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Hidden in Arctic sea ice are microscopic organisms that do more than eke out a meager existence on scraps of light filtered through their frozen habitat. New research has shown that ice diatoms have adapted to move efficiently through the ice, allowing them to navigate to better sources of light and nutrients. During in situ and laboratory experiments, ice diatoms glided through the ice roughly 10 times faster than diatoms from temperate climates and kept gliding even at −15°C, the lowest temperature recorded for single-celled organisms.

“People often think that diatoms are at the mercy of their environment,” said Manu Prakash, a bioengineering researcher at Stanford University in California and lead researcher on this discovery. “What we show in these ice structures is that these organisms can actually move rapidly at these very cold temperatures to find just the right home. It just so happens that home is very cold.”

These findings, published in the Proceedings of the National Academy of Sciences of the United States of America, may help scientists understand how microorganisms and polar ecosystems respond to climate change.

Gliding Through Life Researchers drilled several cores from sea ice in the Chukchi Sea to understand the movement patterns of diatoms. Credit: Natalie Cross

Diatoms are microscopic, single-celled algae that photosynthesize. Up to 2 million species of diatoms produce at least 20% of the oxygen we breathe and form the backbone of ecosystems throughout the world, from the humid tropics to the frigid poles. Scientists have known since the 1960s that diatoms live within and move through the ice matrix but have been unable to decipher how they do it.

“Ice is an incredible porous architecture of highways,” Prakash explained. “Light comes from the top in the ice column, and nutrients come from the bottom. There is an optimal location that [a diatom] might want to be, and that can only be possible with motility.” (Motility is the ability of an organism to expend energy to move independently.)

Prakash and a team of researchers sought to observe ice diatoms’ movements in situ and so set off for the Chukchi Sea aboard the R/V Sikuliaq. On a 45-day expedition in 2023, they collected several cores from young sea ice, extracted diatoms from the cores, and studied the diatoms’ movements on and within icy surfaces under a temperature-controlled microscope customized for subzero temperatures.

At temperatures down to −15°C, Arctic ice diatoms actively glided on ice surfaces and within ice channels. The researchers said that this is the lowest temperature at which gliding motility has been observed for a eukaryotic cell.

“Life is not under suspension in these ultracold temperatures. Life is going about its business.”

“Life is not under suspension in these ultracold temperatures,” Prakash said. “Life is going about its business.”

“This is a notable discovery,” said Julia Diaz, a marine biogeochemist at Scripps Institution of Oceanography in San Diego. “These diatoms push the lowest known temperature limit of motility to a new extreme, not just compared to temperate diatoms, but also compared to more distantly related organisms.” Diaz was not involved with this research.

“Since the 1960s, when J. S. Bunt first described sea ice communities and observed that microbes were concentrated in specific layers of the ice, it has been obvious that they must have a means to navigate through ice matrices,” said Brent Christner, an environmental microbiologist at the University of Florida in Gainesville who also was not involved with this research. “This study makes it clear that some microbes traverse gradients in the ice by gaining traction on one of the most slippery surfaces known!”

“While these diatoms are clearly ice specialists, they nevertheless appear to be equipped with the equivalent of all-season tires!”

The team compared the movement of ice diatoms to those of diatoms from temperate climates. On both icy and glass surfaces under the same conditions, ice diatoms moved roughly 10 times faster than temperate diatoms. In cold conditions on icy surfaces, temperate diatoms lost their ability to move completely and just passively drifted along. These experiments show that ice diatoms adapted specifically to their extreme environments, evolving a way to actively seek out better sources of light to thrive.

“I was surprised the ice diatoms were happily as motile on ice as glass, and much faster on glass that the temperate species examined,” Christner said. “While these diatoms are clearly ice specialists, they nevertheless appear to be equipped with the equivalent of all-season tires!”

On ice (left) and on glass (right) surfaces, ice diatoms (top) move faster than temperate diatoms (bottom). All experiments here were conducted at 0°C and are sped up 50 times to highlight the diatoms’ different gliding speeds. Credit: Zhang et al., 2025, https://doi.org/10.1073/pnas.2423725122, CC BY-NC-ND 4.0 Can Diatoms Adapt to Climate Change?

The Arctic is currently experiencing rapid environmental changes, warming several times faster than the rest of the world. Arctic climate change harms not only charismatic megafauna like polar bears, Prakash said, but microscopic ones, too.

“These ecosystems operate in a manner that every one of these species is under threat.”

Diatoms are “the microbial backbone of the entire ecosystem,” Prakash said. “These ecosystems operate in a manner that every one of these species is under threat.”

Prakash added that he hopes future conservation efforts focus holistically on Arctic ecosystems from the micro- to macroscopic. Future work from his own group aims to understand how diatoms’ gliding ability changes under different chemical conditions like salinity, as well as how the diatoms shape their icy environment.

“Scientists used to think that sea ice was simply an inactive barrier on the ocean surface, but discoveries like these reveal that sea ice is a rich habitat full of biological diversity and innovation,” Diaz said. “Sea ice extent is expected to decline as climate changes, which would challenge these diatoms to change the way they move and navigate their polar environment. It is troubling to think of the biodiversity that would be lost with the disappearance of sea ice.”

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

Citation: Cartier, K. M. S. (2025), Ice diatoms glide at record-low temperatures, Eos, 106, https://doi.org/10.1029/2025EO250371. Published on 7 October 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.

Georgia Tech researchers have developed a mathematical formula to predict the size of lakes that form on melting ice sheets—discovering their depth and span are linked to the topography of the ice sheet itself.

An analysis of forest-based projects funded through the sale of carbon credits shows that 10% of them may have a net warming effect on the climate because of the way they alter Earth's albedo, or how much sunlight is reflected back into space.

Author(s): Lipan Qin, Ze Chen, Meiqi Sun, Jin Yan, Yan Tian, Zhongyi Chen, Yan Wang, Xunjie Ma, Xueqing Yan, and Yunliang Wang

A unique coherent bremsstrahlung (CB) regime is proposed for the generation of an isolated half-cycle attosecond pulse (AP), even for the case of a multicycle driving laser pulse, which is realized by the laser pulse interacting with the double-foil target. When the rising edge of the laser pulse in…

[Phys. Rev. E 112, 045202] Published Tue Oct 07, 2025

The June 2023 heat wave in northern European seas was "unprecedented but not unexpected," new research shows.

In July 2025, I recorded 71 fatal landslides worldwide, with the loss of 214 lives.

Each year, July is one of the key months for the occurrence of fatal landslides globally as the Asian monsoon season cranks up to full strength. Thus, it is time to provide an update on fatal landslides that occurred in July 2025. This is my dataset on landslides that cause loss of life, following the methodology of Froude and Petley (2018). At this point, the monthly data is provisional. I will, when I have time, write a follow up paper to the 2018 one that describes the situation since then.

In July 2025 I recorded 71 fatal landslides worldwide, with the loss of 214 lives. The average for the period from 2004 to 2016 was 58.1 fatal landslides, so this is considerably higher than the long term mean, although it is much lower than 2024, which saw 99 fatal landslides.

So, this is the monthly total graph for 2025 to the end of July:-

The number of fatal landslides to the end of July 2025 by month.

Plotting the data by pentad to the end of pentad 43 (29 July), the trend looks like this (with the exceptional year of 2024, plus the 2004-2016 mean, for comparison):-

The number of fatal landslides to 29 July 2025, displayed in pentads. For comparison, the long term mean (2004 to 2016) and the exceptional year of 2024 are also shown.

The data shows that the acceleration in the rate of fatal landslides occurred much later in the annual cycle than was the case in 2024. It was only late in the month that the rate started to approach that of 2024. Indeed for much of the month, the fatal landslide rate (the gradient of the line) is broadly similar to the long term mean, albeit with a much higher starting point.

But note also the distinct acceleration late in the month, which makes what then happened in August 2025 particularly interesting. Watch this space.

Notable events included the 8 July 2025 catastrophic debris flow at Rasuwagadhi in Nepal, but no single landslide killed more than 18 people in July 2025.

I often draw a link between the rate of fatal landslides and the surface air temperature. The Copernicus data shows that July 2025 was “0.45°C warmer than the 1991-2020 average for July with an absolute surface air temperature of 16.68°C“. It was the “third-warmest July on record, 0.27°C cooler than the warmest July in 2023, and 0.23°C cooler than 2024, the second warmest.”

Reference

Froude M.J. and Petley D.N. 2018. Global fatal landslide occurrence from 2004 to 2016. Natural Hazards and Earth System Science 18, 2161-2181. https://doi.org/10.5194/nhess-18-2161-2018

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.

SummaryA strong earthquake sequence in Storfjorden, south of Svalbard, was initiated by an Mw 6.1 event on 21 February 2008. Earthquake distribution and fault plane solutions indicate that seismic activity is controlled by unmapped NE-SW striking oblique-normal faults, contrasting with the major N-S oriented faults mapped onshore Svalbard. We present a geophysical model derived from an ocean bottom seismometer profile crossing the seismogenic zone to identify structures in the crust and uppermost mantle that potentially control the earthquake source mechanism. Travel-time forward modeling using raytracing, combined with travel-time tomography and gravity-magnetic modeling, reveal distinct crustal domains across the earthquake region. Crystalline crustal P-wave velocities range from 6.1 km/s to 6.7 km/s at the Moho depth in the eastern section. The western profile section exhibits a higher Vp velocity lower crust (6.6–7.0 km/s) with Vp/Vs ratios of 1.75–1.8 and high density (∼3100 kg/m³). Basement depth reaches 8 km in the west, forming a sedimentary basin, and shallows eastward. The Moho remains relatively flat at 29-32 km depth throughout the profile. The N-S oriented Caledonian suture, identified from deep seismic and potential field data, traverses the Storfjorden earthquake zone. The lithological contacts within the suture zone, inferred from the new OBS data, may facilitate seismic failure oblique to the N-S oriented structure, following the regional stress field.

SummaryWe developed a new amplitude correction method for receiver function imaging to analyze velocity contrasts along dipping interfaces. Because receiver function imaging typically assumes a horizontally layered structure, corrections are needed for amplitude and polarity variations of P-to-S converted phases when analyzing dipping interfaces. However, previous studies have not adequately addressed these effects, and improved receiver function analysis is required to better delineate dipping structures, such as subducting plate surfaces and the oceanic Moho. Therefore, we propose formulae that quantify converted S-wave amplitude variations between horizontal and dipping interfaces. This relationship is expressed as a function of the back azimuth, the ray parameter of an incident P wave, and the dip angle and dip direction of a dipping interface, and in this study, the geometry of the dipping interface (dip angle and dip direction) is assumed. We applied these formulae to receiver function imaging using synthetic and observed data and confirmed that the amplitude of seismic discontinuities was successfully reproduced. This method enables the use of numerous receiver functions regardless of the back azimuths of incident P waves, thereby providing more detailed amplitude estimations for dipping interfaces.

Because the hustle and bustle of cities is driven largely by fossil fuels, urban areas have a critical role to play in addressing global greenhouse gas emissions. Currently, cities contribute around 75% of global carbon dioxide (CO2) emissions, and urban populations are projected only to grow in the coming decades.

Earth's climate has fluctuated between cold and warm periods for millions of years. During the so-called "lukewarm interglacials"—warm phases between 800,000 and 430,000 years ago—atmospheric CO2 concentrations were only around 240 to 260 ppm (parts per million, i.e., molecules per 1 million molecules of air). Later interglacials reached values of 280 to 300 ppm.

Coastal communities around the world have long faced challenges related to flood risks. But as sea levels continue to rise and extreme weather events become more frequent, the need for more effective response strategies is greater than ever.

Bivalves, such as clams, oysters and mussels, record seasonal environmental changes in their shells, making them living chronicles of climate history. A new study of bivalve shells has detected two major episodes of instability in the North Atlantic Ocean's circulation systems, suggesting that the region may be heading toward a tipping point that could trigger sudden, dramatic changes in global weather patterns.

Source: AGU Advances

Because the hustle and bustle of cities is driven largely by fossil fuels, urban areas have a critical role to play in addressing global greenhouse gas emissions. Currently, cities contribute around 75% of global carbon dioxide (CO2) emissions, and urban populations are projected only to grow in the coming decades. Members of the C40 Cities Climate Leadership Group, a network of nearly 100 cities that together make up 20% of the global gross domestic product, have pledged to work together to reduce urban greenhouse gas emissions. Most of the cities have pledged to reach net zero emissions by 2050.

To meet these pledges, cities must accurately track their emissions levels. Policymakers in global cities have been relying on a “bottom-up” approach, estimating emissions levels on the basis of activity data (e.g., gasoline sales) and corresponding emissions factors (such as the number of kilograms of carbon emitted from burning a gallon of gasoline). However, previous studies found some regional variations in emissions estimates depending on which datasets are used, especially in certain geographic locations.

Ahn et al. tried a “top-down” approach, using space-based observations to estimate emissions for 54 C40 cities.

They used data from NASA’s Orbiting Carbon Observatory 3 (OCO-3) mission on board the International Space Station (ISS) to collect high-resolution data over global cities. OCO-3 uses a pair of mirrors called the Pointing Mirror Assembly to scan atmospheric CO2 levels as the ISS flies over a target city.

The researchers found that for the 54 cities, the satellite-based estimates match bottom-up estimates within 7%. On the basis of their measurements, the researchers also found that bottom-up techniques tended to overestimate emissions for cities in central East, South, and West Asia but to underestimate emissions for cities in Africa, East and Southeast Asia, Oceania, Europe, and North America.

The team also examined the link between emissions, economies, and populations. They found that wealthier cities tended to have less carbon intensive economies. For example, North American cities emit 0.1 kilogram of CO2 within their boundaries per U.S. dollar (USD) of economic output, whereas African cities emit 0.5 kilogram of CO2 per USD. They also found that residents living in bigger cities emit less CO2—cities with under 5 million people emit 7.7 tons of CO2 per person annually, whereas cities with more than 20 million people emit 1.8 tons per person, for instance.

The authors note that their findings show that satellite data may help cities better track emissions, improve global monitoring transparency, and support global cities’ efforts to mitigate emissions. (AGU Advances, https://doi.org/10.1029/2025AV001747, 2025)

—Sarah Derouin (@sarahderouin.com), Science Writer

Citation: Derouin, S. (2025), Satellite scans can estimate urban emissions, Eos, 106, https://doi.org/10.1029/2025EO250373. Published on 6 October 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.

To start forming a planet, you need a big disk of dust and gas…and a bit of oomph. We see this formation taking place in protoplanetary disks in young star systems, and the same process must have formed the planets in our own solar system, too.

How do you begin planet formation inside a disk? What is the oomph?

But how do you begin planet formation inside a disk? What is the oomph?

A new set of experiments led by Yin Wang at the Princeton Plasma Physics Laboratory (PPPL) in New Jersey suggests a process called magnetic rotational instability (MRI) may be a contributing factor. MRI describes how magnetic fields interact with the rotating, electrically charged gas in a star’s disk.

MRI has long been thought to play a role in disks by pushing charged gas toward young stars, which consolidate it in a process called accretion. This new research shows MRI can also trigger “wobbles” in the protoplanetary disk that begin the planet formation process.

Taking Metals for a Spin

Traditional ways of accreting dust in a young disk include pressure bumps, said Thanawuth Thanathibodee, an astrophysicist at Chulalongkorn University in Thailand who was not involved in the new research. The bumps are caused by processes such as “the transition between the gas phase and solid phase of some molecules…. When you have a pressure bump, you can accumulate more solid mass, and from there start forming a planet.”

Wang’s paper shows another way the accretion process might begin.

In his team’s experiments at PPPL, a cylinder was placed inside another cylinder, separated by about 32 liters (8.4 gallons) of the liquid metal Galinstan, the brand name of an alloy of gallium, indium, and tin. By spinning the two cylinders at different speeds exceeding 2,000 rotations per minute, scientists churned the liquid metal in a washing machine–like fashion, causing it to swirl through the cavity and mimic how gas swirls in a young star’s disk.

The team measured changes in the magnetic field of the Galinstan as it moved around the cylinders. They found that some regions of the liquid metal would interface, forming what are known as free shear layers. In these layers, some parts slow down and some speed up, a hallmark attribute of MRI.

In a protoplanetary disk, similar layers arise where different parts of the disk’s gas flow meet. These interfaces cause turbulence that pushes material (dust) toward or away from the star and create pockets where dust can accumulate and eventually form planets.

Wang said his work shows MRI-induced wobbling might be happening more often than expected, suggesting “there might be more planets across the universe.”

The work was published in Physical Review Letters earlier this year.

Building on a Successful Experiment

The contribution of MRI to protoplanetary disk formation was previously proposed but was not shown experimentally until now. As such, Thanathibodee said the new work is “very interesting.”

In future experiments, Wang hopes to try different rotation speeds to better understand the free shear layers and examine how MRI is produced. “We’ve found this mechanism is way easier [than thought], but the explored parameter space is still limited,” he said.

Still, MRI isn’t a slam dunk explanation for planet formation. To make the magnetic fields that MRI relies on, the central star must ionize the swirling gas in a protoplanetary disk into a plasma, a process that likely takes place near the star itself. But material close to the star quickly falls onto the star and thus is unavailable to make planets.

If the process instigated by MRI is encountered too close to the star, the researchers found, “the material will be absorbed,” explained Wang. “But if this mechanism happens away from the star, then it helps planet formation.”

MRI must work more quickly than the accretion timescale if it contributes to protoplanetary disk formation, but by how much?

“Nature is complicated, but what our results show is this instability is likely more common than we used to think.”

“My sense is that in order for some planets to form, this [MRI] process needs to be prolonged,” said Thanathibodee. “Otherwise, all the mass will get accreted in a short timescale.”

If MRI does occur in a “sweet region” not too close to or not too far from the young star, said Wang, it could play a role in planet formation. “It’s a plausible candidate for explaining a solar system like ours,” he said. “Nature is complicated, but what our results show is this instability is likely more common than we used to think.”

This same process might drive accretion around black holes too, said Wang, where magnetic fields are much stronger.

—Jonathan O’Callaghan (@astrojonny.bsky.social), Science Writer

Citation: O’Callaghan, J. (2025), Planets might form when dust “wobbles” in just the right way, Eos, 106, https://doi.org/10.1029/2025EO250372. Published on 6 October 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.

The Colorado River, which provides water across the Southwest, has lost about 20% of its flow in the last quarter-century, and its depleted reservoirs continue to decline. But negotiations aimed at addressing the water shortage are at an impasse, and leaders of environmental groups say the secrecy surrounding the talks is depriving the public of an opportunity to weigh in.

Sir Ernest Shackleton's ship, Endurance, was crushed by Antarctic sea ice and sank in November 1915. Emblematic of the heroic age of Antarctic exploration, it is widely considered the strongest polar ship of its time, albeit with a fatal flaw—a weakness in the rudder that caused the ship to sink.

New research shows that marine heat waves can reshape ocean food webs, which in turn can slow the transport of carbon to the deep sea and hamper the ocean's ability to buffer against climate change.

Very heavy rainfall across Nepal, NE. India and Bhutan has triggered landslides that have killed at least 60 people.

Over the last few days, parts of the Himalayas have been hit by very high levels of rainfall, causing large numbers of damaging landslides. The picture is not yet fully clear, but Nepal and Bhutan, and Darjeeling in India, have been particularly badly hit.

Over on the wonderful Save the Hills blog, Praful Rao has documented the rainfall at in Darjeeling – for example, on 4 October 2025 Kurseong recorded 393 mm of rainfall, whilst in Kalimpong a peak intensity of about 150 mm per hour was recorded. The scale of this event is well captured by the Global Precipitation Measurement dataset from NASA – this is 24 hour precipitation to 14:30 UTC on 5 October 2025:-

24 hour precipitation in 14:30 on 5 October 2025 for South Asia. Data from NASA.

News reports from Nepal indicate that 47 people have been killed and more are missing. Of these fatalities, 37 are reported to have been the result of landslides in Ilam. The Kathmandu Post has started to document the events:-

“According to the District Administration Office, five people died in Suryodaya Municipality, six in Ilam Municipality, six in Sandakpur Rural Municipality, three in Mangsebung, eight in Maijogmai, eight in Deumai Municipality, and one in Phakphokthum Rural Municipality. Among the deceased are 17 men and 20 women, including eight children, the office said in its official report.”

The picture in NE India is also dire. In Darjeeling, a series of landslides have killed 23 people. These include 11 fatalities in Mirik and five in Nagrakata. Praful Rao has indicated that he will provide more detail on the landslides in Darjeeling on the Save the Hills blog in due course.

The rains have also caused extensive damage in Bhutan. At least five fatalities have been reported, mostly in “flash floods”. In this landscape, the term flash flood is usually used to describe channelised debris flows.

Of great concern is the reported situation at the Tala Hydroelectric Power Station dam on the Wangchu river in the Chukha district of Bhutan. Reports indicate that water has overflowed the structure due to a failure of the dam gates. According to Wikipedia, this dam is 92 metres tall, so a collapse would be a significant event. This is Bhutan’s largest hydropower facility, and dams are not usually designed to withstand a major overtopping event.

The situation across this region will be unclear for a while, but loyal readers will remember the late monsoon event in Nepal in 2024, in which over 200 people were killed. These events reflect changes in patterns of rainfall associated with anthropogenic climate change and changes in the pattern of vulnerability associated with poor development and construction activities. Neither are likely to improve in the next decade and beyond.

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.

SummaryTo better understand the mechanics of injection-induced seismicity, we developed a two-dimensional numerical code to simulate both seismic and aseismic slip on non-planar faults and fault networks driven by fluid diffusion along permeable faults, in an impervious host rock. Our approach integrates a boundary element method to model fault slip governed by rate-and-state friction with a finite-volume method to simulate fluid diffusion along fault networks. We demonstrate the capabilities of the method with two illustrative examples: (1) fluid injection inducing slow slip on a primary rough, rate-strengthening fault, which subsequently triggers microseismicity on nearby secondary, smaller faults, and (2) fluid injection on a single fault in a network of intersecting faults, leading to fluid diffusion and reactivation of slip throughout the network. This work highlights the importance of distinguishing between mechanical and hydrological processes in the analysis of induced seismicity, providing a powerful tool for improving our understanding of fault behavior in response to fluid injection, in particular when a network of geometrically complex faults is involved.

SUMMARYIn mineral exploration, induced polarization and self-potential are two broadly used active and passive geophysical methods, respectively. In the case of ore bodies, both methods are associated with charge distributions associated with a secondary electrical field (induced polarization) and a source current density (self-potential). Both the chargeability and volumetric source current density distributions bring information regarding the shape of ore bodies. Therefore the joint inversion of these datasets is expected to better tomograms of ore bodies. A joint inversion approach is developed to combine both methods. The objective function to minimize includes two independent components plus a cross-gradient joint function. The use of the cross-gradient is justified from the underlying physics of the two geophysical problems at play. The structure of the cost function is tailored to overcome some problems like convergence and parameter determination in the inverse process. Two synthetic tests and a laboratory experiment are used to benchmark the proposed algorithm. We demonstrate that the joint inversion algorithm performs better than the localizations obtained from independent inversion approaches. To refine the interpretation of the shape of ores, we introduce an ore presence index using the chargeability and source current density resulting from the joint inversion algorithm. The K-Medoids clustering algorithm is used to automatically categorize the calculated ore presence index into different clusters. The cluster with larger values successfully identifies the ore bodies associated with strong chargeability and/or volumetric source current density.