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Author(s): Z. J. Chen, Qing Wang, D. J. Liu, S. T. Zhang, R. J. Cheng, X. X. Li, S. Y. Lv, Z. M. Huang, Z. Y. Xu, Qiang Wang, Z. J. Liu, L. H. Cao, and C. Y. Zheng

A moving space-time electron grating can split a laser pulse into two parts, functioning as a pulse splitter. In this paper, the evolution of dynamic gratings generated by two counterpropagating laser pulses with different frequencies is investigated. These gratings are characterized by finite lengt…

[Phys. Rev. E 112, 015203] Published Wed Jul 09, 2025

Yesterday, catastrophic flood swept down the Bhote Kosi river through Tibet and Nepal. At least 28 people have been killed. There is speculation that this might have been a GLOF.

On 8 July 2025, a catastrophic mudslide / flood suddenly struck the Rasuwagadhi border crossing point between Tibet and Nepal, causing extensive damage. The Himalayan Times reports that there are nine confirmed victims, with a further 19 people missing, in Nepal. Xinhua reports that eleven people are missing in Tibet, but it is unclear as to whether the Nepal figures include these people.

The scale of the event is impressive. All India Radio has posted this video to Youtube:-

Meanwhile, the Nepali Times has reported that the bridge at the at the Rasuwagadhi border crossing point was destroyed, along with a significant part of the infrastructure at that location. Four hydroelectric schemes have been damaged or destroyed (Rasuwagadi, Trisuli III, Trisuli and Benighat), removing 8% of Nepal’s generation capacity.

Rasuwagadhi is located at [28.27875, 85.37808], on the Bhote Kosi river. It is going to be important to understand what has happened to cause this flood. There is speculation that this was a glacial lake outburst flood (GLOF), which is very possible. It could also have been the collapse of a landslide dam or a high altitude landslide that transitioned into a debris flow. I’ll keep an eye on the satellite imagery over the coming days, but at the peak of the monsoon, it may take some time to get a clear image.

Kirsten Cook of the Université Grenoble Alpes has posted to Bluesky some seismic data from a station near to Kathmandu (a long distance downstream of Rasuwagadhi), which shows the flood:-

thehimalayantimes.com/nepal/rasuwa…Another destructive Himalayan flood, this time transboundary. And like most of these, we can see the seismic signals created by the flood at a DMG station near Kathmandu. The flood is visible seismically about an hour before it arrived at the Nepali border…

— Kristen Cook (@kristencook.bsky.social) 2025-07-08T21:07:08.342Z

The annual time period in which cross-border trade between Tibet and Nepal is possible is short, so the damage to the border infrastructure is likely to have significant implications for Nepal. The loss of the electricity generating capacity is likely to be a greater issue in the long term.

I have highlighted previously that I am concerned that the risks associated with these catastrophic landslides / floods in Himalayan valleys are not being adequately considered. This is the third time in four years that such an event has caused massive damage to power generation infrastructure (after the 2021 Chamoli event and the 2023 Sikkim event). The investment cases for these projects much be increasingly difficult to justify, which will have a range of significant wider economic implications.

Return to The Landslide Blog homepage Text © 2023. The authors. CC BY-NC-ND 3.0
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SummaryWe used broadband ocean bottom seismometer (BBOBS) data from the RHUM-RUM experiment to derive the compliance function and estimate the shear velocity (Vs) structure of the subsurface at several sites beneath the Indian Ocean. The primary objective is to map the geological features of poorly explored marine regions, utilizing the compliance function, a measure of seafloor deformation in response to infragravity pressure signals at low frequencies (0.003 to 0.04 Hz). Compliance is the transfer function between vertical displacement and pressure, which is most sensitive to subsurface shear velocities. Our analytical process involves several data processing steps, including the removal of glitches, filtering out seismic events, minimizing tilt effects, calibrating pressure gauges, searching over the frequency and coherence domains to determine the optimal data window, and performing depth-velocity inversion using Monte Carlo method, specifically the Metropolis-Hastings algorithm. We present the ’ComPy’ software, which automates these processing steps for seafloor compliance analysis. The data, recorded over 13 months in 2012-2013 over a large region stretching from La Reunion Island to the Central Indian Ridge (CIR) and the South-West Indian Ridge (SWIR) (water depths of 3 to 5 km), confirm the stability of the compliance function over time. Depth-velocity inversions of the derived compliance measurements, using the Metropolis-Hastings algorithm, illuminate the Vs structure of the oceanic crust down to 8 km. Low Vs anomalies in the crust at the SWIR are consistent with significant serpentinization of a crustal component of tectonically exhumed mantle-derived peridotites.

SummaryIn this study, we present a new algorithm and accompanying software for 3D gravity inversion of density structures. The algorithm combines the strengths of the Bayesian approach-which incorporates prior model information through a variogram model-with the advantages of the Tikhonov regularization framework to address the challenge of depth resolution. We also provide a detailed derivation of the procedure for calculating and fitting the 3D experimental variogram, which serves as a fundamental input to the algorithm. The software implementing the proposed algorithm was developed using the widely adopted computational programming language Matlab. To evaluate its effectiveness, we conducted four representative experiments, ranging from simple to complex scenarios. The synthetic results demonstrate that incorporating model covariance constraints yields a more localized and better-focused density distribution compared to results obtained without such constraints. Additionally, we tested the algorithm's robustness by introducing noise into the observation data. The results show that the proposed method is resistant to noise and maintains strong performance. Finally, we applied the algorithm and software to real field data and compared the results with those from previous studies. The comparison confirms that our method is capable of producing reliable, high-resolution 3D density models, with the added advantage of integrating prior information.

Understanding whether lakes are fed predominantly by groundwater or rainwater is critical to managing our water resources in the face of droughts and shortages, new research has found.

Across Europe and around the world, melting glaciers are reshaping landscapes and climate systems. Researchers Elzė Buslavičiūtė and Dr. Laurynas Jukna from the Institute of Geosciences at the Faculty of Chemistry and Geosciences, Vilnius University, explain how satellite data is used to monitor glacier movement, assess their response to climate change, and calculate these changes through remote sensing technologies from space.

New research finds that not only will climate change make heat waves hotter and longer, but the lengthening of heat waves will accelerate with each additional fraction of a degree of warming.

A large increase in atmospheric methane between 2020 and 2022 raised concerns that tropical wetland emissions had surged in response to a changing climate, but a study led by the University of Michigan shows that this was not the case. The methane must have come from somewhere else.

A daily mismatch between temperature and humidity, observed in certain mountain and waterside regions, helps regulate atmospheric dryness. According to a new study published in Science Advances, this protective effect may weaken under global warming.

Over the past two centuries, humans have locked up enough water in dams to shift Earth's poles slightly away from the planet's axis of rotation, according to recent research.

Forests are a crucial resource for carbon mitigation, currently offsetting around 20% of North American carbon emissions. As temperatures continue to rise, scientists are rushing to understand how climate change is affecting forests and their carbon sequestering abilities. A new study, published in the Proceedings of the National Academy of Sciences, provides some valuable insight into how warmer winters might hinder the ability of trees to store carbon—despite warmer summers encouraging their growth.

The ocean absorbs carbon from the atmosphere, but exactly how much is uncertain. For instance, estimates from the 2023 Global Carbon Budget ranged from 2.2 billion to 4 billion metric tons of carbon per year. One source of this uncertainty may be that the effects of bubbles have not been incorporated into air-sea carbon flux estimates, according to a new study by P. Rustogi and colleagues published in Global Biogeochemical Cycles.

Existing sea level rise models for coastal cities often overlook the impacts of rainfall on infrastructure. Researchers at the University of Hawai'i at Mānoa discovered that by 2050, large rain events combined with sea level rise could cause flooding severe enough to disrupt transportation and contaminate stormwater inlets across 70% of Waikīkī on O'ahu, Hawai'i, due to interactions with water in the Ala Wai Canal.

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

Atmospheric models describing climate change rely on accurate depictions of chemical transport. Prather [2025] examines the different ways to define the troposphere, a highly chemically heterogeneous domain influenced by a range of chemical sources and sinks, from lightning, wildfires, and pollution to convection and rainfall.

The author builds on previous work proposing the use of the artificial age-of-air tracer e90. After calibrating the e90 tracer, Prather demonstrates its application in calculating the mass of the troposphere and troposphere ozone values, using output from UC Irvine’s chemical transport model, ozonesondes representing northern and southern mid-latitudes and the tropics, and satellite ozone profiles. This work presents a practical demonstration of the calibration of an age-of-air tropopause that could potentially be applied more widely in other models or other age-of-air tracers.  

Citation: Prather, M. J. (2025). Calibrating the tropospheric air and ozone mass. AGU Advances, 6, e2025AV001651. https://doi.org/10.1029/2025AV001651

—Kristina Vrouwenvelder, Executive Editor, AGU Advances

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

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

Incoming radiation from the Sun is balanced by reflected and emitted radiation from Earth, but greenhouse gases trap radiation in Earth’s atmosphere, causing energy to accumulate in the atmosphere, oceans, and land.

Mauritsen et al. [2025] discuss how recent work analyzing Earth’s energy imbalance reveals that it is increasing much faster than predicted and is now almost double what has been predicted by climate models. The current discrepancy between the measured energy imbalance and that predicted by climate models is likely caused by a decrease in Earth’s solar reflectivity, possibly because models have not correctly accounted for sea surface temperature patterns or effects of aerosol particles.

Understanding these changes in Earth’s energy imbalance and their effects on global warming is critical to science and policy. However, these measurements rely heavily on several satellites scheduled for decommissioning, threatening our understanding of our climate future.

Citation: Mauritsen, T., Tsushima, Y., Meyssignac, B., Loeb, N. G., Hakuba, M., Pilewskie, P., et al. (2025). Earth’s energy imbalance more than doubled in recent decades. AGU Advances, 6, e2024AV001636. https://doi.org/10.1029/2024AV001636

—Kristina Vrouwenvelder, Executive Editor, AGU Advances

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: Global Biogeochemical Cycles

The ocean absorbs carbon from the atmosphere, but exactly how much is uncertain. For instance, estimates from the 2023 Global Carbon Budget ranged from 2.2 billion to 4 billion metric tons of carbon per year. One source of this uncertainty may be that the effects of bubbles have not been incorporated into air-sea carbon flux estimates, according to Rustogi et al.

When waves break, they create multitudes of tiny bubbles that carry gases such as carbon dioxide back and forth between the atmosphere and water. Models used to evaluate how fast this exchange occurs typically rely on measurements of wind speed, assuming that wind speed directly relates to the prevalence of bubble-forming waves. However, waves can be affected by other factors as well, meaning this assumption doesn’t always hold.

To assess the role of bubbles in air-sea carbon exchange in more detail, scientists applied a recently developed “bubble-mediated gas transfer theory” to the ocean. As with other models, the bubble-mediated approach incorporates wind strength, but uniquely, it also accounts for wave conditions that form gas-carrying bubbles. The researchers compared the results from their new model to a simpler, wind-only model that ignores the effect of bubbles.

The two models yielded similar estimates for total annual ocean carbon storage, but the bubble-mediated model showed much higher variability, both seasonally and regionally; in some instances, local fluxes it indicated differed by 20%–50% from the wind-only model. The bubble-mediated model also suggested that intense wave activity in the Southern Hemisphere leads to much higher carbon storage than in the relatively calm Northern Hemisphere—a difference that’s not obvious in the wind-only model.

That north-south difference could have implications for interpreting and projecting carbon cycle dynamics in a changing climate. With average wind speeds and wave heights likely to increase with global warming, it is essential to anticipate accurately how these changes will influence ocean carbon storage, the authors say.

The work is also important for marine carbon dioxide removal projects aiming to enhance carbon uptake to mitigate climate change effects, they note. A prerequisite for these efforts is quantifying how much carbon the ocean takes up naturally. Without a comprehensive understanding of the processes affecting uptake, the impacts of such interventions may be vastly under- or overestimated. (Global Biogeochemical Cycles, https://doi.org/10.1029/2024GB008382, 2025)

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

Citation: Sidik, S. M. (2025), More bubbles means more variation in ocean carbon storage, Eos, 106, https://doi.org/10.1029/2025EO250244. Published on 8 July 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.

This story was originally published by Grist. Sign up for Grist’s weekly newsletter here.

When wildfires devastated a wide swath of Los Angeles last winter, officials warned residents of several ZIP codes not to drink the water, or boil it first if they must. They worried that soot, ash, and other debris from the blazes might have infiltrated the groundwater, or that damaged pipes might allow toxins into the supply. The last of these “do not drink” orders was lifted last month.

At their peak, those pollutants can be found at levels up to 103 times higher than before the fire. There also can be 9 to 286 times as much sediment in water after a fire. 

But the first large-scale study of post-wildfire water quality has found that pollution created by such a blaze can threaten water supplies for eight years—far longer than previous studies indicated. Researchers at the Cooperative Institute for Research in Environmental Science, or CIRES, at the University of Colorado Boulder analyzed 100,000 samples from 500 watersheds across the western United States. They found “contaminants like organic carbon, phosphorus, nitrogen, and sediment” throughout those that had burned. At their peak, those pollutants can be found at levels up to 103 times higher than before the fire. There also can be 9 to 286 times as much sediment in water after a fire.

The findings have great implications for water systems as they prepare for a world in which fires like those that burned in Los Angeles and, more recently, North Carolina and a great swath of Canada, grow more common. One in six people in the United States lives in a wildfire risk zone, and forested watersheds provide water to almost two-thirds of municipalities in the U.S., making water systems everywhere vulnerable.

“I’ve had a lot of conversations with different utilities and water managers in the West, and every single one of them are concerned about wildfire impacts,” said Carli Brucker, lead author of the study, published on 23 June. But, she added, what they don’t have is longer-term data. “I’m hoping that this research provides these concrete numbers that can really back up water managers’ concerns, and turn those concerns into real funding that they can start putting towards climate resilience. Strong evidence can be really helpful in securing funding.”

Water utilities in the LA area addressed the threat posed by the fires that burned in January in the short term by flushing water mains and pipes. Officials with the Los Angeles Department of Water & Power said they are conducting ongoing water testing in the Palisades area, and are offering free water quality testing to any resident that wants it.

“These urban fires are creating these unprecedented challenges that treatment plants can’t really deal with,” Brucker said. “Burning buildings and businesses and roads and cars, it creates all these contaminants that are just way more dangerous and way more difficult to deal with.”

Even years after a fire, a major rainfall can trigger a mudslide, unearthing contaminants.

Across the locations the researchers analyzed, contamination levels varied widely. In general, post-fire pollution was worse in heavily forested or heavily urbanized areas. The “most dramatic spikes” in pollutants like phosphorus, nitrate, organic carbon and sediment generally occurred in the first few years after a fire, according to researcher Ben Livneh.

“We found the impacts to be really persistent,” Livneh wrote in The Conversation. “We saw significantly elevated levels of nitrogen and sediment for up to eight years following a fire.” Even years after a fire, a major rainfall can trigger a mudslide, unearthing contaminants. Beyond polluting groundwater, that can cause unexpected environmental issues. “Nitrogen and phosphorus act like fertilizer for algae. A surge of these nutrients can trigger algal blooms in reservoirs, which can produce toxins and create foul odors,” Livneh said.

There are several ways to fight these threats to water supply.

“The first line of defense is just diversifying water sources,” Brucker said. Ideally, a utility would draw from several watersheds, so it has a backup in the event one of them is impacted by a fire, she said. They also can build additional sedimentation basins to increase their capacity for sediment handling.

“But all of these things cost a lot more,” Brucker said. And it’s difficult to convince strained utilities in Western states—already dealing with things like water shortages—to spend money on wildfire mitigation without numbers. Rural communities, in particular, often rely on single-source water systems and limited funding, which makes responding to emergencies much more challenging.

“Utilities don’t usually have these sorts of process improvements in place, unless they have a good reason,” she said. “I’m hoping this research can point to—this is a pretty good reason to start planning for and trying to budget for those resilience improvements.”

—Sophie Hurwitz (@hurwitz.bsky.social), Science Writer

This article originally appeared in Grist at https://grist.org/wildfires/pollution-from-wildfires-can-contaminate-our-water-for-up-to-eight-years-new-study-finds/.

Grist is a nonprofit, independent media organization dedicated to telling stories of climate solutions and a just future. Learn more at Grist.org

The devastating floods that killed nearly 200 people in Germany four years ago could have been even more damaging, new research suggests. The floods in July 2021 were among the worst disasters in German history. At least 196 people died in Germany, 43 people died in Belgium and the total damage to Central Europe amounted to €46 billion.

Any home gardener knows they have to tailor their watering regime for different plants. Forgetting to water their flowerbed over the weekend could spell disaster, but the trees will likely be fine. Plants have evolved different strategies to manage their water use, but soil moisture models have mostly neglected this until now.

SummaryReliable earthquake forecasts depend on modellers making suitable choices regarding data selection and model implementation. We explore some of these choices in order to construct short-term forecasts for independent background events in Italy, using a Log-Gaussian Cox Process to describe the spatial intensity of seismicity as a function of physical spatial covariates and a random field. We explore correlations between a range of physical covariates available for Italy, and investigate how they might contribute to observed spatial seismicity patterns. We find that historic smoothed seismicity, strain rates and elevation are most useful in describing instrumentally-observed seismicity. We use point process intensity models constructed with combinations of these covariates with past seismicity to generate Bayesian earthquake forecasts, constructing simulated catalogue forecasts of future earthquake catalogues in Italy, discussing modelling choices we make along the way. Finally, we test the performance of these forecasts in a pseudo-prospective manner for the 2010-2021 period and using historical data to assess how well they might perform for extreme events. While the inclusion of historic events improves forecasts, models without historic seismicity also perform well, indicating a degree of stationarity in the process. We demonstrate that combinations of covariates can add predictive power over modern catalogue data alone, and provide a framework for future modelling.