Feed aggregator

A new study from the University of Helsinki has provided a compelling new explanation for the devastating droughts that took place in North America thousands of years ago. This period, known as the Holocene, covers the time of a generally warm climate following the last ice age. These exceptionally long-lasting droughts had drastic impacts on forest dieback and ecosystem transformations; understanding their causes is essential to improving societal resilience to future climate variations.

Source: Water Resources Research

This is an authorized translation of an Eos article. 本文是Eos文章的授权翻译。

河流汇入下游，顺坡而下，最终汇入海洋或终端湖泊：这些是水道和流域运作的基本规律。但规律就是用来打破的。Sowby和Siegel在美洲列出了九条违背水文学预期的河流和湖泊。

所有河流都存在分叉现象，即河流分成几条支流，继续向下游流动。但与典型的分叉不同，这些河流在分叉后不会回到主水道。

例如，南美洲的卡西基亚雷河(Casiquiare)是一条可通航的水道，它连接着美洲大陆最大的两大流域——奥里诺科河(Orinoco)流域和亚马逊河(Amazon)流域，既是前者的支流，也是后者的支流。作者写道，它“在水文学上相当于两个星系之间的虫洞”。卡西基亚雷河从奥里诺科河分叉，蜿蜒流经茂密、近乎平坦的雨林，汇入里内格罗河(Rio Negro)，最终汇入亚马逊河。该研究的作者指出，轻微的坡度（小于0.009%）足以使大量的水顺流而下，这种不寻常的情况是由于河流被不完全捕获造成的。他们指出，对卡西基亚雷河的理解仍在不断加深。

1717年，荷兰殖民者首次绘制了苏里南遥远的韦安博河(Wayambo)的地图。这条河可以向东或向西流动，这取决于降雨量和人类使用水闸对流量的改变。它还靠近金矿和铝土矿开采以及石油生产地点，其双向流动使得预测污染物的扩散变得困难。

研究人员称，在他们调查的所有河流中，位于加拿大荒野高地的埃奇马米什河（Echimamish River）是“最令人费解的”。它的名字在克里语中的意思是“双向流动的水”。这条河连接了海耶斯河和纳尔逊河，根据一些记载，埃奇马米什河从它的中部流向这两条更大的河流。然而，它的河道平坦，间或被海狸水坝阻隔，导致即使在今天，人们仍然无法确定它的流向以及它究竟在何处发生了变化。

作者还探索了另外六条奇特的水道，包括有两个出口的湖泊和同时流入大西洋和太平洋的小溪。通过这些研究，他们强调了关于地球水体如何运作，我们仍有许多未知之处有待探索。(Water Resources Research, https://doi.org/10.1029/2024WR039824, 2025)

—科学撰稿人Rebecca Dzombak

This translation was made by Wiley. 本文翻译由Wiley提供。

Read this article on WeChat. 在微信上阅读本文。

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): Zijia Chu, Jingfeng Yao, Chengxun Yuan, Ying Wang, Zhongxiang Zhou, and Lin Geng

Mixed-mode oscillation (MMO) is a type of complex dynamic behavior commonly seen in multitimescale dynamical systems. As a typical nonlinear medium, MMOs have been experimentally observed in a variety of plasma systems. However, the underlying microscopic physical mechanisms that are responsible for…

[Phys. Rev. E 111, 055202] Published Thu May 08, 2025

Land subsidence is typically considered a coastal problem: The dual threats of sinking land and rising seas intensify flooding, particularly in places like New York City and Louisiana. But even inland, major cities face infrastructure problems and flooding damage from sinking land beneath. 

“Land subsidence does not stop at coastal boundaries.”

A study published in Nature Cities has found that all 28 of the most populous cities in the United States are sinking. Though some of this subsidence is due to long-term geologic processes, much of it is spurred by human activity, including groundwater pumping and the building of new infrastructure. Better groundwater management and stricter building codes could mitigate risks.

“Land subsidence does not stop at coastal boundaries,” said Leonard Ohenhen, a postdoctoral researcher at Columbia University and the first author of the new study. 

From Coast to Coast, and in Between

Rates of sinking or uplifting land, also known as vertical land motion, can be measured from satellites via synthetic aperture radar (SAR), a technology that sends radar pulses to Earth and records how those pulses are reflected back. Ohenhen and the research team used SAR measurements from 2015 to 2021 from the Sentinel-1 mission to create maps of ground deformation in the 28 most populous U.S. cities.

The team found that in every city, at least 20% of the land area was sinking, and in 25 of the 28 cities, at least 65% of the land area was sinking. Estimates from the study show that about 33.8 million people live on sinking land in these 28 cities. 

The study shows a “really good assessment of what the whole local and regional picture of vertical land motion looks like,” said Patrick Barnard, a geologist at the University of California, Santa Cruz Center for Coastal Climate Resilience, who was not involved in the new study. “It gives us more and more confidence and a greater understanding of how [subsidence] is influencing urban areas and increasing the risk to the population.”

Maps created by Ohenhen and his colleagues show which cities are experiencing uplift (positive vertical land motion values) and subsidence (negative vertical land motion values). Credit: Ohenhen et al., 2025, doi.org/10.1038/s44284-025-00240-y

Some of the highest rates of subsidence (>4 millimeters per year) were observed in several cities in Texas: Houston, Fort Worth, and Dallas. The fastest-sinking city in the country was Houston, with more than 40% of its land subsiding at a rate greater than 5 millimeters per year.

Chicago, Detroit, New York, and Denver were among the cities with the most land area affected by subsidence.

Some of the rates described in the study were “alarming,” Barnard said, because typical background subsidence is below a couple of millimeters per year. Rates above 2 millimeters per year can damage infrastructure and buildings, he said.

Vertical land motion is especially problematic where land is sinking unevenly, or where a subsiding region is next to an area that’s rising.

Analyzing building densities and land deformation, the researchers found that San Antonio faces the greatest risk, with one in every 45 buildings at a high risk of damage.

What may seem like slow sinking can build up over time to cause problems, Ohenhen said. “Four millimeters per year becomes 40 millimeters over 10 years, and so on…that cumulative effect can add up.”

Getting Ahead of Ground Deformation

A now-absent ice sheet may be responsible for some of the land deformation. Tens of thousands of years ago, the Laurentide Ice Sheet covered much of North America, compressing the land beneath. Now that the ice sheet has melted, North America is readjusting. Land once underneath the ice sheet is generally rising slowly, while land not covered by the ice sheet is sinking. Ohenhen compared this process to relieving pressure on a mattress: Once pressure is released, some parts of the mattress rise while others sink back to their original height. 

Most of the subsidence described in the study, though, likely comes from groundwater pumping, which decreases pressure in the pore space of rock and sediment. The pore space slowly collapses and the ground sinks.

“We can’t just be pumping the ground without any regard to the potential long-term impacts.”

That can exacerbate flooding and infrastructure damage. Groundwater pumping and oil and gas extraction near Houston caused land subsidence that correlated with flood severity after Hurricane Harvey in 2017, for example.

As climate change continues to intensify drought conditions in some parts of the United States, land subsidence from groundwater pumping could become even more of a risk to infrastructure. An “increasing number of cities may face significant challenges in subsidence management,” the study authors wrote. 

“It’s really a major issue we have to consider, especially in these urban areas,” Barnard said. “We can’t just be pumping the ground without any regard to the potential long-term impacts.”

The risks posed by land subsidence are high enough to warrant policy changes to better manage groundwater pumping across the country, Barnard said. Better enforcement of building codes could also prevent damage, the paper’s authors wrote.

“People are often not attuned to some of these subtle hazards they may be exposed to,” Ohenhen said. “[We should] make people aware of the situation so that we do not wait until the very last moment to respond.”

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

Citation: van Deelen, G. (2025), 33.8 million people in the United States live on sinking land, Eos, 106, https://doi.org/10.1029/2025EO250178. Published on 8 May 2025. Text © 2025. AGU. CC BY-NC-ND 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

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

A few days ago I highlighted the severe landslide and GLOF that occurred on the flanks of Vallunaraju in Peru, on 28 April 2025, which caused substantial damage and at least two fatalities. This appears to have been initiated by a landslide on the mountain flanks, triggering a hazard chain that led to the disaster downstream.

Loyal reader Christopher Cluett kindly got in touch. He was climbing on the flanks of the mountain when the chain of events occurred, and has kindly provided both a narrative and some images. I am reproducing these with his permission.

“The weather has not quite stabilized for the season, so over the course of the week we were there, there were heavy afternoon rains. Earlier in the week on 4/23 to acclimatize, we hiked through the valley to Laguna Llaca and back out on the road, so we have some beforehand pictures. Some pictures attached show previous slide activity at the same location. The previous slide was much smaller, as were the rock sizes. The road had been recently repaired from the recent slide in the last few weeks (if I recall correctly) – they installed a drainage tube under the road and backfilled it. When we were hiking out on the road on 4/23, there were 4 people taking soil samples (or running some type of soil testing).

“On 4/27 we hiked up to the Moraine Camp (~4900m). On 4/28 at 2:30 am, we left Moraine Camp for the summit. We heard consistent rockfall all morning while we were approaching the glacier. Then around 3:30 am, when we were transitioning to the glacier, we heard a freight train loud slide. I would assume this was the main event. Our summit route then started to take us away from the main rockfall area, so slide noises diminished. On the way back by the rockfall area, we continued to hear lighter rock fall. There are some pictures of what we think was the main rockfall face (not shown but below this face are two smaller glacier lakes). Our guide suspected the rockfall overflowed the lakes and subsequently created the landslide into the valley.

“You can see in other pictures the road was destroyed. We had to quickly cross it to get out of the valley to meet our transportation. It was evident looking in the valley on the drive out that large boulders showed mud/water markings of very high river levels (maybe 5-6 ft). A lot of the cattle from the valley had congregated on the high part of the road towards the valley entrance.

“It is a bit alarming to see all the slide activity throughout the area. The region is clearly heavily impacted by climate change. If you look at the road to the next valley over, it also has a lot of recently landslide activity.“

These two images show the valley before the day before the 28 April 2025 event:-

Looking down valley, old slide present (04-23-2025) Old Slide Activity at Same Location (04-23-2025)

This map shows the locations of the images of the landslide:-

A map showing the locations of the rockslide images.

These images show the area from which the rockslide originated:-

The source area of the rockslide. The source area of the rockslide.

And these images show the aftermath:-

The aftermath of the landslide. The aftermath of the landslide. The aftermath of the landslide. The aftermath of the landslide. The aftermath of the landslide. The aftermath of the landslide. The aftermath of the landslide.

Many thanks for Christopher for these amazing images.

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.

SummaryThe Seoul Mega City (SMC), one of the most densely populated regions in the world, has experienced an increase in seismic activity, raising concerns about the potential presence of concealed faults that could trigger clustered earthquakes in the Seongbuk area (SB), located in the central part of the SMC. This study aims to identify such a fault through the interpretation of terrestrially measured gravity field. By employing dip-curvature analysis and the first vertical derivative calculation of the gravity field, supported by S-wave velocity models, reflection seismic profiles, geological data, and borehole data analyses, we provide compelling evidence for the existence of a deeply buried NS-trending fault (DF0) associated with the Dongducheon Fault system. This fault is likely responsible for the clustered seismic activities observed in the SB. The confirmation of DF0’s presence highlights the critical need for further geophysical investigations to better understand seismic risks in the SMC, which has a history of significant seismic events.

Heriot-Watt scientists have discovered giant underwater mud waves buried deep below the Atlantic Ocean, 400 kilometers off the coast of Guinea-Bissau in west Africa.

In a study published today in Science Advances, researchers from the Ocean Discovery League reveal that only a minuscule fraction of the deep seafloor has been imaged. Despite covering 66% of Earth's surface, the deep ocean remains largely unexplored.

Across the globe, monsoon rainfall switches on in spring and off in autumn. Until now, this seasonal pattern was primarily understood as an immediate response to changes in solar radiation.

In a sweeping new study of more than 13,000 urban areas worldwide, researchers have mapped air pollution levels and carbon dioxide emissions, providing comprehensive global analysis of urban environmental quality.

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Journal of Advances in Modeling Earth Systems 

Benchmarking, or comparing models against each other using observational data to identify which performs better under specific conditions (and potentially why), is essential for advancing climate prediction. However, the hydrological community has lacked a global benchmarking framework, largely due to the complexity of allocating gauge data to model grids (see figure above).

Zhou et al. [2025] address this challenge by introducing an automated gauge allocation method that is applicable across various hydrological models. Through a test application using the global river model CaMa-Flood (Catchment-based Macro-scale Floodplain) with runoff inputs, they demonstrate that incorporating bias-corrected runoff data significantly improves model performance across a range of observational variables and performance metrics. This advancement paves the way for more rigorous intercomparisons of global hydrological models and facilitates the inclusion of hydrological components in broader model intercomparison initiatives, such as the Coupled Model Intercomparison Project (CMIP7).

Citation: Zhou, X., Yamazaki, D., Revel, M., Zhao, G., & Modi, P. (2025). Benchmark framework for global river models. Journal of Advances in Modeling Earth Systems, 17, e2024MS004379. https://doi.org/10.1029/2024MS004379

—Kei Yoshimura, Associate Editor, JAMES

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.

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

En Septiembre del 2018, un incendio forestal arrasó con aproximadamente 2,000 hectáreas de matorrales alrededor de Pichu Pichu, un volcán inactivo de los Andes peruanos.

Esta no sería la primera vez. En los últimos años, han incrementado los incendios en este ecosistema único, causados principalmente por actividades humanas como la deforestación y la agricultura de tala y quema. Un nuevo estudio publicado en la Spanish Journal of Soil Science ha revelado que estos incendios no solo dañan la vegetación, sino también el suelo. Incluso cuatro años después de los incendios del 2018, el estudio concluyó que el vulnerable suelo volcánico seguía sin recuperarse.

“Los Andes peruanos no están listos para los incendios forestales”.

“Los Andes peruanos no están listos para los incendios forestales”, dijo Jorge Mataix-Solera, autor principal y científico del suelo de la Universidad Miguel Hernández en España, quien ha pasado más de tres décadas estudiando el impacto de los incendios en diferentes tipos de suelo.

En la región peruana de Arequipa y ubicado a 3,700 metros sobre el nivel del mar, se encuentra el matorral de Pichu Pichu, uno de los lugares más áridos del mundo y considerado un desierto frío, con temperaturas que oscilan entre los 4°C y los 18°C. A diferencia de otros ecosistemas áridos, como los bosques del Mediterraneo o las praderas del Cerrado en el centro de Brasil, las plantas alrededor de Pichu Pichu no han desarrollado características que las ayuden a adaptarse a los incendios forestales, como cortezas gruesas o semillas que germinen con el fuego. Para rematar, debido a las características arenosas del suelo, este es naturalmente seco y altamente hidrofóbico.

Muestreo del suelo y examinación de las plantas

Los investigadores ya tenían sospechas del gran impacto que tendrían los incendios en la región. Pero para comprender de mejor manera el cómo, se recolectaron 40 muestras de suelo de Pichu Pichu tres y cuatro años después del desastre de 2018, siendo la mitad de zonas quemadas y la otra mitad de zonas no quemadas.

Investigadores analizaron el suelo debajo de dos especies de arbustos abundantes en la zona que se vieron afectados por los incendios forestales en la zona de Pichu Pichu. Crédito: Jorge Mataix-Solera

Los análisis físicos y químicos revelaron que los incendios forestales causaron una grave pérdida de carbono en el suelo, que persiste incluso cuatro años después del incidente. El carbono del suelo es un indicador clave para conocer su salud, ayuda a que la tierra retenga agua, nos habla sobre la presencia de materia orgánica, es indispensable para su fertilidad y ayuda a prevenir la erosión. La pérdida de carbono también provoca que el suelo se compacte, haciendo que este se vuelva inhóspito para que crezcan nuevas plantas.

Además de haber analizado la pérdida de carbono, los investigadores también se encargaron de estudiar el impacto que tiene la combustión en diferentes plantas del suelo. Para esto se recolectaron muestras de suelo debajo de las plantas que predominan en la zona: Berberis lutea, un arbusto que se mantiene sus hojas verdes todo el año conocido coloquialmente como “palo amarillo”, y Parastrephia quadrangularis, otra especie de arbusto mas pequeña conocida como tola-tola.

En un incendio forestal, las plantas se comportan como la mecha de una vela, el fuego se concentra en un punto y lo que ocasiona que aumenten las temperaturas en el suelo. Como ya se esperaba, los investigadores descubrieron que el suelo debajo del palo amarillo sufrió mas daños tras un incendio forestal, posiblemente porque al ser un arbusto grande, representaba una mayor fuente de combustible.

La incineración de la vegetación fue otro factor que causó daño al suelo, debido a que las plantas suelen retener humedad y ayudan a filtrar agua al suelo. Sin las plantas, el agua fluye sobre la superficie del suelo, causando una fuerte erosión y pérdida de materia orgánica. “Esta es una problemática muy particular en ecosistemas como Arequipa, donde la lluvia llega en periodos cortos y muy intensos”, afirmó Minerva García Carmona, coautora del estudio y edafóloga de la Universidad Miguel Hernández.

Además, Carmona destacó que la destrucción de la vegetación nativa de estas áreas amenaza directamente a la biodiversidad, y puede tener efectos a largo plazo en la fortaleza de los ecosistemas.

Mataix-Solera tuvo resultados similares en investigaciones previas donde se estudiaron los suelos de Torres del Paine en la Patagonia chilena, los cuales se vieron afectados por un incendio en 2011.

Incendios más intensos

Para Stefan H. Doerr, un experto en incendios forestales suelos de la Universidad de Swansea en el Reino Unido, este nuevo estudio es muy importante, ya que los suelos de los Andes han sido poco estudiados. “Conocemos poco sobre los incendios en los suelos poco aptos al fuego de los ecosistemas andinos”, destacó Doerr, señalando que los suelos de origen volcánico son los más fértiles, además de que alimentan al 10% de la población mundial.

En los últimos años, Perú ha experimentado un aumento considerable en los incendios forestales, causados principalmente por el pastoreo y actividades con fines agrícolas, como la quema y remoción de vegetación. En 2024, más de 200 incendios forestales afectaron a casi todas las regiones del país, exceptuando a dos, y más de 2,200 hectáreas de pastizales fueron destruidas, de acuerdo con el Instituto Nacional de Defensa Civil del Perú.

“Estos ecosistemas son muy frágiles, y lo mejor que podemos hacer es evitar las actividades humanas que ocasionan este tipo de incendios.”

A medida que el clima cambia y las temperaturas aumentan en el mundo, se tiene previsto que los incendios sean más comunes, especialmente en lugares áridos como los Andes peruanos, dificultando aún más la recuperación de los ecosistemas. “El problema con el cambio climático es que está ocurriendo en un periodo muy corto de tiempo, y los ecosistemas no pueden desarrollar estrategias para adaptarse a él”, destacó Mataix-Solera.

Los científicos han mencionado algunas estrategias, como del mantillo o acolchado, que podrían ser probadas para la recuperación del suelo. El mantillo consiste en cubrir el suelo dañado con materia vegetal, como hojas o aserrín, para disminuir la erosión y ayudar a las plantas a crecer.

Sin embargo, los investigadores insisten en que la solución definitiva para los daños causados por los incendios forestales es evitarlos desde el comienzo. “Estos ecosistemas son muy frágiles, y lo mejor que podemos hacer es evitar las actividades humanas que ocasionan este tipo de incendios”, dijo Mataix-Solera.

—Sofia Moutinho (@sofiamoutinho.bsky.social), Escritora de ciencia

This translation by 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. 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.

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.

The National Institutes of Health (NIH), the world’s largest funder of biomedical research, announced a policy on 1 May banning scientists from directing its funding to international research partners, according to Nature. 

A statement from NIH said the agency would not halt foreign subawards—funding that U.S. researchers direct to international research partners—from existing grants “at this time,” but that by October, it will not renew or issue foreign subawards. Last year, the NIH issued about 3,700 subawards to foreign institutions.

The new policy may affect critical international health research and research with humanitarian applications, such as projects investigating HIV prevention, malaria treatments, maternal health, and cancer. 

 
Related

•  NIH to End Billions of Dollars in Foreign Research Grants
•  NIH Bans New Funding From U.S. Scientists to Partners Abroad
•  NIH Cancels Climate and Health Research Grants 
•  Get Involved: AGU Science Policy Action Center
 

“If you can’t clearly justify why you are doing something overseas, as in it can’t possibly be done anywhere else and it benefits the American people, then the project should be closed down,” wrote Matthew J. Memoli, the principal deputy director of the NIH, in an email obtained by Nature. 

Coordinated international research on disease outbreaks keeps U.S. residents safe, Francis Collins, former director of the NIH, told Nature: “Disease outbreaks that start anywhere in the world can reach our shores in hours.” Halting international investigations into infectious diseases is “short-sighted and self-defeating,” he said.

The move could also delay clinical trials for new medical therapies, which rely on the participation of many subjects with particular illnesses. For a childhood cancer therapy, for example, “it could take decades to complete a trial if you only enroll children in the U.S.,” E. Anders Kolb, chief executive of the Leukemia & Lymphoma Society, told the New York Times. “When we collaborate with our international partners, we can finish these trials much more quickly and get the therapies to children as soon as possible.”

The Trump administration has already terminated hundreds of grants from NIH, targeting projects having to do with Covid-19, misinformation, transgender health, and climate change. One prominent environmental health journal, Environmental Health Perspectives, announced last week it would pause accepting new studies for publication amid uncertainty surrounding its NIH funding. The Trump administration’s proposed budget would cut NIH funding by about 40%, or about $18 billion. 

“These decisions will have tragic consequences,” Collins told Nature. “More children and adults in low-income countries will now lose their lives because of research that didn’t get done.”

—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
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.

The ocean plays a large role in cycling carbon dioxide in the atmosphere. Determining how much carbon is locked away in the ocean is critical to understanding Earth's changing climate. However, measuring and monitoring oceanographic processes on a massive scale poses a challenge to scientists.

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

Editors’ Highlights are summaries of recent papers by AGU’s journal editors. Source: Journal of Geophysical Research: Biogeosciences

“Le Léman”, Lake Geneva, is the title and subject of F.-A. Forel’s seminal book series (1892-1904) that examines its catchment, climate, organisms, and solutes such as carbon and organic matter (OM), essentially establishing “limnology” as a holistic freshwater science. At the time, Forel wondered whether it was possible to fully understand the dynamics of organic material in the lake’s water, given that the influencing factors were so complex, and the variation in concentration so small. Today, we have detailed knowledge about the aquatic carbon cycle, but because much of this comes from the study of smaller and organic-rich northern lakes, it is still uncertain what actually applies to lakes of Geneva’s type.

Adding a piece to this longstanding puzzle, White et al. [2025] analyze the spatiotemporal dynamics of organic and inorganic (radio-)carbon dissolved in Lake Geneva and its biggest tributary, the Rhone. Using detailed data on the carbon composition and age, the researchers substantiate that organic carbon (OC) is primarily sourced from the lake’s large inorganic carbon (IC) pool by photosynthesizing plankton, rather than being imported from catchment soils and vegetation.

However, the authors also find exceptions to this rule. Glacial meltwater bears a characteristic signature of old organic matter and young IC that revealed large carbon imports to the lake during the record heat of 2022. Quantitative understanding of such inflows is important for comprehending the functioning of lakes in a warming alpine region. In the future, glaciated catchments will reach “peak water”, after which the receding glaciers contribute less and less to summertime streamflow, potentially exporting from former glaciated/permafrost areas more soil-derived OC, nutrients and also more IC.

These results also coincide with a renewed interest in lakes’ IC dynamics and associated calcite precipitation. During past investigations of terrestrial exports of carbon and energy, hardwater lakes were largely overlooked. Due to the simultaneous CO2 and calcite (CaCO3) formation by plankton (owed to the precipitation stoichiometry), hardwater lakes can become counterintuitive aquatic greenhouse gas sources. Better knowledge about the carbon sinks and sources there, as provided by the authors, consolidates the mechanisms active in similar, numerous and ecologically important peri-alpine lakes. Surely, Forel would approve.

Citation: White, M. E., Mittelbach, B. V. A., Escoffier, N., Rhyner, T. M. Y., Haghipour, N., Janssen, D. J., et al. (2025). Seasonally dynamic dissolved carbon cycling in a large hard water lake. Journal of Geophysical Research: Biogeosciences, 130, e2024JG008645. https://doi.org/10.1029/2024JG008645

—Maximilian Lau, Associate Editor, JGR: Biogeosciences

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.

When does "anomalous weather" become "a new climate"? The moment that variations in a specific climate variable turn into the new normal is termed Time of Emergence (ToE). Scientists from the University of Groningen and the Royal Netherlands Meteorological Institute (KNMI) have developed a method to predict the time of emergence in various Arctic regions, based on warming, wetting, and sea ice melting.

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

Evapotranspiration is a scientific measurement representing the combined sum of evaporation from the soil (or water) surface to the atmosphere and transpiration from plants, where liquid water inside the plant tissue vaporizes and enters the atmosphere, predominately through stomata. This topic cuts across many disciplines and is important to understand as crops are subjected to increasing environmental stress and management practices.

A new article in Reviews of Geophysics explores the effects of changing environments, abiotic stresses, and management practices on cropland evapotranspiration. Here, we asked the lead author to give an overview of evapotranspiration, how scientists measure it, and what questions remain.

Why is it important to study cropland evapotranspiration?

As a key component of water balance in agricultural systems, evapotranspiration represents the ultimate consumption of agricultural water resources.

Evapotranspiration (ETa) is intricately linked to crop physiological activities and closely coupled with carbon cycle processes. As a key component of water balance in agricultural systems, evapotranspiration represents the ultimate consumption of agricultural water resources. Moreover, variation of regional cropland evapotranspiration reflects the changes of the regional agro–ecological environment. The varying vegetation cover and irrigation methods in cropland will lead to differences in mass and energy exchanges between the surface and the atmosphere, which in turn further affect the local climate and atmospheric circulation. Therefore, accurate evapotranspiration information is important for the development of irrigation systems, establishment of crop planting zones, implementation of regional water–saving agriculture practices, efficient assessment of water resources, and effective development, management, and allocation of water resources, among others.

What sets your review paper apart from previous reviews on this subject?

Given the significance of evapotranspiration, there are numerous reviews covering this subject. The varying perspectives concerning evapotranspiration have been recently reviewed, such as the role of evapotranspiration in the global, terrestrial, and local water cycles; the modeling, climatology, and climatic variability of global terrestrial evapotranspiration; best practices for measuring evapotranspiration; evapotranspiration partitioning methods; land-scale evapotranspiration from a boundary-layer meteorology perspective; spatiotemporal patterns of global evapotranspiration variations and their relations with vegetation greening. However, there is a gap in covering issues related to cropland evapotranspiration, which exhibits high variability due to its fast response to numerous factors.

There is a need to re-examine the primary factors influencing cropland evapotranspiration given the proliferation of long-term manipulation experiments, advancements in estimation models, and exponential growth in new and improved measuring methods at multiple spatial and temporal scales. In our new review, the focus is on factors encompassing key changing environments, abiotic stresses, and management practices that impact cropland evapotranspiration, along with their quantification methods.

What different methods are used for measuring evapotranspiration?

Evapotranspiration can be measured by using several methods such as plant physiology, hydrological, micro-meteorological, and remote sensing methods for different spatial and temporal scales. The leaf and plant scale transpiration can be measured by (potometer) portable photosynthesis system and sap flow method, respectively. The plot and field scale evapotranspiration can be determined by water balance, weighting lysimeter, sap flow plus micro-lysimeter, Bowen-ratio energy balance, eddy covariance, residual in the energy balance, surface renewal, and (microwave) scintillometer method. For regional scale evapotranspiration, remote sensing energy balance and remote sensing using vegetation indices are common methods.

Measurement methods for cropland evapotranspiration. Credit: Qiu et al. [2025], Figure 4

What factors do scientists consider when deciding to use one method over another?

When selecting methods to measure evapotranspiration, scientists prioritize a balance between spatial-temporal requirements, accuracy, and practicality. The choice often hinges on the scale of study: small-scale methods, such as weighting lysimeters or eddy covariance methods, provide high-resolution field-level data but lack regional coverage, whereas satellite-based remote sensing methods offer broader spatial insights at the cost of finer temporal or spatial resolution. Accuracy demands must also align with resource constraints: high-precision tools, like weight lysimeters and eddy covariance, require high financial investment, technical expertise, and maintenance, while low-cost methods, such as the water balance method, introduce large error. Environmental context further guides decisions, such as, uniform vegetation may favor Bowen-ratio energy balance and eddy covariance systems.

What are the main factors that affect cropland evapotranspiration?

Cropland evapotranspiration is affected by the meteorological conditions (e.g. radiation, air temperature, relative humidity, wind speed), changing environments (e.g. elevated carbon dioxide concentration (e[CO2]), elevated ozone concentration (e[O3]), global warming), various abiotic stresses (e.g. water, salinity, heat stresses, waterlogging), management practices (e.g. planting density, mulching, irrigation method, fertilizer application, control of diseases and pests, soil management), underlaying surface (e.g. geography, soil types), and crop–specific factors (e.g. crop type, variety, and development stages). The effect of meteorological conditions on evapotranspiration can be surrogated to a reference evapotranspiration. Therefore, in this review, the focus is on the impacts of key changing environments (e[CO2], e[O3], and global warming), abiotic stresses (water, salinity, and heat), and management practices (planting density, mulching, irrigation method, and nitrogen application) on cropland evapotranspiration.

Factors affecting cropland evapotranspiration. Credit: Qiu et al. [2025], Figure 3

What major conclusions have been drawn about these factors?

There is general agreement that e[O3], water and salinity stresses, and adopting drip irrigation all lead to lower total growing–season evapotranspiration for almost all crops. However, total growing–season evapotranspiration in response to e[CO2], warming, heat stress, planting density, and nitrogen application were inconsistent across studies.

The impacts of e[CO2] and e[O3], water and salinity stresses on total growing-season evapotranspiration are mainly through stomatal conductance, the ability of soil to conduct water to roots, development of roots and leaf area, microclimate, and possibly phenology. The effect of warming on total growing–season evapotranspiration can be largely explained by both variations in ambient growing–season mean temperature and growing duration. Total growing-season evapotranspiration in response to heat stress (or mulching and appropriate nitrogen supplement) is a compromise between reduced (or enhanced) transpiration and increased (or decreased) evaporation, along with possibly a shortened growth period. Differences in evapotranspiration under varying planting densities can be explained by the direct and indirect effects of leaf area on the constitutive terms of evapotranspiration. The variation of total growing–season evapotranspiration under drip irrigation compared to conventional irrigation was affected by smaller soil wetting area, shortened growing season, less energy partitioning to evapotranspiration, and changes in crop characteristics and microclimate.

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

1. The influence of elevated ozone concentration on stomatal conductance can be represented using an adjusted version of the Jarvis function. However, there has been little effort to integrate this response into the Penman-Monteith model, which is used to estimate evapotranspiration.
2. Many controlled manipulation experiments are underreported varying types of warming on crop evapotranspiration. Water balance method, the residual in the energy balance method, sap flow plus micro–lysimeters, or even weighting lysimeters can be used to observe cropland evapotranspiration under several warming scenarios.
3. There are few studies on evapotranspiration responses to heat stress, and most are based on pot experiments in phytotrons or artificial climate chambers. Obtaining larger–scale data of evapotranspiration under heat stress is beneficial to understand heat stresses on evapotranspiration.
4. Models for describing effects of elevated CO2 and ozone concentration on evapotranspiration using a modified Priestley–Taylor and crop coefficient models are rarely reported. More efforts are needed to develop and test these two models.
5. In practice, cropland evapotranspiration is jointly affected by multiple factors. The impact of multiple factors on cropland evapotranspiration is a complex and multifaceted phenomenon that requires long–term consideration of many environmental stressors and their interactions.

—Rangjian Qiu (qiurangjian@whu.edu.cn, 0000-0003-0534-0496), Wuhan University, China

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: Qiu, R. (2025), Decoding crop evapotranspiration, Eos, 106, https://doi.org/10.1029/2025EO255015. Published on 6 May 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.

Summers are getting hotter and drier in the Eurasian landmass due to an atmospheric circulation pattern further aggravated by anthropogenic factors. The recent tandem heat-wave-drought events in the region stretching from Eastern Europe to East Asia are unprecedented, as confirmed by a new study that analyzed tree-ring data going back 300 years and climate models.

Up to 250,000 deaths from poor air quality could be prevented annually in central and western Europe by 2050 if greenhouse gas emissions are drastically reduced, say researchers.