EOS

Yesterday, catastrophic flood swept down the Bhote Kosi river through Tibet and Nepal. At least 28 people have been killed. There is speculation that this might have been a GLOF.

On 8 July 2025, a catastrophic mudslide / flood suddenly struck the Rasuwagadhi border crossing point between Tibet and Nepal, causing extensive damage. The Himalayan Times reports that there are nine confirmed victims, with a further 19 people missing, in Nepal. Xinhua reports that eleven people are missing in Tibet, but it is unclear as to whether the Nepal figures include these people.

The scale of the event is impressive. All India Radio has posted this video to Youtube:-

Meanwhile, the Nepali Times has reported that the bridge at the at the Rasuwagadhi border crossing point was destroyed, along with a significant part of the infrastructure at that location. Four hydroelectric schemes have been damaged or destroyed (Rasuwagadi, Trisuli III, Trisuli and Benighat), removing 8% of Nepal’s generation capacity.

Rasuwagadhi is located at [28.27875, 85.37808], on the Bhote Kosi river. It is going to be important to understand what has happened to cause this flood. There is speculation that this was a glacial lake outburst flood (GLOF), which is very possible. It could also have been the collapse of a landslide dam or a high altitude landslide that transitioned into a debris flow. I’ll keep an eye on the satellite imagery over the coming days, but at the peak of the monsoon, it may take some time to get a clear image.

Kirsten Cook of the Université Grenoble Alpes has posted to Bluesky some seismic data from a station near to Kathmandu (a long distance downstream of Rasuwagadhi), which shows the flood:-

thehimalayantimes.com/nepal/rasuwa…Another destructive Himalayan flood, this time transboundary. And like most of these, we can see the seismic signals created by the flood at a DMG station near Kathmandu. The flood is visible seismically about an hour before it arrived at the Nepali border…

— Kristen Cook (@kristencook.bsky.social) 2025-07-08T21:07:08.342Z

The annual time period in which cross-border trade between Tibet and Nepal is possible is short, so the damage to the border infrastructure is likely to have significant implications for Nepal. The loss of the electricity generating capacity is likely to be a greater issue in the long term.

I have highlighted previously that I am concerned that the risks associated with these catastrophic landslides / floods in Himalayan valleys are not being adequately considered. This is the third time in four years that such an event has caused massive damage to power generation infrastructure (after the 2021 Chamoli event and the 2023 Sikkim event). The investment cases for these projects much be increasingly difficult to justify, which will have a range of significant wider economic implications.

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

Atmospheric models describing climate change rely on accurate depictions of chemical transport. Prather [2025] examines the different ways to define the troposphere, a highly chemically heterogeneous domain influenced by a range of chemical sources and sinks, from lightning, wildfires, and pollution to convection and rainfall.

The author builds on previous work proposing the use of the artificial age-of-air tracer e90. After calibrating the e90 tracer, Prather demonstrates its application in calculating the mass of the troposphere and troposphere ozone values, using output from UC Irvine’s chemical transport model, ozonesondes representing northern and southern mid-latitudes and the tropics, and satellite ozone profiles. This work presents a practical demonstration of the calibration of an age-of-air tropopause that could potentially be applied more widely in other models or other age-of-air tracers.  

Citation: Prather, M. J. (2025). Calibrating the tropospheric air and ozone mass. AGU Advances, 6, e2025AV001651. https://doi.org/10.1029/2025AV001651

—Kristina Vrouwenvelder, Executive Editor, AGU Advances

Text © 2025. 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

Incoming radiation from the Sun is balanced by reflected and emitted radiation from Earth, but greenhouse gases trap radiation in Earth’s atmosphere, causing energy to accumulate in the atmosphere, oceans, and land.

Mauritsen et al. [2025] discuss how recent work analyzing Earth’s energy imbalance reveals that it is increasing much faster than predicted and is now almost double what has been predicted by climate models. The current discrepancy between the measured energy imbalance and that predicted by climate models is likely caused by a decrease in Earth’s solar reflectivity, possibly because models have not correctly accounted for sea surface temperature patterns or effects of aerosol particles.

Understanding these changes in Earth’s energy imbalance and their effects on global warming is critical to science and policy. However, these measurements rely heavily on several satellites scheduled for decommissioning, threatening our understanding of our climate future.

Citation: Mauritsen, T., Tsushima, Y., Meyssignac, B., Loeb, N. G., Hakuba, M., Pilewskie, P., et al. (2025). Earth’s energy imbalance more than doubled in recent decades. AGU Advances, 6, e2024AV001636. https://doi.org/10.1029/2024AV001636

—Kristina Vrouwenvelder, Executive Editor, AGU Advances

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Source: Global Biogeochemical Cycles

The ocean absorbs carbon from the atmosphere, but exactly how much is uncertain. For instance, estimates from the 2023 Global Carbon Budget ranged from 2.2 billion to 4 billion metric tons of carbon per year. One source of this uncertainty may be that the effects of bubbles have not been incorporated into air-sea carbon flux estimates, according to Rustogi et al.

When waves break, they create multitudes of tiny bubbles that carry gases such as carbon dioxide back and forth between the atmosphere and water. Models used to evaluate how fast this exchange occurs typically rely on measurements of wind speed, assuming that wind speed directly relates to the prevalence of bubble-forming waves. However, waves can be affected by other factors as well, meaning this assumption doesn’t always hold.

To assess the role of bubbles in air-sea carbon exchange in more detail, scientists applied a recently developed “bubble-mediated gas transfer theory” to the ocean. As with other models, the bubble-mediated approach incorporates wind strength, but uniquely, it also accounts for wave conditions that form gas-carrying bubbles. The researchers compared the results from their new model to a simpler, wind-only model that ignores the effect of bubbles.

The two models yielded similar estimates for total annual ocean carbon storage, but the bubble-mediated model showed much higher variability, both seasonally and regionally; in some instances, local fluxes it indicated differed by 20%–50% from the wind-only model. The bubble-mediated model also suggested that intense wave activity in the Southern Hemisphere leads to much higher carbon storage than in the relatively calm Northern Hemisphere—a difference that’s not obvious in the wind-only model.

That north-south difference could have implications for interpreting and projecting carbon cycle dynamics in a changing climate. With average wind speeds and wave heights likely to increase with global warming, it is essential to anticipate accurately how these changes will influence ocean carbon storage, the authors say.

The work is also important for marine carbon dioxide removal projects aiming to enhance carbon uptake to mitigate climate change effects, they note. A prerequisite for these efforts is quantifying how much carbon the ocean takes up naturally. Without a comprehensive understanding of the processes affecting uptake, the impacts of such interventions may be vastly under- or overestimated. (Global Biogeochemical Cycles, https://doi.org/10.1029/2024GB008382, 2025)

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

Citation: Sidik, S. M. (2025), More bubbles means more variation in ocean carbon storage, Eos, 106, https://doi.org/10.1029/2025EO250244. Published on 8 July 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.

This story was originally published by Grist. Sign up for Grist’s weekly newsletter here.

When wildfires devastated a wide swath of Los Angeles last winter, officials warned residents of several ZIP codes not to drink the water, or boil it first if they must. They worried that soot, ash, and other debris from the blazes might have infiltrated the groundwater, or that damaged pipes might allow toxins into the supply. The last of these “do not drink” orders was lifted last month.

At their peak, those pollutants can be found at levels up to 103 times higher than before the fire. There also can be 9 to 286 times as much sediment in water after a fire. 

But the first large-scale study of post-wildfire water quality has found that pollution created by such a blaze can threaten water supplies for eight years—far longer than previous studies indicated. Researchers at the Cooperative Institute for Research in Environmental Science, or CIRES, at the University of Colorado Boulder analyzed 100,000 samples from 500 watersheds across the western United States. They found “contaminants like organic carbon, phosphorus, nitrogen, and sediment” throughout those that had burned. At their peak, those pollutants can be found at levels up to 103 times higher than before the fire. There also can be 9 to 286 times as much sediment in water after a fire.

The findings have great implications for water systems as they prepare for a world in which fires like those that burned in Los Angeles and, more recently, North Carolina and a great swath of Canada, grow more common. One in six people in the United States lives in a wildfire risk zone, and forested watersheds provide water to almost two-thirds of municipalities in the U.S., making water systems everywhere vulnerable.

“I’ve had a lot of conversations with different utilities and water managers in the West, and every single one of them are concerned about wildfire impacts,” said Carli Brucker, lead author of the study, published on 23 June. But, she added, what they don’t have is longer-term data. “I’m hoping that this research provides these concrete numbers that can really back up water managers’ concerns, and turn those concerns into real funding that they can start putting towards climate resilience. Strong evidence can be really helpful in securing funding.”

Water utilities in the LA area addressed the threat posed by the fires that burned in January in the short term by flushing water mains and pipes. Officials with the Los Angeles Department of Water & Power said they are conducting ongoing water testing in the Palisades area, and are offering free water quality testing to any resident that wants it.

“These urban fires are creating these unprecedented challenges that treatment plants can’t really deal with,” Brucker said. “Burning buildings and businesses and roads and cars, it creates all these contaminants that are just way more dangerous and way more difficult to deal with.”

Even years after a fire, a major rainfall can trigger a mudslide, unearthing contaminants.

Across the locations the researchers analyzed, contamination levels varied widely. In general, post-fire pollution was worse in heavily forested or heavily urbanized areas. The “most dramatic spikes” in pollutants like phosphorus, nitrate, organic carbon and sediment generally occurred in the first few years after a fire, according to researcher Ben Livneh.

“We found the impacts to be really persistent,” Livneh wrote in The Conversation. “We saw significantly elevated levels of nitrogen and sediment for up to eight years following a fire.” Even years after a fire, a major rainfall can trigger a mudslide, unearthing contaminants. Beyond polluting groundwater, that can cause unexpected environmental issues. “Nitrogen and phosphorus act like fertilizer for algae. A surge of these nutrients can trigger algal blooms in reservoirs, which can produce toxins and create foul odors,” Livneh said.

There are several ways to fight these threats to water supply.

“The first line of defense is just diversifying water sources,” Brucker said. Ideally, a utility would draw from several watersheds, so it has a backup in the event one of them is impacted by a fire, she said. They also can build additional sedimentation basins to increase their capacity for sediment handling.

“But all of these things cost a lot more,” Brucker said. And it’s difficult to convince strained utilities in Western states—already dealing with things like water shortages—to spend money on wildfire mitigation without numbers. Rural communities, in particular, often rely on single-source water systems and limited funding, which makes responding to emergencies much more challenging.

“Utilities don’t usually have these sorts of process improvements in place, unless they have a good reason,” she said. “I’m hoping this research can point to—this is a pretty good reason to start planning for and trying to budget for those resilience improvements.”

—Sophie Hurwitz (@hurwitz.bsky.social), Science Writer

This article originally appeared in Grist at https://grist.org/wildfires/pollution-from-wildfires-can-contaminate-our-water-for-up-to-eight-years-new-study-finds/.

Grist is a nonprofit, independent media organization dedicated to telling stories of climate solutions and a just future. Learn more at Grist.org

Takao Doi’s dream is to go to the Moon and plant a tree. The former astronaut is inspired by ancient wooden shrines and temples in Kyoto, Japan, that have lasted more than a thousand years.

“If we can use wood in space, we might be able to have sustainable space development forever,” said Doi, a professor at Ryukoku University.

The idea of a wooden space age gained traction last year with the launch of LignoSat, the world’s first wooden satellite to reach orbit. LignoSat, developed by Doi, a group of Kyoto University scientists, and logging company Sumitomo Forestry, is a CubeSat—a type of minisatellite that is relatively inexpensive and easy to construct. LignoSat’s structure is meant to reduce its environmental impact because wood is a renewable material and creates less pollution when it burns up on reentry into Earth’s atmosphere.

“We think wooden satellites orbiting around the Earth are the future.”

LignoSat was deployed from the International Space Station (ISS) last year by the Japan Aerospace Exploration Agency (JAXA) and stayed in space for 116 days.

Doi and his colleagues are using what they learned to develop LignoSat-2, which they expect to launch in 2028. And they’re not alone—at least one other group is also developing a wooden satellite.

“We think wooden satellites orbiting around the Earth are the future,” Doi said.

Raphaela Günther, an aerospace engineering Ph.D. student at Technische Universität Dresden in Germany who is not involved in the LignoSat project, said she considers the work from the Kyoto University team to be a “small breakthrough” in renewable space materials research.

Lessons Learned

The first LignoSat was a 10-centimeter cube made of magnolia wood panels assembled with traditional wooden joinery. An aluminum frame reinforced the structure.

LignoSat used a traditional joinery method called the blind miter dovetail joint. Credit: Kyoto University

The LignoSat mission had five goals: to measure strain on the wooden structure, to measure temperature inside the satellite, to demonstrate how permeable wood is to magnetic fields in space, to analyze the effects of space radiation on wood, and to establish two-way communication with scientists on the ground.

After the satellite was deployed from the ISS on 9 December 2024, though, scientists in Kyoto weren’t able to communicate with it.

Orbital data from the U.S. Department of Defense show the satellite stayed in one piece during its time in space, proving wooden satellites can work, Doi said. But without the ability to communicate with the satellite, the other four missions weren’t able to be completed, either.

“Unfortunately, we didn’t receive any of the information we wanted to know about,” Doi said.

An analysis indicated that the loss of communication could have been caused by two failures: First, any or all of the three switches needed to activate the satellite system and deploy its antenna may not have turned on, and second, the computer program used in the system may not have started up as expected, Doi said. “We are still analyzing what happened, but we now have two reasons to further investigate.”

Despite the lack of communication, Doi recognized two achievements in the LignoSat mission. First, it demonstrated that a wooden satellite can exist in orbit without falling apart. Second, it streamlined the review process for wooden spacecraft. NASA must complete a safety review of all satellites that head to the ISS, he explained, and now that such a review was completed for LignoSat, reviews for subsequent wooden satellites will be simpler.

LignoSat-2 will have both an external antenna and an internal antenna and will be twice the size of the first LignoSat. Credit: Kyoto University

The Kyoto University team plans to build LignoSat-2 to be twice the size of LignoSat, with two communication systems (one inside the structure and another attached to its surface). Installing the antenna inside the satellite body reduces the drag of the structure as it orbits Earth, Doi said.

“Even if the antenna is not deployed, which might have been the cause of LignoSat 1’s communication problems, we may be able to use this second communication system to communicate with [LignoSat-2],” Doi said.

Finnish space technology company Arctic Astronautics is also thinking about wood in space. In 2021, they and Finnish company UPM Plywood developed the WISA Woodsat, a 10-centimeter birch plywood CubeSat. The satellite contains a suite of sensors meant to gather information about how outer space affects wooden spacecraft. It has a deployable camera, a “selfie stick” meant to take photos of itself in space and allow the team on the ground to monitor it visually.

The WISA Woodsat contains a suite of sensors meant to measure how outer space will affect its materials. It also has a selfie stick. Credit: Arctic Astronautics/Flickr, CC BY 2.0

“There is a niche for these kinds of satellites, and the basic research is extremely interesting,” said Jari Mäkinen, cofounder of Arctic Astronautics and initiator of the WISA Woodsat project. “It’s totally possible that when we see these satellites flying, we realize important information [about how plywood acts in space].”

The WISA Woodsat itself is nearly ready for launch, Mäkinen said, but Arctic Astronautics still needs permitting from Finnish space authorities to proceed. He’s hopeful the launch will take place next year. “We will fly as soon as possible,” he said.

A Sustainable Space Industry

For Doi, the wooden CubeSats are just the beginning. “Let’s create a space timber industry” reads the translation of the bio of the research team’s X (formerly Twitter) account. Doi said he imagines a future where wood overtakes aluminum as the primary material for satellites.

Wood is cheaper, easier to use, and lighter than conventional spacecraft materials. Its use as a potential material could both push the space industry toward using more wood and make space development more accessible to countries with fewer resources, Günther said.

A wooden space age could shrink the environmental footprint of the space industry, too. When aluminum satellites fall back into Earth’s atmosphere, they burn, creating aluminum oxide particles. These particles, sometimes smaller than 1 micrometer, may destroy ozone, disrupt atmospheric processes, and even alter Earth’s magnetic field, some scientists suggest. When wood burns, it generates only carbon dioxide, biodegradable ash, and water vapor.

And though scientists don’t fully understand all the possible ways that particles from decomposing metal or wooden spacecraft interact with the upper atmosphere, the decomposition products of wood are easier to assess because they are already major drivers of atmospheric processes, Günther said.

“It’s not a question if we do or if we don’t” begin to use more sustainable spacecraft materials, she said. “I think we have to.”

With a few hundred tracked objects returning to Earth each year, reentering metal spacecraft are not currently a major environmental problem. But as the space industry quickly grows, it’s crucial to look for more ecofriendly materials, Doi said. Replacing even a small portion of parts on future satellites with wood could significantly reduce pollution, Mäkinen said.

Wood poses challenges for spacecraft engineers, too. Because it’s grown naturally, it has defects and doesn’t behave homogeneously, meaning “the behavior of the material in three different directions is not the same,” Günther said. Her own research is working to create spacecraft materials made of wood fibers and binding material that behave more consistently.

“It’s not a question if we do or if we don’t” begin to use more sustainable spacecraft materials, she said. “I think we have to.”

Mäkinen agreed that wood provides many environmental and technical advantages but said large space companies have likely invested enough in their current manufacturing processes that a large-scale shift to wood as a satellite material is unlikely without pressure from space authorities. “I hope that I’m wrong,” he said.

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

Citation: van Deelen, G. (2025), A new satellite material comes out of the woodwork, Eos, 106, https://doi.org/10.1029/2025EO250241. Published on 7 July 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
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body {background-color: #D2D1D5;} Research & Developments is a blog for brief updates that provide context for the flurry of news regarding law and policy changes that impact science and scientists today.

On 3 June, the U.S. House of Representatives passed a 940-page spending bill containing President Donald Trump’s domestic policy agenda. After the Senate passed the bill 2 days ago, it cleared the House by a four-vote margin and it will now head to Trump’s desk to be signed into law.

The bill provides trillions of dollars in tax cuts, boosts the fossil fuel industry, and dismantles incentives for clean energy, fulfilling Trump’s campaign promise to remake the U.S. energy economy in favor of oil and gas. 

“Congress has betrayed the working people of this country. This budget bill is the largest-ever transfer of wealth from working families to the ultra-rich and one of the most environmentally destructive pieces of legislation in U.S. history,” said Collin Rees, U.S. campaigns manager at Oil Change International, a clean energy advocacy group, in a statement. 

 
Related

•  How the G.O.P. Bill Will Reshape America’s Energy Landscape
•  A List of Nearly Everything in the G.O.P. Bill, and How Much It Would Cost or Save
•  Chart: ​‘Big, Beautiful Bill’ would cause energy bills to go up in every state
• The Most Perverse Part of the ‘Big, Beautiful Bill’
•  Get Involved: AGU Science Policy Action Center
 

Some of the provisions that most concerned renewable energy and environmental advocates ultimately did not make it into the bill. A tax on future wind and solar projects was removed; the bill no longer mandates the scale of public land sales; and tax credits for companies building nuclear, hydroelectric, and geothermal power plants were not targeted by the bill, according to the New York Times. 

“America, get ready for a safer, stronger, more affordable, and Energy Dominant future,” Doug Burgum, secretary of the U.S. Department of the Interior, wrote on X. According to a 25 February report from the Clean Energy Buyers Association, repealing clean energy tax credits, which the bill calls for, would raise electricity prices for U.S. residents by nearly 7% on average by 2026.

Contained within the bill are provisions related to climate, energy, and Earth science that would: 

• Phase out tax credits that have been in place for decades incentivizing wind and solar power projects. “We’ll continue to build out renewables, but we’ll build out a lot slower,” David Carrol, chief renewables officer for ENGIE North America, a major power plant developer, told the New York Times. 
• Repeal tax credits for consumers who buy new or used electric cars, as well as incentives for businesses to buy electric trucks.
• Postpone fees on methane leaks from oil and gas operations.
• End tax credits for homeowners to upgrade energy efficiency in their homes. In 2023, 3.4 million Americans took advantage of these incentives, according to Rewiring America, an electrification advocacy nonprofit.
• Provide tax breaks for oil and gas producers.
• Rescind unspent funding from President Joe Biden’s Inflation Reduction Act. 
• Mandate that millions of additional acres of federal land be made available for mining. 
• Provide tax breaks for U.S. producers of metallurgical coal (a form of coal used to make steel) and lower royalty rates for coal companies that mine on federal lands.
• Mandate oil and gas lease sales in the Gulf of Mexico, the American West, and Alaska’s Arctic National Wildlife Reserve.

“This bill will be the most transformational legislation that we’ve seen in decades in terms of access to both federal lands and federal waters,” Mike Sommers, chief executive of the American Petroleum Institute, told CNBC. “It includes almost all of our priorities.”

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

These updates are made possible through information from the scientific community. Do you have a story about how changes in law or policy are affecting scientists or research? Send us a tip at eos@agu.org. Text © 2025. AGU. CC BY-NC-ND 3.0
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A group of EPA scientists who signed an open letter voicing their dissent from Trump administration policies have been placed on administrative leave.

The letter, addressed to EPA administrator Lee Zeldin, was published 30 June.

As of Thursday afternoon, all 620 signatories are listed as anonymous. However, initially, more than 300 were identified as EPA staffers, and 170 of those staffers chose to be named, according to the Washington Post. Now, about 140 of them have been placed on administrative leave, according to The Hill, E&E News, The New York Times, and other outlets.

“The Environmental Protection Agency has a zero-tolerance policy for career bureaucrats unlawfully undermining, sabotaging and undercutting the administration’s agenda as voted for by the great people of this country last November,” wrote EPA press secretary, Brigit Hirsch, in a statement.

 
Related

•  Declaration of Dissent
•  EPA places staffers who signed ‘dissent’ letter on leave
•  EPA puts 139 employees on leave who criticized administration
• E.P.A. Suspends 144 Employees After They Signed a Letter Criticizing Trump
• Roughly 140 EPA staffers who signed ‘dissent’ letter are put on leave
•  Get Involved: AGU Science Policy Action Center
 

Marie Owens Powell, president of American Federation of Government Employees Council 238, EPA’s largest union, told E&E News that EPA’s actions were “disgraceful” and an “obvious retaliation for individuals expressing their beliefs. She added that the union is investigating its options for legal recourse.

As of Thursday afternoon, the letter also has 4,597 “supporters and endorsers” who had added their name to a running list. The letter outlines five primary concerns:

• That the EPA is undermining public trust by “promot[ing] misinformation and overtly partisan rhetoric.” The letter calls out the use of politicized terms such as “green slush funds” and “clean coal” in EPA messaging.
• That the EPA is ignoring scientific consensus to benefit polluters. The letter states that the “administration’s actions directly contradict EPA’s own scientific assessments on human health risks” related to mercury, asbestos, greenhouse gases, and PFAS.
• That the EPA is reversing previous progress made to protect vulnerable communities. The letter references environmental justice staffers being placed on leave earlier this year and billions of dollars of cancelled grants.
• That the EPA has dismantled the Office of Research and Development (ORD). The letter suggests that placing ORD scientists in regulatory program offices “will make EPA science more vulnerable to political interference” and that budget cuts will leave the office “unable to meet the science needs of the EPA and its partners and will threaten the health of all Americans.”
• That the EPA has promoted a culture of fear. The letter cites comments from private speeches, reported by ProPublica, in which Office of Management and Budget director Russell Vought stated, “We want their funding to be shut down so that the EPA can’t do all of the rules against our energy industry because they have no bandwidth financially to do so.” And, “We want to put them in trauma.”

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

These updates are made possible through information from the scientific community. Do you have a story about how changes in law or policy are affecting scientists or research? Send us a tip at eos@agu.org. Text © 2025. AGU. CC BY-NC-ND 3.0
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As winter gives way to spring, seasonal snowpack in the American West begins to melt.

Though some of that melt flows over and through shallow alpine soil, new research shows that much of it sinks into bedrock where it percolates for years before resurfacing. Fresh snowmelt makes up less than half of the water in the region’s gushing spring streams, according to the study.

The new finding could improve water resources forecasts. Hydrologic models, which inform the forecasts, largely overlook groundwater contributions and assume the spring’s heavy flows come directly from seasonal snowmelt.

The authors of the study, published in Communications Earth & Environment, used a radioactive isotope of hydrogen known as tritium to measure when the water in 42 western U.S. catchments fell as precipitation.

They found that during late winter, when rain and snowmelt were scarce and streams were fed primarily by groundwater, the water fell as precipitation an average of 10.4 years ago. Even during spring, when the same streams were overflowing with fresh runoff, their chilly waters had an average age of 5.7 years, still indicating significant contributions from groundwater.

A Subterranean Bucket

Hydrologic models typically simulate mountains as impermeable masses covered with a thin sponge of alpine soil, said the study’s first author, Paul Brooks, a hydrologist at the University of Utah. The sponge can absorb some water, but anything extra will quickly drain away.

“Snowmelt is being recharged into groundwater and is mobilizing groundwater that has been stored over much longer [periods].”

However, over the past few decades, scientists have uncovered a steady stream of hints that mountains may store huge volumes of water outside their spongy outer layer. Many high-elevation creeks carry dissolved minerals similar to those found in groundwater, suggesting a subterranean origin. Scientists studying healthy alpine ecosystems in arid conditions have wondered whether plants were tapping into a hidden reservoir of water.

Though snowmelt and rainfall immediately increase streamflow, the relationship is not intuitive. “What appears to be happening is that snowmelt is being recharged into groundwater and is mobilizing groundwater that has been stored over much longer [periods],” said James Kirchner, a hydrologist at Eidgenössische Technische Hochschule Zürich who was not involved in the research.

In areas where the mountains were made of porous sandstone, waters monitored in the new study were much older. In one such stream, the average age of water in winter was 14 years.

Mountains are “more like a bucket with a sponge on top.”

The authors were able to convincingly demonstrate the age of the flows because they used tritium, Kirchner said. Though scientists have previously used tritium to date water from individual streams and large bodies such as oceans and lakes, this study is the first to use tritium to date alpine groundwater and snowmelt across multiple catchments, Brooks said.

On the basis of historic flows, annual precipitation, and the ages of the stream water, the mountains could store an order of magnitude more water than accounted for in current models, Brooks said. As opposed to the impermeable masses in traditional models, he explained, mountains are “more like a bucket with a sponge on top.”

This finding could change how scientists think about the alpine water cycle. “If precipitation takes, on average, years to exit as streamflow, that means that streamflow in any one year is a function of years of climate and weather,” Brooks said. That means forecasters should consider more than just the most recent snowpack when estimating spring flows and potential flooding.

But further research is needed to unearth the role mountains play in water storage. The current study is limited because it covers only snowmelt-driven streams in the arid western United States, Kirchner said. Things might work differently in wetter places, he added.

—Mark DeGraff (@markr4nger.bsky.social), Science Writer

Citation: DeGraff, M. (2025), Years-old groundwater dominates spring mountain streams, Eos, 106, https://doi.org/10.1029/2025EO250238. Published on 3 July 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.

In the face of rising atmospheric carbon dioxide, the Gulf of Maine is thought to be particularly vulnerable to ocean acidification. Its vulnerability has to do with temperature: The waters of the gulf are cold, and cold water dissolves carbon dioxide more easily than warmer water does. Increased carbon dioxide decreases the pH of the ocean (making it more acidic), a concern for the health of the region’s ecosystems as well as its lucrative shellfish industry.

But determining seawater chemistry is complicated. It requires advanced equipment and the assessment of complex physical, chemical, and biological processes. Until now, no long-term data existed to put individual measurements into context, so scientists did not know how acidity in the region’s waters was trending.

Using ocean chemistry recorded in algae, researchers have now constructed a nearly 100-year history of acidity (pH) in the region. The analysis, published in Scientific Reports, shows that ocean acidification, seen around the world, has been delayed in the gulf.

The Gulf of Maine is fed by three offshore water masses: icy, acidic northern waters from the Scotian Shelf and Labrador Current and warm, alkaline Gulf Stream waters. It’s also bordered by thousands of kilometers of shoreline to the west, and its estuaries and inshore waters receive significant riverine runoff.

The group expected to see pH fluctuate in the gulf, given the different factors affecting ocean chemistry and human-driven increases in atmospheric carbon dioxide, said Joseph Stewart, a geochemist from the University of Bristol in the United Kingdom and study coauthor. Data from 2011 to now, collected in Maine’s Casco Bay by a local nonprofit, show an increase in acidity in that coastal area. But that time frame is too short to determine long-term trends, according to the study authors.

Ocean Chemistry Recorded in Algae

Crustose coralline algae live for about 40 years in coastal areas of the Gulf of Maine, the southern limit of their range. These cold-loving algae encrust rocks and grow in seasonal increments, leaving growth bands akin to tree rings in their calcified skeletons. They are highly sensitive to changes in pH and serve as a record for past seawater carbon dioxide concentrations.

Using samples of the algae collected from several locations, the team reconstructed a timeline that spanned from 1920 to 2018.

“We’ve been measuring temperature for a long time, but we have not been measuring seawater pH for very long. It’s a very complicated, hard measurement.”

“We’ve been measuring temperature for a long time, but we have not been measuring seawater pH for very long. It’s a very complicated, hard measurement,” said Branwen Williams, a climate scientist at Claremont McKenna College in California and coauthor of the study. “So records like this are really valuable to get a sense of the variability that exists, particularly in these areas with people,” she said.

To the researchers’ surprise, the algae recorded a historic trend of relatively low pH in surface seawater, about 7.9, with a slight increase of 0.2 pH unit over the past 40 years. (On average, ocean water currently has a pH of around 8.1.) That move toward slightly more basic conditions was counterintuitive.

“We were somewhat surprised by that result, but then it made a lot of sense when we put it in the context of how temperature was changing and how nutrients were changing, and the timing of that change that had been previously documented in other papers,” Stewart said.

Starting around 2010, waters in the Gulf of Maine warmed dramatically. The change was driven by the decreasing influence of frigid northern water masses and the rise of Gulf Stream waters, which are not only warm but also alkaline. These waters seem to act as a buffer and delay the onset of ocean acidification.

Warming Waters

Ocean circulation–driven buffering effects will, at some point, reach their limits, researchers said. The ocean’s uptake of rising amounts of atmospheric carbon will persist, however, and leave the region’s ecosystems and economy vulnerable to the effects of acidification.

Ocean acidification presents one more challenge to the gulf’s coastal economy and its commercial fisheries, which stretch from Cape Cod to Nova Scotia. Ecosystems in the Gulf of Maine already face threats from disease, warming waters, habitat degradation, and invasive species. The added threat of acidification may push individual species past their ability to persist and redefine the biotic and abiotic factors contributing to those species’ ecosystems—a tipping point.

“It’s not just pH on its own that’s going to cause the ecosystem tipping point to occur, but a combination of pH and temperature, and both of those things are changing. The more data we have to understand the systems, all those different factors, the better,” said study coauthor Michèle LaVigne, an ocean scientist at Bowdoin College in Maine.

This and other studies provide insight into acidification trends, but the challenge of understanding and addressing competing factors influencing ocean pH feels intractable, said Damian Brady, an oceanographer at the University of Maine who was not involved in the study. “The dynamics are such that we have these countervailing forces all the time. We have these rises in total alkalinity from offshore source water, increases in temperature, while also, we as a species increase the carbon dioxide that goes in there,” he said. “It’s really complex.”

—Kimberly Hatfield, Science Writer

Citation: Hatfield, K. (2025), Warming Gulf of Maine buffers ocean acidification—for now, Eos, 106, https://doi.org/10.1029/2025EO250239. Published on 3 July 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: AGU Advances

Waves in the polar jet stream over eastern North America are often responsible for cold air outbreaks and extreme winter storms. A 1990-2010 increase in jet stream waviness has, controversially, been linked to unusually rapid warming in the Arctic and has been thought to foreshadow a rise in extreme weather as climate change progresses. However, the United States “warming hole” —an enigmatic 1958-1988 cooling trend centered over the eastern U.S.— has also been linked to an increase in jet stream waviness several decades before the 1990s shift in waviness. This timing difference raises questions about whether the jet stream behavior since the 1990s is historically unusual.

Chalif et al. [2025] leverage information from long-term climate reconstructions and find that the jet stream was wavier than it is today during many periods of the 20th century and was the dominant factor driving the winter warming hole. The results highlight the strong relationship between jet stream waviness and eastern U.S. climate, and question whether accelerated Arctic warming is responsible for recent jet stream waviness.

Citation: Chalif, J. I., Osterberg, E. C., & Partridge, T. F. (2025). A wavier polar jet stream contributed to the mid-20th century winter warming hole in the United States. AGU Advances, 6, e2024AV001399. https://doi.org/10.1029/2024AV001399

—Alberto Montanari, Editor-in-Chief, AGU Advances

Text © 2025. The authors. CC BY-NC-ND 3.0
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In April 2025, I recorded 41 fatal landslides that cost 107 lives.

I’m somewhat behind with posting updates on global fatal landslides due to other workload pressures – please accept my apologies. Please be assured that I’m still collecting the data and that I will make a summary available as soon as I can.

Somewhat belatedly, here is a summary for April 2025 (the same report for the previous month is available here). As always, a reminder that this is a dataset on landslides that cause loss of life, following the methodology of Froude and Petley (2018). At this point, the monthly data is provisional.

The headlines are as follows. In April 2025, I recorded 41 fatal landslides that cost 107 lives. The April Average for 2004 to 2016 is 28 fatal landslides, so this is once again substantially above the long term mean. In the exceptional year of 2024, I recorded 40 landslides, so as at 30 April 2025, the cumulative total is proving to be comparable to the prior year. This is a little bit surprising.

Loyal readers will know that my preferred way of displaying these data is using pentads – 73 five day blocks over the course of the year. The end of April takes us to pentad 24:-

The number of fatal landslides to the end of April 2025, displayed in pentads. For comparison, the long term mean (2004 to 2016) and the exceptional year of 2024 are also shown.

As the graph shows, the cumulative total number of fatal landslides to the end of April 2025 has tracked in a very similar way to April 2024. The trend is very substantially higher than for the long term average. But note also that 2024 saw a very early transition to the much higher event rate through the Northern Hemisphere summer (in 2024 this occurred in the latter part of April, the norm is at least a month later). At the end of April 2025, it was too early to tell whether this would be replicated.

I find this continued high rate of global fatal landslides through April 2025 quite surprising, but global temperatures have remained high. As the US Government dismantles its climate infrastructure (an act of pure vandalism), we are increasingly reliant on data being provided elsewhere. Fortunately, the European Copernicus Clime Change Service system remains wonderful and fully available. This shows that:

“April 2025 was the second-warmest April globally, with an average ERA5 surface air temperature of 14.96°C, 0.60°C above the 1991-2020 average for April. April 2025 was 0.07°C cooler than the record April of 2024, and 0.07°C warmer than the third warmest of 2016.”

Thus, the high event rate for fatal landslides may be associated with the continued high global temperatures, and thus high peak rainfall intensities, through the early part of 2025.

Reference

Froude M.J. and Petley D.N. 2018. Global fatal landslide occurrence from 2004 to 2016. Natural Hazards and Earth System Science 18, 2161-2181. https://doi.org/10.5194/nhess-18-2161-2018

Return to The Landslide Blog homepage Text © 2023. 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.