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Taking carbon out of the atmosphere is essential for slowing global warming—and a team of Cornell University researchers has estimated "huge" potential for carbon capture using a method that is low-tech, sustainable and relatively simple: burying wood, especially the debris from managed forests.

A recent study by The Hong Kong University of Science and Technology (HKUST) reveals a looming climate crisis: the world could face heightened risks of "precipitation whiplashes"—violent swings between extreme droughts and floods—as early as 2028.

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.

Staff at the National Science Foundation (NSF) were notified on 25 June that the agency’s office space, located in Alexandria, Va., will be taken over by Department of Housing and Urban Development (HUD) staff, raising the question of where more than 1,800 NSF employees will work. 

One NSF employee told E&E News that they had “literally zero idea” the news was coming until word spread among staff the previous evening. Many NSF employees had relocated to Northern Virginia on short notice when return-to-work orders were issued in January. NSF only moved into the newly constructed building in 2017 from its prior location in Arlington, Va.

In front of a banner reading “The New Golden Age of HUD” at a 25 June press conference, HUD Secretary Scott Turner announced that a “staggered and thoughtful” relocation process would take place. The relocation will move forward “as quickly as possible,” Michael Peters, commissioner of the Public Buildings Service for the U.S. General Services Administration, said at the press conference.

On 24 June, Jesus Soriano, president of the American Federation of Government Employees (AGFE) Local 3403, a union representing NSF staff, sent an alert to union members informing them that “HUD will take over the NSF building” and that NSF had not been involved in the decision, according to E&E News.

Speakers at the press conference did not provide details about HUD’s plans for the space. In a statement, AGFE Local 3403 indicated that the union was told that plans would include an executive suite for Turner, the construction of a new executive dining room, exclusive use of one elevator for Turner, and a gym for Turner and his family.

 
Related

•  Press Conference: The New Golden Age of HUD
•  American Federation of Government Employees Local 3403 Statement
•  Science Agency Staff Brace for HQ Takeover
•  Get Involved: AGU Science Policy Action Center
 

“While Secretary Turner and his staff are busy enjoying private dining and a custom gym, NSF employees are being displaced with no plan, no communication, and no respect,” AGFE Local 3403 wrote in the statement.

Turner rebuked the idea that the move was about personal perks. “This is not about Scott Turner. I didn’t come to government to get nice things,” Turner said. “This is about the HUD employees.”

Turner added that unsafe working conditions at the current HUD office space in Washington, D.C. were the reason for the move. “I would hope that no leader in government or otherwise would expect staff to work in an atmosphere where the air quality is questionable, leaks are nearly unstoppable, and the HVAC is almost unworkable. It’s time for a change.”

Addressing the coming transition for NSF, Peters said, “We are going to continue to support the National Science Foundation as we support every agency across the federal government to identify space that allows them to continue to fulfill their mission.” 

In its statement, AGFE Local 3403 pointedly questioned the merit of the relocation plan: “At a time when they claim to be cutting government waste, it is unbelievable that government funding is being redirected to build a palace-like office for the Secretary of Housing and Urban Development. The hypocrisy is truly dumbfounding.”

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

These updates are made possible through information from the scientific community. Do you have a story about how changes in law or policy are affecting scientists or research? Send us a tip at eos@agu.org. Text © 2025. AGU. CC BY-NC-ND 3.0
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In a first-of-its-kind study, Stanford researchers have measured how the abundance of ocean life has changed over the past half-billion years of Earth's history.

As Britain's first heat wave of 2025 hits with temperatures climbing above 30°C, Yorkshire has joined the northwest in official drought status.

Editors’ Vox is a blog from AGU’s Publications Department.

In the Arctic, one of the primary paths for water to flow is along water tracks, stream-like features that fill with and route water when the soil above permafrost thaws in the summer. While these water tracks are important for water and nutrient movement, little is known about their formation and how they might change in the future.

A new study in Reviews of Geophysics explores our current understanding of water tracks and what aspects are still unclear. Here, we asked the authors to give an overview of water tracks, the leading theories about their formation, and what questions remain.

What are water tracks and where do they form?

Remote sensing image of tundra water tracks in northern Russia. Credit: Del Vecchio and Evans [2025], Figure 1a

Water tracks are stream-like features that concentrate water flow in cold places where the ground is frozen in the winter. Since frozen ground doesn’t let water soak in, any water from rain, melting snow, or ice ends up moving along the surface or just under the top layer when it thaws in the summer, like through moss or soil.

Interestingly, water tracks do not have a stream channel like a typical stream. You don’t need steep hills for water tracks to occur either; even a gentle slope is enough to get water moving. Water tracks are mostly found in places with permafrost including the Arctic, parts of Alaska, northern Canada, Siberia, and even Antarctica.

What roles do water tracks play in polar regions?

Water tracks move a surprising amount of water across frozen landscapes, especially in places with hills or gentle slopes. Because the water gets funneled into these narrow paths, it also brings along nutrients, making water tracks hotspots for plant growth and biological activity in otherwise cold and dry areas. You’ll often see greener, thicker vegetation in these zones, and they can be places where more carbon dioxide and methane are produced.

From a landscape perspective, they act like pseudo-channels for water, but interestingly, they don’t seem to carve out the land or move much sediment. However, that could change with climate shifts, and if these areas start eroding, it might reshape parts of the Arctic landscape in new ways.

How do scientists identify and monitor water tracks at different spatial scales?

Water tracks were first spotted from the air using aerial photos, and today we still rely heavily on remote sensing to study them. On the ground, scientists can look at vegetation changes, soil wetness, and evidence of surface water flow, but because water tracks can stretch for hundreds of meters, satellite and drone imagery are super helpful. They show up well in high-resolution images and in certain types of data, like infrared, because the plants growing on water tracks are greener and more productive. Tools like LiDAR can also help track changes in elevation, which is useful for spotting subtle shifts or erosion over time. While coarser satellites like Landsat might miss them, newer ones like Sentinel or PlanetScope can pick them up much more clearly.

Appalachian State University undergraduate students Noah Caldwell, Key Hatch, and Emma Ferm walk to collect water and soil samples from a water track on the North Slope of Alaska, USA in July 2023. Credit: Thomas Tobul

What are leading theories that describe how water tracks form?

In our literature review, most studies only consider their individual water tracks, so there weren’t really generalized models of water track formation out there before our review. But from literature and our own work, we noted two main theories: one theory is that they’re the result of thawing ground ice like ice wedges that create long, linear paths for water to flow. As the ice thaws, water keeps following that path, advecting heat which causes further thawing, reinforcing the track.

The other theory is a slightly different feedback mechanism: a dip or disturbance in the permafrost table, maybe from a snowdrift, vegetation, or other small indent, collects more water, which causes more thawing and even more water to flow there, creating a self-reinforcing loop. Both theories not only help explain how water tracks form, but also why they tend to show up in regular, repeating patterns across the landscape.

How is climate change expected to influence water tracks?

This is still a big unknown, but we’re starting to get some ideas. As permafrost landscapes warm, snow melts earlier and the ground thaws deeper, which could change how and where water flows. If water starts moving through deeper, less porous soil layers, it might cause erosion in places that used to be stable, turning soft, spongy mats into channels that cut into the ground. That could release stored sediment and carbon, and even shift how water tracks connect and drain the landscape. We are also seeing signs that water tracks are drying out or consolidating into fewer, deeper gullies, which could lead to even more dramatic changes over time.

How could water tracks be used to understand the hydrosphere on Mars?

Studying water tracks helps us think differently about how water might emerge and flow on other planets.

Scientists have long compared water tracks on Earth to the dark streaks seen on Martian slopes like recurring slope lineae (RSL), especially since both appear and change seasonally in cold, dry environments. Places like Antarctica and the Canadian Arctic often serve as analogs for Mars for geoscientists, where similar streaky patterns show up seasonally, which some researchers have called water tracks. While recent research suggests these Martian features might be caused by dust and wind rather than water, Earth’s water tracks still offer clues. They show that even in frozen conditions, water can move across the surface without leaving a noticeable fingerprint of erosion, which is something that might have happened on Mars in the past. So, studying water tracks helps us think differently about how water might emerge and flow on other planets, even if it doesn’t leave obvious signs behind.

What are some of the remaining questions where additional modeling, data, or research efforts are needed?

We’ve only studied a handful of water tracks in detail, so our understanding is based on a small slice of the Arctic. There’s a big need for more field data and better remote sensing to match the huge areas where water tracks actually exist. We also need more modeling to figure out what really drives their behavior and how that will change in a warmer climate, whether it’s snow, vegetation, or water flow. Questions like how water tracks “remember” past years, or how they evolve over time, are still wide open. So, more data and better models are key to unlocking how these features work and how they might change in the future.

—Joanmarie Del Vecchio (joanmarie@wm.edu, 0000-0003-3313-6097), College of William and Mary, United States; and Sarah G. Evans (0000-0001-5383-8382), Appalachian State University, United States

Editor’s Note: It is the policy of AGU Publications to invite the authors of articles published in Reviews of Geophysics to write a summary for Eos Editors’ Vox.

Citation: Del Vecchio, J., and S. G. Evans (2025), Water tracks: the veins of thawing landscapes, Eos, 106, https://doi.org/10.1029/2025EO255021. Published on 25 June 2025. 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 © 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: AGU Advances

This is an authorized translation of an Eos article. Esta es una traducción al español autorizada de un artículo de Eos.

No se tienen registros suficientes en las bases de datos globales de los peligros meteorológicos extremos. Por ejemplo, los eventos donde las temperaturas son potencialmente mortales y que se ajustan a las normas climatológicas generalmente no son incluidos en los estudios de riesgos, y las inundaciones locales o regionales a menudo suelen pasar desapercibidas para los instrumentos satelitales.

En los últimos 20 años Texas ha experimentado una cantidad inusualmente alta de fenómenos climáticos extremos, incluyendo un incremento en inundaciones y olas de calor. Usando datos satelitales de fácil acceso de precipitación y temperatura tomados diariamente, Preisser y Passalacqua crearon una visión más amplia de los riesgos por inundaciones y olas de calor que han afectado al estado en los últimos años.

Al consultar los datos de precipitación del 2001 al 2020, los investigadores definieron como un evento de inundación peligrosa a aquellos que ocurren en promedio una vez cada dos años o más, lo que significa que un evento de esa magnitud ocurre en un área determinada con una frecuencia que no supera los dos años. Compararon sus resultados con los registrados en la Base de Datos de Eventos de Tormentas de la NOAA y la base de datos del Observatorio de Inundaciones de Dartmouth (DFO por sus siglas en inglés). Su análisis detectó tres veces más inundaciones que en la base de datos del DFO y se identificaron daños adicionales de $320 millones de dólares.

El equipo también amplió el análisis sobre el calor extremo. En muchos estudios previos sobre amenazas múltiples sólo se consideraron las olas de calor, donde las temperaturas superaron un percentil, como el 90 o el 95, durante tres días seguidos. Este estudio también consideró los periodos donde la temperatura de globo de bulbo húmedo (índice WBGT) supera un umbral de salud de 30°C, en lugar de un percentil determinado. Bajo esta definición, los científicos determinaron que, entre 2003 y 2020, Texas vivió 2,517 días con eventos peligrosos de calor, lo que equivale a casi el 40% de los días dentro de este periodo. Estos eventos afectaron un total de 253.2 millones de kilómetros cuadrados.

El estudio consideró como eventos de amenazas múltiples aquellos en los que coinciden inundaciones y episodios de calor extremo. Usando el método del intervalo de recurrencia promedio, junto con la definición más amplia de peligros, los investigadores encontraron que las zonas del estado con una alta concentración de poblaciones minoritarias estaban expuestas a un mayor riesgo ante este tipo de eventos multiriesgo. Esto sugiere que los métodos más antiguos pueden subestimar tanto la magnitud de los eventos de amenaza múltiple como el impacto desproporcionado en comunidades marginadas, de acuerdo con los investigadores. (AGU Advances, https://doi.org/10.1029/2025AV001667, 2025)

—Rebecca Owen (@beccapox.bsky.social), Escritora de ciencia

This translation by translator Oscar Uriel Soto was made possible by a partnership with Planeteando y GeoLatinas. Esta traducción fue posible gracias a una asociación con Planeteando and GeoLatinas.

Text © 2025. AGU. CC BY-NC-ND 3.0
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The Arctic is experiencing the most rapid climate change on Earth as average temperatures there rise up to 4 times faster than on the rest of the planet. Among the many environmental effects of this warming, the Arctic Ocean, critically, is moving toward a “blue” state, meaning it is increasingly becoming ice free during the summer months.

This shift raises significant concerns about the region’s future. Arctic Indigenous peoples, for instance, heavily rely on stable ice conditions for traditional hunting, fishing, and travel. As ice disappears, these activities become more dangerous or impossible, threatening food security, cultural practices, and the transmission of Traditional Knowledge. Global geopolitical and economic pressures will also rise as new shipping routes open, previously inaccessible resources become available for extraction, and international competition over these resources rises.

Currently, scientists struggle to predict how an ice-free Arctic will react to and amplify a warmer global climate.

Currently, however, scientists struggle to predict how an ice-free Arctic will react to and amplify a warmer global climate. The lack of clear climate projections for the region is largely due to a shortage of key geological data describing former climatic conditions and how the Arctic has responded to past changes, as well as to difficulties interpreting the records we do have. Making sense of these data is essential for understanding how the Arctic will evolve in the coming decades.

Deep-sea sediment cores provide some of the best available archives from the Arctic Ocean. These cores, drilled and collected from sites around the region, contain sediments deposited over hundreds of thousands of years that offer clues about past ocean temperatures, sea ice and ice sheets, and ocean circulation changes. To gain insights specifically into how the Arctic may respond to future warming—and the broader implications for the planet—scientists focus on past “greenhouse” states, when Earth’s climate was warmer than it is today, such as the Last Interglacial, about 130,000 years ago.

The German R/V Polarstern, shown here during an expedition into the central Arctic Ocean in 2015, has enabled the acquisition of numerous sediment cores that archive past Arctic climate changes. Credit: Alfred Wegener Institute/Mario Hoppmann, CC BY 4.0

However, reconstructing past warm climates from deep-sea core records is challenging, particularly because the chronology of Arctic Ocean sediments has been difficult to establish. The lack of biological remains and the dissolution of calcium carbonate in these sediments complicate efforts to determine their ages (i.e., their chronostratigraphy). Furthermore, the use of different dating methods and uncertainties about sedimentation rates have led to conflicting interpretations of core records and hindered the development of a solid timeline for Arctic climate history [e.g., Stein et al., 2025].

Recent advances in research have raised questions about the accuracy of prior published ages of Arctic Ocean sediments. These developments have also highlighted ongoing uncertainties and the need to understand the abilities and limitations of different dating tools. Without this understanding, it will be difficult to identify and detail past greenhouse climates with confidence, which in turn, will limit our ability to apply knowledge of these past conditions to inform climate models.

The Arctic Ocean Stratigraphic Toolbox

In fall 2024, more than 40 scientists gathered at the ArcSTRAT conference in Tromsø, Norway, to discuss the latest research and how available methods can best be used to develop a reliable chronostratigraphic framework, or age model, for Arctic sediments. Additional goals were to foster shared understanding of the region’s climate history and to improve our ability to provide accurate data to climate modelers.

A key challenge in studying Arctic paleoclimate is that oceanic sedimentation rates are typically low across the region.

A key challenge in studying Arctic paleoclimate is that oceanic sedimentation rates are typically low across the region. In fact, the central Arctic Ocean is one of the slowest accumulating marine sedimentary environments globally because of limited sediment sources and biological productivity, suppression of sediment transport by sea ice, and sediment trapping on broad circum-Arctic continental shelves.

The slow sediment accumulation results in thin sediment layers that can make it difficult to obtain clear chronological data. Dissolution of calcium carbonate from deposited sediments, which can occur where deep seawater is undersaturated with respect to the mineral, further reduces the possibility of finding datable microfossils in the sedimentary record.

In some areas, biostratigraphy (the distribution of ancient life in sedimentary rocks) and stable isotope geochronology (which compares ratios of nonradioactive isotopes of, e.g., carbon or oxygen) can be used to refine age models. In other areas, alternative methods are needed to provide age constraints. Such methods include magnetostratigraphy, which dates sediment layers by correlating their magnetism to the record of Earth’s magnetic field reversals; amino acid racemization, which measures the time-dependent breakdown of proteins in fossils too old for radiocarbon dating; luminescence dating, which measures radiation that builds up in materials as they age; and radionuclide dating.

Fig. 1. Age models of Arctic Ocean sediments can incorporate data from many analytical methods. The sediment core seen here (brown bands at far left) is from Lomonosov Ridge near the geographic North Pole. Photographs of the upper 4 meters of the core are shown beside microfossil (planktic foraminifera) abundance in blue and the concentration of the cosmogenically derived isotope beryllium-10 (10Be) in yellow [Spielhagen et al., 1997]. Increases in either parameter are commonly associated with past interglacials. The global benthic (deep-water) oxygen-18 curve (δ18O) shows the ratio of oxygen-18 to oxygen-16 over time [Lisiecki and Raymo, 2005], highlighting the timing of interglacial marine isotope stages (MIS; red numbers near bottom) over the past 1 million years. This curve is shown above the geomagnetic polarity timescale, which shows the most recent magnetic reversal—from the Matuyama epoch to the Brunhes epoch—at roughly 781,000 years ago. Two end member age models have been commonly applied in the past: a high sedimentation rate (SR) scenario and low sedimentation rate scenario. These models produce widely varying age estimates for the same sedimentary layer. Some of the key new data (in red) being used to evaluate the age model options come from advances in biostratigraphy (notably, the discovery of Pseudoemiliania lacunosa, a calcareous nanofossil that went extinct during MIS 12) [Razmjooei et al., 2023], radiometric dating of bulk sediments using the uranium decay series isotopes protactinium-231 (231Pa) and thorium-230 (230Th) [Hillaire-Marcel et al., 2017], and amino acid racemization measured in the fossilized shells of planktic and benthic foraminifera [West et al., 2023]. Click image for larger version.

Recent breakthroughs, particularly in applying radionuclide methods, have shown promise in improving the accuracy of Arctic Ocean sediment age models (Figure 1). For example, novel applications of uranium series isotopes (e.g., thorium-230 and protactinium-231) have been used to propose new age constraints for marine sediment sequences from important topographic regions, such as the Mendeleev-Alpha and Lomonosov Ridges, where low sedimentation and poor preservation of fossil material have hampered previous attempts to date these sequences [Hillaire-Marcel et al., 2017]. These isotopes decay predictably over time, allowing scientists to date past interglacial periods more confidently, including the Last Interglacial and others occurring around 200,000 years ago.

These new radionuclide-based age constraints are supported in part by recent applications of more traditional dating methods like biostratigraphy. Specifically, a newly revised Arctic sediment chronology for the late Pleistocene (400,000–10,000 years ago) established on the basis of analyses of calcareous nanoplankton, although not perfectly aligned, showed less uncertainty in the identification of interglacial periods in the central Arctic Ocean [Razmjooei et al., 2023]. Tracking changes in the concentration of cosmogenic radionuclides, like beryllium-10, in Arctic sediments has also provided new insights into the timing of interglacials [Spielhagen et al., 1997].

The Need for a Multimethod Approach

Some methods are better suited than others for studying sediments from given locations because environmental conditions across the Arctic differ.

The generally low sedimentation rates across the Arctic Ocean produce thin sediment layers that require precise sampling and, because not every dating method works well everywhere, careful selection of analytical methods. Some methods are better suited than others for studying sediments from given locations because environmental conditions across the Arctic differ, contributing to variable sedimentation rates, variable preservation of fossils, and disturbances like erosion and bioturbation (the reworking of sediment layers by living organisms).

Whereas relying on a single method to study sediments from across the Arctic Ocean may lead to inaccuracies and gaps in understanding, different methods can complement each other, providing a fuller, more robust picture of the past. Discussions during the ArcSTRAT conference highlighted the importance of using a multimethod approach, combining the various available stratigraphic and isotopic dating methods.

The challenge lies in carefully selecting appropriate methods to study cores from different regions to minimize errors and uncertainties and provide a reliable reconstruction of past Arctic environments. In areas where calcium carbonate is well preserved (e.g., topographic highs), for example, biostratigraphy and isotope geochronology are extremely useful. In areas where it is not (e.g., deep basins), litho- and magnetostratigraphy combined with radionuclide dating might be better options.

The past few decades have seen the development and application of a veritable toolbox of different techniques for dating Arctic Ocean sediments. These tools must now be integrated and applied to study newly collected sediment archives.

New Arctic Archives

Alongside methodological developments, new Arctic sediment cores have been retrieved recently, including during the International Ocean Discovery Program’s Expedition 403. In 2024, this campaign successfully drilled more than 5 kilometers of sediment cores from the Fram Strait west of Svalbard that offer a high-resolution record of past Arctic climates [Lucchi et al., 2024].

The scientific aim of this drilling was to better understand the ocean system and cryosphere during past warm intervals and how they relate to high insolation (exposure to sunlight) and atmospheric carbon dioxide levels. This information is essential for comprehending the climatic evolution of the Northern Hemisphere and the dynamics of ice sheets, sea ice, and ocean circulation. Data from these cores will be invaluable for studying the mechanisms that lead to ice-free Arctic summers and for understanding the effects of these conditions within and beyond the Arctic.

The Norwegian icebreaker R/V Kronprins Haakon sails in the Arctic Ocean. Credit: Dimitri Kalenitchenko, UiT The Arctic University of Norway

In 2025, the European Research Council’s (ERC) Synergy Grant–funded “Into The Blue” (i2B) Arctic expedition aboard R/V Kronprins Haakon will focus on recovering additional unique sediment archives from the central Arctic Ocean. The plan is to use a combination of classical and cutting-edge techniques to explore the Arctic’s climate history as completely as possible, matching the methods to the demands of each core. Together with stratigraphic methods, these techniques include analyses of molecular biomarkers, palynology (the study of preserved pollen grains and spores), ancient DNA, radionuclides, and stable isotopes to reconstruct past sea ice conditions, ocean heat transport, and cryosphere variability during warmer-than-present climate states such as the Last Interglacial.

A Promising Start to the Work Ahead

The ArcSTRAT conference made clear that the work ahead is challenging but promising. The outcomes and consensus about coordinating multimethod approaches will provide a crucial framework for analyzing new cores from the i2B expedition and, hopefully, additional future expeditions. The meeting also helped to establish a forum for continued collaboration and knowledge exchange among Arctic stratigraphy experts—an important step toward resolving continuing disparities among dating methods and developing a robust Arctic Ocean chronostratigraphy.

As the Arctic continues changing at an unprecedented rate and advancing toward blue summers, understanding its past is more critical than ever.

As the Arctic continues changing at an unprecedented rate and advancing toward blue summers, understanding its past is more critical than ever. By piecing together the climatic history of past greenhouse states, scientists are building the foundation for more accurate climate models, which are essential for informing accurate global climate assessments that, in turn, guide policy decisions in countries and communities around the world.

With ongoing advances in the toolbox of techniques for studying ocean sediment stratigraphy, as well as the collection of new sediment records, we will be better positioned to predict how the Arctic will respond to further warming and what the far-reaching consequences of this response will be.

Acknowledgments

We thank the participants in the 2024 ArcSTRAT conference in Tromsø, Norway, especially keynote speakers Ruediger Stein, Anne de Vernal, Renata Lucchi, Jutta Wollenburg, and Stijn De Schepper. The conference was funded by the Research Council of Norway, as well as by ERC through the Synergy Grant “i2B–Into The Blue” (grant 101118519).

References

Hillaire-Marcel, C., et al. (2017), A new chronology of late Quaternary sequences from the central Arctic Ocean based on “extinction ages” of their excesses in 231Pa and 230Th, Geochem. Geophys. Geosyst., 18(12), 4,573–4,585, https://doi.org/10.1002/2017GC007050.

Lisiecki, L. E., and M. E. Raymo (2005), A Pliocene‐Pleistocene stack of 57 globally distributed benthic δ18O records, Paleoceanography, 20(1), PA1003, https://doi.org/10.1029/2004PA001071.

Lucchi, R. G., et al. (2024), Expedition 403 preliminary report: Eastern Fram Strait paleo-archive, Int. Ocean Discovery Program, https://doi.org/10.14379/iodp.pr.403.2024.

Razmjooei, M. J., et al. (2023), Revision of the Quaternary calcareous nannofossil biochronology of Arctic Ocean sediments, Quat. Sci. Rev., 321, 108382, https://doi.org/10.1016/j.quascirev.2023.108382.

Spielhagen, R. F., et al. (1997), Arctic Ocean evidence for late Quaternary initiation of northern Eurasian ice sheets, Geology, 25(9), 783–786, https://doi.org/10.1130/0091-7613(1997)025%3C0783:AOEFLQ%3E2.3.CO;2.

Stein, R., et al. (2025), A 430 kyr record of ice-sheet dynamics and organic-carbon burial in the central Eurasian Arctic Ocean, Nat. Commun., 16, 3822, https://doi.org/10.1038/s41467-025-59112-7.

West, G., et al. (2023), Amino acid racemization in Neogloboquadrina pachyderma and Cibicidoides wuellerstorfi from the Arctic Ocean and its implications for age models, Geochronology, 5(1), 285–299, https://doi.org/10.5194/gchron-5-285-2023.

Author Information

Jochen Knies (Jochen.Knies@uit.no), UiT The Arctic University of Norway, Tromsø; Matt O’Regan, Stockholm University, Sweden; and Claude Hillaire Marcel, Université du Québec à Montréal, Montreal, Canada

Citation: Knies, J., M. O’Regan, and C. H. Marcel (2025), Finding consensus on Arctic Ocean climate history, Eos, 106, https://doi.org/10.1029/2025EO250230. Published on 25 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.

A study published in Geophysical Research Letters reveals that glaciers in western Canada, the United States, and Switzerland lost around 12% of their ice between 2001 and 2024.

The past year of 2024 was characterized by repeated runs of extreme rainfall and floods worldwide. Among these, one of the most devastating events was the Central Asian flood in the spring of 2024.

Research led by Earth scientists at the University of Southampton has uncovered evidence of rhythmic surges of molten mantle rock rising from deep within the Earth beneath Africa. These pulses are gradually tearing the continent apart and forming a new ocean.

Earth is hotter than it has been in 125,000 years, scientists say, and Las Vegas continues to break temperature records. The extreme heat claimed more than 500 lives in southern Nevada last year alone, and scientists and city officials are clamoring for solutions.

A significant landslide has destroyed a major bridge on the Xiarong Expressway in Guizhou, China.

On 24 June 2025, intense rainfall triggered a significant landslide at the site of the Houzihé Grand Bridge, which is a part of the Xiarong Expressway (a key road that is also known as Xiamen–Chengdu Expressway (route G76).

The landslide toppled the bridge carrying both sides of the highway. The driver of an articulated truck had a very lucky escape when his vehicle stopped with the cab over the chasm. He was rescued successfully.

The best image I have found of this event is on the website of CNR:-

The aftermath of the 24 June 2025 landslide at Houzihé Grand Bridge in Guizhou, China. Image from CNR.

The failure appears to have removed at least one column supporting the carriageway on each side. Note the red truck partially hanging over the void.

Reports suggest that the landslide occurred at 7:40 am, but that problems had been identified at 5:51 am and that traffic control had been put in place. If that is the case, I am a little unsure as to how the truck ended up in that position.

I believe that the location of this landslide is [26.0111, 108.1241]. This is a Google Earth image of the site, collected in March 2013:-

Google Earth image of the site of the 24 June 2025 landslide at Houzihé Grand Bridge in Guizhou, China.

It is interesting to note that the rear scarp of the landslide appears to coincide with the small road that cuts across the hillside. In 2013 it appears that there were no buildings at this location, but the image above shows that some have been built since. In terms of understanding the failure, I would be interested in determining whether there was a fill slope at this point and/or whether the area had a properly engineered drainage system.

This failure will ask serious questions about the safety of the highway. The piers of the viaduct look to have been extremely vulnerable to this type of failure. A quick scan of Google Earth suggests that this configuration may have been replicated elsewhere. Take a look at this image from Google Earth, for example, from 2020 (located at 26.0817, 107.9566]:-

Google Earth image of another site on the Xiarong Expressway in Guizhou, China.

This failure also highlights another key issue – the management of slopes close to, but not a part of, major infrastructure sites such as roads and railways.

This part of China is suffering intense rainfall at the moment, driving record floods along some of the local rivers. Over 80,000 people have been evacuated.

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SummaryWe present a novel model-based seismic data redatuming method based upon time-domain data-assimilated wavefield (DAW) reconstruction. Seismic redatuming refers to the positioning of sources and/or receivers from the acquisition surface to a virtual datum level along with the computation of the dataset that would have been recorded by the virtual acquisition. Physically, DAWs approximate the true wavefields by least-squares time-reversal extrapolation of the recorded data in a background subsurface model. To this end, DAWs are first formulated as the sum of the background wavefields and an approximation of the scattered wavefields by the unknown contrasts between the true model and the background model. We estimate the scattered fields via the estimation of their volume scattering sources by fitting in a least-squares sense the differences between the recorded data and the simulated data in the background model, namely the restriction at receivers of the scattered fields. These underdetermined linear source problems involve two main steps: a multidimensional deconvolution of the scattered data by the data-domain Hessian, followed by the propagation of the deconvolved scattered data backward in time. Once the source problems have been solved, DAWs follow by solving the wave equation in the background model using the sum of the experimental sources and the scattering sources as extended sources. Finally, the redatumed datasets, whose accuracy depends on the precision of the background medium between the acquisition surface and the datum, are readily obtained by sampling the DAWs at arbitrary datum levels. The primary challenge in computing accurate DAWs lies in the multidimensional deconvolution of the scattered data, which requires solving a data-domain normal equation with preconditioned Krylov-subspace iterative methods, where each iteration requires one forward and one backward simulation. We demonstrate the accuracy of the method and discuss its computational cost with several benchmarks representing various experimental environments (onshore with weathered layers, shallow and deep offshore).

SummaryDistributed acoustic sensing (DAS) has emerged as a potential solution to the sparse instrumentation issue in the world’s oceans. DAS involves repurposing fibre optic cables into dense receivers. The spatial undersampling limits our understanding of fundamental oceanic processes, like ocean dynamics. We use long-term DAS recordings from Svalbard, Norway, over two roughly perpendicular fibre segments to analyse ocean surface gravity wave (OSGW) signals and gain additional insight into their dynamics. This fibre layout allows estimation of the angle of arrival for OSGW generated under different weather conditions, while the long-term recording allows one to study seasonal variations. By investigating different wind directions, we observe two sets of OSGW arrivals: swells generated by distant storms and waves generated by the local winds. The swells consistently originate from the south-west, whereas the wind-forced OSGW follows, more or less, the local wind direction. Moreover, we conduct a detailed analysis of the recorded swell waves by computing their origin time, great circle propagation distance, group velocity, incidence angle, location, and interference pattern. This yields important data that can be used to characterise local and distant Atlantic storms. Only one receiver system has been employed, and more receivers are needed to validate the results obtained here and gain additional insight into the OSGW signals recorded on DAS systems.

SummaryInversion of geophysical data usually exhibits strong non-uniqueness, arising from sparse data coverage, limited number of measurements, inherent nonlinearity of governing physical laws, noise, and other factors. Methods based on Monte Carlo sampling are commonly used to explore the posterior model distributions, but these approaches are computationally demanding. Variational inference (VI) provides an alternative by transforming a high-dimensional sampling problem into an optimization problem, thereby significantly reducing the computational time. However, conventional VI methods, which typically use simple distribution families, like Gaussians, to approximate the posterior, may lack flexibility necessary to capture the complexity of the posterior distributions. Normalizing flows (NFs), a type of deep generative models, address this limitation by transforming a simple initial distribution into a highly complex target distribution through a sequence of invertible and differentiable transformations. In this study, we develop an NF-based VI method and apply it to electromagnetic (EM) data. This approach allows for explicit integration of prior knowledge and reference models into the inversion process. Both synthetic tests and field applications on EM data demonstrate that NF-based inversion effectively recovers the posterior model distribution in a more efficient manner, while providing excellent data fitting performance. Unlike many other machine learning algorithms, NFs do not require a training set, making it highly transferable across various inversion problems with minimal adjustments. The proposed NF-based method offers a more robust and computationally efficient solution to uncertainty quantification and shows great potential to be extended to solve 3-D geophysical Bayesian inversions, a major challenge that the geophysical community has faced for decades.

Peak wind gusts in Boulder and possibly other locations along the Front Range don't pack the same punch they used to, according to a new analysis led by scientists at the U.S. National Science Foundation National Center for Atmospheric Research (NSF NCAR).

The Western Pacific Subtropical High (WPSH) functions like Earth's atmospheric traffic controller, directing summer monsoon flows that regulate rainfall and temperatures across East Asia. When this high-pressure system misbehaves, the consequences can be dramatic—from the devastating Yangtze River floods of 1931 and 1998, to 2020's endless rainy season, and the record-shattering 2022 heat waves that baked the Yangtze basin.

Source: AGU Advances

In 2003, several states and environmental groups sued the U.S. EPA for violating the Clean Air Act by not regulating emissions from new vehicles.

When the case eventually reached the Supreme Court, a group of climate scientists contributed an amicus brief—a legal document in which a third party not directly involved in the case can offer testimony—sharing data demonstrating that rising global temperatures were directly caused by human activity. This led to the Supreme Court deciding that greenhouse gases did constitute pollutants under the Clean Air Act and, ultimately, to the EPA’s 2009 endangerment finding that greenhouse gas emissions endanger human health. The endangerment finding became the basis for governmental regulation of greenhouse gases. Sixteen years later, the Trump administration is poised to repeal it, along with other environmental protections.

In a new commentary, Saleska et al., the authors of the amicus brief, reflect on the brief and the damage the endangerment finding’s potential repeal could cause.

Today, many of the climate scientists’ concerns from the early 2000s have become reality, the authors say. The Earth’s 12 warmest years on record all occurred after 2009. The oceans are growing hotter and more acidic, and Arctic sea ice is retreating. Sea level rise is speeding up—from 2.1 millimeters per year between 1993 and 2003 to 4.3 millimeters per year between 2013 and 2023. Continued warming is also affecting human health. Direct heat-related deaths are on the rise, and so too are wildfires, precipitation extremes such as flooding and drought, climate-enabled spread of disease, and disruptions in agricultural productivity.

The amicus brief authors also note that attribution science, the field that links specific weather events to climate change, has advanced since 2009. Today, they are even more firm in their stance that climate change poses a serious threat to society.

A reversal of the endangerment finding would likely require a lengthy legal process and compelling evidence that climate change does not pose a risk to human health and well-being. But the possibility of a repeal implies a worrying lack of trust in the science and increasing politicalization surrounding climate issues, the authors say. If the role of climate science in policymaking is weakened, it will harm scientific progress and our national well-being, they warn. (AGU Advances, https://doi.org/10.1029/2025AV001808, 2025)

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

Citation: Owen, R. (2025), What’s changed—and what hasn’t—since the EPA’s endangerment finding, Eos, 106, https://doi.org/10.1029/2025EO250219. Published on 24 June 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.

Mars’s current atmosphere is downright tenuous—conferring less than 1% the pressure of Earth’s—but there’s good evidence that it was substantially thicker in the past. Researchers have now directly observed atoms escaping in a hitherto unobserved way.

That process, known as atmospheric sputtering, may have facilitated Mars’s transition from a watery planet to the arid world it is today, the team reported in Science Advances.

“I’ve been looking for this since I was a postdoc.”

Since the early 2010s, planetary scientist Shannon Curry at the University of Colorado Boulder has pored over data from Mars, looking for signs that the Red Planet’s atmosphere is eroding. It’s been a long journey, she said. “I’ve been looking for this since I was a postdoc.” Colleagues even took to ribbing Curry that her search might be folly. “Every year, I would run my code, and I would look for it,” she said. “We started joking that it was like a unicorn.”

But Curry, the principal investigator of NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission, now has reason to celebrate: She and her colleagues believe they’ve finally captured the first direct observations of sputtering on Mars.

Escaping via Kicks

Planetary atmospheres are constantly changing; everything from solar eclipses to volcanic eruptions to fossil fuel burning can alter their composition, density, and structure. Atmospheres can also erode via several processes. One is photodissociation, in which photons break apart molecules, creating lighter constituents that can go on to escape. Sputtering is another. That process involves high-energy ions, accelerated by the Sun’s electric field, plowing through a planet’s upper atmosphere and colliding with neutral atoms. Those energetic kicks impart enough energy to the neutral particles that they go on to escape the planet’s gravitational field.

Sputtering plays only a minor role in the escape of Mars’s atmosphere today—the rate of sputtering is currently several orders of magnitude lower than that of photodissociation. “But we think, billions of years ago, it was the main driver of escape,” Curry said.

Thanks to nearly a decade’s worth of MAVEN observations, Curry and her collaborators had access to detailed records of the Sun’s electric field and neutral particles in Mars’s atmosphere. They focused on neutral argon, a heavy noble gas. It’s generally difficult to remove argon from the Martian atmosphere in other ways, said Manuel Scherf, an astrophysicist at the Space Research Institute at the Austrian Academy of Sciences in Graz, Austria, who was not involved in the research. “The only really efficient escape mechanism at the moment is sputtering.”

Follow the Darkness

“We have to get out of the sunlight in order to detect sputtering.”

The team used simulations of Mars’s atmosphere to home in on where they might find a signal of sputtering. Looking above an altitude of roughly 360 kilometers seemed to be key, the modeling revealed. The team furthermore knew that it was critical to look at the side of Mars pointing away from the Sun. That’s because photodissociation dominates during the day. “We have to get out of the sunlight in order to detect sputtering,” said Janet Luhmann, a space scientist at the University of California, Berkeley, and a member of the research team.

The researchers compared the abundances of argon in the Martian atmosphere in two altitude bins: 250–300 and 350–400 kilometers. They also compared periods during which the Sun’s electric field pointed either toward or away from Mars. Sputtering should preferentially occur in the higher-altitude bin when the Sun’s electric field points toward Mars—that’s when ions are accelerated toward the planet’s atmosphere. Indeed, Curry and her colleagues found statistically higher densities of argon in that group of data.

The team calculated that argon was being sputtered at a rate of about 1023 atoms per second. That might seem like a large number, but it’s actually about 100 times lower than the current rate of photodissociation, Luhmann said. But billions of years ago, the Sun’s electric field was likely far stronger than it is today, and sputtering rates could have been much higher, possibly being the dominant contributor to eroding Mars’s atmosphere.

Such a shift could help explain what happened to Mars’s water.

There’s copious evidence that liquid water once existed on the surface of Mars—river valleys, dried lake beds, and other water-carved features persist to this day. This means that Mars’s atmosphere must have once been thick enough to support liquid water. “You need that atmospheric pressure pushing down on water to make it a liquid,” Curry said. But the Red Planet today is an arid world devoid of visible water. Sputtering could explain, at least partially, how the loss of pressure occurred.

And because liquid water is intimately tied to our conception of life, these results have important meaning, Scherf said. “You cannot know whether life can exist somewhere if you don’t understand the atmosphere and how it behaves.”

Curry and her colleagues are hoping to use MAVEN data for years to come, but the team recently learned that they may not have that opportunity: The mission is slated to be canceled in the proposed 2026 federal budget. That’s been a huge blow emotionally, said Curry, but the team isn’t giving up yet. “The United States right now is number one in Mars exploration,” Curry said. “We will lose that if we cancel these assets.”

—Katherine Kornei (@KatherineKornei), Science Writer

Citation: Kornei, K. (2025), Scientists spot sputtering on Mars, Eos, 106, https://doi.org/10.1029/2025EO250231. Published on 24 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.