Feed aggregator

Publication date: Available online 19 November 2025

Source: Advances in Space Research

Author(s): Zixuan Ge, Yongkai Wang, Wenhao Wu, Jie Liu, Weijie Ran, Peixian Yuan, Yanan Su, Jiangtao Xu, Jiyuan Hu, Peijie Zhu, Yu Zhang

AbstractWe present an earthquake catalog in northeastern Tibetan plateau between September 2013 to April 2016 during the ChinArray-II deployment. Using continuous records from 676 transportable ChinArray-II stations and 172 permanent stations, the P/S phases are obtained using one deep learning phase picker. After associating these phases, the events are identified and located to establish the ChinArray-II Regional Earthquake Database (CARED-II). Benefiting from both improved station coverage and sensitive phase picker, CARED-II catalog has 156 057 events (around 3 million picks), about tenfold more than the manual routine catalog (15 967 events) using the permanent stations. The improved event catalog delineates the fault structures clearly. The deep structure of south-dipping north Qilian thrust faults is revealed, consisting with previous geology studies. The hidden faults and fault connectivity are revealed by improved seismicity, especially in the Alxa Block with sparse permanent stations and severe environments restricting geological field work. Moreover, small anthropogenic events are identified and related to highway tunnel construction across Qinling Mountain, forming a straight event cluster. The results demonstrate the high event detection ability of our procedure and reliability of the automatic catalog. Our array-based CARED-II catalog provides improved seismicity images in northeastern Tibet and could be used for further seismology and geotectonic studies.

SummaryThe global prevalence of organic pollutants presents a significant environmental challenge, necessitating sustainable remediation strategies. In situ biodegradation emerges as a cost-effective and eco-friendly solution. However, the real-time monitoring of in situ bacterial activities, particularly biodegradation processes, remains a challenge due to the limitations of traditional intrusive methods, including issues of representativeness, reproducibility, and high associated costs. Spectral induced polarization (SIP) has shown sensitivity to surface changes in subsurface environments, especially for biogeochemical reactivity monitoring including those associated with biodegradation. Despite this potential, advances have to be made to quantitatively link SIP parameters to in situ biodegradation processes. This study addresses this gap by conducting controlled biogeophysical experiments on a sand-packed column undergoing biodegradation facilitated by Rhodococcus wratislaviensis IFP 2006. SIP measurements were paired with bacterial growth kinetics to develop a quantitative model estimating bacterial growth. The results demonstrate that SIP, coupled with routine laboratory measurements, can effectively and quantitatively assess bacterial growth and the biodegradation of organic pollutants. These findings highlight the potential of SIP as a non-intrusive and reliable method for monitoring biodegradation in contaminated subsurface environments.

AbstractThe Surface Water and Ocean Topography mission (SWOT), equipped with the Ka-band Radar Interferometer (KaRIn), provides groundbreaking two-dimensional sea surface heights (SSHs), bringing new potential for optimizing the deflection of the vertical (DOVs). However, conventional DOV modeling—combining along- and cross-track geoid gradients with equal weights—fail to fully exploit the potential of SWOT/KaRIn observations and overlook the spatial variability in precision. We present a tailored method for optimizing DOVs estimation. The method combines geoid gradients in the along-track, cross-track, diagonal (forward and backward) directions with adaptive weighting. The refined weights are employed to exploit the potential of each geoid gradient based on the relationship between the standard deviation of SSHs and the significant wave height. To mitigate data gaps, prior and locally averaged geoid gradients are incorporated in the gaps and overlapping regions. SWOT/KaRIn-derived DOVs and gravity anomalies from the science-phase observations are validated against shipborne gravity in the Philippine Sea. Results indicate that the DOV model derived by the tailored method—particularly by combining triple-directional (along, cross, and diagonally forward) geoid gradients with refined weights—achieves a 7.3% improvement in accuracy over the conventional method. The supplement of additional geoid gradients is critical for mitigating leakage errors caused by missing or reduced observations in the gap regions. Furthermore, the gravity anomaly model recovered from DOVs by stacking 17-cycle observations achieved an accuracy of 2.97 mGal, representing a 7.2% improvement over single-cycle observations. The clear advantages of SWOT/KaRIn observations are gradually emerging in marine gravity recovery.

A new study published in Science Advances overturns a long-standing paradigm in climate science that stronger Northern Hemisphere summer insolation produces stronger tropical rainfall. Instead, a precisely dated 129,000-year rainfall reconstruction from a Cuban cave shows that the Caribbean often did the opposite, drying during intervals of intensified summer insolation.

Researchers from the Institute of Applied Ecology of the Chinese Academy of Sciences and the University of California, Riverside, have investigated how the loss of forest soil gaseous nitrogen (NO, N2O, and N2) is affected by climate warming, highlighting the critical role of these gases in regulating forest nutrient cycling and ecosystem functioning.

There are fewer ice nuclei in the air above the large ice surfaces of Antarctica than anywhere else in the world. This is the conclusion reached by an international research team led by the Leibniz Institute for Tropospheric Research (TROPOS) based on filter measurements of cloud particles at three locations in Antarctica. These are the first of their kind on the continent. The data fills a knowledge gap and could explain the large proportion of supercooled liquid water in the clouds of the southern polar region.

SummaryThe estimation of topographic gravity field models has attracted significant interest in recent years due to its growing relevance in Earth sciences. In this study, we present a robust methodology for the computation and comprehensive validation of global, complete spherical Bouguer and isostatic gravity anomalies that are essential for accurately interpreting subsurface mass distributions therefore geological structures. We synthesize these crucial gravitational functionals by leveraging spherical harmonic coefficients from high-resolution global gravity field models and various topographic/topographic-isostatic gravity field models. Our findings underscore the critical role of comprehensive terrain corrections in deriving physically meaningful, complete Bouguer gravity fields. The calculated global anomalies demonstrate strong coherence with established benchmark datasets, such as the World Gravity Map 2012. Residual differences are primarily attributed to variations in input Digital Terrain Models. Comparisons with regional Bouguer datasets reveal systematic biases that are largely explained by differing terrain correction methodologies. After removing this effect, there is a high level of consistency between the calculated global and published regional datasets, highlighting the utility of our global solutions, particularly in regions with sparse terrestrial data. Furthermore, the globally computed isostatic gravity anomalies exhibit significant agreement with both external global and diverse regional datasets, notably without the large systematic biases observed in Bouguer comparisons. This agreement reflects the effectiveness of the combined topographic and isostatic corrections in capturing Earth’s mass balance. This research provides valuable tools for new studies in the geoscience community by offering globally consistent and complete Bouguer and isostatic gravity field anomalies that have been rigorously validated for the ICGEM service.

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.

The U.S. Environmental Protection Agency moved this week to reduce limits on fine particulate air pollution, including soot, set by the Biden administration last year. 

The administration gave up defense of a rule which lowered the standard for air pollution particles measuring less than 2.5 micrometers in diameter, also known as PM2.5. The rule, which would have been fully implemented in 2032, took the standard from 12 micrograms of PM2.5 per cubic meter of air to 9. Such tiny particles, which come from vehicle exhaust, factories, and power plants, are especially harmful to human health because they can infiltrate the lungs and the bloodstream. 

In 2024, EPA estimated the 9-microgram standard could prevent up to 4,500 premature deaths, 2,000 hospital visits, and 800,000 cases of asthma per year. 

“An abundance of scientific evidence shows that going back to the previous standard would fail to provide the level of protection for public health required under the Clean Air Act.”

On 24 November, EPA asked the U.S. Court of Appeals for the D.C. Circuit to strike down the new standard, abandoning its defense against industry trade associations and attorneys general from conservative states that had sued Biden’s EPA over the rule.

In the court filing, EPA took the side of its challengers, stating the rule was created “without the rigorous, stepwise process that Congress required.”

“EPA now confesses error,” the filing said. Though the 9-microgram standard remains in effect currently, the EPA proposed in its filing that the standard revert to the 12-microgram rule finalized in 2020.

Environmental groups said the action undermines the agency’s obligations under the Clean Air Act. “EPA’s motion is a blatant attempt to avoid legal requirements for a rollback, in this case for one of the most impactful actions the agency has taken in recent years to protect public health,” Hayden Hashimoto, an attorney for the Clean Air Task Force, a nonprofit, told AP. “An abundance of scientific evidence shows that going back to the previous standard would fail to provide the level of protection for public health required under the Clean Air Act.”

Particulate air pollution disproportionately affects Black communities and other communities of color, as well as low-income groups. One 2018 study found that people living in poverty were exposed to 35% more PM2.5 than the overall population, and Black people were exposed to 54% higher amounts.

 
Related

•  EPA to Abandon Air Pollution Rule That Would Prevent Thousands of U.S. Deaths
•  Trump EPA Moves to Abandon Rule That Sets Tough Standards for Deadly Soot Pollution
•  EPA: Health and Environmental Effects of Particulate Matter (PM)
• Some Communities Feel the Effects of Air Pollution More Than Others
•  Get Involved: AGU Science Policy Action Center

In April, a coalition of public health and community groups wrote a letter to EPA Administrator Lee Zeldin asking him to quickly implement the strengthened standard. “There is no legally viable basis for weakening it,” they wrote.

“Our communities already carry the burden of polluted air and higher rates of asthma and heart disease. Weakening soot protections will only deepen these disparities and cost more Black lives,” Yvonka Hall, executive director of the Northeast Ohio Black Health Coalition, one of the groups that signed the letter, said in a statement.

The move to vacate defense of the rule is part of a broader rollback of regulations on industrial facilities by the EPA. Earlier this year, the agency proposed repealing requirements for polluting facilities to report their greenhouse gas emissions. The EPA is expected to propose its own PM2.5 rule early next year.

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

In Antarctica, beneath the ice, there is liquid water—and potentially a lot of it. That’s the takeaway from new research that used seismographic instruments to probe the still largely unstudied boundary between Antarctica’s bedrock and its ice sheet.

Previous hydrological studies and modeling work have found evidence of lakes and rivers beneath the Antarctic Ice Sheet, though much remains unknown about the region.

Now, using an array of seismic sensors, researchers from Stony Brook University have added more data points to the map of subglacial Antarctica, finding evidence of a layer of water-saturated sediments or rock under the ice. That layer could have implications for models of Antarctic groundwater systems, as well as for future movements of the ice sheet as it slides toward the ocean.

Looking Beneath the Ice with Earthquakes

The data, which will be presented at AGU’s 2025 Annual Meeting, come from an array of more than 600 seismic sensors strung in two long lines totaling about 600 kilometers near the South Pole, put there over the course of two field seasons in Antarctica. The sensors listen for seismic waves that travel through the upper layers of Earth and into the ice sheet.

Those waves carry the signatures of every medium through which they’ve traveled, said Weisen Shen, a geoscientist at Stony Brook University and a paper coauthor. To isolate that information, the researchers applied a mathematical technique called a receiver function to remove the waves’ source information, leaving only the signatures of what they moved through on their journey to the sensor.

In their data from beneath the South Pole, in a region known as the Pensacola-Pole Basin, the researchers found a very low velocity layer, where seismic waves travel too slowly for the conducting medium to be bedrock or ice.

While the authors can’t say exactly what this layer looks like, Shen said the best explanation is a layer of water-saturated sediments or sandstone, likely hundreds of meters thick.

“Anything we can do to try and enhance our knowledge of what’s going on…is just going to help us try and narrow down this really bizarre landscape underneath the ice.”

“We believe…there must be some aquifer system, a groundwater system, that must be preserved beneath the ice,” he said.

The water there could even be connected to groundwater elsewhere in Antarctica, Shen noted. If so, water might be moving around beneath the surface of Antarctica through hydrologically linked basins, and perhaps even out to the ocean.

That scenario could have implications for sea level rise, but, as University of Waterloo glaciologist Christine Dow pointed out, we know far too little to say for sure. In her own modeling, Dow, who wasn’t affiliated with the research, said it appears these basins aren’t connected to the ocean.

“But these are models based on our current knowledge of where’s frozen and where’s not under the Antarctic,” she said. “Perhaps this new information will change that.”

Dow welcomed new data on the mostly uncharted landscape of subglacial Antarctica, where scientists have evidence of lakes, rivers, and groundwater interacting in complex ways, but little hard evidence of the continent’s topography.

“Anything we can do to try and enhance our knowledge of what’s going on…is just going to help us try and narrow down this really bizarre landscape underneath the ice,” she said.

More Questions Than Answers

One question the new data raise is where the heat energy needed to melt the water comes from, noted Hanxiao Wu, a Ph.D. candidate at Stony Brook University and the paper’s first author. It could come from geothermal heat from below, friction caused by the movement of ice at the surface, or some combination of both.

One takeaway from the research is that estimates of geothermal heat flux below Antarctica may need to be bumped upward, Dow said. Models of ice sheet movement and evolution may also need to change to accommodate hundreds of meters of water-saturated sediments. “That’s a game changer,” Dow said.

Should there turn out to be more water beneath Antarctica than previously thought, and should that water move greater distances and in greater amounts, sea levels could rise beyond current predictions, Shen said. It’s too early, however, to estimate any of these probabilities with much certainty, he cautioned.

Right now, Shen and his fellow researchers are focused on improving their dataset and seeking collaborations with other geophysicists to map out the implications of their findings. Wu traveled back to Antarctica for the 2025–2026 field season, where the team is adding another line of seismic sensors to increase coverage and working on tracking the array to better understand changes in snow surface elevation.

In the future, they hope to add additional data from satellites, magnetotelluric surveys, and fiber-optic cables for a more comprehensive look at the ice pack and its underbelly, perhaps as part of the 5th International Polar Year in 2032.

What the scientists will find is unknown. But with millions of square miles of land underneath the ice, the potential for discovery is appropriately vast.

—Nathaniel Scharping (@nathanielscharp), Science Writer

Citation: Scharping, N. (2025), The land beneath Antarctica’s ice might be full of water, Eos, 105, https://doi.org/10.1029/2025EO250435. Published on 26 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.

Powerful summertime thunderstorms are injecting particulate matter from wildfires and additional moisture into the stratosphere—a layer of the atmosphere scientists have long thought was mostly pristine.

“The lower stratosphere almost looked more like a smoke cloud.”

A new study, published in Nature Geoscience, detailed these findings, which could have implications for Earth’s ozone layer and atmospheric circulation, especially as the climate continues to warm.

“We as atmospheric scientists have this preconceived notion that [the stratosphere] is a really stable, clean area of our atmosphere. We don’t think about it being perturbed all that often,” said Dan Cziczo, an atmospheric scientist at Purdue University and a coauthor of the new study. 

But in the new observations, “the lower stratosphere almost looked more like a smoke cloud,” he said.

Stratospheric Science

North America’s monsoon season starts when warm, moisture-laden air from the Gulf of Mexico collides with the Rocky Mountains. This process can create powerful summer storms familiar to those living in the U.S. Midwest.

If those storms get powerful enough, some clouds “overshoot,” or extend multiple kilometers above the troposphere and into the stratosphere—a cold, thin layer of Earth’s atmosphere beginning at about 12,000 meters (39,000 feet) above sea level.

This overshoot happens often in the United States: There are about 50,000–100,000 overshooting storms each summer, though some last only a minute or two, said Ken Bowman, an atmospheric scientist at Texas A&M University and a coauthor of the new study. 

Bowman is the lead scientist of a 6-year project called Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) that is investigating these overshooting storms. 

To study overshooting storms, DCOTSS researchers use a unique aircraft called Earth Resources 2, or ER-2, which was built by NASA and flies as high as 22,860 meters (75,000 feet)—higher than 95% of the Earth’s atmosphere. Cziczo and his team used DCOTSS data from 31 May to 27 June 2022, an active fire season in the United States, for their new study. The data came from flights over the U.S. Midwest and Great Plains that specifically targeted overshooting storms. 

Their observations showed an unexpected amount of biomass-burning particles in the lower stratosphere during periods affected by overshooting clouds.

“Once we got the aircraft into the stratosphere, we just found it to be littered with these biomass-burning particles, particles from wildfires,” Cziczo said. There had been previous evidence from flights in 2002 that biomass-burning particles existed in the stratosphere, but not to this extent—Cziczo and his team found particles as high as 4 kilometers into the stratosphere, about 4 times higher than previous detection.

The new study “is really the first time people have seen a really large contribution from smoke in the lower stratosphere,” said Brian Toon, an atmospheric scientist at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder who was not involved in the new study. 

“When you add lots of water vapor, it changes a lot of things.”

Cziczo explained that powerful storm clouds pick up smoke, either directly from burning areas or from smoke already mixed into the troposphere, then “spit” that smoke out into the stratosphere after clouds build up and cross the boundary between the two layers. Virtually all the observed biomass-burning particles were probably transported by overshooting storms, as there are no other likely mechanisms for the particles to enter the stratosphere, Bowman said.

The particles the team observed in the lower 4 kilometers of the stratosphere will likely stay suspended there for months.

The researchers didn’t have a way to track exactly where the particles they observed originated. But wildfires across the United States and Canada in the summer of 2022 were a likely source: “We just have to sort of infer that it was the smoke that was in the Midwest,” Cziczo said.

In addition to the biomass-burning particles, the overshooting storms brought a lot of moisture to the stratosphere. As the ER-2 aircraft flew through overshooting clouds, instruments on board detected additional water, sometimes taking the stratosphere’s usual 4 or 5 parts per million of water up to 20 or 30 parts per million. 

Such an influx of water can affect the chemistry, heating, and cooling of the stratosphere, but more research is needed to figure out exactly how. “When you add lots of water vapor, it changes a lot of things,” Bowman said.

Atmospheric Alterations

The combined forces of stronger storms and more wildfires could make the occurrence of these sooty particles in the stratosphere more likely as the climate continues to warm. 

Additional biomass-burning particles in the stratosphere could have consequences for Earth’s ozone layer. Particles provide additional surface area for the stratosphere’s gas molecules to stick to, encounter other gas particles, and react. Many of these reactions over time can damage the ozone layer, a shield of ozone molecules that protects Earth from too much ultraviolet radiation from the Sun.

“It’s important to make sure we understand this so that we can see what might happen in the future.”

“This is not a paper to panic about,” Bowman said. “But as the number of wildfires increases, which it’s likely to continue doing, we’ll get more biomass-burning particles in the stratosphere. And as the climate warms up, it’s likely that the amount of overshooting convection is going to increase, so that’s going to put more material into the stratosphere.”

The findings also raise numerous questions about how additional particles in the stratosphere might affect Earth’s other atmospheric processes. Additional dark, sooty particles could heat the atmosphere, which could change its dynamics or even blur the typically stark boundary between the troposphere and the stratosphere.

“It’s important to make sure we understand this so that we can see what might happen in the future,” Bowman said.

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

Citation: van Deelen, G. (2025), Some summer storms spit sooty particles into the stratosphere, Eos, 106, https://doi.org/10.1029/2025EO250443. Published on 26 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 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.

Author(s): Vincent L. Kooij and Dirk Bouwmeester

Laser-generated, transient toroidal helium plasma at atmospheric pressure is studied experimentally. Tomographically reconstructed cross-sectional images reveal the gas flow responsible for the formation of the toroidal structure. A splitting of the toroidal plasma during the final phase of its evol…

[Phys. Rev. E 112, 055209] Published Tue Nov 25, 2025

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.

Author(s): Nicholas Mitchell, David Chapman, and Grigory Kagan

Electron heat flux is an important and often dominant mechanism of energy transport in a variety of collisional plasmas in a confined fusion or astrophysical context. While nonlocal conductive heat transport, driven by strong temperature gradients, has been investigated extensively in previous liter…

[Phys. Rev. E 112, L053202] Published Mon Nov 24, 2025