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

Rock glaciers are debris landforms found in many mountain ranges on Earth. They represent the movement of permanently frozen ground over long periods of time and can be used to understand how climate change is affecting permafrost.  

A new article in Reviews of Geophysics explores the use of “Rock Glacier Velocity” to measure how fast these landforms move each year, and its relationship with climatic factors. Here, we asked the authors to give an overview of Rock Glacier Velocity, how scientists measure it, and what questions remain.

What makes rock glaciers unique landforms? 

Rock glaciers primarily form where the ground temperature ranges from approximately -3 to 0°C. Generated by gravity-driven deformation of permafrost, rock glaciers exhibit distinct morphologies indicative of a cohesive flow. The motion mechanism, known as rock glacier creep, involves shearing in one or more layers (i.e., shear horizons) at depth within the permafrost and deformation of the frozen materials above. Changes in rock glacier creep rates depend primarily on changes in ground temperature. Rock glaciers provide a unique opportunity to indirectly document the evolution of permafrost temperatures in mountainous regions.

Remote sensing and field photos of rock glaciers. Credit: Hu et al. [2025], Figure 1

What is “Rock Glacier Velocity” and why is it important to measure? 

“Rock Glacier Velocity (RGV)” refers to the time series of annualized surface velocity reflecting the movement related to rock glacier creep. Since 2022, RGV has been accepted by the Global Climate Observing System (GCOS) as an Essential Climate Variable (ECV) Permafrost Quantity. An ECV is defined as “a physical, chemical, or biological variable (or group of linked variables) that is critical for characterizing the Earth’s climate.” An ECV Quantity is a measurable parameter necessary for characterizing an ECV. Rock Glacier Velocity is instrumental in assessing the state of permafrost under climate change, especially in places where direct monitoring is scarce. From a climate-oriented perspective, relative changes in Rock Glacier Velocity are significant.

What are the main factors that control Rock Glacier Velocity? 

Rock Glacier Velocity is collectively controlled by the geomorphologic features such as slope and landform geometry, as well as the thermo-mechanical properties of the frozen ground, such as ice content, subsurface structure, temperature, and the presence of unfrozen water under permafrost conditions. On a given rock glacier, relative changes in surface velocity over time usually reflect the climatic impacts, with temperature forcing being the dominant factor, especially when temperatures approach 0°C.

How do scientists observe and monitor Rock Glacier Velocity at different spatial scales? 

An illustration showing different survey methods for quantifying Rock Glacier Velocity. Credit: Hu et al. [2025], Figure 5a

Rock Glacier Velocity can be observed and monitored using in-situ and remote sensing methods. Global Navigation Satellite System (GNSS), theodolite, and total station surveys, provide point-based in-situ measurements. Regional-scale surveys typically employ remote sensing techniques, such as laser scanning, photogrammetry, radar interferometry, and radar offset tracking. In-situ RGV time series’ are rare and have mostly been provided from the European Alps, but they can be more than 20 years long. The goal is to leverage the experience gained from the systematic compilation of those in-situ time series to expand the RGV collection to regional-scale surveys using remote sensing techniques.

What kinds of patterns have been observed in Rock Glacier Velocity? 

According to the Rock Glacier Velocity data from across the European Alps, rock glaciers have generally accelerated alongside increasing air temperatures over the past three decades. At the interannual scale, RGV exhibits a regionally synchronous pattern with distinct acceleration phases (i.e., 2000–2004, 2008–2015, and 2018–2020) which are interrupted by deceleration or a steady kinematic state. However, systematic monitoring and documentation of Rock Glacier Velocity is currently lacking in many parts of the world.

How is climate change expected to influence Rock Glacier Velocity? 

Among the climatic factors, multi-annual air temperature changes primarily influence Rock Glacier Velocity by altering the ground thermal state of rock glaciers. Snow cover acts as an insulating layer whose development varies from year to year, causing the ground temperature to deviate from the air temperature on an interannual scale.

In general, warmer ground temperatures favor rock glacier movement. This pattern is expected to occur in many rock glaciers in the future as the climate continues to warm.  When the ground temperature reaches 0°C, some rock glaciers experience drastic acceleration. However, consequent thawing at the tipping point of 0°C causes the rock glacier creep to decline.

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

First, a standardized strategy for monitoring Rock Glacier Velocity using different methods is under development. We call for more systematic and consistent velocity measurements that can be used to generate Rock Glacier Velocity data products.

Second, the mechanisms linking climatic factors to Rock Glacier Velocity still need to be explored further, such as whether water infiltrates the partially frozen body of a rock glacier and how cold temperatures influence winter deceleration.

Additionally, an in-depth understanding of the relationship between Rock Glacier Velocity, environmental factors, and permafrost conditions requires observations combined with laboratory work and numerical modeling. This is necessary in order to incorporate rock glacier processes into land surface models and predict future changes in a warming climate.

—Yan Hu (huyan@link.cuhk.edu.hk, 0000-0001-8380-276X), University of Fribourg, Switzerland; and Reynald Delaloye (0000-0002-2037-2018), University of Fribourg, Switzerland

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: Hu, Y., and R. Delaloye (2025), Rock Glacier Velocity: monitoring permafrost amid climate change, Eos, 106, https://doi.org/10.1029/2025EO255017. Published on 3 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.

The clean-up and site restoration of a New Zealand research station in Antarctica has provided valuable lessons on the challenges of contaminated sites, according to a study in the journal Polar Record.

Author(s): Shu-Chao Duan, Shao-Tong Zhou, Gang-Hua Wang, Ming-Xian Kan, Qiang Xu, Bo Xiao, Hai-Bin Ou, Long Xie, and Qiang Wang

Inertial confinement of fusion plasmas can be realized using the dynamic Z pinch, an electromagnetically driven cylindrical implosion system that is also used to generate intense x rays. However, the Z pinch is subject to magnetic Rayleigh-Taylor (MRT) instability, which must be suppressed for pract…

[Phys. Rev. E 111, 065203] Published Tue Jun 03, 2025

In September 2023, a bizarre global seismic signal was observed which appeared every 90 seconds over nine days—and was then repeated a month later. Almost a year later, two scientific studies proposed that the cause of these seismic anomalies were two mega tsunamis which were triggered in a remote East Greenland fjord by two major landslides which occurred due to warming of an unnamed glacier.

In the United States, earthen levees are an integral part of flood control systems, protecting around 23 million Americans and crucial infrastructure. Recently, the American Society of Civil Engineers' 2025 Report Card for America's Infrastructure rated the nation's levees a D+, with an estimated $70 billion needed for maintenance to bring them into a state of good repair.

Nine people have been killed in a series of landslides, triggered by heavy rainfall, that have struck an army camp.

At about 7 pm local time on 1st June 2025, a series of landslides struck an army camp at Chaten in the Lachen District of Sikkim in India. It is believed that nine people have been killed, although at the time of writing six of these people were still missing, including an army officer, his wife and daughter.

Chaten is located at [27.7188, 85.5581]. This is a Google Earth image of the site, collected in March 2022:-

Google Earth image of the site of the 1 June 2025 landslide at Chaten in Sikkim, India.

The best imagery of the landslides that I have found is on a Youtube video posted by Excelsior News:-

This still captures the site well:-

The 1 June 2025 landslides at Chaten in Sikkim, India. Still from a video posted to Youtube by Excelsior News.

The image shows two main landslide complexes (plus one in the background). Each consists of a series of shallow slips on steep terrain – the one on the left has at least three initial failures, on the right there are also at least three). These have combined to create open hillslope landslides that have stripped the vegetation and surficial materials. Note the very steep lower slopes to the river.

These shallow landslide complexes are characteristic of extremely intense rainfall events, which saturate the soil and regolith from the boundary with the underlying bedrock. This causes a rapid loss of suction forces and a reduction in effective stress, triggering failure. The high water content of the soil then promotes mobility.

It is interesting to note that the natural vegetation has been removed from these slopes. It would be premature to assert that this was an underlying cause of the landslides, but it may have been a factor.

It appears that there has also been erosion of the riverside cliffs, which has left other parts of the camp in severe danger.

Sadly, given the terrain and the availability of people to participate in a rescue (which is one advantage of an event in an army camp), the prospects for those who are missing are not postive.

Return to The Landslide Blog homepage Text © 2023. The authors. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

SummaryInfrasonic signals of interest can occur during periods with persistent, coherent, background noise, which may be natural or anthropogenic. For high signal-to-noise (SNR) ratio transient signals, an “overprinting” of the coherent background may occur, and the signal may still be detected. However, this approach fails for low SNR signals of interest, which may be obscured by coherent noise. An infrasound beamforming method based on generalized least squares (GLS) is investigated for detecting transient signals of interest in the presence of coherent and incoherent background noise. This approach relies on an estimate of the noise covariance, captured in a covariance matrix, to effectively null contributions to the array response from noisy directions of arrival. Synthetic array data is used to investigate the performance of the GLS beamformer compared to the Bartlett beamformer when coherent and incoherent backgrounds are present. Additionally, the effects of array element number and relative strength of the interfering signal on the GLS estimates is investigated. GLS empirical area under the curve estimates suggest that the beamformer can recover coherent power for a signal of interest lower in amplitude than the coherent background, but this effectiveness degrades more quickly with SNR for a four element array compared to a six or eight element infrasound array. Finally, infrasound from the Forensic Surface Experiment, a bolide signal observed at IMS array I37NO, and a volcanic signal recorded at the Alaska Volcano Observatory array ADKI are used to evaluate GLS performance on recorded data. A ten minute window was used to capture the background noise, and the coherent background signal was nulled in all three examples.

In the southern flanks of the Indian Ocean and the central and eastern Pacific, just north of the Antarctic Circumpolar Current, lie the Subantarctic Mode Waters. As part of the global ocean conveyor belt, these large masses of seawater transfer substantial amounts of heat and carbon northward into the interiors of the Indian and Pacific oceans. These waters hold about 20% of all anthropogenic carbon found in the ocean, and their warming accounted for about 36% of all ocean warming over the past two decades—making them critical players in Earth's climate system.

Along with nutrients like nitrogen and phosphorus, iron is essential for the growth of microscopic phytoplankton in the ocean. However, a new study led by oceanographers at the University of Hawaii'i (UH) at Mānoa revealed that iron released from industrial processes, such as coal combustion and steel making, is altering the ecosystem in the North Pacific Transition Zone, a region just north of Hawai'i that is important for fisheries in the Pacific.

When it comes to carbon emissions, there's no bigger foe than the building and construction sectors, which contribute at least a third of global greenhouse gases.

A small international team of volcanologists has built a more detailed picture of the Campi Flegrei caldera's internal structure using high-resolution seismic imaging and results from rock physics experiments conducted on core samples collected from deep wells.

A newly published study finds that California's Salton Sea emits hydrogen sulfide, a toxic and foul-smelling gas, at rates that regularly exceed the state's air quality standards. The presence of these emissions in communities surrounding the Salton Sea is "vastly underestimated" by government air-quality monitoring systems, the researchers found.

A study co-led by Irina Gorodetskaya, a researcher at the Interdisciplinary Center of Marine and Environmental Research (CIIMAR), brings together all up-to-date data on the phenomenon of atmospheric rivers in Antarctica and reveals the uncertainties arising from the effects of climate change.

New research led by the University of Sydney adds to our understanding of how rapidly rising sea levels due to climate change foreshadow the end of the Great Barrier Reef as we know it.

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.

In a move that worried politicians and space scientists alike, President Trump announced on 31 May that he will withdraw his nomination of Jared Isaacman for the position of NASA administrator, according to Semafor. Isaacman’s nomination received bipartisan support and he was expected to easily pass a Senate confirmation vote in a few days.

 
Related

•  White House to pull NASA nominee Isaacman
•  Trump withdraws Jared Isaacman’s nomination as NASA administrator
• The Planetary Society reissues urgent call to reject disastrous budget proposal for NASA
• Get Involved: AGU Science Policy Action Center

This is seismic.Isaacman had clearly articulated a strong support for science, and the withdrawal of his nomination yet further imperils NASA's Science Mission Directorate.www.semafor.com/article/05/3…

— Paul Byrne (@theplanetaryguy.bsky.social) 2025-05-31T20:49:52.860Z

Trump cited a “thorough review of prior associations” as the reason for withdrawing the nomination. It was not immediately clear whether he was referring to Isaacman’s past donations to Democrats or his ongoing associations with former DOGE head and SpaceX CEO Elon Musk, who spent the weekend distancing himself from the president. Both of these associations were public at the time of Isaacman’s nomination.

Isaacman, a billionaire, private astronaut, and CEO of credit processing company Shift4 Payments, was questioned by the Senate Committee on Commerce, Science, and Transportation in a nomination hearing in April. Despite a few contentious moments regarding Isaacman’s association with Musk and some waffling over NASA’s Moon-to-Mars plan, the committee ultimately approved Isaacman’s nomination with strong bipartisan support.

When Trump announced Isaacman’s nomination in December 2024, very early for a NASA administrator, space scientists greeted the news with cautious optimism. Isaacman had vocally expressed support for the imperiled Chandra X-ray Observatory, and is a known space enthusiast.

Now, with the withdrawal of his nomination just days after a president’s budget request that would devastate Earth and space science, scientists fear for the future of NASA.

—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.

North America's deepest gorge, Hells Canyon, which slithers along the border of Idaho and Oregon, is a surprisingly new addition to the Earth's ancient landscape. A recent study suggests that a monumental shift in Snake river drainage around 2.1 million years ago reshaped the topography, carving out Hells Canyon, which plunges an astonishing 2,400 m, significantly deeper than the Grand Canyon.

Source: AGU Advances

In the southern flanks of the Indian Ocean and the central and eastern Pacific, just north of the Antarctic Circumpolar Current, lie the Subantarctic Mode Waters. As part of the global ocean conveyor belt, these large masses of seawater transfer substantial amounts of heat and carbon northward into the interiors of the Indian and Pacific Oceans. These waters hold about 20% of all anthropogenic carbon found in the ocean, and their warming accounted for about 36% of all ocean warming over the past 2 decades—making them critical players in Earth’s climate system.

Prior research has suggested Subantarctic Mode Waters form when seawater flowing from warm, shallow subtropical regions mixes with water flowing from cold, deep Antarctic regions. But the relative contributions of each source have long been debated.

Fernández Castro et al. used the Biogeochemical Southern Ocean State Estimate model to investigate how these water masses form. The model incorporates real-world physical and biogeochemical observations—including data from free-roaming floats—to simulate the flow and properties of seawater. The researchers used it to virtually track 100,000 simulated particles of water backward in time over multiple decades to determine where they came from before winding up in Subantarctic Mode Waters.

The particle-tracking experiment confirmed that subtropical and Antarctic waters indeed meet and mix in all areas where Subantarctic Mode Waters form but offered more insight into the journeys and roles of the two water sources.

In the Indian Ocean, the simulations suggest, Subantarctic Mode Waters come mainly from warm, shallow, subtropical waters to the north. In contrast, in the Pacific Ocean, Subantarctic Mode Waters originate primarily from a water mass to the south known as Circumpolar Deep Water.

Along their southward flow to the subantarctic, subtropical waters release heat into the atmosphere and become denser, while ocean mixing reduces their salinity. Meanwhile, the cooler Circumpolar Deep Water absorbs heat and becomes fresher and lighter as it upwells and flows northward from the Antarctic region to the subantarctic.

These findings suggest that Subantarctic Mode Waters affect Earth’s climate differently depending on whether they form in the Indian or Pacific Ocean—with potential implications for northward transport of carbon and nutrients. Further observations could help confirm and deepen understanding of these intricacies. (AGU Advances, https://doi.org/10.1029/2024AV001449, 2025)

—Sarah Stanley, Science Writer

Citation: Stanley, S. (2025), On the origins of Subantarctic Mode Waters, Eos, 106, https://doi.org/10.1029/2025EO250207. Published on 2 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.

Author(s): Ajaz Mir, Pintu Bandyopadhyay, Madhurima Choudhury, Krishan Kumar, and Abhijit Sen

We compare model solutions of a forced Kadomtsev-Petviashvili (fKP) equation with experimental observations of dust acoustic precursor solitons excited by a supersonically moving charged cylindrical object in a dusty plasma medium. The fKP equation is derived from a three-fluid-Poisson model of the …

[Phys. Rev. E 111, 065201] Published Mon Jun 02, 2025

Author(s): Alan A. Kaptanoglu, Matt Landreman, and Michael C. Zarnstorff

We consider the problem of optimizing a set of passive superconducting coils (PSCs) with currents induced by a background magnetic field rather than power supplies. In the nuclear fusion literature, such coils have been proposed to partially produce the 3D magnetic fields for stellarators and provid…

[Phys. Rev. E 111, 065202] Published Mon Jun 02, 2025

In the Paris Agreement of 2015, the international community of countries agreed to limit global warming to well below 2 °C, and preferably to 1.5 °C, compared to pre-industrial levels. This refers to the increase in global surface air temperature, inspected at any time of interest as an average over 20 years.