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On a summer day not long ago, 10 people gathered to eat cheese in the name of science. They nibbled on small rounds of Cantal, a firm cow’s milk cheese historically produced in south central France, and evaluated more than 25 attributes spanning color, odor, taste, aroma, and texture. The tasting was just one component of a larger study on the effects of shifting cows’ diets from grass to corn because of industrialization and climate change. The new findings highlight the importance of maintaining at least some grass in cows’ diets.

“Their physiology and digestive tracts are made to digest grass.”

Cows, with their four stomach pouches, are evolutionarily primed to consume grass and extract all the nutrients possible from that roughage. “Cows are herbivores,” said Elisa Manzocchi, a dairy researcher at Agroscope in Posieux, Switzerland, who was not involved in the research. (Agroscope is a Swiss governmental organization devoted to agricultural research.) “Their physiology and digestive tracts are made to digest grass.”

But bovines around the world are increasingly being fed a corn-based diet as industrial-scale farming proliferates—it’s often easier, more efficient, and more scalable to feed cows from a trough rather than allow them to forage in a pasture.

Climate change is also driving that shift. Even in regions that have long turned cows out to green pastures, farmers are facing summertime grass shortages due to droughts. That’s true in Marcenat, the site of an experimental farm run by the National Research Institute for Agriculture, Food and Environment (INRAE), said Matthieu Bouchon, an animal husbandry scientist there. It’s hotter in the summer than it used to be, but there’s still a lot of spring rainfall, he said. “The conditions are perfect for corn cultivation.”

Seeing cornfields in Marcenat, a mountainous region in south central France at an elevation of 1,000 meters, is jarring, Bouchon said. “It’s not something we’re used to.”

Bouchon and his colleagues at INRAE, led by microbiologist Céline Delbès, recently investigated how changing a cow’s diet has a slew of trickle-down effects on the quantity, quality, nutritional value, and flavor of its milk and resultant cheese. Earlier work compared outcomes of grass- and corn-fed diets in cows, Manzocchi said, but this investigation is particularly thorough. “It’s one of the first studies where they looked at many parameters.”

Soil to Grass to Cow to Milk to Cheese

The team focused on 40 Prim’Holstein and Montbéliarde cows, dividing them into two groups: one fed a largely grass-based diet and the other fed a corn-based diet with some access to pasture grass. After 2 months, half of the cows in the first group were switched to a less grass-based diet, and half of the cows in the second group were entirely denied access to pasture grass. The result was a cohort of four bovine groups that for nearly three more months, ate roughly 75%, 50%, 25%, and 0% grazed grass, respectively.

Throughout the experiment, Delbès and her collaborators collected milk samples two times per week (the cows were milked twice per day), soil samples from the pasture grass, and even swabs from the cows’ udders. The goal was to better understand how a dietary shift induced by climate change translates into changes in the attributes of a herd’s milk and, ultimately, cheese. “There were a lot of things in this experiment,” Bouchon said.

The researchers enlisted the help of a cheese-making facility near the farm to produce small rounds of Cantal cheese, each weighing about half a kilogram, using milk from the cows in each of the four groups. The cheeses were aged for 9 weeks before being served to panelists trained in tasting Cantal-type cheeses.

Preserve the Grass

Consistent with previous findings, the researchers found that cheese made from milk from cows fed primarily grass were more flavorful and had higher levels of certain fatty acids compared with cheeses produced from cows primarily fed corn. However, cows fed diets with a higher proportion of grass also yielded less milk relative to the amount of food they consumed, the team noted.

Overall, Delbès and her collaborators found that the shift from a diet of 25% grazed grass to one of 0% grazed grass was more detrimental to a cheese’s nutritional and sensory qualities than the shift from a 75% grazed grass diet to a 50% grazed grass diet.

“It’s surprising that just a quarter of the diet can do so much [to affect] the sensory quality of the cheese.”

The finding suggests that maintaining at least a modicum of fresh grass is critical to ensuring quality cheese, Delbès said.

“It’s surprising that just a quarter of the diet can do so much [to affect] the sensory quality of the cheese,” Manzocchi said. But perhaps that finding should be reassuring to traditional cheese producers who might no longer be able to feed their herds a largely grass-based diet, she added. “Maybe it’s good news.”

Delbès and her team aren’t yet finished with their Prim’Holstein and Montbéliarde herds. Future work will focus on examining how microbes present in the soil and bedding areas of the cows, for example, are correlated with microbes present in the human gut after cheese is consumed.

—Katherine Kornei (@KatherineKornei), Science Writer

28 May 2025: This story has been updated to correct the location of the experimental farm.

Citation: Kornei, K. (2025), Cheese in the time of industrial farming and climate change, Eos, 106, https://doi.org/10.1029/2025EO250198. Published on 23 May 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Source: Geophysical Research Letters

Soil moisture is a key regulator of temperature and humidity, one that’s positioned to be affected substantially by climate change. But despite the importance of soil moisture, efforts to model it involve dozens of poorly constrained parameters, and different models tend to disagree about how soil moisture levels will change in a warming world.

Gallagher and McColl took a “radically simpler” approach and modeled soil moisture solely in terms of precipitation and net surface radiation. The model worked well when tested using both fifth-generation European Centre for Medium-Range Weather Forecasts atmospheric reanalysis (ERA5) and Coupled Model Intercomparison Project Phase 6 (CMIP6) climate datasets.

That’s surprising, the researchers say, because the simple model excludes measurements that much of the recent literature has focused on: vapor pressure deficit (the difference between the amount of moisture the air has the capacity to hold and the amount it is actually holding) and atmospheric carbon dioxide (CO2) levels. Both are expected to rise alongside greenhouse gas emissions.

The researchers suggest their model still works well because vapor pressure deficit is a poor measure of atmospheric demand for water; net surface radiation, which is included in the model, is a better measure. In regard to CO2, the researchers say that some prior studies have overestimated the role of the gas.

The simple model offers potential answers to two fundamental questions about soil moisture: (1) Why does soil moisture follow a W-shaped longitudinal profile, with high moisture at the equator and poles and low moisture in between, and (2) why does soil moisture increase with warmer temperatures in some locations but decrease in others?

The W-shaped profile may be caused by a combination of precipitation rates and radiation intensity. High precipitation near the equator dominates the model and causes high soil moisture. The midlatitudes and the poles both see moderate levels of precipitation. But the midlatitudes receive more intense radiation than the poles, which leads to comparatively dryer midlatitude soils.

As for the second question, the researchers suggest warming may have varying effects on soil moisture because warming can come with both increased precipitation, which raises soil moisture, and increased net surface radiation, which lowers soil moisture. These two variables balance each other out to different degrees at different locations, meaning that warming sometimes raises soil moisture and sometimes lowers it. (Geophysical Research Letters, https://doi.org/10.1029/2025GL115044, 2025)

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

Citation: Sidik, S. M. (2025), Simplicity may be the key to understanding soil moisture, Eos, 106, https://doi.org/10.1029/2025EO250197. Published on 23 May 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

A new international study led by researchers at Tulane University shows that the El Niño and La Niña climate patterns affect nearly half of the world's mangrove forests, underscoring the vulnerability of these vital coastal ecosystems to climatic shifts. Mangroves are shrubs or trees that grow in dense thickets mainly in coastal saline or brackish water.

SummaryGeological Carbon Storage (GCS) is one of the most viable climate-change mitigating net-negative CO2-emission technologies for large-scale CO2 sequestration. However, subsurface complexities and reservoir heterogeneity demand a systematic approach to uncertainty quantification to ensure both containment and conformance, as well as to optimize operations. As a step toward a Digital Twin for monitoring and control of underground storage, we introduce a new machine-learning-based data-assimilation framework validated on realistic numerical simulations. The proposed Digital Shadow combines Simulation-Based Inference (SBI) with a novel neural adaptation of a recently developed nonlinear ensemble filtering technique. To characterize the posterior distribution of CO2 plume states (saturation and pressure) conditioned on multimodal time-lapse data, consisting of imaged surface seismic and well-log data, a generic recursive scheme is employed, where neural networks are trained on simulated ensembles for the time-advanced state and observations. Once trained, the Digital Shadow infers the state as time-lapse field data become available. Unlike ensemble Kalman filtering, corrections to predicted states are computed via a learned nonlinear prior-to-posterior mapping that supports non-Gaussian statistics and nonlinear models for the dynamics and observations. Training and inference are facilitated by the combined use of conditional invertible neural networks and bespoke physics-based summary statistics. Starting with a probabilistic permeability model derived from a baseline seismic survey, the Digital Shadow is validated against unseen simulated ground-truth time-lapse data. Results show that injection-site-specific uncertainty in permeability can be incorporated into state uncertainty, and the highest reconstruction quality is achieved when conditioning on both seismic and wellbore data. Despite incomplete permeability knowledge, the Digital Shadow accurately tracks the subsurface state throughout a realistic CO2 injection project. This work establishes the first proof-of-concept for an uncertainty-aware, scalable Digital Shadow, laying the foundation for a Digital Twin to optimize underground storage operations.

SummaryThe Ecuadorian forearc, formed by the accretion of oceanic plateaus, island arcs, subduction of an aseismic ridge, records a history of long-lived subduction. The modern system includes subduction of the Carnegie Ridge and seamounts, young forearc coastal ranges, and translation of a forearc sliver from oblique subduction of the Nazca Plate beneath South America. The margin has experienced large megathrust earthquakes and exhibits slow-slip events and earthquake swarms. We present results from joint tomographic inversion of local earthquakes for 3D velocity structure and earthquake location. Our joint inversion uses seismic arrival-time data from local earthquakes recorded by permanent stations and dense seismic temporary networks deployed near the coast after the 2016 Mw 7.8 Pedernales megathrust rupture and across the entire northern forearc into the foothills of the Andes in 2021-2022. Our results show that seismicity distribution and megathrust rupture are controlled by inherited and modern structures in the upper plate forearc and subducting Nazca Plate. Forearc sedimentary basins observed as low-velocities (Vp < 5.8 km/s, Vs < 3.2 km/s) are dissected by forearc basement highs observed as fast velocities (Vp 6.6-7.2 km/s, Vs. 3.6-4.0 km/s). Localized deep depocenters adjacent to basement highs preserve older sedimentary sections beneath younger forearc deposits. Differences in velocity allow discrimination between oceanic plateau basement associated with the Piñón terrane beneath the forearc and accreted island arc terranes along the eastern forearc boundary with the Andes. Along the coast, basement velocities are consistent with a hydrated upper plate. We observe an apparent transient in Vp/Vs (higher to lower) in the upper plate after the 2016 megathrust rupture, representing a transient flux of fluids from the subducting slab into the upper plate triggered by the earthquake. We observe variable thickness of the subducting Nazca plate from ∼10 km north of the Carnegie Ridge reaching 20-25 km where the Carnegie Ridge subducts beneath the forearc. Lateral velocity variations in the subducting plate indicate heterogeneity along strike and dip associated with magmatic evolution of the ridge. High-velocity domains at depth correlate with seamounts and subducted relief along the Carnegie Ridge. A low-velocity zone marks the boundary between the subducting and overriding plates. The downdip termination of the Pedernales megathrust rupture coincides with structure of the Carnegie Ridge and along strike changes in the plate interface. The downdip edge of the rupture occurs where the low-velocity zone is absent, and the subducting Carnegie Ridge intersects the overlying mantle wedge. Earthquakes located with the joint inversion focus into tight clusters controlled by relief at the top of the subducting slab and basement structure in the overriding plate. Along the coast, seismicity shallows from south to north across the east-west striking Canandé Fault. South of the fault, seismicity locates predominantly within the subducting plate and plate interface. To the north, seismicity concentrates within the plate interface and upper plate. The northward shift in hypocenter depths and an offset in the eastern limit of thick subducting Nazca plate across the Canandé fault marks a significant transition in the forearc across the fault.

Understanding how Earth's climate has naturally fluctuated during the Holocene—the current geological epoch spanning the last 11,700 years—is crucial for contextualizing modern human-driven warming and improving future climate projections. However, the climate history of tropical Australasia has remained unclear, with scientists often divided over interpretations of paleoclimate records.

Earth's largest gold reserves are not kept inside Fort Knox, the United States Bullion Depository. In fact, they are hidden much deeper in the ground than one would expect. More than 99.999% of Earth's stores of gold and other precious metals lie buried under 3,000 km of solid rock, locked away within Earth's metallic core and far beyond the reaches of humankind.

Forests once hailed as reliable carbon sinks are rapidly becoming "super‑emitters" as record‑breaking wildfires sweep boreal, Amazonian, and Australian landscapes. Today's climate policies and voluntary carbon markets seldom account for the sharp rise in fire‑driven emissions.

Global warming will likely hinder our future ability to control ground-level ozone, a harmful air pollutant that is a primary component of smog, according to a new MIT study.

The upcoming Atlantic hurricane season will likely have above-normal activity, according to the annual outlook produced by NOAA.

NOAA issues an Atlantic hurricane season outlook each May, using computer models that consider current climate and ocean conditions.

“Everything is in place for an above-average season.”

The agency estimates that this year’s Atlantic hurricane season, which runs from 1 June to 30 November, will have up to 19 named storms and up to 10 hurricanes. Three to five of those hurricanes are projected to reach major hurricane strength (categories 3, 4, and 5).

Between 1991 and 2020, the Atlantic hurricane season featured seven hurricanes on average.

The report predicts a 60% chance of an above-normal season, a 30% chance of a near-normal season, and a 10% chance of a below-normal season.

“Everything is in place for an above-average season,” said Ken Graham, director of the National Weather Service, at a press conference held in Jefferson Parish, La. NOAA selected Jefferson Parish as the location for the announcement to commemorate the 20-year anniversary of Hurricane Katrina.

Above-average Atlantic Ocean temperatures will fuel an above-average Atlantic hurricane season, according to a NOAA report. Credit: NOAA NWS

The above-average activity forecasted by NOAA will be fueled by above-average temperatures in the Atlantic and Caribbean Sea, forecasts for weak wind conditions, and the potential for higher activity of this year’s West African Monsoon.

The NOAA predictions align with predictions from other institutions, including Colorado State University’s (CSU) Tropical Weather and Climate Research Group. CSU’s forecast predicted 9 hurricanes and 17 named storms for the 2025 season, with 4 of those storms predicted to reach major hurricane strength.

Scientists expect the El Niño–Southern Oscillation (ENSO), a climate phenomenon that affects how heat is stored in the oceans, to remain in a neutral condition or transition to La Niña conditions this summer. Such conditions lead to decreased wind shear, which slightly favors hurricane formation.

In 2024, El Niño conditions, along with human-caused climate change, fueled a spike in ocean temperatures that caused a destructive Atlantic hurricane season. Warming oceans fuel stronger hurricanes that bring more heavy rainfall and higher storm surge when they make landfall.

“It takes only one storm near you to make this an active season for you.”

The odds of El Niño developing this year as the hurricane season peaks are low—less than 15%, according to the latest NOAA prediction. While El Niño conditions tend to increase ocean temperatures, El Niño also creates wind shear that breaks up weather patterns, hindering hurricane intensification. If El Niño conditions do return by the fall, the likelihood of hurricane formation could drop. CSU plans to release an updated forecast on 11 June.

At the press conference, NOAA officials asked those in hurricane-prone areas to prepare for the busy season. “A community that is more informed and prepared will have a greater opportunity to rebound quickly from weather and climate related events,” said Cynthia Lee Sheng, president of Jefferson Parish.

Each year, the World Meteorological Organization selects a list of names for the season’s tropical storms. Credit: NOAA NWS

“It takes only one storm near you to make this an active season for you,” said Michael Bell, a meteorologist at CSU and author of the CSU outlook, in a statement.

The above-average season coincides with unprecedented staffing shortages due to layoffs and staff buyouts at NOAA and its National Weather Service (NWS), which issues hurricane and flood warnings and provides critical emergency information during storms. In a 2 May open letter, five former NWS directors said the agency “will have an impossible task” trying to continue its current level of services amid staff and funding cuts.

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

Citation: van Deelen, G. (2025), Busy hurricane season expected in 2025, Eos, 106, https://doi.org/10.1029/2025EO250200. Published on 22 May 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Ammonia released from penguin poop helps produce cloud-seeding aerosols in Antarctica, which can affect local climate by increasing cloud formation. The discovery came when scientists measured air downwind of two colonies of Adélie penguins on the tip of the Antarctic Peninsula.

Penguin poop emitted 100–1,000 times baseline levels of ammonia. New aerosol particles formed when that ammonia mixed with sulfur compounds from marine phytoplankton. The research was published in Communications Earth & Environment.

“This shows a deep connection between the natural ecosystem emissions and atmospheric processes, where emissions from both local seabird and penguin colonies and marine microbiology have a synergistic role that can impact clouds and climate,” said Matthew Boyer, a doctoral student in atmospheric science at the University of Helsinki in Finland and lead author of the study.

Strong Whiffs of Ammonia

Although only trace amounts of ammonia exist in Earth’s atmosphere, scientists have found that when it mixes with certain sulfur compounds it creates ultrafine particles (<0.1 micrometer in size). Those aerosols can grow into cloud condensation nuclei.

“Aerosol particles are necessary for cloud formation; liquid water will not condense to form cloud droplets without the presence of aerosol particles,” Boyer explained.

The presence of these aerosols is especially important in pristine environments such as Antarctica that have low background levels of cloud-forming particles.

“The new particle formation process doesn’t strictly need ammonia to proceed, but ammonia boosts the rate of the process considerably—up to 1,000 times faster,” Boyer said. Gases emitted from natural sources such as penguins and the ocean are an important source of aerosols in the region, he added.

But the extremely low concentrations of gaseous ammonia, combined with the remoteness of Antarctica, have made understanding this cloud formation pathway challenging.

To tackle this problem, the researchers set up atmospheric samplers on the ground near Argentina’s Marambio Station, located on Seymour Island near the northernmost tip of the Antarctic Peninsula. Two large colonies of Adélie penguins nested a few kilometers away, one with about 30,000 breeding pairs and another with roughly 15,000 penguin pairs, as well as 800 cormorant pairs.

Researchers put sensors near the main buildings at Marambio Station on Seymour Island. Credit: Lauriane Quéléver

From 10 January to 20 March 2023 (during austral summer), the team measured concentrations of ammonia, fine aerosol particles, and larger cloud condensation nuclei, as well as relative abundance of certain elements, cloud droplet distribution, and other atmospheric properties. By late February, the penguins left their breeding grounds and traveled to their wintering site, enabling the researchers to analyze the atmosphere with and without the birds present.

When wind blew air from the nesting grounds to the monitoring station, the team found that the penguin colonies emitted up to 13.5 parts per billion of ammonia, more than 1,000 times more than background levels without poop. However, when winds blew in from the sea, the Southern Ocean was a “negligible” source of ammonia.

“The footprint of ammonia emissions from penguins may cover more area of coastal Antarctica than indicated by the location of their colonies alone.”

Even after the penguins migrated, the poop they left behind continued to elevate ammonia to 100 times higher than background levels, which was the most surprising discovery for Boyer.

“This means that the footprint of ammonia emissions from penguins may cover more area of coastal Antarctica than indicated by the location of their colonies alone,” he said.

The team found that 30 times more aerosol particles formed when gaseous ammonia mixed with sulfuric gases released by marine phytoplankton. When that combination then mixed with dimethylamine gas, also emitted by penguin poop, aerosol formation increased 10,000-fold.

Gaseous ammonia lasts only a few hours in the atmosphere, but the aerosol particles it creates can survive for several days. Under the right wind conditions, those particles could travel out over the Southern Ocean and generate clouds where cloud condensation nuclei sources are limited.

Climate change threatens the survival of Adélie penguins, but the penguins also help shape their local atmosphere and climate. Credit: Matthew Boyer

The new results align with past research that examined the impact of Arctic seabirds on atmosphere and climate. They also agree with past laboratory and modeling studies of Antarctic cloud formation, which have been considered more reliable in the past than in situ measurements.

“Measuring ammonia on its own under normal circumstances can be tricky,” said Greg Wentworth, an atmospheric scientist with the government of Alberta in Canada who was not involved with the new research. “To do all the sophisticated measurements required to tease apart the details of new particle formation is remarkable, especially since they did this at the ends of the Earth!”

Penguin Feedback Loops

“How remarkable is it that emissions from penguin poop and phytoplankton can kick-start chemistry in the atmosphere that can alter clouds and affect climate?”

“This study provides the most compelling evidence to date that ammonia and sulfur compounds…are an important source of cloud condensation nuclei during summertime in Antarctica,” Wentworth added. “How remarkable is it that emissions from penguin poop and phytoplankton can kick-start chemistry in the atmosphere that can alter clouds and affect climate?”

The polar regions are experiencing dangerous levels of warming, and more cloud cover can help cool things down…sometimes. Higher concentrations of aerosol particles tend to create thicker, low-atmosphere clouds that are more reflective and can cool the surface, Boyer said. Thinner clouds high in the atmosphere tend to trap heat and warm the surface.

Understanding whether seabirds generate aerosols at a consistent, high-enough rate to cool local climate would require more atmospheric monitoring and climate modeling, he added.

A connection between penguins and their environment means that when one is threatened, both feel the impacts. As climate change warms the polar regions and endangers the species that live there, the loss of those species could reduce cloud cover and further accelerate warming.

“It’s important to understand how ecosystems, especially sensitive ones in remote regions, will respond to climate change,” Wentworth said. “It’s doubly important to understand those changes when components of those ecosystems also impact climate change.”

“The more we understand about specific processes that impact ecosystems and climate change, the better we can predict and adapt to change,” Wentworth said.

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

Citation: Cartier, K. M. S. (2025), Pungent penguin poop produces polar cloud particles, Eos, 106, https://doi.org/10.1029/2025EO250201. Published on 22 May 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Increasingly powerful AI models can make short-term weather forecasts with surprising accuracy. But neural networks only predict based on patterns from the past—what happens when the weather does something that's unprecedented in recorded history?

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

Early on 22 May, the U.S. House of Representatives passed a massive GOP-backed bill that seeks to push forward President Trump’s domestic policy agenda. Within the bill’s 1,082 pages are sweeping repeals of regulations that defend the environment, mitigate climate change, and protect public health.

 
Related

•  Here’s What’s in the GOP Megabill that’s Just Passed the House
•  House Republicans Strike a Bigger Blow Against Democrats’ Clean Energy Tax Credits
•  Get Involved: AGU Science Policy Action Center
 

In their place, the bill promotes fossil fuel production and burning; scales back safety net programs such as Medicaid and supplemental nutrition and assistance program (SNAP); rescinds funds and blocks plans for natural resource management; reforms student loan lending and repayment; advances aggressive anti-immigration policies; and funds tax cuts for the ultra-wealthy.

Some of the Earth science-related provisions in the bill would:

• Rescind unused funding allocated to maintain facilities for NOAA and the National Marine Sanctuary;
• Bring an earlier end to clean energy tax credits and subsidies provided under the Inflation Reduction Act;
• Repeal rules related to vehicles’ greenhouse gas emissions and vehicle fuel economy standards;
• Rescind Clean Air Act funds related to environmental and climate justice, as well as other funds meant to reduce or regulate greenhouse gas emissions, improve air quality at schools, and require businesses to publicly report their carbon footprints;
• Rescind funds that would have invested in coastal communities to build climate resilience, and that helped U.S. Forest Service and the National Park Service protect federal land;
• Interfere with several states’ plans to manage their own resources, including in Wyoming, Montana, North Dakota, and along the Colorado River;
• Enhance timber production and logging on National Forest Service lands and allow mineral mining in Alaska to move forward.

The bill passed by a 1-vote margin in the House (215-214). It now moves to the Senate, where it is expected to face additional opposition from the Democratic Party and GOP deficit hawks.

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

These updates are made possible through information from the scientific community. Do you have a story about how changes in law or policy are affecting scientists or research? Send us a tip at eos@agu.org. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Eos is welcoming June (that’s National Ocean Month in the United States) with a rhyming tradition of something old, something new, something borrowed, and something blue.

Our “something old” is the spectacularly upgraded, 60-years-young Alvin, probably the world’s most famous human-occupied deep-sea submersible. Alvin can now dive to 6,500 meters—a full 2,000 meters more than its previous limit—and explore 99% of the seafloor. Read all about it in “An Upgraded Alvin Puts New Ocean Depths Within Reach.”

“Something new” is the two-vehicle fleet of midsize remotely operated vehicles (mROVs) that will join the U.S. Academic Research Fleet. The mROVs will “fill the niche between large, work-class vehicles such as Jason and small vehicles used primarily for observation.”

“Something borrowed” is time on the JOIDES Resolution (JR), the legendary research vessel that retired last year. In this month’s opinion, three early-career researchers share what they learned, from sediment cores to transdisciplinary collaboration, as part of the JR’s final voyage.

Something blue? That’s the deep blue sea, of course. Dive in!

—Caryl-Sue Micalizio, Editor in Chief

Citation: Micalizio, C.-S. (2025), Submerged in science, Eos, 106, https://doi.org/10.1029/2025EO250199. Published on 22 June 2025. Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

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

Large earthquakes generally nucleate at the base of seismogenic crust, between 10 and 15 kilometers deep, where the interplay between brittle and plastic deformation is complex due to the combined effects of pressure and temperature at these depths. In consequence, how earthquake fractures may nucleate under these conditions remains relatively enigmatic.

Yeo et al. [2025] present evidence of the formation of nanocavities under these conditions from the geological rock record. The studied rocks are ultramylonites, i.e. rocks of ultrafine grainsize, brought back from an outcrop of the Median Tectonic Line, the largest on‐land fault (>1,000 kilometers along strike) of Japan. Ultramylonites generally deform via intracrystalline plasticity and grain boundary sliding. Yet, the ones presented by the authors have also kept records of the formation of nanoscale cavities, formed at the base of seismogenic zone. When the density of these cavities becomes critical, they may coalesce leading to the formation of a ductile fracture, a phenomenon well-known in metallurgy. The authors observe that these ductile fractures, generally filled with secondary hydrous minerals such as chlorite, were ubiquitous along the entire length of the ultramylonite exposure, spanning over 7 kilometers.

Ductile fractures, observed along one the world’s most active shear zone highlight the importance of fracturing due to ductile deformation in the source region of large earthquakes. In such way, nano-scale cavities generated 15 kilometers deep may well be the initial nucleation point of large continental earthquakes.

Citation: Yeo, T., Shigematsu, N., Wallis, S. R., Kobayashi, K., Zhang, C., & Ujiie, K. (2025). Evolution of nanocavities to ductile fractures in crustal-scale faults at the base of the seismogenic zone. Journal of Geophysical Research: Solid Earth, 130, e2024JB029868. https://doi.org/10.1029/2024JB029868

—Alexandre Schubnel, Editor-in-Chief, JGR: Solid Earth

Text © 2025. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

Author(s): J. Candy, A. Dudkovskaia, and E. A. Belli

Using a wave-number-advection algorithm, we describe a method to add global profile curvature terms to the local gyrokinetic equations. This approach enables a high-precision global simulation capability without sacrificing the efficiency and spectral accuracy of local simulations. Preliminary numer…

[Phys. Rev. E 111, L053201] Published Thu May 22, 2025

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

On 21 May 2025, a family lost their home to a quick clay landslide in Sainte Monique, to the northeast of Montreal in Quebec, Canada.

Radio-Canada Info has posted to Youtube some excellent drone footage of the aftermath of this landslide:-

Meanwhile, The Globe and Mail has a good account of the event:–

“Andre Lemire said he was woken up early Wednesday morning by his partner, who had heard ominous noises outside the farm where they live in Sainte-Monique, Que.

“They left the home, and when he looked back he saw the ground open up, swallowing up the land and his neighbour’s house.

“The path disappeared behind me,” Lemire said in an interview.

“A major landslide swept away a home and part of a road northeast of Montreal at around 6 a.m. Wednesday, leaving a gaping hole in the land but no injuries. The landslide – estimated at 760 metres long and 150 wide – was described by an expert as one of the biggest the province has seen in recent years.”

This is a classic quick clay landslide, a well-known hazard in this part of Canada. The location of the landslide is [46.13890, -72.49700] – this is a Google Earth image of the site:-

Google Earth image of the site of the 21 May 2025 quick clay landslide at Sainte Monique in Canada.

It is interesting that the location is at the apex of the river meander, where erosion is intense. Google Street View shows that this is an area with a low slope angle, which is normal in quick clay landslides:-

Google Street View image of the site of the 21 May 2025 quick clay landslide at Sainte Monique in Canada.

The dramatic nature of landslides of this type can be seen in this still from the Youtube footage:-

A drone image of the site of the 21 May 2025 quick clay landslide at Sainte Monique in Canada. Still from a drobe video posted to Youtube by Radio-Canada Info.

It is likely that this area sits on the Leda Clay, a material that is prone to failures of this type. This landslide is reminiscent of the 10 May 2010 landslide at St Jude, which tragically killed four people. It is fortunate that at Sainte Monique the owners of the house were able to escape.

Thanks to loyal readers George Heah and Maurice Lamontagne for highlighting this event to me.

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SummaryCharacterizing the hydraulic and geomechanical behavior of crystalline rocks is of importance for a wide range of geological and engineering applications. Geophysical methods in general and seismic techniques in particular are extensively used for these purposes due to their cost-effective and non-invasive nature. In this study, we combine legacy seismic observations to analyze the seismic attenuation and velocity characteristics in macroscopically intact regions of the granodiorite hosting the underground Grimsel Test Site in the central Swiss Alps across a wide frequency range. By focusing on data from the intact rock volumes we aim to assess the importance of viscoelastic effects in the crystalline host rock. Our results show consistent frequency-dependent characteristics of the seismic velocity and attenuation. We illustrate that it is possible to fit a microcrack-related wave-induced fluid flow (WIFF) model to the data over the entire frequency spectrum under examination extending from the Hertz to the Megahertz range. Utilizing complementary pressure-dependent ultrasonic measurements, we infer microcrack properties that validate the key parameters of the proposed WIFF model. These findings deepen our understanding of dispersion and attenuation mechanisms at the microscopic scale in crystalline environments, which is critical for a coherent analysis and integration of data from different seismic techniques as well as for the identification of dispersion and attenuation effects related to macroscale heterogeneities, such as fractures and faults.

In a first, researchers from NASA and Virginia Tech have used satellite data to measure the height and speed of potentially hazardous flood waves traveling down U.S. rivers. The three waves they tracked were likely caused by extreme rainfall and by a loosened ice jam.

Lake Tahoe is experiencing large-scale shifts in ultraviolet radiation (UV) as climate change intensifies wet and dry extremes in the region. That is according to a study led by the University of California, Davis's Tahoe Environmental Research Center and co-leading collaborator Miami University in Ohio.