EOS

A new paper in the journal landslides (Yang et al. 2026) details the 6.8 million cubic metre Huangci Landslide in China, which was a reactivation on a slope that has suffered two other failures in recent decades.

On 10 December 2025, failure occurred in the large Huangci landslide in Gansu Province, China. The event is described in a new paper (Yang et al. 2026) in the journal Landslides (this link should provide access even though the article is paywalled). The paper is fascinating as this is a very complex slope with an interesting history of deformation, and because large failures do not usually occur in the winter months in this part of China.

The location of the Huangci landslide is [36.08983, 103.32412]. This is a Google Earth image of the site, captured in 2004:-

Google Earth image of the Huangci landslide in 2004.

The geology consists of loess overlying mudstones. As the image above shows, the site had previously failed. The houses at the foot of the slope are the homes of people displaced in 1968 during the impoundment of the Liujiaxia Reservoir. Note also the farmland on the terrace behind the landslide. This is an arid area, so this farming requires extensive irrigation.

According to Yang et al. (2026), the failure that can be seen in the image above occurred on 30 January 1995. About 6 million cubic metres of rock and loess were involved, creating a landslide with a width of about 500 metres and a length of about 370 m.

The Huangci landslide failed again on 14 May 2006, this time with a volume of about 4 million cubic metres. The image below, captured in 2013, shows the aftermath:-

Google Earth image of the Huangci landslide in 2012.

In this failure, 10 houses were destroyed.

The most recent failure of the Huangci landslide occurred on 10 December 2025. This time, a larger mass failed, creating a landslide with a volume of about 6.77 million cubic metres, a length of up to about 740 metres and a width of up to about 420 metres. There is a spectacular video on Youtube showing the aftermath of the failure:-

The still below gives an impression of the scale of the failure:-

An image from a drone showing the aftermath of the 10 December 2025 Huangci landslide in China. Still from a video posted to Youtube by 阿龍說牆內事.

According to Yang et al. (2026), this failure destroyed 39 houses plus a range of infrastructure that includes power transmission systems, irrigation systems, water supply systems and transportation facilities. The site had been successfully evacuated as a result of a community-operated early warning system.

As noted above, this is an unusual time of the year for a landslide of this type. However, Yang et al. (2026) conclude that the underlying driver is irrigation on the terrace upslope from the landslide, driving a rise in the groundwater and consequent progressive deformation of the slope. This led to weakening of the mudstones that were buttressing the failure, eventually triggering collapse.

Reference

Yang, Y. et al. 2026. The reactivated Huangci landslide at the Heifangtai terrace, Gansu Province, China, on December 10, 2025. Landslides. https://doi.org/10.1007/s10346-026-02765-2.

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In its annual forecast of the upcoming Atlantic Hurricane season, NOAA suggests the 2026 season has a 55% chance of being below normal, compared with a 35% chance of being near normal and just a 10% chance of being above normal.

The forecast, announced at a press conference at the NOAA Aircraft Operations Center in Lakeland, Fla., includes 8 to 14 named storms (with winds of at least 39 miles per hour), 3 to 6 of which will be hurricanes (with winds of at least 74 miles per hour). One to three of those are forecast to be major hurricanes (category 3 to 5 storms, with winds of at least 111 miles per hour).

NOAA forecasts that a below-average hurricane season is most likely in 2026, largely because of El Niño conditions. Credit: NOAA

A below-average number of hurricanes does not reduce the need for people to be prepared, NOAA representatives emphasized.

“Even though we’re expecting a below-average season in the Atlantic, it’s very important to understand that it only takes one.”

“Even though we’re expecting a below-average season in the Atlantic, it’s very important to understand that it only takes one,” said Under Secretary of Commerce for Oceans and Atmosphere and NOAA Administrator Neil Jacobs. “We have had category 5s make landfall in the past during below-average seasons.”

In contrast, NOAA is forecasting an above-average season in the Pacific, with a 70% likelihood of above-normal activity.

Matthew Rosencrans, lead hurricane forecaster with NOAA’s National Weather Service, noted that the Atlantic forecast does not yet contain information about potential hurricane landfalls, just the likelihood of their formation. National Weather Service Director Ken Graham said the potential for rapid intensification—when wind speed increases by at least 35 miles per hour over the course of 24 hours—makes early preparedness particularly important.

“Every category 5 that’s made landfall in this country was a tropical storm or less 3 days out,” he said. “So they rapidly intensified that quick. You think you might have a week on your timeline. The reality is you may only have days.”

“There will never be a ‘Hurricane Justa,’” he added. “There’s no such thing as just a category 1, just a tropical storm, just a category 2.…Even the smallest storm, if it’s slow enough and big enough, it’s going to be catastrophic flooding and storm surge.”

The Atlantic hurricane season runs from 1 June to 30 November. The NOAA forecast is in line with an Atlantic hurricane forecast issued 9 April by Colorado State University (CSU), which predicted 13 named storms and 6 hurricanes, including 2 major hurricanes. Similarly, a forecast released 22 April by North Carolina State University predicted 12 to 15 named storms, 6 to 9 hurricanes, and 2 to 3 major hurricanes.

All three forecasts are slightly below the average Atlantic hurricane numbers for 1991–2020: 14.4 named storms, 7.2 hurricanes, and 3.2 major hurricanes.

The World Meteorological Organization has released its list of 2026 Atlantic tropical cyclone names. Credit: NOAA El Niño

The forecast for below-average activity levels largely stems from El Niño, a climate pattern that increases vertical wind shear over the tropical Atlantic. Vertical wind shear is how much the speed and direction of wind change with altitude. When wind shear is too high, it can tear a hurricane apart before it forms.

“Wind shear is good for us, bad for the hurricanes,” said Phil Klotzbach, a hurricane forecaster at Colorado State University and lead author of the CSU report.

This year, researchers suggest El Niño could become the strongest in modern history, which could have ripple effects on global temperatures. At the NOAA press conference, Jacobs said that there is a 98% chance of El Niño conditions occurring later this season and an 80% chance that it will be moderate to strong. The forecasted strength of El Niño has only grown since CSU issued its forecast, Klotzbach said.

However, in addition to high wind shear, El Niño is also characterized by unusually warm waters in the Pacific. Klotzbach compared the warm waters of El Niño to loaded dice.

“If the waters are a little bit warmer, that will load the dice for the storm to get stronger.”

“To get to a hurricane, you need to have warm water,” he said. “You need to have a lot of other stuff as well, but if the waters are a little bit warmer, that will load the dice for the storm to get stronger.”

El Niño isn’t the only reason our oceans are warming.

At a press briefing hosted by Covering Climate Now prior to the NOAA press conference, Shel Winkley, a meteorologist at Climate Central, noted that about 90% of the excess heat caused by greenhouse gas emissions has gone into Earth’s oceans, as the planet tries to keep our atmosphere in balance.

“We’re not saying that climate change necessarily creates hurricanes,” Winkley said. “But it is supercharging them: More intense winds, heavier rain, bigger flooding. That’s the connection that we can confidently draw.”

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

Citation: Gardner, E. (2026), NOAA forecasts a below-average hurricane season, Eos, 107, https://doi.org/10.1029/2026EO260171. Published on 21 May 2026. Text © 2026. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

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

At subduction zones, one tectonic plate dives beneath another, dragging rocks tens of kilometers into Earth’s interior where they are transformed by extreme pressures and temperatures. Some of these deeply buried rocks make it back to the surface, carrying a record of conditions along the plate boundary at depth. Geologists have long debated how these high-pressure rocks are exhumed and how they end up mixed into younger, lower-grade surrounding material.

Wang et al. [2026] address this question with detailed geologic mapping, Ar-Ar analyses, and U-Pb geochronology from subduction complex rocks on Cedros Island, offshore Baja California, Mexico. Their data show that high-pressure blocks yield cooling ages between 172 and 144 million years old, yet they are hosted in sedimentary rocks no older than about 92 million years. This age mismatch, combined with field evidence that the blocks are enveloped in sedimentary matrix rather than tectonically sheared into place, leads the authors to propose that the high-pressure rocks were exhumed to the surface, eroded, and recycled back into the subduction trench as sedimentary debris, potentially multiple times. The authors suggest that rapid exhumation was driven by extension within the forearc wedge. When plate convergence rates dropped abruptly, the wedge became gravitationally unstable and stretched along brittle-ductile shear zones, bringing deeply buried rocks to shallow crustal levels.

This polycyclic model is incompatible with alternative interpretations in which exotic blocks were mixed into their host matrix by viscous return flow within the subduction channel, because such models predict that blocks and their surrounding matrix should share similar thermal histories. Instead, the data require that blocks completed their journey to depth and back long before the surrounding sediments even entered the trench. The new understanding of subduction dynamics on Cedros Islands illuminates connections with the broader Franciscan Complex of California, where the origin of similar high-pressure blocks in younger matrix has been debated for decades. Together, these findings offer new perspectives on how subduction zones operate over long timescales and how their fragmentary rock record preserves fundamental evidence of the tectonic history of the continental margin. 

Citation: Wang, J. W., Kapp, P., Holder, R., He, J., Hernández-Uribe, D., & Worthington, J. (2026). Polycyclic metamorphism, exhumation, and recycling of subduction complex rocks, Cedros Island, Baja California. Tectonics, 45, e2025TC009340. https://doi.org/10.1029/2025TC009340

­­—Alexis Ault, Associate Editor, Tectonics

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Wind-driven waves on Earth move sediments and shape shorelines. They transport energy between the atmosphere and planetary surface and also mix bodies of liquid, affecting both chemistry and biology. On other worlds with surface liquids, either now or in the past, wind waves would likely perform the same function and so would play a key role in climate and astrobiological potential.

“They’re basically the interface between how the atmosphere communicates with the landscape, especially at the coast.”

New research went back to the fundamentals and explored the conditions that can generate waves on worlds with different physical properties and different liquids, such as Titan, Mars, and select exoplanets.

“Wind waves are really interesting phenomena,” said Una Schneck, a planetary science doctoral student at the Massachusetts Institute of Technology (MIT) in Cambridge. “They’re basically the interface between how the atmosphere communicates with the landscape, especially at the coast.”

The Physics of Waves

Past models of wind generation on other planets struggled because they tended to start from preexisting models of Earth waves. Those models were developed to describe waves in Earth’s specific combination of gravity, atmosphere, and surface liquid, namely, water, said Schneck, who led the new research. Such models were sometimes tailored to describe a particular location and season. Adapting those models for conditions on other worlds, including other liquids like methane and sulfuric acid, always seems to leave traces of Earth behind.

However, the physics of what creates wind-driven waves should be universal, Schneck said, so the team went back to the basics of wave generation. They developed a wave model that explores the relationship between a world’s bulk properties, like gravity and air density, and liquid properties, like surface tension, to determine the wind strength needed to produce a wave.

The team “created this model that went back to the basic physics of waves, instead of just trying to fit to known wave conditions,” said Taylor Perron, an MIT geomorphologist and planetary scientist and coauthor of the research.

The Curiosity rover landed in Gale Crater on Mars (left) and has since found evidence—wavy bedforms—that this former crater lake had waves. Titan’s northern hemisphere hosts a sprawling lake district (right). The shores of one of the moon’s largest bodies of liquid, Ligeia Mare, shows evidence of wave activity. Credit: Left: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS; right: NASA/JPL-Caltech/ASI/USGS

The model showed that the threshold wind speed to generate a wave is lower for liquids with less surface tension, which makes it easier to change the liquid’s shape. Higher air density provides more force to push against a liquid’s surface, and lower gravity makes it easier for a wave to rise up—both factors allow a weaker wind to create a wave. The team published these results in the Journal of Geophysical Research: Planets in April.

Waves on Other Worlds

The team first tested their model on the only set of wind and wave data we have—Earth. They used 20 years of wave and weather data for Lake Superior. The model found, correctly, that it takes wind speeds of 2.2 meters per second to generate waves on the lake’s surface and accurately predicted the height of waves for different wind speeds.

They then used the model to predict wave conditions on other worlds. They started with Mars, which likely had ancient oceans and lakes. Winds of 1.2 meters per second would have created waves in the lake that filled Gale Crater millions of years ago. A wave in Gale Crater would have been taller than a wave on Earth produced by wind of the same strength owing to Mars’s lower gravity.

The story is similar on Titan, the largest moon of Saturn. Waves in Titan’s hydrocarbon lakes would swell with a mere 0.5 meter per second of wind and would rise higher than an Earth wave under similar wind conditions. But they would travel much more slowly than Earth waves and would be spaced farther apart.

“The paper represents our best theoretical understanding of how we expect for waves to behave in a variety of environments,” said Jason Barnes, a planetary scientist at the University of Idaho in Moscow who was not involved with this research. “The movie of Titan waves is particularly awesome—very slow moving for such large amplitudes! Although I don’t expect waves to get that high ever in Titan’s sluggish atmosphere, it’s fun to be able to visualize what they might look like if they did.”

“In theory, this is something that people could do.”

The team also explored wave-generating conditions on three Earth-sized exoplanets. The possible sulfuric acid lakes of the exo-Venus Kepler-1649 b would grow in winds of 5.3 meters per second but would grow to a height similar to that of Earth waves because of its Earth-like gravity. Water lakes on LHS 1140 b would grow in 2.7 meter winds, similar to those on Earth, but would not grow as high because of its higher gravity. And on 55 Cancri e, a lava world, it would take winds of 37 meters per second—a category 1 hurricane—to move tiny waves of molten rock.

“Would you be able to ever detect this? Is this a useful thing to think about, or is it just a fun thought experiment?” Schneck asked. “If the waves are tall enough, you should be able to detect a change in the polarization [of an exoplanet’s light curve] that would not only suggest that there is a liquid surface on that exoplanet, but that liquid surface has waves.…In theory, this is something that people could do.”

Will We See It? Not Soon

Right now, the only world known to have surface liquid other than Earth is Titan, but we don’t have the right observations of Titan to test the new model. The European Space Agency’s Huygens probe landed on the moon in 2005, but nowhere near the northern lake district. NASA’s Cassini mission (of which Huygens was a part) did not detect any waves but did observe a changing lake shore that hinted at wave activity.

It’s possible that Titan’s waves are seasonal and Cassini just didn’t have the right timing, Perron noted. Temperature changes during Saturn’s year could affect wind speeds and also the composition of Titan’s lakes, changing the conditions of wave generation.

Still, the wind speed needed to make a wave on Titan is so low that “it would be very surprising if waves never formed. It just may be difficult to catch them when they’re there,” he said.

“The best way to test this work would be to send a sea probe to float or motor on one of Titan’s big 3 seas.”

“The best way to test this work would be to send a sea probe to float or motor on one of Titan’s big 3 seas—Kraken Mare, Ligeia Mare, or Punga Mare,” Barnes said. “Such a ‘buoy’ probe would be able to simultaneously measure both the sea conditions and the wind conditions, allowing for a comprehensive test of the model.”

Alas, no such mission is in the works, and the upcoming Dragonfly mission won’t travel near any lakes to test this theory either. A future Titan orbiter might provide that information, while a current or future Mars rover might yet gather evidence showing how lakes worked in that planet’s past.

“The improved understanding of waves from this paper might help to constrain the possibilities for wave erosion at the margins of bodies of water…thereby helping us to probe into the past climates of Mars and Titan,” Barnes said.

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

Citation: Cartier, K. M. S. (2026), What winds whip up otherworldly waves?, Eos, 107, https://doi.org/10.1029/2026EO260165. Published on 21 May 2026. Text © 2026. 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.

Arsenic-contaminated groundwater affects more than 230 million people living in 108 countries. About 180 million of these people live in the Indian subcontinent (which includes Bangladesh, Nepal, and Pakistan, in addition to India) and Southeast Asia. The Indian state of Bihar, which borders Nepal, has several regions with extremely high levels of naturally occurring arsenic in their groundwater.

In Bihar, silt from the Himalayas containing arsenic and other heavy metals is routinely deposited in floodplains and seeps into the groundwater below. This phenomenon puts up to 21 million residents in Bihar at risk of consuming arsenic-contaminated water each day. Arsenic is a carcinogen that has also been linked to diabetes, pulmonary disease, cardiovascular disease, and infant mortality.

Though Bihar has close to 600 groundwater treatment units designed to filter out arsenic, a recent study of 98 units found that 90% of them were installed in parts of the state where groundwater arsenic levels were within the World Health Organization’s permissible limits (below 10 parts per billion)—which means almost all the communities that need these units the most still do not have access to them. The research was published in Groundwater for Sustainable Development.

“Some of the areas with these units had reported a higher prevalence of gallbladder cancer, which is associated with arsenic poisoning. But we found that it was the food that was the main source of arsenic exposure, not groundwater,” said Arun Kumar, a study author and senior scientist at Mahavir Cancer Sansthan & Research Centre in Patna, the state’s capital city. “In the last decade, we have observed drastic changes in groundwater arsenic levels in Bihar. Along with that, the cancer burden has also reduced in some parts of the state.”

In another city, Buxar, Kumar and his colleagues observed levels of arsenic of up to 1,900 parts per billion in the groundwater in 2015. But when the researchers retested that region’s water samples last year, the arsenic levels had gone down to 100–200 parts per billion.

“We hypothesize that because Bihar is prone to earthquakes, the seismic activity might have changed the properties of sediments and silt in groundwater. And perhaps, at some stage, those regions with the groundwater treatment units had experienced arsenic contamination,” added Kumar. “It is still a mystery to us” why the levels changed so drastically.

Ditching Groundwater for River Water

Kumar acknowledged that in the past few years, there has been a mushrooming of public and private groundwater arsenic treatment units in regions located within 10 kilometers (6.2 miles) of the Ganges River in Bihar. The majority of the 98 units included in the study were installed by the state government from 2016 onward. The researchers observed that privately owned units underwent regular maintenance, unlike many of the government-run units.

“Much of the previous large-scale groundwater testing conducted in Bihar was limited to the 6-mile stretch on either side of the Ganges River.”

The corresponding author of the study, Laura Richards, a professor of water resources and geochemistry at the University of Manchester, explained that regions close to the Ganges River may have been given higher priority mainly because they are situated along major roads and highways, making them easier to access than inland Bihar.

“Much of the previous large-scale groundwater testing conducted in Bihar was limited to the 6-mile stretch on either side of the Ganges River. The issue with that is that the regions selected for arsenic remediation units were likely based on nonrepresentative spatial sampling of the state, and those locations might not have necessarily covered all areas with arsenic contamination in the groundwater,” said Richards. “Arsenic distribution across the state is really quite heterogeneous.”

The researchers further found that in 10% of the locations where groundwater arsenic treatment units were installed by the state government, high levels of fluoride posed a greater public health risk than arsenic, suggesting that governmental policies were rolled out without site-specific water quality monitoring and testing.

“Alluvial or sand-rich aquifers are the main culprits of arsenic-contaminated water in Indian terrains.”

In addition to arsenic and fluoride, the groundwater in different parts of Bihar has high levels of manganese and iron. Currently, the state has more than 3,000 groundwater treatment units for arsenic, fluoride, and iron. However, Kumar said a better solution would be to look to other sources for drinking water and to ensure water treatment centers are properly maintained.

“People would be a lot safer if they stopped consuming groundwater altogether,” Kumar said. “This is why the state government has started treating and supplying water from the Ganges River to villages. They have already started doing it in two districts and plan on expanding the supply of river water.”

“Alluvial or sand-rich aquifers are the main culprits of arsenic-contaminated water in Indian terrains,” said M. Santosh, a professor at the China University of Geosciences in Beijing who was not involved in this study. “This study clearly shows how we can rectify remedial measures on a local level. We should encourage more such studies on how to tackle this problem.”

—Anuradha Varanasi, Science Writer

Citation: Varanasi, A. (2026), In Bihar, groundwater treatment units were installed in regions that didn’t need them, Eos, 107, https://doi.org/10.1029/2026EO260168. Published on 21 May 2026. Text © 2026. 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

Most auroras appear in the “auroral oval” at high latitudes surrounding the magnetic poles. However, some can appear as a detached auroral arc from the auroral oval, at lower latitudes in mid-afternoon and connected to the oval only at a tip or two. Such a detached arc is believed to be linked to the “plasmaspheric plume,” the tongue-shaped extension of the plasmasphere during the recovery phase of a geomagnetic storm. (The plasmasphere is the torus-shaped region of cold, dense plasma above the low- and mid-latitude ionosphere.) The surface waves at the plume boundary cause it to ripple and modulate the various plasma waves in the plume.

Based on observations from multiple satellites and ground stations, Feng et al. [2026] find sawtooth-like undulations along the equatorward boundary of a detached auroral arc in the ultraviolet that was produced by energetic (>keV) electrons and accompanied by energetic (>10 keV) ions. The authors attribute the undulations to Electromagnetic Ion Cyclotron (EMIC) waves that are modulated by the surface waves and resonating with the energetic ions. The study unravels the fine-scale structures of detached auroral arcs and sheds important light on the dynamics underlying their formation.

Schematic illustration of the formation mechanism for the sawtooth-like undulations of a detached auroral arc. The surface waves modulate the Electromagnetic Ion Cyclotron (EMIC) waves in the plasmaspheric plume, causing the energetic ions to precipitate into the ionosphere and resulting in the formation of an afternoon detached auroral arc with sawtooth-like undulations. Credit: Feng et al. [2026], Figure 4

Citation: Feng, H., Wang, D., Hao, Y., Miyoshi, Y., Fu, H., Jun, C.-W., et al. (2026). First observation of sawtooth-like undulations in afternoon detached auroral arcs modulated by surface waves at the plasmaspheric plume boundary. AGU Advances, 7, e2025AV002234. https://doi.org/10.1029/2025AV002234

—Andrew Yau, Editor, AGU Advances

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Forecasts for the 2026 South Asia monsoon are for below average rainfall, but some of the most landslide prone areas of India may receive totals that are above average.

As usual, we are now starting to see the number of reported global fatal landslides increase as the northern hemisphere rainy season commences. In recent days, there have been fatal floods and landslides across several provinces of mainland China as well as landslides on the pilgrimage route to Kederath in northern India.

The global pattern is dominated by the South Asia (southwest / summer) monsoon, so it is interesting at this point to to consider the prospects for this year. The monsoon itself is expected to start in SW India next week, timing that is normal. It will then build over the following month or so.

The current forecast for the monsoon itself is that the total rainfall is likely to be below average. This is the WMO forecast:-

The WMO 2026 South Asia monsoon forecast from the WMO.

The map shows below average precipitation for much of South Asia. The IMD also forecasts below average rainfall.

Of course, in landslide terms we are interested mainly in SW India (Kerala), which has a below average forecast, and the mountainous areas of Pakistan, India, Nepal, Bhutan and Bangladesh. Much of this is also forecast to receive below average precipitation, but note the above average forecast for parts of northern India (Jammu and Kashmir, Himachal Pradesh) and NE India (Sikkim, Arunachal Pradesh). These are some of the most landslide-prone areas of India, suggesting that we may well see substantial landslide challenges in these areas.

The caveat of course is that monsoon-triggered landslides are sensitive to rainfall intensity as well as rainfall magnitude. A below average monsoon can bring intense rainfall events that trigged catastrophic landslides. Unfortunately, the forecasts cannot resolve this issue.

As an aside, the next few days in the European Alps will be interesting. We are about to see a few days of unusually high temperatures, which are likely to drive a wave of snowmelt and permafrost thawing. Given the time of year, this could well trigger extensive rockfall activity.

Unfortunately, by the time I get to Switzerland in nine days the weather is forecast to have reverted to cool drizzle!

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body {background-color: #D2D1D5;} Research & Developments is a blog for brief updates that provide context for the flurry of news that impacts science and scientists today.

Human-driven climate change is driving the rise of sea levels, worsening flood conditions and threatening coastal communities around the world. Not only is sea level rising, but it’s rising faster every year. Understanding the degree to which different processes contribute to sea level, known as the sea level budget, can help scientists better predict where and how quickly sea level will rise under potential climate futures.

 
Related

•  Read the paper: Improved closure of the global mean sea level budget from observational advances since 1960
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But for several decades there has been a “budget gap” between measurements of sea level change and the total estimated contributions from glaciers, polar ice, land storage, and oceans expanding as they heat up (thermospheric expansion). Research published today in Science Advances has helped close that budget gap by incorporating more recent sea level observations, reconciling measurements taken by different instruments, and including recent community estimates of sea level rise and its components.

The new analysis breaks down the drivers of sea level rise from 1960 to 2023. The team found that the largest contributor is heat-driven expansion of seawater, responsible for 43% of sea level rise since 1960. Melting ice contributed the next largest amount of sea level rise: 27% came from mountain glaciers, while 15% came from the Greenland Ice Sheet and 12% from the Antarctic Ice Sheet. Lastly, sea level rose 3% as land reduced its capacity to store water.

Since 1960, 43% of global sea level rise can be attributed to thermal expansion of water, just 3% to a reduction in land water storage, and the remainder from melting ice and glaciers. Credit: Zheng et al., Science Advances (2026)

“For years, there has been a frustrating gap between how much the oceans were observed to be rising and how much we could explain from the individual causes,” John Abraham, an engineer at the University of St. Thomas in St Paul, Minn., and a coauthor on the new research, said in a press release. “This work shows that, with better instruments, processes, and smarter analysis, this knowledge gap can be closed. We can explain sea level rise with greater confidence.”

The researchers also calculated the rate at which sea level has risen since 1960 and how each component factored in. They found that the rate of sea level rise has recently doubled: It was 2 millimeters per year averaged over 1960­–2023 and 4 millimeters per year averaged over just 2005–2023. The strongest driver of that doubling is ocean warming, responsible for 41% of the accelerating rate of sea level rise, followed by reduced land water storage (21%).

In the past, glacial melt was the largest contributor to sea level rise before it was overtaken by thermospheric ocean expansion overtook (left). The rate of sea level rise has been speeding up since about 1980, also driven by thermospheric ocean expansion (right). Credit: Zheng et al., Science Advances (2026)

This research demonstrates the importance of maintaining detailed records of sea level rise, collecting new measurements, and not backing away from global change research. With better data on which processes contribute to sea level rise and its acceleration, policymakers and local communities can create informed mitigation strategies that account for future rise.

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

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Roughly the size of Texas, the Karoo Basin of central western South Africa is brutally dry, sparsely populated, and known in part for its potentially “massive” hydrocarbon deposits.

South Africa, which consumes more energy than any other country in sub-Saharan Africa, has shown a growing interest in commercial fracking for shale gas and oil across the Karoo hinterland, with the country moving in late 2025 to lift a 13-year ban on shale gas exploration in the area.

However, a recent study from the University of Cape Town, published in Seismological Research Letters, cautioned that the Karoo might not be as seismologically calm as it appears, meaning fracking efforts could have the potential to induce earthquakes in the region.

A Swarm of Earthquakes

The researchers observed 66 earthquakes in this cluster between 2007 and 2022, ranging from 0.7 to 4.8 in magnitude.

The researchers investigated what they call a sudden swarm of earthquakes that occurred in the Leeu Gamka cluster, a region of the Karoo that was previously considered seismically stable. They observed 66 earthquakes in this cluster between 2007 and 2022, ranging from 0.7 to 4.8 in magnitude.

“The individual earthquakes here are very small,” said Alastair Sloan, a tectonics and structural geologist at the University of Cape Town.

Using ambient noise tomography, previous geophysical surveys, and information about the locations of past earthquakes, the researchers identified a critically stressed fault underlying the region. The fault appears to extend for at least 30 kilometers roughly west-northwest to east-northeast.

Looking at South Africa more generally, there are other places where there have been “fairly large” earthquakes with a similar orientation, Sloan said. He cited a series of large earthquakes in the early 20th century in a place called Koffiefontein, north of the study area, and the disastrous 1969 Tulbagh earthquake, west of the team’s study area.

Both of those earthquakes occurred in regions that are geologically similar to the Karoo, though they’re outside of the area being considered for shale gas exploration, Sloan said.

Fracking Risks?

In other parts of the globe, such as Oklahoma in the United States, processes related to oil and gas extraction have led to “induced earthquakes.” Most of these earthquakes have been triggered by wastewater disposal associated with oil production, not by fracking directly.

Researchers are unsure if industrial fluid injection in the Karoo, as is applied in shale gas fracking processes, could trigger significant seismic action in the region’s existing faults.

“Some locations which undergo shale gas development don’t see very much seismicity, and there is a catalog of things which need to be present for [seismicity] to be something that you would particularly worry about,” Sloan said.

For instance, if faults are only within the crystalline basement and therefore separated from the sedimentary layers where the fracking occurs, then it’s not likely they’ll be reactivated, because there’s no way for the fracking fluid to get down to the fault zone itself. Another factor, Sloan added, is that for significant earthquakes to occur, large faults that are already critically stressed need to be present in the region undergoing fracking.

The new study showed that both of these conditions may be met in the Karoo: Microseismicity does extend to the depths at which the carbonaceous shale is present. And this microseismicity is occurring on a reasonably extensive structure with a similar orientation to larger earthquakes that have already occurred in the region.

However, Sloan stressed, this isn’t a cause for immediate panic.

“I don’t want to be too alarmist; the size of the structure revealed by the microseismicity is not huge, and so we do not have evidence to expect an earthquake much larger than the damaging historical earthquakes that we have already seen in the wider region,” he said. “Globally, large earthquakes triggered by fracking (rather than associated deep wastewater exposure) are very rare, but the study suggests the necessary preconditions are present. And so the possibility needs to be considered and monitored carefully.”

Not Unique

Raymond Durrheim, a geoscientist and the South African Research Chair in Exploration, Earthquake and Mining Seismology at the University of the Witwatersrand, and who also examined the Ph.D. thesis on which the new study is based, said no area is perfectly seismically quiet.

“We know the way seismicity works in this whole area of southern Africa is that swarms occur,” he said. “They’ll last for years or even decades, and then they’ll die away. This is not a unique occurrence.”

This study was “useful,” though, Durrheim added, especially with the possibility of shale gas development in the Karoo. “It’s very important that we understand this because we know that when you inject fluid under high pressure, there’s always a chance you could trigger an earthquake,” he said, noting examples of fluid injection triggering earthquakes in places such as Canada. “It’s always a risk.”

To mitigate risks, Sloan suggested it would be useful to have a much denser network of seismometers within this region of South Africa.

—Ray Mwareya (@RMwareya), Science Writer

Citation: Mwareya, R. (2026), A swarm of earthquakes in South Africa’s Karoo Basin poses questions for oil and gas development, Eos, 107, https://doi.org/10.1029/2026EO260159. Published on 20 May 2026. Text © 2026. 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: Water Resources Research

Evapotranspiration is a critical link between water, energy, and carbon. Scientists need to understand it well to accurately predict weather, droughts, streamflows, and even carbon emissions.

Eddy covariance towers, which measure changes in the atmosphere, are one of the primary ways that scientists measure evapotranspiration in an ecosystem. But these measurements often have a problem with energy imbalance, in which the measured fluxes of sensible heat and latent heat add up to less than they should. (Sensible heat refers to measurable temperature changes occurring via conduction or convection, whereas latent heat refers to water in the atmosphere changing phases.) There’s something missing—up to 30% of the system’s energy—in the math, and that can cause problems for later uses of the measurements, from forecasts to climate policies.

Scientists can adjust evapotranspiration measurements to try to correct for this problem, but a commonly used method to do so assumes that the Bowen ratio, or the ratio between sensible and latent heat, remains constant. However, this assumption may be flawed.

Raghav and Kumar present a new way of tackling this old problem without making assumptions about the Bowen ratio. It’s based on water use efficiency, which is how effectively plants use water to produce biomass.

The method first uses a suite of data from an eddy covariance tower to estimate evapotranspiration and energy balance through time. Then it derives the underlying water use efficiency potential while accounting for the influence of atmospheric dryness. In general, for a given vegetation type, this potential underlying efficiency is considered to be relatively stable over a growing season. The statistically smoothed potential underlying water use efficiencies is then compared to reference values derived during periods when the energy balance is well constrained. The ratio of the two is then used to correct evapotranspiration.

The new method is more consistent and more tied to the physics of plant physiology than current methods when results from each are compared, the authors found.

The new method is appropriate for use with any eddy covariance tower location or dataset because the authors used data from more than 250 towers around the world, in a range of ecosystem and climate types, to build their approach. However, they add, it may be less reliable in environments where evaporation dominates transpiration, such as wetlands. Nevertheless, the authors say, this work marks an important advance in measuring evapotranspiration, with broad implications for water management, agriculture, and adapting to climate extremes and drought. (Water Resources Research, https://doi.org/10.1029/2025WR042766, 2026)

—Rebecca Dzombak (@rdzombak.bsky.social), Science Writer

Citation: Dzombak, R. (2026), Improving eddy tower evapotranspiration estimates, Eos, 107, https://doi.org/10.1029/2026EO260163. Published on 20 May 2026. Text © 2026. AGU. CC BY-NC-ND 3.0
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Tiny saltwater channels have a big influence on sea ice.

Sea ice typically includes pockets or channels of brine that allow salt water to flow vertically through the ice. When those channels align neatly, they need to make up only about 5% of the ice volume before the water can flow. But in more disordered, granular ice, salt water starts to flow only when the brine channels take up more space—roughly 10% of the ice volume, according to a new study published in Scientific Reports.

“If we’re trying to find predictive models about how these ice cores are responding under climate change, it’s going to be necessary to take into account these structural and microstructural conditions.”

This higher threshold could slow the drainage of surface melt ponds, as well as the transport of nutrients to microbial communities inside the ice.

“If we’re trying to find predictive models about how these ice cores are responding under climate change, it’s going to be necessary to take into account these structural and microstructural conditions,” said Stephen Ackley, a sea ice researcher at the University of Texas at San Antonio who was not involved in the study.

Disorderly Constructs

As seawater freezes, it forms a mixture of ice crystals and brine. In calm conditions, the ice slowly grows into long, parallel crystals separated by orderly brine channels. This columnar sea ice is common in the Arctic, and its properties have been widely used in sea ice models.

But in choppy waves or when the ice’s snow-covered surface floods and refreezes, new ice can’t grow into these ordered columns. Instead, it forms small, randomly oriented grains separated by more complex pores containing brine and gases. Called granular ice, this form is more common in Antarctica but is becoming increasingly prevalent in the Arctic as temperatures rise and ice cover thins.

“It’s the sequel we’ve been waiting decades for.”

In 1998, University of Utah mathematician Kenneth Golden established the first estimate of the point at which the brine channels are connected enough to allow water to flow in columnar ice, called the percolation threshold. The new work, also led by Golden, extends a similar analysis to granular sea ice.

“It’s the sequel we’ve been waiting decades for,” said Don Perovich, a sea ice researcher at Dartmouth who was not involved in the new work.

To quantify the percolation threshold for granular ice, Golden and his colleagues collected sea ice samples during two expeditions off the eastern coast of Antarctica in 2007 and 2012. They measured how quickly water moved through the brine channels in the ice. After the 2012 expedition, they also mapped the arrangement of ice crystals within the ice blocks to correlate those permeability measurements with the microscale structure of the ice.

Most climate models are based on the assumption that the microstructure of sea ice is organized into columns, like those in the image on the left. But new research shows that granular ice, as seen on the right, is growing more common in the Arctic, which could affect climate modeling. Credit: Golden et al., 2026, https://doi.org/10.1038/s41598-026-41706-w, CC BY-NC-ND 4.0

The finding that in granular ice, about twice as much of the ice volume needs to be brine for water to flow compared to columnar ice suggests that brine channels within granular ice are much less interconnected.

With the higher threshold, “you have to reassess all these models, anything that relies on fluid flow through sea ice,” if granular ice is present, said Golden. Granular ice will require warmer or saltier conditions to leave enough brine in the ice structure to meet the percolation threshold and allow water to flow vertically.

Researchers extracted blocks of ice in Antarctica with a chainsaw and poured dyed salt water on top. In this way, they observed how quickly the fluid descended through the ice. Credit: Kenneth Golden

For example, the new value could influence models of how meltwater ponds behave atop an underlying ice sheet. If meltwater ponds form above a base of granular sea ice, those ponds will require warmer temperatures before they start draining than melt ponds on columnar ice will.

If these melt ponds remain on the surface longer waiting for those warmer temperatures, they could lower the albedo, or reflectivity, of the ice sheet. That could cause the ice sheet to absorb more heat, leading to a feedback loop that could accelerate melting.

The higher percolation threshold could also affect algae that lives within the ice. Ice algae make up an important food source for krill and crustaceans, which in turn become food for fish, penguins, and whales. Algae rely on water flowing through the ice to deliver nutrients. Because granular ice requires warmer temperatures for that flow to start, it could affect the depth at which algae can live inside the ice, Golden said.

Percolation Consideration

Still, experts say more data are needed to establish percolation thresholds across both Arctic and Antarctic ice. The size of the grains in granular ice can vary substantially at different temperatures, under different formation conditions, and between the poles. Larger grains could lower the percolation threshold, allowing water to flow even when the ice contains much less than 10% brine by volume, said Sønke Maus, a scientist studying ice microstructure at the Norwegian University of Science and Technology who was not involved in the study.

“The data that we have at the moment for the granular sea ice is sparse,” Maus said. “You need a big campaign to collect such data.”

Golden said that in future work he also plans to develop models to compute the electromagnetic properties of both columnar and granular sea ice. Knowing these properties can help scientists determine the thickness and age of an ice sheet from satellite data.

—Skyler Ware (@skylerdware), Science Writer

Citation: Ware, S. (2026), Changes in sea ice microstructure could affect climate models, Eos, 107, https://doi.org/10.1029/2026EO260164. Published on 20 May 2026. Text © 2026. The authors. CC BY-NC-ND 3.0
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In British Columbia a CAN$115 million project is almost complete to mitigate the risk posed by debris flows to the town of Squamish.

Upstream of the town of Squamish in British Columbia, Canada, an extraordinary project is underway to mitigate the risk of debris flows. Known as the Cheekeye Debris Barrier Project, the scheme involves the construction of a concrete barrier that is 24 metres high across the Cheekeye Fan, designed to catch debris flows with a volume up to 2.4 million cubic metres of debris.

The project is almost complete, with hand-over expected in the summer of this year. There is an excellent article about the project on The Tyee website, which includes some very interesting images of the structure. The estimated cost of the project is around CAN$115 million. The location of the Cheekeye Debris Barrier Project is [49.79417, 1123.10878]. This is a render of the final form of the barrier (but take a look at the images of the almost completed structure too):

A render of the completed Cheekeye Debris Barrier. Image via the District of Squamish.

This is a fascinating project that makes a great case study for teaching, not least because both the detailed design considerations and the regulatory process for approving the programme are available in detail.

In terms of the detailed design considerations, there is an excellent open access paper in the Canadian Geotechnical Journal (Lesueur et al. 2025) that provides a very comprehensive analysis of the estimation of the potential volume and mobility of the debris flows on the Cheekeye Fan, and of the considerations that went into the final deisign of the structure.

In terms of the approval process, the District of Squamish has an online archive of documents and Council minutes that extends back to 2003.

I would highlight the challenges around determining the optimal size of a barrier of this type. The team has been balancing risk against cost, following the principle as outlined in Lesueur et al. (2025):-

“The local government specifies that tolerable debris-flow risks be reduced “as low as reasonably practicable” (ALARP), defined in this project as the point where the cost of additional mitigation measures is grossly disproportionate to the benefits gained.”

Thus, the barrier is not designed to stop the maximum credible debris flow, which is 5.5 million cubic metres (more than double the design event). This is pragmatic engineering at its best, and the Cheekeye Debris Barrier Project provides the level of detail that allows the decision-making process to be fully understood.

Reference

LeSueur, P. et al. 2026. Risk-informed design of debris-flow mitigation at Cheekeye Fan. Canadian Geotechnical Journal. 62: 1-16. https://doi.org/10.1139/cgj-2023-0008

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body {background-color: #D2D1D5;} Research & Developments is a blog for brief updates that provide context for the flurry of news that impacts science and scientists today.

The Intergovernmental Panel on Climate Change (IPCC), the United Nations body whose mission is to “provide governments at all levels with scientific information that they can use to develop climate policies” will likely update the emissions and land use scenarios used in the models it considers in its bellwether assessment reports.

The IPCC has used these scenarios, known as Shared Socioeconomic Pathways (SSPs) or Representative Concentration Pathways (RCPs), in its two most recent assessment reports (AR), AR5 released in 2014 and AR6 released in 2023. The upcoming AR7 will be informed by a new set of scenarios, as described in a paper published last month in Geoscientific Model Development.

The paper is drawing widespread attention—both within the scientific community and in wider discourse—for its statement regarding one current scenario that has become familiar to anyone following climate science and policy. The scientists said the emissions levels associated with the most extreme, worst-case scenario, SSP5-8.5 (and its predecessor, RCP8.5), “have become implausible.”

 
Related

•  On the death of RCP8.5, from The Climate Brink
•  Read the study: The Scenario Model Intercomparison Project for CMIP7
•  Scientists now say this worst-case climate scenario is ‘implausible.’ Here’s what it means.
 

Even President Donald Trump weighed in with a post on Truth Social on 17 May, where he wrote “GOOD RIDDANCE,” and “the United Nations TOP Climate Committee just admitted that its own projections (RCP8.5) were WRONG! WRONG! WRONG!”

But as scientists have pointed out for years, RCP8.5 was never meant to represent a likely emissions scenario or a forecast of humanity’s future. Some scientists questioned whether it’s even possible for RCP8.5 to play out in real life. 

RCP8.5 is one of four hypothetical emissions scenarios developed in 2011 for climate modeling experiments. When RCP8.5 was created, it was meant to represent a “very high baseline emission scenario” that would warm the world nearly 5°C (9°F) compared with preindustrial temperatures by 2100. Parallel scenarios (SSPs) were presented in 2017. SSP5-8.5 is the worst-case scenario in that framework, representing a world in which fossil fuels are widely exploited and more of the world adopts energy-intensive lifestyles alongside the warming projected by RCP8.5. 

“The scenarios we create today are different than the scenarios we created 15 years ago, because the world is different today than 15 years ago.”

The authors of the new paper wrote that “trends in the costs of renewables, the emergence of climate policy and recent emissions trends” justify the implausibility of the highest-emissions scenarios such as RCP8.5 and SSP5-8.5. 

For scientists, the idea of dropping these scenarios is neither new nor controversial. As three climate scientists (Zeke Hausfather of Berkeley Earth, Glen Peters of the CICERO Center for International Climate Research, and Piers Forster at the University of Leeds) wrote in a blog post: “[RCP8.5] was never a likely outcome even in a world that did not address climate change; rather it was always intended to represent a worst case scenario that pushed fossil fuel expansion to the max.”

The new scenarios presented in Geoscientific Model Development include a high-emissions scenario in which clean energy policy is rolled back, and the world warms about 3.5°C (6.3°F) by 2100—still a level at which humanity can expect very severe impacts, from worsening weather extremes to rapidly rising sea levels.

The IPCC’s likely elimination of RCP8.5, even if it was never a plausible scenario, is a small sign of improvement in global climate change mitigation efforts, Hausfather, Peters, and Forster wrote: “Rapid declines in clean energy costs have bent the curve of future emissions downward, with new scenarios designed to reflect current policies notably lower than most baseline scenarios in the literature.”

“Of course, we still have a long way to go to get emissions down to (net) zero and stabilize global temperatures,” they noted.

The new paper captures the difficult road ahead for climate action: The new scenarios are based on a reduced projection for the increase in emissions, not for the overall amount of emissions—those are still increasing. Unlike before, none of the new emissions scenarios keep the world below 1.5°C (2.7°F) of warming, the limit originally set by the Paris Agreement in 2016. That’s no surprise to scientists, who suggest Earth is already in the 20-year period in which warming will formally surpass this benchmark. 

“The scenarios we create today are different than the scenarios we created 15 years ago, because the world is different today than 15 years ago,” Hausfather told the Washington Post.

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

These updates are made possible through information from the scientific community. Do you have a story about science or scientists? Send us a tip at eos@agu.org. Text © 2026. AGU. CC BY-NC-ND 3.0
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Months after wildfires eliminate vegetation that holds hillside sediment together, debris flows—destructive landslides that carry bulky material down once-stable slopes—can devastate infrastructure, taking out roads and buildings in their wake.

Though the U.S. Geological Survey (USGS) creates hazard predictions used to warn communities of the risk of these postfire debris flows, those predictions haven’t fully considered how recovering vegetation reduces risk over time—until now.

A new study published in Geosphere presents a new way to calculate postfire debris flow risk that takes vegetation recovery into account. The USGS will begin using the new method this wildfire season to create more accurate maps of debris flow hazard in the years after a fire.

“I’m so appreciative that the focus on how the debris flow hazard changes over time after fire is being addressed,” said Nancy Calhoun, a geologist and postwildfire debris flow program manager at the Washington Geological Survey who was not involved in the new study. Calhoun said she relies on the USGS hazard assessments for virtually everything her job requires.

“We’re glad to have a way that we can help our partners moderate those situations where the hazard has decreased,” said Andrew Graber, a geologist at the USGS Landslide Hazards Program and lead author of the new study.

Assessing Hazard, Again

After a wildfire, the USGS creates hazard maps that incorporate information about soil type, steepness, and burn severity (how much vegetation has been lost) to show where the risk of a debris flow may be elevated.

Then, the agency distributes this guidance to the National Weather Service, which uses it to set rainfall thresholds: levels of rainfall at which a debris flow becomes likely. State, county, and city agencies use those rainfall thresholds to issue warnings or take action when rainfall is imminent, for example, by closing highways or triggering evacuations.

“That left us with some uncertainty when we started to get further away in time from the fire.”

The methods used to create the USGS maps, however, historically relied on a snapshot of the burned area taken just after the fire, and the maps weren’t updated to reflect conditions as vegetation grew back and began holding soil in place again.

That led to situations where public safety decisions were made on the basis of outdated maps and rainfall thresholds. For example, concern over debris flows after the 2020 Grizzly Creek Fire in Colorado led to several closures of Interstate 70 in 2022, but the debris flows never happened.

“What [the original assessments] didn’t capture is how the vegetation came back,” Graber said. “That left us with some uncertainty when we started to get further away in time from the fire.”

Intense rainfall in July 2025 triggered a debris flow near Dayton, Wyo., in the 2024 Elk Fire burn area. Credit: USGS, Public Domain

To test an improved method for these hazard assessments, Graber and the research team incorporated satellite imagery of 12 burned areas that showed the degree of vegetation recovery right after the fire, 1 year after the fire, and 2 years after the fire. Then, they tested their new method by comparing its predictions to rainfall and debris flow data from the 12 burned areas.

The updated method better reflected what had actually happened after the fires, reducing the number of unnecessary warnings without missing real-world debris flows.

Risk Recalibration

The USGS plans to begin using their new workflow to create hazard maps for some higher-profile fires during the coming wildfire season.

“It’s a really important question: Are we still worried about this burn scar?”

That’s exciting for Calhoun. As part of her job, she’s in constant contact with emergency managers who periodically ask how worried they should be about debris flows in areas that burned years ago. “It’s a really important question: Are we still worried about this burn scar?” she said.

Right now, Calhoun has no data to point to in the years after a fire to give an updated answer to that question. Using the new method from Graber and the research team, she will.

“Because they’re using satellite [imagery] and repeatable quantitative methods to look at these burn scars over time, we’ll actually be able to say something useful and informed about vegetation recovery,” she said.

Having a deeper understanding of how debris flow risk evolves over time is especially important because debris flows themselves are becoming a greater risk to the public as a result of increasingly intense wildfires and rainstorms. In addition, more accurate assessments can reduce warning fatigue, which occurs when too many false alarms lead to people ignoring or opting out of alerts.

Graber hopes he and the USGS will continue to improve their methods for assessing debris flow hazards by collecting more debris flow data across the country and improving the underlying equation for hazard assessments so that it better reflects the unique conditions of different ecosystems in the United States. USGS researchers also published a new study in March presenting a method to generate maps of where debris flows might travel if they do occur.

“It’s a big year for USGS’s useful postfire products,” Calhoun said.

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

This news article is included in our ENGAGE resource for educators seeking science news for their classroom lessons. Browse all ENGAGE articles, and share with your fellow educators how you integrated the article into an activity in the comments section below.

Citation: van Deelen, G. (2026), A new approach can better predict debris flow hazards years after fires, Eos, 107, https://doi.org/10.1029/2026EO260160. Published on 19 May 2026. Text © 2026. AGU. CC BY-NC-ND 3.0
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Source: Geophysical Research Letters  

Real-time hydrologic forecasting predicts river level and flooding inundation by combining continuously updated rainfall measurements, river gauge readings, and weather forecasts. Most of these flood forecasting systems depend on human interpretation and adjustments, or a “forecasters-in-the-loop” approach, which pairs computer models with a human expert on flood dynamics and local conditions. In contrast, in a “forecasters-over-the-loop” system, humans supervise automated forecasts and intervene only if necessary.

Recently, artificial intelligence (AI) and machine learning (ML) have become more integrated into flood prediction, and many of these systems are faster at processing large datasets and learning complex patterns from historical records than traditional models alone. But these new technologies also come with limitations—AI and ML require extensive data and may struggle to capture extreme, rare events.

Even though ML and AI are often touted as the future of flood forecasting, most studies have tested this technology against models that provide historical simulations, not the real-time operational systems that would be used during a flood. These simplified models may lack local details or are tested at daily rather than hourly resolution. Their effectiveness may be overestimated. 

Tran et al. produced the first study comparing the performance of ML models to an actual flood forecasting system used at the California Nevada River Forecast Center (CNRFC) that uses professional forecasters and traditional hydrologic models. The study suggests that a forecasters-in-the-loop approach outperforms the ML models in several key ways, including streamflow predictions and flood event detection, because forecasters can recognize model errors and account for poor input data—actions models cannot take on their own.

The researchers used data gathered from CNRFC river stage forecasts across 50 California and Nevada locations between 2012 and 2022 and river condition lead times from 1 to 96 hours. Compared to the ML models, the Community Hydrologic Prediction System used at CNRFC generally performed better at predicting stream flow and flood peaks, especially with longer lead times. Though the ML models could perform better at very short lead times, their accuracy declined quickly. Though automated forecasting options may seem promising, they are not yet a suitable replacement for human expertise when it comes to protecting lives and livelihoods from damaging floods, the researchers say. (Geophysical Research Letters, https://doi.org/10.1029/2025GL118317, 2026)

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

Citation: Owen. R. (2026), Keeping humans in the loop improves flood forecasting, Eos, 107, https://doi.org/10.1029/2026EO260161. Published on 19 May 2026. Text © 2026. AGU. CC BY-NC-ND 3.0
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Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Journal of Geophysical Research: Earth Surface

Sediment transport shapes the Earth surface in different ways, by forming desert dunes and by sculpting the topography of rivers, but the physics of sediment transport initiation is still incompletely understood. For decades, models have generally assumed two basic entrainment mechanisms: a grain resting on the sediment bed is either lifted directly by fluid forces, or it is emitted from the soil indirectly, as product of a granular splash caused by the heavy impact of another grain.

However, recent breakthroughs in grain-based simulations and high-speed visualization have been offering a much clearer look at the processes that trigger grain motion. Insights from these recent advances have revealed a rather broad spectrum of indirect particle-particle and particle-fluid interactions driving entrainment, including the rearrangement of surface grains after splash and changes in near‐bed flow structure due to moving grains. These interactions exert non-local influences on transport thresholds, giving rise to a dynamic process known as collective particle entrainment—a mechanism that remains poorly understood at a fundamental level.

In a new study, Chartrand [2026] shows that collective particle entrainment is size-dependent: large grains interact primarily with their peers, while smaller grains are mobilized by both large and similar-sized particles. This distinction leads to divergent transport signatures, with a new stochastic model predicting temporally correlated motion for small grains and uncorrelated, white-noise entrainment statistics for larger particles.

Although theoretical modeling will be required to shed further light on the physics of collective entrainment, the author’s study is a step toward a quantitative model of sediment transport from a probabilistic perspective. Looking ahead, Chartrand’s ideas could now be extended to other environments, potentially transforming our understanding of entrainment in other contexts such as wind-blown transport and extraterrestrial atmospheric processes.

Citation: Chartrand, S. M. (2026). Collective particle entrainment explored with experimental data and coupled transfer functions. Journal of Geophysical Research: Earth Surface, 131, e2025JF008657. https://doi.org/10.1029/2025JF008657

—Eric Parteli, Associate Editor, JGR: Earth Surface

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Central Mongolia’s Hangay Mountains have long posed a conundrum. Rising 4 kilometers above sea level, the dome-shaped range plays a key role in shaping the region’s climate. But it couldn’t have formed in the same way as most equally tall mountain ranges.

“These mountains in central Mongolia are very far from any plate boundary, about 5,000 kilometers away from the Pacific margin,” said Pengfei Li, a geologist at the Chinese Academy of Sciences’ Guangzhou Institute of Geochemistry. “It’s very hard to understand why we have such a mountain range so far from the plate boundary.”

Li recently led research finding that geochemical evidence supports a compelling explanation of how these oddball mountains formed. The researchers proposed that at the site of the future mountains, a U-shaped bend in a tectonic plate led to an extra-thick lithosphere. A chunk of that heavy lithosphere eventually broke off and sunk into the mantle. Free of the extra weight, the crust then rebounded upward as the Hangay Mountains.

Bend and Snap

“It’s the first discovery of volcanism for this period.”

Tectonic plates are far from rigid. As they move above, below, and against each other, sections of the plates far from the boundary can develop curves and folds like a scrunched up tablecloth. Curved sections, called oroclines, are common around the world. At about 6,000 kilometers long, the Mongolian orocline is one of the longest, and the Hangay Mountains sit right at the curviest part of the orocline’s U shape.

Li and his colleagues suspected that the Hangays’ location along the orocline is no coincidence. During multiple field expeditions from 2018 through 2026, the researchers collected rock samples from several sites in the Hangay Mountains that showed signs of ancient volcanic activity. Uranium-lead dating of zircons within those samples showed that the area experienced volcanic activity in the early Cretaceous period 124–114 million years ago.

“When I saw the age, I was surprised,” Li said. “120 million years—no one had ever reported volcanoes [in Mongolia] during this period.…It’s the first discovery of volcanism for this period.”

The team also analyzed the samples for major and trace elements to determine the depth at which the rocks formed. Their geochemical analysis revealed that the rocks formed in the lithosphere 80 kilometers below the surface. They published these results in Geology in April.

It’s pretty odd that the rocks originated so deep, Li said, because the modern-day lithosphere is only 70 kilometers thick.

The team proposed that when the continental plate folded and created the Mongolian orocline 200 million years ago, the lithosphere bunched up and became thicker in the curve of the U shape. That thicker section of lithosphere, a root at least 80 kilometers thick, would have been unstable in the long term, Li explained.

The lithospheric root would have been too heavy to remain attached to the crust above for long, and a chunk of it would have eventually snapped off. When it sunk, or foundered, into the deep mantle, it would have melted and generated the volcanic activity recorded in the rocks the team studied. Free from the weight of that lithospheric root, the crust above would have rebounded into the dome-shaped mountain range visible today.

Complicated Yet Compelling

“Their story, though complicated, makes a great deal of sense and in a way provides affirmation of a prediction made some time ago regarding oroclines.”

“The story that [the researchers] have put together to explain the massive Hangay topographic ‘dome’ of central west Mongolia is a compelling one that spans more than the past 200 million years of Earth history,” said Stephen Johnston, a tectonics researcher at the University of Alberta in Canada who was not involved with this research. Past research into the Iberian orocline suggested that oroclines might lead to lithospheric thickening, and this explanation of the Hangay Mountains fits that narrative.

“Their story, though complicated, makes a great deal of sense and in a way provides affirmation of a prediction made some time ago regarding oroclines,” Johnston added.

Johnston said that the new explanation of how the Hangay Mountains formed makes him wonder why it took so long—80 million years—between when the orocline formed and when the lithospheric root sank.

“This seems a long time for a gravitationally unstable mantle root to have remained attached to the overlying crust,” he said. He hopes that future work can help determine whether this process has taken place at other oroclines around the world and has simply been overlooked or whether there is something special about the Mongolian orocline.

Li and his team have turned their attention to how the formation of the Hangay Mountains shaped the region’s ancient climate. Today, the towering mountain range prevents moist air from northern Mongolia from reaching the parched Gobi Desert in the south. They hope to connect how a process deep underground, like lithospheric foundering, affected the paleoclimate and, consequently, the region’s habitability.

“It’s very new to try to understand the Earth’s habitability from a deeper sense,” Li said.

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

This news article is included in our ENGAGE resource for educators seeking science news for their classroom lessons. Browse all ENGAGE articles, and share with your fellow educators how you integrated the article into an activity in the comments section below.

Citation: Cartier, K. M. S. (2026), Mongolian mountains rose when the crust bounced back, Eos, 107, https://doi.org/10.1029/2026EO260153. Published on 15 May 2026. Text © 2026. 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.

Since the beginning of the 20th century, global sea level has risen by about 20 centimeters (roughly 8 inches) [Fox-Kemper et al., 2021]. As a result, coastal and island communities around the world are experiencing more frequent high-tide flooding, worsening storm surges, and increasing damage to homes and infrastructure. In the United States, for example, human-caused sea level rise alone increased damages from 2012’s Hurricane Sandy by about $8 billion [Strauss et al., 2021].

The United States has long been a key member of the global climate research community. However, that role is now threatened.

Scientific understanding of the magnitudes and rates of sea level rise, of how they vary around the planet, and of why the ocean is rising is based on a body of rigorous research that, for decades, has tracked past and present sea levels and projected future rise.

The United States has long been a key member of the global climate research community, including in producing the wealth of sea level research that has informed countries, states, and communities of what lies ahead for their shorelines. However, that role is now threatened by the Trump administration’s attacks on the country’s scientific research enterprise broadly and on climate research especially.

Analysis of the evolution of sea level rise projection science [Garner et al., 2018] underscores both the country’s prominent past role in the field and how the ongoing attacks may undermine progress in our understanding of sea level change. It also points to the urgency of acting across multiple fronts to preserve scientific knowledge and prevent further harm to the capacity to measure and project how much and how fast rising seas will affect global coastlines.

Four Decades of Advancing Sea Level Science

By the late 1970s, scientists around the world had begun to recognize the growing threat that climate change posed to the Greenland and Antarctic ice sheets and the danger their melting presented to coastal regions [Mercer, 1978]. The first global mean sea level (GMSL) projections were published in 1982 [Gornitz et al., 1982], and the first planning-oriented sea level scenarios were published just a few years later [e.g., National Research Council, 1987].

Since 1982, 103 studies have produced GMSL projections [Garner et al., 2018]. About one third of the studies (33 in total), including the first five, were published by teams led by scientists at U.S. institutions (Figure 1). Thirty-three studies (some, but not all, of which were also led by U.S.-based scientists) have also benefited from U.S. federal funding, sometimes from multiple agencies (Figure 2), including the National Science Foundation (NSF; 16 studies), NASA (10 studies), NOAA (8 studies), the U.S. Department of Energy (DOE; 6 studies), the U.S. Department of Defense (3 studies), the U.S. Geological Survey (2 studies), and the EPA (2 studies).

Fig. 1. This time series shows the total number of sea level rise projection studies published each year from 1982 to 2025 (gray bars) and the number of studies each year that were led by scientists based at U.S. institutions (purple bars). The text at top left tabulates the total number of studies led by authors in each country or region listed. Fig. 2. The total number of sea level rise projection studies published each year from 1982 to 2025 is shown again here (gray bars), this time beside the number of studies each year that were supported by funding from various U.S. federal science agencies (stacked colored bars). Note that some studies were supported by more than one U.S. federal agency.

U.S. scientists have further played critical roles in developing GMSL projections for Intergovernmental Panel on Climate Change (IPCC) assessments. For example, chapters producing sea level projections for the IPCC Fifth Assessment Report [Church et al., 2013], the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate [Oppenheimer et al., 2019], and the IPCC Sixth Assessment Report (AR6) [Fox-Kemper et al., 2021] were all coled by U.S.-based scientists.

Meanwhile, U.S. funding has been essential to the IPCC, constituting more than 25% of the nearly $207 million invested globally in the organization from 1989 to 2024 [IPCC, 2025]. NASA also played a key role in making IPCC AR6 sea level projections more accessible and usable through the NASA/IPCC Sea Level Projection Tool [Kopp et al., 2023; Fox-Kemper et al., 2021; Garner et al., 2021], which supports local assessments of sea level change around the world and has about 400,000 users annually.

U.S. institutions have been vital in developing, hosting, and maintaining critical sea level datasets.

Beyond direct contributions of U.S. scientists and federal funding to the global scientific community’s sea level projection research, U.S. institutions have been vital in developing, hosting, and maintaining critical sea level datasets. For example, the University of Hawai‘i Sea Level Center is a crucial part of the Global Sea Level Observing System, operating a network of more than 90 tide gauge stations and supporting global real-time oceanographic operations and long-term climate studies. NASA satellite missions, including TOPEX/Poseidon and the Gravity Recovery and Climate Experiment (GRACE and GRACE-FO), have been instrumental in helping to measure changes in GMSL and ice sheets, providing new ways to assess the accuracy of global sea level projections [Törnqvist et al., 2025]. And the Sea Level Research Group at the University of Colorado has consistently processed such datasets, providing critical data access for the broader research community.

Pushed to a Precipice

Since January 2025, climate and sea level science in the United States has come under an unprecedented attack. Scientists have seen congressionally approved research funding revoked or frozen. Agencies like NASA, NOAA, and NSF have been stripped of physical resources, talented scientific experts, and independent advisory and governing boards. The Trump administration, in its fiscal year (FY) 2026 budget, sought debilitating funding cuts for federal scientific agencies, including proposed budget reductions of 24% for NASA, 27% for NOAA, 57% for NSF, and 55% for EPA. Although the scale of these cuts was reduced in the enacted FY2026 budget, the administration is pushing for similarly steep cuts in its FY2027 budget request.

In May 2025, NASA’s Goddard Institute for Space Studies, which produced the first global sea level projections [Gornitz et al., 1982], was evicted from its 49-year home, and efforts to undermine the institute have continued into 2026. Since December, the administration has advanced plans to dismantle the National Center for Atmospheric Research, which developed and maintains a host of climate datasets and resources, including the Community Earth System Model that is widely used to help generate GMSL projections. And in January 2026, the government announced it would withdraw from more than 60 international bodies, including the IPCC, as part of a broader move to pull back from international scientific cooperation.

Efforts to apply climate science in U.S. policy have been hindered not only by political polarization and proposed funding cuts but also by deliberate suppression of data and research.

Efforts to apply climate science in U.S. policy have been hindered not only by political polarization and proposed funding cuts but also by deliberate suppression of data and research. Broadly, the current U.S. administration has removed more than 2,000 datasets from federal platforms, and more specifically, it has systematically scrubbed climate-related content from agency websites. Such erasures disrupt public access to critical information and undermine scientific transparency.

Furthermore, the DOE published a report that without conducting any statistical analysis, denied the scientific evidence for sea level acceleration. It similarly claimed, without any analysis of the numerous sea level projection studies documented here, that sea level is “rising at a lower rate than predicted.” The EPA went further, falsely claiming that “aggregate sea level rise has been minimal.” In fact, the most recent IPCC sea level projections are in good agreement with observations [Törnqvist et al., 2025; Dessler and Kopp, 2025].

The U.S. scientific community now stands at a precipice. Efforts to dismantle federal scientific agencies and diminish research are eroding the United States’ foundational contributions to our knowledge of global change and sea level rise.

The Path to Preserving Critical Science

As we plummet toward a loss of data, expertise, and innovation, we face a future that would not only further damage the United States’ reputation for scientific excellence and transparency but also cripple the global sea level research community at a time when the risks from sea level rise are rapidly increasing [Fox-Kemper et al., 2021].

While some U.S.-based sea level scientists could move to countries more committed to climate science, there are not enough positions in the world nor enough mobility for the vast majority to relocate. Grassroots archiving efforts have helped preserve some critical datasets, but this is a temporary and often insufficient stopgap. An urgent need remains for resilient and transparent scientific infrastructure, so that U.S. taxpayer–funded research findings and datasets are, and remain, publicly accessible.

Historically, federally funded scientific initiatives have enjoyed strong support across the political spectrum in the United States.

Historically, federally funded scientific initiatives have enjoyed strong support across the political spectrum in the United States. However, the unprecedented hostility facing science in the country today has revealed that new institutional safeguards and legal protections to prevent political interference are critically needed.

Expanding collaborations between U.S. universities and private foundations and donors provides one potential route to providing some protection and improving long-term stability for sea level science data and initiatives. Climate Central’s Surging Seas project offers one model to emulate. However, philanthropic efforts are far from sufficient to preserve the U.S. scientific enterprise.

Another avenue to protect federally funded science from political pressure is through bipartisan legislation. Bills such as the Scientific Integrity Act (which aims to ensure that scientific findings are not influenced or altered by political pressure) and the Protect America’s Workforce Act (which aims to restore collective bargaining rights for unionized federal employees) represent such opportunities.

Yet the effectiveness of such legislative efforts hinges on the critical caveat that the people holding authority in government recognize and abide by enacted legislation. Under an executive who does not abide by the rule of law, such legislative efforts, even if they are passed successfully, will offer little actual protection. The path to preserving U.S. climate and sea level science, therefore, cannot be separated from the path to restoring the rule of law within the U.S. government.

Progressing on this front requires the scientific community to advocate for its priorities more vocally and to build coalitions that include both academics and the stakeholders who benefit from scientific climate projections. It also requires making use of tools and levers that many scientists are unaccustomed to, such as the court system. AGU and other institutions have modeled this approach over the past year, joining legal efforts to protect federal workers, for example, and speaking up against the dismantling of valued science agencies.

Restoring the rule of law also requires electoral organizing to reestablish Congress as an independent and coequal branch of government that wields, rather than abdicates, lawful oversight of administration officials and federal agencies.

Scientific understanding of sea level processes and projections of future changes inform local, national, and international decisionmaking and provide a pathway to resilience against the risks of rising coastal waters. Safeguarding the long-standing leadership, integrity, and continuity of U.S. climate and sea level science is both a national and global imperative—one that many scientists are already stepping up to support. Now we need the rest of the scientific community—and its allies in academia, philanthropy, industry, and the public—to join in.

Acknowledgments

The authors thank Amy Appollina and Jessica Slotter for their assistance in curating a database of global sea level rise projections.

References

Church, J. A., et al. (2013), Sea level change, in Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, edited by T. F. Stocker et al., pp. 1,137–1,216, Cambridge Univ. Press, Cambridge, U.K., https://doi.org/10.1017/CBO9781107415324.026.

Dessler, A., and R. E. Kopp (2025), Climate experts’ review of the DOE Climate Working Group Report, ESS Open Archive, https://doi.org/10.22541/ESSOAR.175745244.41950365/V2.

Fox-Kemper, B., et al. (2021), Ocean, cryosphere and sea level change, in Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, edited by V. Masson-Delmotte et al., pp. 1,211–1,362, Cambridge Univ. Press, Cambridge, U.K., https://doi.org/10.1017/9781009157896.011.

Garner, A. J., et al. (2018), Evolution of 21st century sea level rise projections, Earth’s Future, 6, 1,603–1,615, https://doi.org/10.1029/2018EF000991.

Garner, G. G., et al. (2021), IPCC AR6 Sea Level Projection Tool, NASA Sea Level Change Portal, sealevel.nasa.gov/data_tools/17.

Gornitz, V., S. Lebedeff, and J. Hansen (1982), Global sea level trend in the past century, Science, 215(4540), 1,611–1,614, https://doi.org/10.1126/science.215.4540.1611.

Intergovernmental Panel on Climate Change (IPCC) (2025), IPCC Trust Fund Programme and Budget, IPCC-LXII/Doc. 2, rev. 1, IPCC Secr., Geneva, Switzerland, apps.ipcc.ch/eventmanager/documents/88/180220250655-Doc.%202,%20Rev.1%20-%20IPCC%20Programme%20and%20Budget.pdf.

Kopp, R. E., et al. (2023), The Framework for Assessing Changes To Sea-level (FACTS) v1.0: A platform for characterizing parametric and structural uncertainty in future global, relative, and extreme sea-level change, Geosci. Model Dev., 16, 7,461–7,489, https://doi.org/10.5194/gmd-16-7461-2023.

Mercer, J. (1978), West Antarctic ice sheet and CO2 greenhouse effect: A threat of disaster, Nature, 271, 321–325, https://doi.org/10.1038/271321a0.

National Research Council (1987), Responding to Changes in Sea Level: Engineering Implications, Natl. Acad. Press, Washington, D.C.

Oppenheimer, M., et al. (2019), Sea level rise and implications for low-lying islands, coasts and communities, in IPCC Special Report on the Ocean and Cryosphere in a Changing Climate, edited by H.-O. Pörtner et al., pp. 321–445, Cambridge Univ. Press, Cambridge, U.K., https://doi.org/10.1017/9781009157964.006.

Strauss, B. H., et al. (2021), Economic damages from Hurricane Sandy attributable to sea level rise caused by anthropogenic climate change, Nat. Commun., 12, 2720, https://doi.org/10.1038/s41467-021-22838-1.

Törnqvist, T. E., et al. (2025), Evaluating IPCC projections of global sea-level change from the pre-satellite era, Earth’s Future, 13, e2025EF006533, https://doi.org/10.1029/2025EF006533.

Author Information

Andra J. Garner (garnera@rowan.edu), Department of Environmental Science, Rowan University, Glassboro, N.J.; Robert E. Kopp, Department of Earth and Planetary Sciences and Rutgers Climate and Energy Institute, Rutgers University, New Brunswick, N.J.; Gregory G. Garner, Glassboro, N.J.; Aimée B. A. Slangen, Department of Estuarine and Delta Systems, Royal Netherlands Institute for Sea Research, Yerseke; and Benjamin P. Horton, School of Energy and Environment, City University of Hong Kong

Citation: Garner, A. J., R. E. Kopp, G. G. Garner, A. B. A. Slangen, and B. P. Horton (2026), The global impact of losing U.S. sea level science, Eos, 107, https://doi.org/10.1029/2026EO260156. Published on 15 May 2026. This article does not represent the opinion of AGU, Eos, or any of its affiliates. It is solely the opinion of the author(s). Text © 2026. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Source: AGU Advances

Across the western United States, wildfires are increasing in size and intensity. As the climate continues to warm, more extreme wildfires will reshape landscapes and pose a growing risk to human health and natural ecosystems throughout the West.

Climate models, used to predict other effects of climate change, are unable to directly simulate wildfires. Instead, researchers link previously burned areas to climate variables such as temperature, precipitation, drought, and evaporation, then apply those relationships to future climate projections.

Many recent studies have connected higher vapor pressure deficit (VPD)—a measure of atmospheric dryness—to more area burned in previous fires. VPD increases as the temperature rises, so models that rely on it generally predict an increase in wildfire activity as the climate warms.

Cheng et al. raise questions about the role VPD plays in modeling wildfire, suggesting that VPD is a poor measure of fuel dryness at larger scales and overestimates potential burned areas under significant warming conditions. Instead, researchers suggest soil moisture could be a more reliable indicator of fuel dryness and lead to more moderate projections of wildfire increases.

The researchers looked at five forested ecoregions in the western states. Using the Western US MTBS-Interagency wildfire dataset from 1984 to 2020 combined with climate data (temperature, VPD, and soil moisture), the researchers analyzed drivers of the area burned from May through October. They connected this information with output from climate models to look at future burn potential.

VPD-based wildfire predictions increase sharply under warming conditions. These predictions showed that under 3°C of average global warming, 16 times as much land would burn by the end of the century, compared to historical levels. Under 4°C of warming, up to 66 times more land would burn by the end of the century. This “truly massive” increase, the authors say, would mean fires consuming vegetation almost as soon as it regrows.

Soil moisture, on the other hand, provides a more moderate, though still concerning, picture. Under the same warming scenarios, soil moisture changes would lead to an increase in burned area of only 2–3 times that of the historical period. The researchers argue that projections relying on VPD severely exaggerate wildfire risk. (AGU Advances, https://doi.org/10.1029/2026AV002350, 2026)

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

Citation: Owen, R. (2026), How much will western wildfires worsen under warming?, Eos, 107, https://doi.org/10.1029/2026EO260147. Published on 15 May 2026. Text © 2026. 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.

On 19 July 2025, intense, long duration rainfall triggered over 550 landslides in Sancheong, South Korea, killing at least 10 people.

On 19 July 2025, extremely heavy rainfall triggered multiple landslides in Sancheong, South Korea. This event has been described by a new paper (Nguyen et al. 2026) just published in the journal Landslides. The paper is behind a paywall, but this link should give you access at the time of writing.

The core of the affected area is at [35.4333, 127.9111] (as usual, Landslides provides the location in degrees minutes and seconds when digital degrees is so much more useful – a pet frustration of mine!). This is a Planet Labs image of a part of the area, captured before the event. The marker is at the coordinate noted above:-

Planet Labs image of a part of the area affected by landslides during heavy rainfall in Sancheong County, South Korea on 19 July 2025. Image copyright Planet Labs, used with permission. Image dated 10 July 2025.

And this is the same area after 19 July 2025:-

Planet Labs image of a part of the area affected by landslides during heavy rainfall in Sancheong County, South Korea on 19 July 2025. Image copyright Planet Labs, used with permission. Image dated 23 July 2025.

And here is a slider to allow a comparison:-

Images by Planet Labs.

Nguyen et al. (2026) have mapped 568 individual landslides triggered by this rainfall event, triggered by rainfall in the range of 498 – 619 mm over a c. 55 hour period. These landslides killed at least 10 people and caused damage to homes and infrastructure. It is estimated that the restoration costs are in the order of US$800 million.

In common with many other events of this type, the landslides are mainly shallow, translational failures in soil or regolith on steeper slopes. As I have frequently noted, such terrain is very susceptible to unusually intense rainfall events, which often trigger a cluster of landslides in close proximity. These often merge to form channelised debris flows. Nguyen et al. (2026) note however that their modelling indicates that it was a combination of the intensity of the rainfall and its duration that led to these failures.

As rainfall intensities increase due to climate change, we are seeing increasing numbers of these landslide clusters. I greatly welcome studies such as Nguyen et al. (2026) , which allow us to build understanding in each case.

Reference and acknowledgement

Nguyen, H.H.D., Song, C.H. & Kim, Y.T. 2026. Physically based data-driven analysis for large-scale investigation of the July 2025 rainfall-induced landslide in Sancheong, South Korea. Landslides. https://doi.org/10.1007/s10346-026-02778-x

Planet Team 20246. Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/

Return to The Landslide Blog homepage Text © 2026. 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.