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Source: Journal of Geophysical Research: Oceans

In shallow coastal waters around the world, mud and other fine-grained sediments such as clay and silt form critical blue carbon sinks. Offshore infrastructure such as wind turbines and oil platforms, as well as fishing practices such as bottom trawling, can have major effects on the seafloor. So knowing the locations of these mud-rich sedimentary deposits is key to making coastal management decisions.

Ward et al. set out to map three mud depocenters—large offshore muddy deposits—in the coastal waters around Great Britain and Ireland. The mud-rich areas they selected were Fladen Ground, northeast of Scotland in the North Sea; the Celtic Deep, southeast of Ireland; and the Western Irish Sea Mud Belt, in the Irish Sea.

Their location at the bottom of the ocean makes these muddy deposits notoriously difficult to map. Furthermore, contemporary sedimentary deposits do not necessarily stem from modern conditions—some deposits are relicts from past ocean behavior.

To address these challenges, the authors built a paleotidal model that can re-create factors dictating the behavior and movement of ocean water, such as water depth and the speed and path of tidal currents. They reconstructed ancient seafloor topography using past sea level changes interpreted via glacial isostatic adjustment models. Using this reconstruction, they were able to simulate the tidal conditions driving the formation of the mud deposits as far back as 17,000 years ago.

The model revealed that mud settled differently across the three focal areas. In the Celtic Deep and the Western Irish Sea Mud Belt, mud appears to have accumulated over the past 10,000 years and continues to accrue today. Conversely, in Fladen Ground, the mud deposits are the result of past sea conditions and are preserved by today’s calmer tidal conditions. The results demonstrate how modeling past conditions can help map today’s carbon stores, especially in data-limited areas. The approach offers a valuable tool for managing coastal waters and preserving blue carbon, the authors say. (Journal of Geophysical Research: Oceans, https://doi.org/10.1029/2024JC022092, 2025)

—Aaron Sidder, Science Writer

Citation: Sidder, A. (2025), Mapping the ocean floor with ancient tides, Eos, 106, https://doi.org/10.1029/2025EO250172. Published on 6 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.

Author(s): G. Röpke, R. Redmer, Max Schörner, Heidi Reinholz, Uwe Kleinschmidt, and M. Bethkenhagen

Density-functional-theory-based molecular dynamics simulations (DFT-MD) are a very successful tool to calculate the electrical conductivity of materials in the region of warm and dense matter. However, it requires a correction to implement the contribution of electron-electron collisions in the low-…

[Phys. Rev. E 111, 055201] Published Tue May 06, 2025

Coastal waters around the world are increasingly losing oxygen, with dramatic consequences for both ecosystems and the people who depend on them. The Baltic Sea is a well-known example: with the consequences of spreading hypoxic or anoxic zones evident in fish kills, the decline of spawning grounds and toxic blue-green algae blooms. So why not introduce oxygen into the sea where it is most urgently needed?

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

A fascinating new paper (Corominas et al. 2025) has just been published in the journal Geoenvironmental Disasters that describes the compilation and analysis of a new dataset on fatal non-seismic rockfalls in Spain. The dataset extends back for 220 years – a remarkable feat in itself – although the detailed analysis focuses on a 150 year period between 1872 and 2021. Even better, the paper has been published open access and under a creative commons license, which means that the information can be widely circulated.

Over the period of the study, Corominas et al. (2025) identified 1,118 fatal rockfalls in Spain, causing 1,550 deaths. This is the occurrence with time:-

Temporal distribution of rockfall events and fatalities in Spain within the last 220 years. Source: Corominas et al. (2025).

The reason for starting the analysis in 1872 is clear. It is always most interesting to look at the event rate (rather than the number of deaths) – the grey line – as this is less noisy.

It is notable that the rate has fluctuated considerably with time, but that there is a distinct increase in the last 20 years.

Corominas et al. (2025) have put a great deal of effort into understanding these trends. They correctly note that a fatal rockfall is the consequence of a complex interaction of a range of factors, which can include the topography, the climate, human modification to slopes and changes to vulnerability. To illustrate this, take a look at these two graphs, from the paper:-

Temporal evolution of the number of victims caused by landslides on quarries and excavations grouped by decades. Vertical dashed blue lines represent the wettest periods identified. Source: Corominas et al. (2025). Evolution of the number of victims of road accidents caused by rockfalls. grouped by decades. Vertical dashed blue lines represent the wettest periods. Source: Corominas et al. (2025).

As before, take a look at the event rate (the grey lines). In the case of quarries and excavations, the event rate has dropped very substantially in more recent years. This is the result of changes to regulation and practice in quarries – in other words, these locations have simply become safer. The authors describe this in some detail:-

“The reason must be sought in the operational changes introduced in the quarries. One hundred years ago, quarries and slope cuts were excavated with non-technical criteria or with poor engineering design. In our opinion, the observed decrease is due to improvements in excavation procedures and the adoption of occupational safety measures. These include the Regulation of Basic Mining Safety Standards in force since 1985 and the Occupational Risk Prevention Law in force since 1996. Studies on occupational and mining safety in Spain have highlighted the role of safety standards and safety measures and risk prevention in the substantial reduction of accidents.”

On the other hand, the event rate on roads has increased dramatically, although number of actual deaths shows no clear trend. A part of this might be better reporting – perhaps rockfalls in remote mountain areas are better reported than in the past. However, Corominas et al. (2025) note the following:-

“…[T]he vast majority of events occur in mountain roads, including those of the Canary Islands and the Balearic Islands. It is therefore logical to assume that the higher incidence is due to the increase in traffic on the most dangerous mountain road sections.”

And…

“The increase in the number of victims contrasts with the investment made by the administration in mitigation measures against rockfalls and the execution of road bypasses as mentioned in the previous section. This apparent lack of effectiveness of the set of preventive actions has been observed on other mountain roads … In any case, the trend of increasing accidents highlights the difficulty of risk management on roads that cross mountain ranges following the course of the main river valleys. These are stretches affected by a diffuse hazard originated far above the road and with innumerable source areas.”

Similar increases in events and losses were also noted in mountain trails and in coastal settings, which Corominas et al. (2025) ascribe primarily to changes in human activity – i.e. more recreational activities in the mountains and on the coast. As someone once put it to me, rather starkly, there are simply more targets in these locations than used to be the case.

This summary does no more than skate over the surface of a really fabulous piece of work. There s huge insight and richness in the data, demonstrating the complexity of these events. It would be fantastic to see more studies of this type.

Reference

Corominas, J., Lantada, N., Núñez-Andrés, M.A. et al. 2025. Fatal non-seismic rockfalls in Spain. Geoenvironmental Disasters 12 [17]. https://doi.org/10.1186/s40677-025-00317-9.

Return to The Landslide Blog homepage Text © 2023. The authors. CC BY-NC-ND 3.0
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SummaryThe Lamb problem stands as a classic issue in theoretical seismology aimed at obtaining solutions for the Green's functions of point sources in elastic half-spaces. It serves as the foundation for studying vibrational signals from many sources such as walking and driving, bearing significant theoretical and practical value. While the analytical solutions exist for the Lamb problem when both excitation and reception occur on the ground, the presence of singularity makes the numerical stability of calculating the Green's functions from these analytical solutions a challenge. In this study, we propose a stable algorithm that circumvents the impact of time singularity in the analytical solutions of the Lamb problem by introducing a tiny time parameter perturbation and judiciously selecting the starting position for time discretization sampling. This means that the zero time point (i.e. the excitation time of the source pulse) and the starting time of discretization sampling may not be coincident. The advantages of this method lie in its stability, simplicity, and practical accuracy, with the calculation results aligning consistently with the theoretical geometric decay of surface waves. Additionally, analysis of field data demonstrates that our stable algorithm effectively captures the amplitude characteristics of measured footstep responses and vehicle signals. Building upon the foundation of obtaining stable discrete solutions, we further elaborate on the process of transforming the discrete sampling starting point to approach the actual zero time point infinitely, even though this tiny time parameter perturbation does not affect the simulation results.

Growing communities and extensive agriculture throughout the Western United States rely on meltwater that spills out of snow-capped mountains every spring. The models for predicting the amount of this streamflow available each year have long assumed that a small fraction of snowmelt each year enters shallow soil, with the remainder rapidly exiting in rivers and creeks.

As the new Biomass satellite settles into life in orbit following its launch on April 29, ESA has released its most extensive satellite-based maps of above-ground forest carbon to date. Spanning nearly two decades, the dataset offers the clearest global picture yet of how forest carbon stocks have changed over time.

The National Hurricane Center's forecasts in 2024 were its most accurate on record, from its one-day forecasts, as tropical cyclones neared the coast, to its forecasts five days into the future, when storms were only beginning to come together.

Communities on small islands are on the front lines of worsening flood risks—not just from severe storms but from persistent tidal flooding events. Scientists estimate that within 15 years, high-tide flood events could triple for two thirds of communities along the East and Gulf Coasts of the United States.

Have you ever thought about what would happen if all life in the ocean disappeared? A recent study explores this extreme scenario to understand how ocean biology shapes the past, present, and future climate.

Clouds form upon existing particles in the atmosphere and extreme weather events like flooding and snowstorms are related to the production of large amounts of ice in clouds.

Rare earth elements are critical to many industries—used in electric motors, medical imaging and diagnostics, oil and gas refining, and computer and phone screens. The 17 rare earth elements all have important uses and are now in the news, with China halting exports to the U.S. in retaliation for tariffs and a recently signed deal for U.S. access to these and other minerals in Ukraine.

Whale carcasses sinking to the ocean floor bring a buffet of nutrients to the deep sea. But whales don’t have to be dead to be big movers of nutrients. Migrating baleen whales transport more than 3,700 tons of nitrogen and more than 46,000 tons of biomass each year from high-latitude feeding areas to warm, shallow breeding waters near the tropics, according to a recent study published in Nature Communications.

“In places like Hawaii, or the Caribbean, or the coastal waters of Western Australia, where nitrogen is often a limiting nutrient, migrating whales can have a big impact on the local biogeochemistry,” said Joe Roman, lead author of the new study and a conservation biologist at the University of Vermont.

“It’s a bit like adding fertilizer to a garden in New York City,” he said. “On the scale of the entire city, any change is probably undetectable, but the garden is profoundly affected.”

Roman and his colleagues found that in some breeding areas, the transport of whale-borne nutrients like nitrogen can be as significant as that from nonbiological processes, such as nutrient-rich upwellings. In the Hawaiian Islands Humpback Whale National Marine Sanctuary, nitrogen brought in each day by migrating humpback whales can be 125%–175% that of nitrogen from abiotic processes during the breeding season.

Though whales move only a small portion of the total nutrients swirling through the oceans, they still have a significant effect on the ecosystems in the breeding area, according to Matt Savoca, a marine ecologist at the Stanford University Hopkins Marine Station, who wasn’t involved with the study. “It’s a bit like adding fertilizer to a garden in New York City,” he said. “On the scale of the entire city, any change is probably undetectable, but the garden is profoundly affected.”

Nitrogen in Whale Pee

Roman and his colleagues used publicly available databases and whale sightings from ships and aerial surveys to estimate populations in feeding and breeding areas. They focused on gray, humpback, and right whales. (They avoided other baleen whales such as blue, fin, and minke because less is known about the migration patterns of these species.)

To calculate how much nitrogen migrating whales transport to breeding areas, the researchers turned to a perhaps unexpected animal: the northern elephant seal. “What makes northern elephant seals and baleen whales similar is that they are both capital breeders,” Roman said. Capital breeders bulk up for part of the year while in their feeding grounds. Then, after traveling to their breeding areas, they gestate, give birth, and lactate, all while fasting. This behavior contrasts with that of income breeders, such as seabirds, which feed throughout the year.

The elephant seal is the only capital breeding marine mammal for which data on nitrogen levels in urine for feeding and lactating animals exist. The researchers used information on elephant seal urine and supplemented the calculations with limited existing measurements of urine from whales in feeding and breeding areas to estimate how much nitrogen whales transport. (They didn’t include data on whale feces because adult baleen whales that are not feeding while in the breeding areas rarely defecate.)

Each year, whale species in the study may be adding more than 3,700 tons of nitrogen and more than 46,000 tons of biomass—which includes placentas released during births as well as carcasses of newborn and adult whales that die—to breeding areas. More conservatively, mothers and calves alone may transport more than 2,300 tons of nitrogen and 12,000 tons of biomass per year.

The Great Whale Conveyor Belt

Scientists still don’t fully agree on why whales migrate, usually from cold, nutrient-rich waters in high latitudes to warmer, nutrient-poor tropical waters. Some baleen whales make tremendously long journeys—gray whales can travel more than 11,000 kilometers from the waters around Sakhalin Island, Russia, to Baja California, for example.

“Other mammals and birds also migrate long distances, but what makes baleen whales different is their size and the fact that they are capital breeders,” Roman said. That means “most of the waste generated by the whales in the breeding areas, from placentas to urine, introduces external nutrients into the ecosystems.”

And baleen whales urinate a lot; a 2003 study estimated that one fin whale can produce almost a thousand liters of urine each day. Even whales that are fasting while in the breeding areas urinate copiously because they are breaking down stored fats and proteins to make milk for calves. Whale urine contains many elements, including phosphorus, magnesium, potassium, and nitrogen. The researchers were interested in nitrogen because it is often a limiting nutrient in many marine ecosystems.

“This study helps us realize that whales are not only charismatic species, but they also provide vital ecosystem services by connecting environments separated by thousands of miles.”

The researchers estimate that the nitrogen that whales bring in could increase the amount of food available in breeding waters. Whale urine contains nitrogen mainly in the form of urea, which organisms such as phytoplankton can readily use to convert carbon dioxide into thousands of tons of biological carbon per year through photosynthesis.

Some uncertainty is unavoidable when researching large marine mammals that travel huge distances, Savoca said. “But the study provides data-driven estimates that are as good as it gets at this time.”

“We are at the early stage of understanding how the nutrients, like nitrogen, that the whales bring in move through the ecosystems and the food chain,” Roman said. This understanding is especially important as whale populations face various threats, including pollution and climate change. “This study helps us realize that whales are not only charismatic species, but they also provide vital ecosystem services by connecting environments separated by thousands of miles,” Savoca said.

—Adityarup Chakravorty, Science Writer

Citation: Chakravorty, A. (2025), A great whale conveyor belt transports nutrients across oceans, Eos, 106, https://doi.org/10.1029/2025EO250171. Published on 5 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.

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

There is increased interest in the potential to store carbon in soils to improve soil health and offset some fraction of fossil fuel emissions. One reason we think carbon is stable in soils is that it is old, as evidenced by radiocarbon dating.

However, Evans et al. [2025] point out that many soils are developed on sedimentary rocks or deposits that contain ancient organic matter. The authors highlight several questions that still need answering: how much can this petrogenic carbon contribute to soil carbon stocks and the old ages of deep soil organic matter? Is it just passively transiting the soil system to be eroded and eventually end up in sediments again, or is some of it metabolized within the soil? And finally, how important can its presence influence our interpretation of the cycling of biologically-sourced organic carbon in soil, aquatic, and sedimentary environments?

Citation: Evans, D. L., Doetterl, S., Gallarotti, N., Georgiadis, E., Nabhan, S., Wartenweiler, S. H., et al. (2025). The known unknowns of petrogenic organic carbon in soils. AGU Advances, 6, e2024AV001625. https://doi.org/10.1029/2024AV001625

—Susan Trumbore, Editor, AGU Advances

Text © 2025. The authors. CC BY-NC-ND 3.0
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SummaryThe cross-correlation of the ambient noise recordings, also known as noise correlation functions (NCFs), can converge to Green’s functions (GFs) which describe wave propagation between a pair of stations. However, the NCFs are often biased from the true GFs due to the presence of random noise and spurious arrivals arising from non-diffuse wavefields. Additionally, the limited spatial and temporal coverage of recording stations can lead to large data gaps in the retrieved virtual shot gathers, particularly at large inter-station distances (far offsets). Both these factors impose great challenges to retrieving high-quality NCFs and conducting reliable subsurface imaging. In this study, we propose a multi-dimensional (4D) reconstruction method to compensate for the insufficient station coverage and simultaneously attenuate incoherent noise in the NCFs. We test the feasibility of the proposed method using a dense seismic array deployed in western Canada. Our results demonstrate that the reconstructed virtual common mid-point gather (VCMG) can greatly improve the stability and reliability of the surface-wave dispersion measurements and subsequent shear velocity inversions compared to the conventional approaches. The proposed ambient noise processing framework enables us to construct accurate 3D velocity model of the subsurface.

SummaryThis paper describes a refined version of the point acceleration approach, referred to as the refined acceleration approach, which makes use of K-band range-acceleration observations to derive high-precision monthly gravity field solutions. For overcoming shortcomings of the conventional approach, several refinements are made as follows. (1) The inter-epoch correlated errors caused by numerical differentiation are decorrelated by a decorrelation operator. (2) The satellite velocity is transformed into a function of satellite positions and dynamic parameters. (3) The effect of satellite position error is taken into consideration while building the range-acceleration observational equation. (4) An autoregression (AR) model is used for modelling the high-frequency error of K-band range-acceleration observations. Applying the proposed approach, GRACE-FO observation data spanning the period from January 2019 to December 2022 were processed and a time series of monthly gravity field solutions, referred to as SSM-ACC-GFO, was derived. This time series is comprehensively compared with three official time series, i.e. CSR RL06, JPL RL06 and GFZ RL06, both in spectral and spatial domain. Comparison results demonstrate that SSM-ACC-GFO performs comparably with JPL RL06 and GFZ RL06 indicating that the refined acceleration approach has the ability of deriving high-precision monthly gravity field solutions.

AbstractUnderstanding the mechanical behavior of a fractured geothermal reservoir during its operation phase, when a sustained circulation of fluid is taking place, is of crucial importance for the appraisal of this technology. This knowledge is also essential for understanding natural fault systems that exhibit fluid-induced seismicity, as the geothermal reservoir serves as a small-scale analog to these systems. Here we analyze the seismicity of a geothermal reservoir in France, which has been the primary target for heat exploitation over the last 8 years. Fluid circulation in the granite has been maintained along a main fractured zone through pathways with enhanced permeability thanks to the continuous injection of fluid from a single well. We show that the seismicity occurring during the operation of this reservoir exhibits a progressive expansion outpacing the zone initially activated during the hydraulic stimulation. We also show that most recorded earthquakes are clustered in time within discrete bursts that activate different portions of the fault system. The migration of the events included in these bursts indicates that they are likely related to aseismic transients developing over the creeping fault interfaces. It therefore demonstrates that the intermittency of the seismic activity characterizing earthquake swarms can arise naturally as the complex hydro-thermo-mechanical response of a system under continuous forcing conditions.

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.

President Trump’s proposed 2026 budget, released today, slashes non-defense discretionary spending by $163 billion, a 22.6% reduction from 2025.

In the budget request, sent from Russell T. Vought, director of the Office of Management and Budget, to Senate Appropriations Chair Susan Collins, Vought wrote that the suggestions came after a rigorous review of the 2025 budget, which was found to be “tilted toward funding niche non-governmental organizations and institutions of higher education committed to radical gender and climate ideologies antithetical to the American way of life.”

Among the proposed cuts:

 

Related

•  Live Updates: Trump Proposes Slashing Domestic Spending to the Lowest Level of the Modern Era
•  Trump’s 2026 Budget Plan Nearly Eliminates Federal Funding for Clean Water in America
•  Trump budget proposes slashes to renewable energy, farms, EPA
• Trump Budget Request Shrinks Federal Science Agencies
• Get Involved: AGU Science Policy Action Center

 

• A 9.4% cut, or $4.7 billion, to the Department of Energy
  • In addition, the budget proposes cancelling “over $15 billion in Green New Scam funds, committed to build unreliable renewable energy, removing carbon dioxide from the air, and other costly technologies burdensome to ratepayers and consumers.”
• A 54% cut, or $5  billion, to the Environmental Protection Agency
  • This includes eliminating the EPA’s environmental justice program and atmospheric protection program, as well as cutting funds for the Hazardous Substance Superfund and the Clean and Drinking Water State Revolving Loan Funds.
  • “Trump’s plan to virtually eliminate federal funding for clean, safe water represents a malevolent disregard for public health. Even by Trump’s appalling standards, this direct attack on a benchmark water safety program is unconscionable,” said Food & Water Watch Executive Director Wenonah Hauter in a statement.
• A 30.5% cut, or $5.1 billion, to the Interior Department, including $198 billion from the Bureau of Land Management, $900 million from the National Park Service, and $564 million from the U.S. Geological Survey
  • From the proposal: “Eliminates programs that provide grants to universities, duplicate other Federal research programs and focus on social agendas (e.g. climate change) to instead focus on achieving dominance in energy and critical minerals.”
• A 24.3% cut, or $6 billion, to NASA, including a 47% cut to the science budget
  • Among many other cuts, the budget “eliminates funding for low-priority climate monitoring satellites,” “reduces Space Technology by approximately half,” and “terminate[s] unaffordable missions such as the Mars Sample Return Mission.” It suggests cutting the lunar Gateway, Space Launch System rocket, and Orion capsule, as well as the Office of Science, Technology, Engineering, and Mathematics (STEM) engagement. NASA’s overall cut takes into account a proposed $647 million budget increase for human space exploration.
  • In a statement, The Planetary Society urged Congress to reject the proposed budget, calling it “a historic step backward for American leadership in space science, exploration, and innovation.”
  • In a statement, the American Astronomical Society expressed “grave concerns” over these cuts, and said, “This will derail not only cutting-edge scientific advances, but also the training of the nation’s future STEM workforce.”
• A 55.8% cut, or $4.9 billion, to the National Science Foundation
  • From the proposal: “The Budget cuts funding for: climate; clean energy; woke social, behavioral, and economic sciences; and programs in low priority areas of science. NSF has fueled research with dubious public value, like speculative impacts from extreme climate scenarios and niche social studies.”
• An approximately 25% cut, or $1.5 billion, to NOAA
  • From the proposal: “The Budget terminates a variety of climate-dominated research, data, and grant programs, which are not aligned with Administration policy-ending “Green New Deal” initiatives.”

The budget proposal also includes suggestions to increase defense spending by 13%, to $1.01 trillion; and for “a historic $175 billion investment to, at long last, fully secure our border.”

Read more about the budget proposal at AGU’s The Bridge.

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

These updates are made possible through information from the scientific community. Do you have a story about how changes in law or policy are affecting scientists or research? Send us a tip at eos@agu.org. Text © 2025. AGU. CC BY-NC-ND 3.0
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New research reveals that shifts in plant life played a key role in speeding up major climate changes during the late Miocene, a period spanning 11.6 to 5.3 million years ago.

Swarms of earthquakes have been jolting southern Italy with increasing intensity since 2022, threatening hundreds of thousands of people living atop a volcanic area known as Campi Flegrei, where the land experiences slow vertical movements.