions with the positions predicted by Voyager 2 data, some of the moons were not where they seemingly should have been.

“Perdita was quite a bit off,” Herman said. “And there’s also Cupid, which was surprising.” The positions of Cordelia, Ophelia, Cressida, and Desdemona were also off, but not by much. The team is still trying to figure out whether the differences are just a matter of having more precise observations of these tiny objects or if there are unknown dynamics in play.

“These new observations are quite useful for improving our understanding of the inner Uranian system, especially its orbital dynamics.”

“These new observations are quite useful for improving our understanding of the inner Uranian system, especially its orbital dynamics,” said Matija Ćuk, who researches solar system dynamics at the SETI Institute in Mountain View, Calif.

Ćuk, who was not involved with this research, pointed out that Cordelia and Ophelia shepherd Uranus’s epsilon ring, Cressida and Desdemona are part of a pack of moons with chaotic orbits, and Perdita is known to interact with another moon, Belinda. “So the fact that these [five] moons are not in their predicted positions is valuable for understanding the system, but I wouldn’t say it’s unexpected,” Ćuk said.

These observations hint at just how many mysteries Uranus is still hiding.

“For a dynamicist like me,” Ćuk said, “knowing the precise masses of these moons would be ideal, because then we could predict their future interactions and also estimate with some confidence how stable they are on long timescales.”

Hedman and their team plan to observe the Uranian system again with JWST, are looking through archived and technical images, and hope to establish long-term monitoring to better understand the moons’ dynamics and possibly estimate their masses. The researchers are also leaning on their colleagues who simulate planetary orbits to better understand how Uranus’s moons and rings might be influencing each other.

“It’s a very dynamic and interconnected system,” Herman said.

—Kimberly M. S. Cartier (@astrokimcartier.bsky.social), Staff Writer

Citation: Cartier, K. M. S. (2025), Uranus’s small moons are dark, red, and water-poor, Eos, 106, https://doi.org/10.1029/2025EO250442. Published on 25 November 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 rapid retreat of glaciers, an increasingly common phenomenon, could potentially lead to complex changes in ocean chemistry. A new study has revealed that sediment runoff from retreating glaciers is less nutritious for marine life than meltwater from stable glaciers. This finding has important implications for high-latitude marine ecosystems, such as the Gulf of Alaska, where trace metals like iron and manganese are essential for supporting microorganisms at the base of the food web.

Glacial runoff, which carries sediments produced by the relentless grinding of ice on the bedrock below, is an important source of trace metal micronutrients in the ocean. These nutrients, in turn, are essential for phytoplankton growth, which sustains the marine food web and plays a major role in absorbing atmospheric carbon dioxide.

Intrigued by the effects of climate change on nutrient availability, a team of researchers used two adjacent glaciers on Alaska’s Kenai Peninsula as a natural laboratory. One of them, Aialik Glacier, is stable and terminates on the sea, while the other, Northwestern Glacier, has retreated inland approximately 15 kilometers (9.3 miles) since 1950. Because both glaciers erode the same bedrock, the researchers knew the source material for their sediments would be nearly identical.

In late May 2022, as seasonal melting intensified, the team—led by marine chemist Kiefer Forsch, who conducted the research as a postdoctoral fellow at Scripps Institution of Oceanography and is now at the University of Southern California—collected samples from the fjords of both glaciers. Working from a small aluminum boat provided by Kenai Fjords National Park, they sampled and analyzed surface water, suspended sediments, and iceberg material, looking to analyze the concentration and bioavailability of metals like iron and manganese, as well as macronutrients such as phosphorus. (Bioavailability describes the proportion of nutrients that is readily usable by marine organisms.)

The analysis revealed important differences in the proportion of bioavailable metals in the sediment plumes. Sediments from the stable Aialik Glacier were substantially richer, with approximately 18% of the iron and 26% of the manganese in bioavailable forms. In contrast, the retreating Northwestern Glacier’s sediments contained only 13% bioavailable iron and 14%–15% bioavailable manganese. The researchers described their findings in Nature Communications.

Stale Nutrients

Researchers think this drop in bioavailable nutrients may be caused by the time lapse between when the sediments were produced and when they were released into the ocean. In the stable Aialik Glacier, which ends directly in the fjord, the sediments have a very short trip from the point of erosion to the ocean. This short distance results in fresh and labile—reactive—nutrients that microorganisms can readily use.

“The impact it could have on the ecology downstream might be muted quite a bit by its lower bioavailability.”

The retreating Northwestern Glacier’s erosive action has moved far inland. As its sediments are transported to the ocean by fluvial waters, they are chemically altered, transformed into less reactive compounds. By the time the runoff reaches the fjord, Forsch said, “it’s lost a lot of its nutritious value just by sitting there, chemically weathering.”

But that’s not the whole story. In absolute terms, the amount of bioavailable metals was similar in both fjords because the overall volume of sediment in the retreating glacier’s fjord was higher. Even if the runoff was less nutritious, researchers concluded, there seemed to be more of it.

Regardless, “the impact it could have on the ecology downstream might be muted quite a bit by its lower bioavailability,” Forsch said.

The Coast Is Not the Ocean

The implications for nutrient availability extend beyond trace metals. Glaciers that terminate in the ocean, called tidewater glaciers, provide an extra benefit by inducing powerful upwelling currents. Meltwater enters the ocean at depth and quickly rises, bringing with it deep ocean water loaded with macronutrients like nitrogen and phosphorus. Phytoplankton near the ocean surface consume these nutrients and can themselves become bioavailable to the fjord’s primary consumers like zooplankton and krill. This upwelling mechanism is what makes these fjords highly productive ecosystems.

“Losing this macronutrient supply [as tidewater glaciers retreat inland] is considered the more devastating impact for coastal ecosystems,” said Jon Hawkings, a glacial biogeochemist at the University of Pennsylvania. “There’s much more iron and manganese in these fjords than there is in the ocean by orders of magnitude; they’re limited by nitrogen mainly.”

“Once the upwelling mechanism is lost, the fjord starts to become less productive,” Forsch added.

Making things worse, when a glacier retreats onto land, its sediments are ultimately delivered at the ocean surface, creating a plume that blocks light, further inhibiting phytoplankton growth. In terms of the geochemistry and biology of these ecosystems, “it’s not really a dial, it’s a switch that occurs when a glacier retreats onto land,” he said.

While the loss of tidewater glaciers will likely lead to reduced productivity within fjords, the implications for the wider ocean are different. The Gulf of Alaska is home to very important fisheries, but its overall productivity is limited by micronutrients like iron, rather than macronutrients such as nitrogen and phosphorus. Glacial retreat might accelerate the delivery of more dissolved iron and manganese out of the fjords and onto the continental shelf, but at the same time these sediments will be less nutritious than they used to be.

In fact, Hawkings suggested, researchers might want to look “off the fjords.… This is probably where this work should go next, looking at these plumes as they exit the fjords into the Gulf of Alaska.”

The study “opens up a number of new questions,” Hawkings said, but much more research is needed to answer them. “What is the impact…for marine productivity? Is this just a one-off? Should we go back to the same place and test again? What about other places like Greenland, Alaska and Patagonia? … The jury is still out in my view.”

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

Citation: Barbuzano, J. (2025), Glacier runoff becomes less nutritious as glaciers retreat, Eos, 106, https://doi.org/10.1029/2025EO250431. Published on 25 November 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.

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

Gestionar los incendios en bosques tropicales puede ser una tarea muy abrumadora: los taladores y los pirómanos comúnmente se mueven más rápido que los equipos de primera intervención, los recursos son escasos y el territorio es inmenso. En la Amazonia Brasileña, estos obstáculos aprietan a un sector ambiental que crónicamente ha recibido pocos fondos, cuyos agentes de campo enfrentan amenazas de granjeros y, cada vez más, de el crimen organizado.

En 2024, los incendios arrasaron con 30.8 millones de hectáreas en Brasil, un 79% más que en 2023. Más del 80% del área total que se quemó se encontraba dentro de la Amazonia Legal, según la plataforma de datos ambientales MapBiomas (La Amazonia Legal es una región designada por el gobierno que comprende los 9 estados que están en la cuenca del Amazonas). Debido a la escala de los incendios, en agosto de 2024, el Instituto Brasileño del Ambiente y Recursos Naturales Renovables de Brasil (IBAMA, por sus siglas en portugués) incrementó la cantidad de vigilantes a 2 227 brigadistas (bomberos), con 1 239 de ellos – más de la mitad – con base en la Amazonia Legal.

Millones de hectáreas en Acre

Acre es el estado más al oeste de Brasil, colinda con Perú y Bolivia y es parte de la Amazonia Legal. En Acre, cuatro brigadas de incendios profesionales con 68 bomberos de tiempo completo operan en tres municipalidades y un área protegida. Una brigada voluntaria también opera en la ciudad más grande, que también es la capital, Rio Branco.

Con cerca de 14 millones de hectáreas de bosque que patrullar, estos grupos apenas pueden cubrir una fracción del territorio de Acre.

Resulta que la ciencia ha sido una herramienta importante para llenar el hueco, ya que el desafío de combatir el fuego en Acre no es solo sobre la falta de grupos en el campo; también está relacionada al acceso de datos. La información ambiental de Brasil está esparcida a lo largo de varias agencias: El Instituto Nacional de Investigación Espacial (INPE, por sus siglas en portugués), agencias ambientales federales como el IBAMA y el Instituto Chico Mendes para la Conservación de la Biodiversidad, la agencia Nacional de Agua (ANA, por sus siglas en portugués), y el centro Nacional para Monitoreo y Alertas de Desastres Naturales de Brasil, así como secretarías individuales de estado, cada una trabajando con sus propias prioridades y cadencias.

Sin datos arreglados en formatos compatibles, algunos de ellos se pueden sobrelapar o contradecir. “Para saber dónde tenemos que actuar, necesitamos información calificada, tenencia de tierras, zoneamientos y puntos calientes de incendios. Sin eso, cualquier política pública para incendios o deforestación va a ser inefectiva en el Amazonas”, dijo Claudio Cavalcante, jefe del Centro para Geoprocesamiento Ambiental (CIGMA, por sus siglas en portugués), el centro geoespacial que Acre creó dentro de la Secretaría del Ambiente en 2020 para conectar la deforestación y el monitoreo de incendios con la respuesta de políticas públicas.

CIGMA ha hecho los esfuerzos de integrar los datos de todas las agencias estatales y federales de Brasil para informar a los agentes en el campo. “Hemos trabajado con estratificación de datos: deforestación [en áreas] de 1 a 5 hectáreas y luego de 10 a 50. Automatizar algunos flujos de datos ha sido un trabajo muy complejo y laborioso” añadió Cavalcante, quien formó parte de una junta con investigadores, comunicadores y expertos en políticas públicas en las oficinas centrales del CIGMA en julio.

La mirada en los datos

Toda la integración sucede en el Cuarto de Situaciones de CIGMA, donde científicos y analistas evalúan alertas de incendio en vivo, niveles de los ríos, lluvia, índices de sequía y otra cantidad de datos.

“Todos los mapas para la acción en el campo se desarrollan aquí. También preparamos los reportes y notas técnicas mensuales de la deforestación”, dijo Quelyson Souza, quien coordina el Grupo de Mando y Control Ambiental de la Secretaría Ambiental de Acre.

Quelyson Souza, quien coordina el Grupo de Comando y Control Ambiental de Acre, explica cómo las alertas de tala funcionan y cómo esos datos pueden ser integrados en las respuestas para el combate a los incendios. Crédito: Bibiana Garrido/IPAM Amazonia

El sistema de CIGMA fusiona las alertas de incendios del INPE con los datos de tenencia de tierras y zoneamiento para identificar potenciales infractores. Los datos hidrogeológicos de ANA, la agencia de agua, se actualizan cada 15 minutos y alimentan los datos de la Defensa Civil y el Departamento de Incendios del estado. Los sensores de calidad del aire detectan humo que viene de la selva dentro y fuera de los límites de Brasil.

Para el coordinador de las Operaciones de Protección Ambiental del Cuerpo de Bomberos de Acre, el Mayor Freitas Filho, los datos científicos a los que sus cuerpos tienen acceso en el campo “son esenciales para optimizar y refinar el uso de los recursos operacionales”. El departamento de incendios de Acre lidera la Operación Controlada de Incendios, la cual se enfoca en integrar los equipos de agentes militares y ambientales para combatir los incendios en la estación seca, que abarca la segunda mitad del año.

Según un informe de manejo de incendios en la selva del Amazonas publicados este mes por el Instituto de Investigación Ambiental de la Amazonia (IPAM Amazônia), Acre tiene un modelo muy efectivo para vincular datos y gobernanza que recomienda sistemas de alerta temprana e intercambio abierto de datos para que las municipalidades puedan actuar de forma rápida.

Lecciones de Acre

A pesar de los desafíos, Acre resalta como uno de los pocos estados Amazónicos donde científicos, bomberos y creadores de políticas públicas comparten un mismo cuarto.

“Es inspirador ver la evolución del Cuarto de Situación de Acre. Lo uso como un ejemplo nacional porque la acción sucede en el campo, incluso más allá de las fronteras”, dijo Liana Anderson, una investigadora de percepción remota en el INPE.

“Es mucho más difícil que nos engañen los delincuentes que quieren salirse con la suya con sus delitos medioambientales”

Mientras Brasil se prepara para albergar la COP30 (la Conferencia de Cambio Climático de las Organización de las Naciones Unidas) en Belém, científicos y tomadores de decisiones esperan que la experiencia de Acre pueda ser un ejemplo de manejo del ambiente centrado en la ciencia: las bases de datos unificadas, los paneles compartidos y la colaboración pueden convertir a la información en planeación y acción.

“Cuando tenemos una idea más clara con la información a la que tenemos acceso ahora, es mucho más difícil que nos engañen los delincuentes que quieren salirse con la suya con sus delitos medioambientales”, dijo Souza. “Es como cuando te levantas la venda de un ojo cuando estas jugando a la gallina ciega”

—Meghie Rodrigues (@meghier.bsky.social), Science Writer

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.

This translation by Anthony Ramírez-Salazar (@Anthnyy) was made possible by a partnership with Planeteando and GeoLatinas. Esta traducción fue posible gracias a una asociación con Planeteando and GeoLatinas.

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

Groundwater supports billions of people, but many regions are removing it from aquifers faster than nature can refill them. Bhalla et al. [2025] examine the concept of “peak groundwater”, the moment when use reaches its maximum and begins to decline due to physical, economic, or policy limits. The authors trace how climate pressures, population growth, and management choices interact to determine when those limits arrive. They show that peak groundwater is not only a physical threshold but also a social and institutional one, shaped by how communities plan for scarcity.

The review offers a clear framework for recognizing early signs of stress and explores practical actions that can extend the life of aquifers. By bringing together insights across disciplines, it lays out pathways for governments, water managers, and communities to respond proactively. This synthesis offers a timely guide for protecting groundwater in an era of rising uncertainty.

Citation: Bhalla, S., Cherry, J. A., Konikow, L. F., Taylor, R. G., & Parker, B. L. (2025). Peak groundwater: Aquifer-scale limits to groundwater withdrawals. Earth’s Future, 13, e2025EF006221. https://doi.org/10.1029/2025EF006221

—Kelly Caylor, Editor-in-Chief, Earth’s Future

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’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Community Science

Frontline communities are commonly described as groups most affected by environmental and social challenges. Marston et al. [2025] offer a broader definition based on the experiences of community-based organizations that directly serve these communities.

Drawing on surveys, interviews, and text analysis, the authors show that “frontline” refers not only to vulnerability but also to active leadership, resistance, and cultural strength. The study finds that community-based organizations want support that respects their self-determination and avoids imposing outside definitions of success. They also emphasize the need for respectful, two-way partnerships rather than top-down guidance. These insights matter because misalignment between funders and communities can weaken well-intended projects. The study provides a rare look at what frontline organizations say they truly need. Overall, it offers practical guidance for building ethical, reciprocal, and community-centered partnerships.

Citation: Marston, R., Lutz, N., Mangabat, D., Sánchez Ainsa, G., Stober, J., Brown, M., & Turner, K. M. (2025). A mixed-methods needs assessment of frontline communities: Insights for engagement and partnerships between communities and intermediary organizations. Community Science, 4, e2025CSJ000133. https://doi.org/10.1029/2025CSJ000133  

—Claire Beveridge, Editor, Community Science

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.

Imagining Earth millions of years ago—its landscapes, atmosphere, temperature—is challenging.

In Antarctica, however, rare formations known as blue ice areas may offer a distinct look into that deep past. These areas, which make up barely 1% of the continent, form where strong winds strip away surface snow. Not all blue ice areas contain very old ice, but sometimes the slow movement of the ice sheet preserves ancient layers.

The Allan Hills region, situated on the edge of the East Antarctic Ice Sheet, is one such blue ice area. Here researchers have discovered ice up to 6 million years old—the oldest yet found.

Their study of the ice, published in Proceedings of the National Academy of Sciences of the United States of America, revealed that parts of it formed during periods far warmer than today—times when sea levels were higher and open forests and grasslands covered much of the planet.

The Allan Hills ice cores are not continuous. The oldest continuous ice core, also extracted from Antarctica, may reach back about 1.2 million years. Scientists compare continuous cores to a video: an uninterrupted, sequential history. Blue ice samples like the ones taken from Allan Hills, on the other hand, function as scattered fragments or disassembled snapshots that capture events beyond the video’s timeline.

“The advantage of Allan Hills is how far back these snapshots extend,” said Sarah Shackleton of the Woods Hole Oceanographic Institution and lead author of the study. “Modeling suggests the oldest possible continuous ice core in Antarctica might not go beyond 1.5 million years. To study earlier times, we need alternative samples.”

The Allan Hills project is part of the Center for Oldest Ice Exploration (COLDEX), which seeks to uncover the oldest possible ice records to better understand Earth’s climate history.

A Frozen Archive of Deep Time

The team, led by Shackleton and John Higgins of Princeton University, drilled 200 meters to uncover these ice fragments that trap “ancient precipitation—and, more importantly, ancient air,” Higgins explained. The researchers measured isotopes of gases (such as argon-40) to estimate the ice’s age and isotopes of water (such as oxygen-18 and deuterium) to reconstruct past climates.

According to the study, the Antarctic region cooled by about 12°C over the past 6 million years, documenting the long-term transition from a relatively mild Miocene to the relatively icy world we know today.

This record is critical because while the planet has sustained much hotter temperatures, many of its human inhabitants have not: Although the last interglacial period was warmer, we have rarely experienced the planet as warm as it is today. The past is a valuable source for identifying potential warming scenarios.

“These are pieces of a larger puzzle,” said Lidia Ferri, a glaciologist with the PARANTAR project, a research project carried out at the Universidad de Oviedo in Spain to study Antarctica’s South Shetland Islands. “We can establish cycles and identify inflection points. If the ice disappears, other factors are triggered, like changes in atmospheric dynamics and ocean currents. It’s a deeply interconnected system.”

Toward Future Climate Projections

“We use the planet’s past climate as a way to ground-truth the models we’re developing to predict what’s ahead.”

A main question posed by the new research is why past climates were so warm: Was it because concentrations of atmospheric greenhouse gases were higher, or were other factors at play? By studying the atmospheric remnants trapped in blue ice, the researchers hope to refine the models used to project Earth’s future.

“We use the planet’s past climate as a way to ground-truth the models we’re developing to predict what’s ahead,” Shackleton explained.

Ferri concurred, noting the value of gathering data from different time periods. “Today’s models are becoming more precise because the data is more varied,” she said. “The temperature increase predicted for the next 50 years isn’t the same as one 10,000 years ago, and this ancient data helps enrich those models.”

Despite spartan accommodations and extreme weather, researchers plan to return to Antarctica to collect more data from the PARANTAR project. Credit: Jordi Rovira

The team plans to return to Allan Hills, though Antarctic fieldwork is notoriously challenging. “We’re in a remote field camp with no permanent structures,” Higgins said. “It’s incredibly windy and completely isolated.”

—Mariana Mastache-Maldonado (@deerenoir.bsky.social), Science Writer

Citation: Mastache-Maldonado, M. (2025), New lessons from old ice: How we understand past (and future) heating, Eos, 106, https://doi.org/10.1029/2025EO250441. Published on 24 November 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.

Source: Journal of Geophysical Research: Biogeosciences

Many ecosystems on Earth are affected by pulses of activity: temperature swings between seasons, incoming and outgoing tides, the yearly advent of rainy periods. These variations can play an important role in providing nutrients and other important inputs, but climate change often makes the amplitude of these pulses more extreme, with sometimes catastrophic results.

We need better data on the effects of changes to these pulses of activity, argues Lee. The author describes ongoing efforts to gather such data using the eddy covariance method, which measures exchanges between ecosystems and the atmosphere. The work focuses on fluxes in drylands and coastal blue carbon ecosystems—two ends of the dryness spectrum that are home to high levels of biodiversity and carbon storage and that are under increasing threats from climate change.

Scientists are gathering data from networks of flux towers, with plans to expand their data collection methods, for example, pairing mobile measuring devices with existing towers and synergizing flux data with other measurements. These strategies are increasingly important, the author notes, for assessing unconventional water inputs such as tides and condensation during dry conditions, as well as considering how disturbances like wildfire smoke and dust storms affect ecosystem function. The author argues that understanding how ecosystems are adapting to recent changes to these and other factors is crucial for refining Earth system models and constructing more accurate predictions of how ecosystems will adapt—or fail to adapt—in the future.

The author and his colleagues are also exploring the use of machine learning for Earth science endeavors and are pursuing hybrid approaches that combine process-based models with machine learning techniques. A key advantage of hybrid models is their usefulness in solving parameterization problems and the option to incorporate additional data sources, he notes. These advances could help unlock the potential of flux data to reveal crucial insights about our changing world. (Journal of Geophysical Research: Biogeosciences, https://doi.org/10.1029/2025JG009249, 2025)

—Nathaniel Scharping (@nathanielscharp), Science Writer

Citation: Scharping, N. (2025), Understanding flux, from the wettest ecosystems to the driest, Eos, 106, https://doi.org/10.1029/2025EO250438. Published on 24 November 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.

Over the weekend, Planet captured near-perfect images of the Mae Moh Mine landslide in Thailand.

Last week, I posted a set of Planet satellite images that captured most of the 4 November 2025 landslide at Mae Moh Mine in Thailand. However, there was considerable cloud in the imagery, which prevented a full understanding of the landslide. Over the last few days, near perfect conditions have allowed a full, cloud-free image to be captured by Planet:-

The aftermath of the 4 November 2025 landslide at Mae Moh Mine in Thailand. Image copyright Planet, captured on 22 and 23 November 2025, used with permission.

This image is a composite of two sets captured on 22 and 23 November 2025. The crown of the landslider is on the west side, with the failure moving towards the east.

I think there are twof interesting aspects to this landslide. The first is the light coloured material in the upper part of the landslide – this is the mine waste that was being deposited shortly before the failure. It is the dumping of this mine waste that is my primary hypothesis for the cause of this landslide.

The second is the configuration towards the toe of the landslide (on the east side of the image). This is the area in question:-

The lower part of the 4 November 2025 landslide at Mae Moh Mine in Thailand. Image copyright Planet, captured on 22 and 23 November 2025, used with permission.

I have placed a marker at a key point on the image. The main part of the landslide terminates in the area of the marker, but a smaller flow type failure has then developed from this point. This appears to have been quite mobile – note how a lobe has moved to the north. The main portion has moved generally eastward, with one lobe reaching the pond, and another moving towards the southwest. There are indications that this SW tending portion might have been the final movement. The distance from marker to toe is over 1,400 metres – this was a major event in its own right. I’m quite intrigued by this lower failure – was this saturated mine waste that failed through undrained loading, for example?

It is worth reiterating that the 4th November 2025 event is not the first major failure of waste at Mae Moh Mine – a 70 million cubic metre failure occurred on 18 March 2018. In fact, I wrote about that landslide too, back at the time of the failure. I included this quote, originally from The Nation:-

Maliwan Nakwirot, a resident living near the mine in Lampang, yesterday said a landslide in the area on Sunday was the result of misconduct by the mine operator, which had been piling excavated soil into unstable piles instead to storing it in abandoned mine pits.  It is not the first time that there have been landslides at Mae Moh mine. There have already been three major landslides at the mine since last year, as these mountains of soil are not stable and are ready to slide anytime,” Maliwan said.

Interesting! Finally, a brief note as to the scale of this landslide. It covers an area of about 5.7 km2 – this is extremely large. The 2018 failure covered an area of 1.56 km2 and had a volume of 70 million m3. The surface area of this failure is about 3.65 times as large. The volume is unlikely to scale in a linear manner, but might seem to indicate that the volume may exceed 100 million m3? To put that in context, the infamous 2013 Bingham Canyon landslide was “only” 55 million m3.

Reference

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

Return to The Landslide Blog homepage Text © 2023. The authors. CC BY-NC-ND 3.0
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Shackleford Banks is an 8-mile-long barrier island off the coast of North Carolina made up of sandy beaches, marshes, and maritime forests. There are no vacation rentals, boardwalks, or seafood restaurants serving the residents of Shackleford Banks. That’s because the residents are more than 100 wild horses that call the sandy dunes of this island home.

The delicate ecosystem of Shackleford Banks is facing the effects of a changing climate, such as increasingly volatile storms and flooding, drought, erosion, and saltwater intrusion. The island’s low elevation means its freshwater sources can be infiltrated with salt water during king tide events and storm surges. During stretches of drought, freshwater sources for the island’s equine residents can run dry, leaving the horses to compete for these vital resources.

“These horses have been out here long enough to adapt and survive, but freshwater availability is a critical resource,” said Matthew Sirianni, a geoscientist at East Carolina University who will present his research on 16 December at AGU’s Annual Meeting. Sirianni and colleagues monitored freshwater sources on Shackleford Banks, finding that horse behavior changed when freshwater sources were scarce. As saltwater intrusion and coastal hazards increase along the islands off the coast of North Carolina known as the Outer Banks, these findings can improve understanding of how to manage wildlife during a changing climate.

Foraging for Fresh Water

Wild horses have lived on Shackleford Banks for centuries. One theory suggests they arrived in the 1500s, swimming to shore after Spanish explorers were shipwrecked along the East Coast. Genetic testing suggests today’s Shackleford Banks horses are related to Spanish horse breeds, but early English settlers also brought horses with them that may also have escaped or been abandoned along the Outer Banks.

A horse digs in a pool of surface water at a groundwater seep during low tide on Shackleford Banks. These temporary pools will be flooded by the next high tide. Credit: Matthew Sirianni

Today, Shackleford Banks’s wild horse population must be kept to a manageable number so that the island and its resources aren’t overwhelmed. National Park Service workers dart the mares with hormonal birth control each year to keep herd size low. The small, hardy equines have adapted to a life of eating marsh grass, sea oats, and wax myrtle. They drink from ponds and freshwater seeps, and they also dig holes in the sand to reach the freshwater belowground when other sources have dried up.

In the new study, researchers monitored surface and groundwater levels and conductivity—a proxy measurement for salinity because higher conductivity values mean saltier water—in six water sources (two ponds, one groundwater seep, and three dig sites) located across the island.

“Barrier islands often develop a freshwater lens in the subsurface that floats on top of the denser, saltier water,” Sirianni said. “By monitoring water level and water conductivity, we can, over time, see whether the freshwater lens is shrinking, growing, or getting saltier, which tells us how the island’s water resources are responding to things like tides, storms, or droughts.”

Researchers installed motion-activated trail cameras near the water sources to capture still shots of animals drinking. They then grouped time-stamped photos to connect the horses’ drinking activities with water level and conductivity data. From there, they searched for water usage patterns, as well as for information about how long horse-dug holes (some as deep as 3 feet) stayed full of fresh water.

“Preliminary results from July 2024 to April 2025 indicate that horses spend more time drinking at dig sites, where conductivity is lower and more stable, compared to ponds and the groundwater seep, where conductivity is higher and more variable. However, when rainfall is low, dig sites often run dry, leading horses to drink from these higher-conductivity sources,” Sirianni said.

A Saltier Future?

“In the past, we’ve said that horses wouldn’t drink brackish water, but we were wrong. They do drink brackish water when that’s the only thing available to them.”

“With the research that [Sirianni] is doing, we have learned that these ponds can be really brackish,” said Linda Kuhn, a volunteer veterinarian with the National Park Service who was not involved with the research. “In the past, we’ve said that horses wouldn’t drink brackish water, but we were wrong. They do drink brackish water when that’s the only thing available to them.”

If the freshwater sources become saltier, history has already shown how the wild horses could be in trouble. On the island of Chincoteague, Virginia, equine deaths and illness were linked to a toxic increase in salinity in freshwater supplies, possibly wrought by the storm surge from Hurricane Erin.

It took 2 weeks for volunteers and observers to figure out what was wrong at Chincoteague. “Here we have [Sirianni] giving us data in real time. He also has cameras out there so he can see who’s drinking.” In light of what happened to the Chincoteague ponies after Hurricane Erin, “it’s just such an important study at this time,” Kuhn said.

“These horses have been here for many years and weathered many storms, so…they are a symbol of wildness and freedom even in the face of adversity.”

And with the potential for stronger, damaging storms in the future, the wild horses in this precarious island habitat may face more water and food shortages—along with danger from the land itself. Previous modeling studies suggest sea level rise will cause the already shallow groundwater table to reach the surface, as well as cause the shoreline to retreat as land subsidence and erosion worsen.

Sirianni plans to continue monitoring Shackleford Banks’s wild horses and water sources through at least July 2026 while he works on a final study manuscript about his findings. But he hopes to fund this research into the future. “These horses have been here for many years and weathered many storms, so I like that they are a symbol of wildness and freedom even in the face of adversity,” he said.

—Rebecca Owen (@beccapox.bsky.social), Science Writer

Citation: Owen, R. (2025), What salty water means for wild horses, Eos, 105, https://doi.org/10.1029/2025EO250433. Published on 21 November 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.

Source: Geophysical Research Letters

Ancient Mars boasted abundant water, but the cold and dry conditions of today make liquid water on the Red Planet seem far less probable. However, the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) detected strong radar reflections from a 20-kilometer-wide area over the base of Mars’s southern polar ice cap, hinting at the possibility of liquid water below the icy surface. Such a finding would have major implications for the planet’s possible habitability.

But sustaining liquid water underneath the ice might not be feasible without very salty brines or localized volcanic heat. Scientists have deliberated about other possible “dry” explanations for the bright reflections detected by MARSIS, such as layers of carbon dioxide and water ices or salty ice and clay causing elevated radar reflectivity.

Aboard the Mars Reconnaissance Orbiter, the Shallow Radar (SHARAD) uses higher frequencies than MARSIS. Until recently, though, SHARAD’s signals couldn’t reach deep enough into Mars to bounce off the base layer of the ice where the potential water lies—meaning its results couldn’t be compared with those from MARSIS.

However, the Mars Reconnaissance Orbiter team recently tested a new maneuver that rolls the spacecraft on its flight axis by 120°—whereas it previously could roll only up to 28°. The new maneuver, termed a “very large roll,” or VLR, can increase SHARAD’s signal strength and penetration depth, allowing researchers to examine the base of the ice in the enigmatic high-reflectivity zone.

Morgan et al. examined 91 SHARAD observations that crossed the high-reflectivity zone. Only when using the VLR maneuver was a SHARAD basal echo detected at the site. In contrast to the MARSIS detection, the SHARAD detection was very weak, meaning it is unlikely that liquid water is present in the high-reflectivity zone. The researchers suggest that the faint detection returned by SHARAD under this portion of the ice cap is likely due to a localized region of smooth ground beneath the ice. They add that further research is needed to reconcile the differences between the MARSIS and SHARAD findings. (Geophysical Research Letters, https://doi.org/10.1029/2025GL118537, 2025)

—Rebecca Owen (@beccapox.bsky.social), Science Writer

Citation: Owen, R. (2025), Maybe that’s not liquid water on Mars after all, Eos, 106, https://doi.org/10.1029/2025EO250437. Published on 21 November 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.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Journal of Geophysical Research: Solid Earth

Continental extension often unfolds in multiple deformation phases, where earlier faults steer the geometry and behavior of later ones. In a new study, Liu et al. [2025] explore the complexity of fault interaction by analogue modeling. 

The models reveal how shifts in stress—from biaxial to triaxial and back—govern the evolution of the fault network. In the triaxial phase, faults from the earlier biaxial phase are reactivated and new conjugate faults appear. When stress shifts back to biaxial, older faults may become inactive or partly reactivated. Stress conditions determine whether old faults block or guide the growth of new ones. Their modeling results are applied to explain the patterns of abandoned, reactivated and newly developed faults seen in the Aegean and Barents Seas. In general, their findings help to shed light on both the tectonic history of their study areas and the distribution of earthquakes.

Citaiton: Liu, J., Rosenau, M., Kosari, E., Brune, S., Zwaan, F., & Oncken, O. (2025). The evolution of fault networks during multiphase triaxial and biaxial strain: An analogue modeling approach. Journal of Geophysical Research: Solid Earth, 130, e2025JB031180. https://doi.org/10.1029/2025JB031180

—Birgit Müller, Associate Editor, JGR: Solid Earth

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 that impacts science and scientists today.

Rising sea levels have put thousands of facilities containing hazardous materials at risk of flooding this century, according to a new study published in Nature Communications. 

Global sea level rise is accelerating, leading to an increase in coastal flooding that scientists expect to worsen. As seas rise, floodwater reaches infrastructure that was not built to withstand it.

“Flooding from sea level rise is dangerous on its own—but when facilities with hazardous materials are in the path of those floodwaters, the danger multiplies.”

These extreme events can release toxins into the environment. For example, an estimated 10 million pounds of pollutants from refineries, petrochemical facilities, and manufacturing sites spilled into the environment following flooding from Hurricane Harvey in 2017.

The new study reports that 5,500 facilities containing hazardous substances are at risk of a similar event, threatening the health of nearby communities. 

“Flooding from sea level rise is dangerous on its own—but when facilities with hazardous materials are in the path of those floodwaters, the danger multiplies,” Lara Cushing, an environmental researcher at the University of California, Los Angeles and lead author of the new study, told The Guardian. 

In the study, scientists analyzed the location of 47,646 coastal power plants, sewage treatment facilities, fossil fuel infrastructure sites, industrial facilities, and former defense sites. Then, they used sea level rise projections under various climate scenarios to determine whether those sites were at risk from a 1-in-100-year flood event by 2100. 

They found that 11% of the sites analyzed were at risk of such a flood by 2100 in a high-emissions, business-as-usual scenario (RCP 8.5). Eighty percent of the at-risk sites were in just seven states: Louisiana, Florida, New Jersey, Texas, California, New York, and Massachusetts. Oil and gas wells made up a large proportion of sites considered to be at risk. 

These maps and graphs show the number and types of coastal facilities at risk of flooding due to sea level rise by 2050 and 2100 under a high-emissions, business-as-usual scenario. Credit: Cushing et al. 2025, doi:10.1038/s41467-025-65168-2, CC BY 4.0

In total, 22% of coastal sewage treatments facilities, 24% of coastal refineries, 44% of coastal fossil fuel ports and terminals, 12% of coastal industrial facilities, 21% of former coastal defense sites, and 21% of coastal fossil fuel and nuclear power plants are at risk of flooding by 2100. 

Disproportionate Effects

Marginalized groups are more likely to live near hazardous waste sites and industrial facilities, making these groups more vulnerable when such facilities flood. 

In the study, researchers analyzed the location of at-risk sites compared to community demographics. They found that households in Hispanic neighborhoods, households with incomes below twice the federal poverty line, and households that rented rather than owned their homes were especially likely to be located within one kilometer (0.62 miles) from a facility at risk of flooding.

 
Related

•  Read the study: “Sea level rise and flooding of hazardous sites in marginalized communities across the United States.”
•  Climate Central Report: Toxic Tides
•  Thousands of Toxic Sites Across U.S. Face Risk of Coastal Flooding
•  Sea Level Rise Threatens Hundreds of Wastewater Treatment Plants
• Sea Level Rise May Swamp Many Coastal U.S. Sewage Plants
 

“These projected dangers are falling disproportionately on poorer communities and communities that have faced discrimination and therefore often lack the resources to prepare for, retreat, or recover from exposure to toxic floodwaters,” Cushing said.

Reducing greenhouse gas emissions is key to slowing sea level rise and reducing flooding. The study’s projections showed that restricting greenhouse gas emissions to a low-emissions scenario (RCP 4.5) would reduce the number of at-risk sites from 5,500 to 5,138. 

In addition, the authors write that keeping communities safe from future hazardous floodwaters will require federal and state governments to “provide publicly available, accessible, and continually updated data on projections of [sea level rise]-related flooding threats.”

—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 science or scientists? Send us a tip at eos@agu.org. Text © 2025. AGU. CC BY-NC-ND 3.0
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The world is warming, yet summer temperatures on the southern slope of Mount Everest, measured continuously by the Pyramid Laboratory since 1994, have dropped over the past 15 years.

The reason? Cold downslope winds, caused by the increased temperature differences between the warmer air above the glacier and the air mass in direct contact with the glacier’s frozen surface.

These katabatic winds create a cooling effect around mountain glaciers, explained Thomas Shaw, a glaciologist at the Institute of Science and Technology Austria. “They’re melting more slowly than they would if there was a one-to-one correspondence between atmospheric temperature and the temperature of the glacier boundary layer.”

Scientists have made note of this phenomenon since the late 1990s, but studies have so far been limited to specific glaciers.

To understand the phenomenon’s extent and the factors influencing it on a global scale, Shaw and his colleagues collected and analyzed a dataset from 62 glaciers across 169 glacier campaigns, amounting to an unprecedented 3.7 million hours of air temperature data.

While much of the data were easily accessible, some were “almost the equivalent of being written on the back of a napkin,” said Shaw, who was able to include previously unpublished data from other researchers. “It takes a lot of emailing, clicking, finding, searching, and thinking, ‘Oh, I remember there was someone that published something on this.’”

Changing Projections

The study, published in Nature Climate Change, found that the glacier boundary layer warms an average of 0.83°C for every degree of ambient warming.

“This is not the only process affecting glacier melt, but it’s an important one that we didn’t have proof of before,” said Inés Dussaillant, a glaciologist at Centro de Investigación en Ecosistemas de la Patagonia in Chile who was not involved in the study.

“It may change our projections…and IPCC reports for the future evolution of glaciers or sea level contribution.”

Currently, this effect is not taken into account when modeling how glaciers will change over time, said Harry Zekollari, a glaciologist at Vrije Universiteit Brussel in Belgium who was not involved with the study. “It may change our projections and how we make them, and it may change projections and [Intergovernmental Panel on Climate Change] reports for the future evolution of glaciers or sea level contribution.”

According to Shaw’s analysis, the main factors driving the cooling effect are the temperature difference between the glacier boundary layer and the surrounding air, the size of the glacier, and humidity. Debris cover on the glacier and strong synoptic winds hinder the effect.

This phenomenon means that rising ambient temperatures actually increase the cooling effect on large glaciers—but only up to a point. “Glaciers are not protected because of this; they’re not cooling. It’s a bit of a misnomer,” said Shaw. While they are melting more slowly than would be expected with linear warming, the effect is still substantial. The study projects that globally, these near-surface cooling effects will peak during the late 2030s as temperatures rise.

As glaciers shrink in size, they will no longer be able to generate katabatic winds, and their rate of warming will begin to reflect ambient temperatures. According to the study, this will lead to accelerated melting from mid-century onward.

Going, Going, Gone

Shaw and his coauthors noted large regional variations in the data. While the cooling effect is not expected to peak until the 2090s for glaciers in New Zealand and the southern Andes, glaciers in central Europe have likely already passed this mark and are deteriorating at an increasing pace.

The study’s results tally with other findings. Earlier this year, a study of global glacier mass changes found that central Europe lost 39% of its ice mass between 2000 and 2023, faring the worst of all 19 regions studied.

A prime example is Pasterze, an Austrian glacier where research into the cooling phenomenon first started in the 1990s. “This was once a much larger glacier, with a much stronger observed katabatic cooling effect. Now it’s disintegrating very fast,” said Shaw, noting it will likely not be Austria’s largest glacier for much longer. “It’s already showing evidence of how rapidly glaciers can react to climate when they begin to disappear.”

But while troves of reliable long-term data are available for areas like the European Alps, Iceland, Svalbard, and western North America, glacier monitoring is not equally distributed worldwide. Dussaillant would like to see more support for regions where governments are not able to maintain ongoing glacier monitoring. “We cannot really say that this is the global picture, when in fact, some regions still have huge gaps which we need to fill and better understand.”

With around 200,000 glaciers worldwide, there is, indeed, still a lot of work to be done before a truly global picture emerges, said Zekollari. “But it’s a massive step forward compared to what we had.”

—Kaja Šeruga, Science Writer

Citation: Šeruga, K. (2025), Glaciers are warming more slowly than expected, but not for long, Eos, 106, https://doi.org/10.1029/2025EO250430. Published on 20 November 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.

Thin layers of sedimentary rock in Mars’s Gale Crater suggest that the planet once had a moon much larger than the two that orbit it today, according to work to be presented at AGU’s Annual Meeting 2025 on 17 December. Unlike the current Martian moons Phobos and Deimos, the gravitational pull of the hypothesized moon would have been strong enough to create tides in bodies of water on or below the planet’s surface.

The team analyzed images from cameras on the Curiosity rover, which has been trundling across Gale Crater since 2012. The Mars Hand Lens Imager, for instance, captures images with resolutions up to 13.9 micrometers per pixel.

Pictures of a rocky outcrop snapped during four Martian days in late 2017 and early 2018 revealed a section of fine, repeating layers in alternating light and dark colors. The researchers interpret those layers as tidal rhythmites, or sediments deposited by the regular back-and-forth sloshing of the tides.

“Our study provides sedimentary evidence for the case of tidally deposited rhythmites, hinting at a past larger moon for Mars.”

“Our study provides sedimentary evidence for the case of tidally deposited rhythmites, hinting at a past larger moon for Mars,” Ranjan Sarkar, a planetary scientist at the Max Planck Institute for Solar System Research in Gottingen, Germany, told Eos via email. “This, in turn, aligns with the hypothesis that Mars has repeatedly had larger moons that were tidally destroyed into rings, which then reformed into successively smaller moons.” That is, the larger moon or moons would have been pulled apart by the force of Martian gravity, which would have exerted a stronger pull on the planet-facing side of the moon than the opposite side.

The layering was detected at Vera Rubin Ridge on the flank of Mount Sharp, a sedimentary peak in the middle of Gale Crater. The studied area was about 35 centimeters long and 20 centimeters thick. Individual bands in the rock ranged from submillimeters to millimeters thick, with wider, light-toned bands and darker, thinner bands.

This graphic, for presentation at AGU’s Annual Meeting 2025, traces Curiosity’s path to the Jura outcrop on Vera Rubin Ridge. Color-enhanced images from the rover show the layered rocks interpreted as evidence of tidal rhythmites, with similar layers in an Earth setting shown for comparison. Click image for larger version. Credit: Ranjan Sarkar, Priyabrata Das, Suniti Karunatillake

Comparison with other observations along the ridge suggests the layers were deposited roughly 3.8 billion years ago, when Gale Crater contained a lake.

“Back-of-the-Envelope” Profile

Not all rhythmites are tidal: Similar sedimentary layers can be deposited by winds, seasonal variations in precipitation or glacier melts, or other processes, the researchers note.

“The finely laminated rhythmites in this crater are most likely varves, or deposits that reflect seasonal changes in the climate,” said Bob Craddock, a geologist at the National Air and Space Museum who was not involved in the study. More water flows into a lake during the warmer summer months, producing thicker sediment layers with larger grains compared to those laid during winter, he said. “As this continues through time, you get rhythmites.”

“It’s very tricky. We can’t be decisive, so our argument is one of consistency.”

Sarkar, however, said the structure of these layers doesn’t match what would be expected of seasonal deposits. “Annual varves usually show simple light-dark couplets, but we observe alternating thick-thin bands showing paired dark laminae,” he said. Such patterns “are commonly used as markers of tidal sedimentary signatures on Earth.”

“It’s very tricky,” said team member Suniti Karunatillake, a geologist and geophysicist at Louisiana State University. “We can’t be decisive, so our argument is one of consistency.…We felt that the observations are generally more consistent with a tidal setting.”

The layers probably were deposited with a “monthly” cycle of about 30 days, Karunatillake said. Even if Phobos or Deimos were much closer to Mars than they are today, neither is massive enough to create such a tidal cycle. Instead, combining this new work with modeling by previous researchers, the team estimated the tides were raised by a body at least 18 times the mass of Phobos, the larger moon, orbiting at an altitude of about 3 times the radius of Mars.

Phobos, photographed by the Mars Reconnaissance Orbiter, is not massive enough to have raised tides on Mars. It could be a remnant of a larger moon that was destroyed in a giant impact. Credit: NASA/JPL-Caltech/University of Arizona

“That’s our back-of-the-envelope calculation,” Karunatillake said. “Anything smaller and it would be difficult to induce this type of tidal activity, especially when you consider that Gale Crater is quite small as a water body on the planetary scale.”

The possibility of a smaller moon causing the observed tidal activity might be more realistic, Karunatillake added, if there were a connection between Gale Crater and the northern ocean, but no connection has yet been seen. However, even a subterranean link, such as the network of flooded caves and tunnels beneath Earth’s Yucatán Peninsula that leads to the Caribbean Sea, would suffice. “There are instances where you get tidal variations inland, as long as there’s a subsurface connection with the ocean,” he said.

Pondering the Martian Moons

Planetary scientists have pondered the origins of Phobos and Deimos extensively in recent decades. The original theory said they were captured asteroids, but it’s not easy for a planet to nab even one asteroid, much less two.

Some studies have suggested that Mars originally had a larger moon—either a captured asteroid or one that formed from an early giant impact. That body then could have been pulverized by the gravity of Mars or by its own collision, forming a ring that then gave birth to smaller moons. In fact, such a scenario could have played out multiple times. “Our study provides actual (ground) evidence, from measured laminae periodicities, for the predicted/hypothesized past larger moon,” Sarkar said.

The researchers are considering conducting a detailed celestial mechanics study to refine their estimates of the mass, distance, and orbital period of the proposed moon. They’re also examining two other sites in Gale Crater that appear to show similar tidal rhythms.

Any inconsistencies among the sites would “dispute our model, and possibly falsify it,” Karunatillake said. “But any agreement would take us toward a stronger argument for an ancient large moon.”

—Damond Benningfield, Science Writer

Citation: Benningfield, D. (2025), Sediments hint at large ancient Martian moon, Eos, 106, https://doi.org/10.1029/2025EO250434. Published on 20 November 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’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Geophysical Research Letters

How do the deep forces of the Earth’s interior shape surface faults, fractures and rivers? The results of a new global analysis show that rivers, faults, and stresses often align, but the degree of correspondence depends on fault type, stress source, and river size.

Kuhasubpasin et al. [2025] present a new framework to quantify the relative roles of lithospheric structures and mantle dynamics, offering fresh insights into how deep Earth processes govern the surface. A novel procedure is proposed to assess the relative role of mantle flow and lithospheric differences to the surface features, which may help constrain the individual forces acting to deform the lithosphere, creating topography. This holistic perspective on the coupled evolution of Earth’s interior and its surface shows how the interior of the Earth affects and perhaps even controls the surface.

Citation: Kuhasubpasin, B., Moon, S., & Lithgow-Bertelloni, C. (2025). Unraveling the connection between subsurface stress and geomorphic features. Geophysical Research Letters, 52, e2025GL116798. https://doi.org/10.1029/2025GL116798

—Fabio A. Capitanio, Editor, Geophysical Research Letters

Text © 2025. The authors. CC BY-NC-ND 3.0
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Planet imagery shows the massive coal waste landslide at Mae Moh Mine. The failure was about 4.8 km long and 1.4 km wide

As I noted in an earlier post on this blog, at about 4 am on 4 November 2025, a very large landslide occurred in a coal waste pile at the Mae Moh Mine in Thailand. News reports have indicated that this failure, which occurred in a slope formed from coal waste material, caused significant damage.

Unfortunately, this area is very often cloudy, so obtaining good satellite imagery is a challenge. However, Planet captured an image on 15 November 2025 that shows a substantial part of the landslide.

The image below was captured on 28 October 2025, showing the site:-

The site of the 4 November 2025 landslide at Mae Moh Mine in Thailand. Image copyright Planet, captured on 28 October 2025, used with permission.

This image shows the aftermath of the landslide:-

The aftermath of the 4 November 2025 landslide at Mae Moh Mine in Thailand. Image copyright Planet, captured on 15 November 2025, used with permission.

And here is a slider to allow the images to be compared:-

Images copyright Planet

The crown of the landslide is to the west, with movement in an eastward direction. The landslide is very large – a rough estimate is 4.77 km long and 1.37 km wide. The archive of satellite image suggests that three was large-scale dumping of mine waste in the area that became the head scarp in the weeks ahead of the landslide. This freshly deposited material can be clearly seen in the pre-failure material, and is also discernible, after the failure. The presence of this material is a good starting point in terms of understanding the causes.

Cleaning up this site is going to be a very major, and very expensive, task.

Reference

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

Return to The Landslide Blog homepage Text © 2023. The authors. 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 Hawaiian Islands formed through the Pacific plate’s movement over a relatively stationary, hot mantle plume, creating a succession of progressively older volcanic centers. New land continues forming on the Big Island’s south side, where the Kīlauea volcano system has remained active for decades. After nearly 40 years of spectacular surface flows entering the sea at Pu’u’ō’ō, volcanic activity shifted to the summit caldera.

Wu et al. [2025] employ seismological techniques to analyze subtle changes in shallow crustal velocities from 2013 to 2018, combining these data with geodetic and geological observations to better understand magma reservoir interactions between Kīlauea’s caldera and Pu’u’ō’ō. Their analysis reveals a fascinating sequence of cross-communication involving pressurization and magma transport processes affected by earthquake valving. When integrated with other monitoring and modeling, such research provides valuable insights into Kīlauea’s plumbing and basaltic volcanic systems more broadly. The work also reemphasizes the importance of seismological monitoring, and deployment of dense seismic networks at as many active volcanoes as possible would enable new comparative analyses.

Citation: Wu, S.-M., Lin, G., & Shearer, P. (2025). Seismic velocity monitoring reveals complex magma transport dynamics at Kīlauea Volcano prior to the 2018 eruption. AGU Advances, 6, e2025AV001759. https://doi.org/10.1029/2025AV001759

—Thorsten Becker, Editor, AGU Advances

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.

Land has been reclaimed for many centuries, and with the present-day demand for land, this process will continue in the future. The impact of such land reclamations has, up to now, been evaluated on a case-by-case basis, while studies integrating a wider range of land reclamation impacts is missing. Insights into the way tides interact with basin topography and the complex feedback mechanisms associated with fine-grained sediments is crucial to understanding the long-term response of coastal systems to a land reclamation.

A new article in Reviews of Geophysics synthesizes earlier findings on the effect of land reclamations on the coastal environment. Here, the lead author gives an overview of land reclamations, their impacts on coastal environments, and challenges for future research efforts.

Why and where is land reclaimed?

Fertile and low‐lying coastal landscapes are often densely populated because of their food supply (agriculture, aquaculture, and fisheries) and easy navigability (shipping lanes). At present 10% of the global population lives in Low Elevation Coastal Zones (LECZ’s; less than 10 meters above Mean Sea Level) and the population growth in LECZ’s is larger than the global average, especially in river deltas.

As this population pressure drives a continuous need for land, much of the low-lying land that was regularly inundated by the sea has been converted to agricultural land or urban environments. Especially the deltas of muddy rivers are suitable for reclamation, because of their shallow coastal waters and high sedimentation rates.

In our study we investigate how tide-influenced, typically muddy areas with wide intertidal areas, respond to reclamation by analyzing long-term datasets on tidal and bed level changes.

What kind of land reclamation techniques are used in such tide-influenced coastal environments?

Humans have reshaped deltas and other coastal areas for thousands of years. Traditional land reclamation techniques include the construction of wooden structures to dampen waves, allowing fine sediments to deposit. Eventually the area becomes vegetated and reclaimed through the construction of dikes. Although centuries old, this practice continues today, for example, in the Dutch-German Wadden Sea.

Figure 1: Traditional land reclamation technique in the Dutch-German Wadden Sea. Sediment is trapped by permeable brushwood groin fields (squares of 200 by 300 m) developing into saltmarshes. After construction of a dike the salt marshes are converted into agricultural land: the land protected by the sea dike in the picture above (lower right) was permanently reclaimed in 1969. Photo courtesy of Rijkswaterstaat Noord Nederland.

Other techniques include the construction of levees to convert wetlands into aquaculture or salt ponds (see Figure 1), or concrete revetments on the intertidal areas which gradually advance seaward. Such latter techniques are especially employed along the megadeltas of Asia. The most recent technique is the closure of tidal (sub)basins using barriers. Such closed basins may be converted into dry land (through pumping, creating polders) or remain reservoirs. In both cases, they profoundly influence the tidal dynamics of the coastal environment seaward of the closure for many decades or centuries.

How do these land reclamations influence coastal environments?

Land reclamations influence both the hydrodynamics (water levels and flow velocity) and the morphological response (erosion and sedimentation) of coastal environments. Both the hydrodynamic and morphological response are controlled by the reclamation type, the hydrodynamic conditions and sediment availability, and the location of the reclamation within the coastal environment.

Based on an analysis of all studies describing the effects of land reclamations, we have developed a classification scheme to explain the impact of reclamations on the coastal environment. A first major distinction herein is whether the reclamation takes place along an open coast, within a bay, or within an estuary. Open coast reclamations may lead to both erosion or sedimentation, likely depending on sediment availability. Reclamations in bays reduce tidal flows and mixing rates, and therefore lead to a reduction in water quality. The largest variability in response is observed in estuaries, where tides may amplify or dampen, and channels may erode or fill in (Figure 2).

Figure 2. Classification scheme conceptually describing how tides and bed levels respond to land reclamation. Credit: van Maren et al. [2025], Figure 9

Why do estuaries display such a large difference in response?

The large variability in estuarine response is caused by tide-topography interactions. Intertidal areas flanking an estuary reduce tidal energy and amplitude as the tide propagates through the estuary. Reclaiming land along the length of an estuary removes these intertidal areas and therefore leads to tidal amplification, especially if the estuary becomes more funnel-shaped (bottom left in Figure 2).

In contrast, reclaiming the most upstream intertidal areas of an estuary especially leads to a reduced tidal discharge (less water flowing in and out of the estuary with each tide) and therefore lower flow velocities (top right in Figure 2). As most estuaries are rich in sediments, such a reduction in flow velocities usually leads to sediment deposition. Reclaiming land at the mouth of an estuary only limitedly influences the tidal discharge, but the resulting smaller channel width leads to higher flow velocities and deepening of the channel (bottom right in Figure 2).

Why is the impact of land reclamation sometimes very large and prolonged?

Land reclamations may lead to an increase in tidal range of several meters but also to complete infilling of tidal channels. These adaptations are typically slow and may take decades to centuries. The impact is so large and takes such a long time because fine-grained sediments introduce a number of positive feedback mechanisms strengthening the effect of the original disturbance. We have identified five such feedback mechanisms. One example is the infilling of channels because upstream land reclamation reduces the tidal discharge (Figure 3).

Figure 3. Two positive feedback mechanism strengthening the initial response of tidal systems to land reclamation. Credit: van Maren et al. [2025], Figure 6 (modified)

As channel infilling continues, the tidal discharge further declines, promoting more sediment deposition. This infilling process slowly progresses in the seaward direction, in time leading to complete abandonment of a tidal system. Such impacts are most pronounced in branching tidal channel networks, such as the Ganges-Brahmaputra delta in Bangladesh. In such networks, infilling in one tidal channel may lead to large-scale erosion in another because of channel rearrangement, with its devastating effects illustrated in Figure 4.

Figure 4. Riverbank along a tidal channel in the Ganges-Brahmaputra delta eroding in response to land reclamation. Credit:  van Maren et al. [2023], Figure 13

Why are the effects of land reclamations relatively unknown?

The physical impact of land reclamations (changing tides, erosion, or deposition) are surprisingly poorly known. The ecological effects of land reclamations have been extensively studied, and these studies in turn synthesized in several reviews. The impact on tides and bed levels has received much less attention and has so far only been investigated in individual case studies, which do not reveal the full extent of land reclamation impacts. We believe that the number of studies are limited because (1) large amounts of land were reclaimed before data was collected; (2) the response time is slow and variable (and therefore changes are insufficiently correlated with a reclamation); and (3) many contemporary reclamations are executed simultaneously with other interventions (deepening of channels for navigation; reduction of sediment supply by upstream reservoirs) obscuring the effect of the reclamation.

What are key challenges for future research?

We have identified three key challenges for follow-up research. Firstly, the impact of reclamations is so large and prolonged because of a number of positive feedback mechanisms. A better understanding of such mechanisms is needed to explain historic changes but even more to predict future impacts of present-day land reclamations (especially tidal amplification which may influence high water level increase in the coming decades much more than sea level rise).

Secondly, we infer that land reclamation leads to higher suspended sediment concentrations in estuarine environments, negatively impacting coastal ecosystems but also being a key factor driving the positive feedback loops. However, studies relating suspended sediment dynamics to reclamations are limited.

And finally, more attention should be given to the long adaptation timescales. Present-day reclamations will impact their coastal environment for the coming decades to centuries. Forecasting how coastal systems will respond to rising sea levels, for example, is only possible with sufficient understanding of their slow response to existing reclamations.

—Bas van Maren (Bas.vanMaren@deltares.nl; 0000-0001-5820-3212), Delft University of Technology and Deltares, 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: van Maren, B. (2025), Echoes from the past: how land reclamation slowly modifies coastal environments, Eos, 106, https://doi.org/10.1029/2025EO255035. Published on 19 November 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.

Source: AGU Advances

Imagine the catastrophic winds of a category 5 hurricane. Now, imagine even faster winds of more than 100 meters per second, encircling the planet and whipping clouds across the sky, with no end in sight. This scenario would be astonishing on Earth, but it’s business as usual on Venus, where the atmosphere at cloud level rotates about 60 times faster than the planet itself—a phenomenon known as superrotation. In contrast, Earth’s cloud-level atmosphere rotates at about the same speed as the planet’s surface.

Prior research has explored the mechanisms driving atmospheric superrotation on Venus, but the details remain murky. New evidence from Lai et al. suggests that a once-daily atmospheric tidal cycle, fueled by heat from the Sun, contributes much more to the planet’s extreme winds than previously thought.

Rapid atmospheric rotation often occurs on rocky planets that, like Venus, are located relatively close to their stars and rotate very slowly. On Venus, one full rotation takes 243 Earth days. Meanwhile, the atmosphere races around the planet in a mere 4 Earth days.

To better understand this superrotation, the researchers analyzed data collected between 2006 and 2022 by the European Space Agency’s Venus Express satellite and the Japan Aerospace Exploration Agency’s Akatsuki satellite, which both studied Venus’s atmosphere by detecting how it bends radio waves. The research team also simulated superrotation using a numerical model of Venus’s atmosphere.

The analysis focused specifically on thermal tides—one of several atmospheric processes, alongside meridional circulation and planetary waves, whose interactions have previously been shown to sustain Venus’s superrotation by transporting momentum. Thermal tides are patterns of air movement that occur when sunlight heats air on the dayside of a planet. Venusian thermal tides can be broken into two major components: diurnal tides, which follow a cyclical pattern repeating once per Venusian day, and semidiurnal tides, which have two cycles per day.

Earlier research suggested that semidiurnal tides are the main thermal tide component involved in superrotation. However, this study—which includes the first analysis of thermal tides in Venus’s southern hemisphere—found that diurnal tides play a primary role in transporting momentum toward the tops of Venus’s thick clouds, suggesting diurnal tides are major contributors to the rapid winds.

Though the researchers note that further clarification of the contributions of diurnal tides is needed, the work sheds new light on Venus’s extreme winds and could aid meteorological research on other slowly rotating planets. (AGU Advances, https://doi.org/10.1029/2025AV001880, 2025)

—Sarah Stanley, Science Writer

Citation: Stanley, S. (2025), Key driver of extreme winds on Venus identified, Eos, 106, https://doi.org/10.1029/2025EO250436. Published on 19 November 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
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A new tool aims to do for heat waves what Saffir and Simpson did for hurricanes.

CalHeatScore, an online mapping tool developed by the California Office of Environmental Health Hazard Assessment, ranks heat wave risk on a straightforward scale of 0 to 4. And just like the Saffir-Simpson scale for hurricane strength, CalHeatScore delivers its warnings days in advance. It’s designed to help Californians prepare for heat emergencies and uses socioeconomic factors to tailor information for each individual zip code.

“[CalHeatScore] gives you a warning for your community that reflects the characteristics of your community.”

“It gives you a warning for your community that reflects the characteristics of your community,” explained John Molitor, an environmental data scientist at Oregon State University who helped build the tool.

The hyperlocal method provides meteorologists, emergency managers, and the public with a shared understanding of risk during California’s extreme heat. Molitor and his colleagues will share their work at AGU’s Annual Meeting 2025 in New Orleans on 16 December.

Scorching in Sacramento

CalHeatScore was born during a heat wave. Legislators had been pushing for a warning system for months, and the bill was finally approved in September 2022 during a 10-day heat wave that broke 1,500 temperature records across California. The heat wave caused 395 excess deaths in the state, 4 times the toll of California’s deadliest wildfire, according to the Los Angeles Times.

The tool—officially dubbed the California Communities Extreme Heat Scoring System and launched in December 2024—was designed to prevent future heat deaths by providing a streamlined and site-specific warning system. It includes targeted public health information, like community heat risk and the locations of the nearest public cooling centers.

Building a Model

CalHeatScore draws from a range of data sources, recognizing that heat risk is more than just temperature.

First, developers established a baseline using temperature data and emergency room visits from 2008 to 2018, looking specifically for diagnoses that increase with heat. The current operational model uses zip codes as a proxy for socioeconomic data, while a second-stage model will add specific population data to pinpoint communities of concern.

Other warning systems look at empirical distributions of heat, Molitor explained, but CalHeatScore looks for causal effects. The interdisciplinary team of physicians, health experts, and data scientists is specifically looking for drivers of heat impacts.

“People experience heat very differently through space and time,” Molitor said. A community with swimming pools and air-conditioning will experience a 100°F day different than a neighborhood of pavement and parking lots. Similarly, indoor office workers are protected from the heat in a way roofers, gardeners, and carpenters aren’t. By considering factors like age brackets and average income, CalHeatScore can determine the heat-related health risk for a community.

The platform’s clickable, searchable map is built on spatial modeling. “What happens in one zip code is going to be highly informed by what happens in nearby zip codes,” Molitor said. Multilevel modeling “is allowing us to take the data and drill down into all these little zip codes and come up with an appropriate heat warning system for each,” he said.

Decisionmaking Data

All that complexity results in a very simple scale. Heat risk is ranked 0 (low) through 4 (severe) and provided for the next 7 days.

That’s a useful approach, said Ashish Sharma, an atmospheric scientist at the University of Illinois Urbana-Champaign who was not involved in the project.

“If we look at decisionmaking, it’s binary. Either you act upon it, or you don’t,” he said. “Combining this information at the zip code level can really improve decisionmaking.”

But while the tool has a lot of strengths, the current map seems geared more for agencies and governments than the public, he noted. He hopes future iterations are more user-friendly.

To that end, the CalHeatScore team is exploring options to develop a mobile app. That would be a helpful addition, said Amy Cilimburg, the director of Climate Smart Missoula who’s also worked on local heat mapping. A phone app could allow a football coach on the sidelines or a daycare director on the playground to plan their week around the heat.

“There is a lot of utility and strength in a hyper-local map,” she said. The next test is making sure people know about the tool and start making decisions based on it.

Expanding the Map

The developers aim to expand awareness at the AGU Annual Meeting, sharing their work with an international audience. CalHeatScore is replicable. Any state or country with similar data could develop a 7-day warning system.

“What we have here is really advanced, and we’d like to be doing this for other jurisdictions.”

“What we have here is really advanced, and we’d like to be doing this for other jurisdictions,” said David Eisenman, a project principal investigator, professor of medicine, and codirector of the Center for Healthy Climate Solutions at the University of California, Los Angeles.

The blend of health outcomes, temperature levels, and demographic data is “a really unique approach,” Eisenman said.

CalHeatScore is built with health outcomes and heat vulnerability in mind. When the next heat wave rolls through California, residents will have a new way to communicate and tolerate the temperature.

—J. Besl (@j_besl, @jbesl.bsky.social), Science Writer

20 November 2025: This article has been updated to correct the role of David Eisenman.

Citation: Besl, J. (2025), New tool maps the overlap of heat and health in California, Eos, 106, https://doi.org/10.1029/2025EO250432. Published on 19 November 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.