Warmer winters and snow drought may threaten western U.S. water by speeding flows, study finds

Oregon State University

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Naches River in Washington. 

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Credit: Zach Butler, Oregon Stat University

CORVALLIS, Ore. – As future shifts in climate lead to more rain and less snow in the western United States, new research finds that water will move faster through a landscape, likely leading to negative impacts on summer water levels and water quality.

The study is especially relevant at this moment because the western United States experienced similar snow drought conditions this past winter, with generally typical precipitation amounts, but less snow because of warmer temperatures.

“This winter has been exactly like what our paper had said the future will be like,” said Zach Butler, a postdoctoral scholar at Oregon State University and lead study author, who has a part-time job forecasting winter weather in Oregon for the site OpenSnow.

The research can help inform future water management decisions. While the timing of water release relative to snowpack has long informed water planning, understanding how long it takes for water to travel through a landscape is not well understood and is important, especially at a time of increasing weather disturbances and extreme conditions.

In the new study, recently published in Scientific Reports, Butler and a team of researchers from Oregon State, Pacific Northwest National Laboratory and the National Center for Atmospheric Research in Colorado estimated “water transit times” – the time between rain or snow falling on the landscape and leaving as streamflow – will be 18% faster on average in the late century.

Faster water transit times have been shown to negatively influence water quality because during high-water events there are often spikes of contaminants that have been stored for a shorter period in shallow subsurface layers. Additionally, during low-water conditions, contaminants can be stored for a longer period of time.

The seasonal shift to faster water transit times in the winter will also likely lead to less water in streams, rivers, lakes and reservoirs in the summer, which could have negative implications for aquatic species such as salmon and trout and less water for drinking and agriculture.

The study focused on the Naches River, the main tributary of the Yakima River in Washington. The river basin is one of the most climate-sensitive basins within the Columbia River basin due to projected warming and snowpack declines, the researchers note.

Snowpack declines in the Naches River basin from 1991-2020 have already resulted in discharge peaking earlier in the spring. Other research has projected a 16% decrease in snow and a 25% increase in rain by 2036-2050.

While the researchers focused on that one basin, the framework they developed can be used to predict historical and future water transit times in other parts of the western United States and the world. Their work builds and aligns with studies conducted by other scientists in the Rocky Mountains and Europe.

The research is important because one-sixth of the world’s population relies on snowmelt water for drinking or agriculture, the researchers note. In the United States west of Colorado, 53% of water runoff originates as snowmelt.

Variability of water transit times is traditionally calculated by analyzing natural chemical tracers, such as stable water isotopes, found in precipitation and streamflow. This is costly and logistically challenging because it requires collecting water samples in the field.

Butler and scientists from the Pacific Northwest National Laboratory collected samples from the Naches River and coupled those in a novel way with an advanced hydrologic model to estimate water transit times both in the past and future.

“This study provides a crucial step in improving projections of water resource responses to climate change and underscores the value of integrating water transit time dynamics into future hydrologic assessments,” Butler said.

Co-authors of the paper are Stephen Good, Mark Raleigh and Catalina Segura, of Oregon State; Huancui Hu and Xingyuan Chen of Pacific Northwest National Laboratory; and Aubrey Dugger of the National Center for Atmospheric Research.

Good is an associate professor in the College of Agricultural Sciences and director of the interdisciplinary Water Graduate Resources Program. Raleigh is an assistant professor in the College of Earth, Ocean, and Atmospheric Sciences. Segura is a professor in the College of Forestry.

 

Zach Butler, an Oregon State University postdoctoral scholar, collecting a water sample on the Naches River in Washington.

Credit

Lupita Renteria

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Journal

Scientific Reports

DOI

10.1038/s41598-026-46539-1 

Subject of Research

Not applicable

Estonia’s first cloned foal born with the help of Estonian University of Life Sciences scientists

Estonian Research Council

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1_Cloned foal Wodan M Alpha, three days after birth.

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Credit: Estonian University of Life Sciences/Kristina Haan

The birth of the first cloned foal is the result of years of research and development, carried out in partnership between scientists at the Estonian University of Life Sciences and Luunja Stud Ltd. “The foal is strong and viable, but to protect its health, we will keep the stable under quarantine for some time,” said Elina Tsopp, embryologist at the Estonian University of Life Sciences and lead scientist of the cloning process.

The foal is a genetic copy of the former sport stallion Wodan M and has been named Wodan M Alpha. Wodan M was a successful competition horse owned by Urmas Raag and achieved notable results in sport. As a breeding stallion, he produced many high-quality offspring. “One of the aims of horse cloning is to preserve the genetics of top-performing horses. Even more importantly, cloning technology can also help conserve endangered horse breeds,” added Tsopp.

Estonia is one of the few countries in Europe working at such a high level in equine reproductive biotechnologies. It is now the second country in Europe where a cloned foal has been successfully produced, following earlier successes at the Avantea center in Italy. In 2024, scientists from the Estonian University of Life Sciences, in cooperation with Luunja and Perila stables, also achieved the birth of Estonia’s first ICSI foal, Endex. This marked an important step in the development of reproductive technologies in Estonia and provided momentum for pursuing horse cloning.

Cloned foal is the result of outstanding teamwork and fruitful international collaboration. The horse cloning research group includes Elina Tsopp, Anni Viljaste-Seera, Andres Reilent, Felipe Corrêa, and Andrès Gambini from the University of Queensland. A long-term partner of the University’s scientists is Luunja Stud Ltd, led by Sven Šois and Urmas Raag.

 

2_Mare with foal Wodan M Alpha.

 

3_Mare with foal Wodan M Alpha in stable.

4_Cloned foal Wodan M Alpha in his stable.

Credit

Estonian University of Life Sciences/Kristina Haan

Method of Research

News article

Subject of Research

Animals

 

From specialized to adaptable AI systems

André Biedenkapp receives Emmy Noether award for research on generalizability in reinforcement learning

Karlsruher Institut für Technologie (KIT)

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Dr. André Biedenkapp, winner of an Emmy Noether award from the German Research Foundation (André Biedenkapp, KIT).

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Credit: André Biedenkapp, KIT

“The Emmy Noether award helps outstanding young researchers to become academically independent at an early stage in their careers,” said Professor Stefan Hinz, Vice Provost Early Career Researchers at KIT. “His work on developing adaptive AI systems makes Dr. André Biedenkapp a prime example of an excellent young researcher at KIT.”

 

Reinforcement learning (RL) is an artificial intelligence (AI) learning paradigm in which an AI agent learns how to behave in a specific environment by trial and error. Feedback in the form of rewards helps a system to repeat desired behaviors and avoid inappropriate ones. This is an especially powerful method for problems in which decisions must be made sequentially, e.g. in robotics, logistics, or resource management. 

 

However, a key problem with traditional RL approaches is that the learned strategies often depend strongly on the training environment. Even small changes can mean that an AI agent no longer knows how to behave appropriately. “Today’s RL agents work superbly under the conditions they’ve been trained for, but they reach their limits quickly when those conditions change,” said Biedenkapp, who is working at the University of Freiburg through August 2026. From September 2026, he will be leading the newly funded DFG Emmy Noether Group “From Mediocre to Masterful Generalists: The Power of Context in RL” at KIT’s Institute for Anthropomatics and Robotics.

 

More Context for More Robust Learning Processes

The Emmy Noether Group’s goal is to extend RL training methods so that AIs become more robust and adaptable. To do so, Biedenkapp’s team will make use of additional information about the environment or world in which an agent acts. In this way, an AI can learn which behavior is best suited to which situation and then apply that knowledge to similar unknown situations later.

 

In the long term, this approach could be a key step toward increased use of RL in real-world applications. Many RL-based AI systems have thus far had to rely on very exact simulations of real environments, but the required simulators are complicated, expensive, and difficult to implement for complex scenarios. “If RL-based systems could generalize better, it would no longer be so important to simulate every possible situation perfectly. That would expand the range of possible applications for this technology considerably,” Biedenkapp said.

 

About the Emmy Noether Program

The Emmy Noether Program gives exceptionally well qualified scientists in the early phase of their career the opportunity to qualify for a university professorship by independently leading a research group over a period of six years.

 

More information

 

In close partnership with society, KIT develops solutions for urgent challenges – from climate change, energy transition and sustainable use of natural resources to artificial intelligence, sovereignty and an aging population. As The University in the Helmholtz Association, KIT unites scientific excellence from insight to application-driven research under one roof – and is thus in a unique position to drive this transformation. As a University of Excellence, KIT offers its more than 10,000 employees and 22,800 students outstanding opportunities to shape a sustainable and resilient future. KIT – Science for Impact.

 

Industrial chemicals delay recovery of the ozone layer

Ozone protection under pressure

Swiss Federal Laboratories for Materials Science and Technology (Empa)

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The Jungfraujoch high alpine research station is located at 3,580 meters above sea level on a mountain saddle in the central Swiss Alps.

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Credit: Empa

Although ozone-depleting chemicals such as carbon tetrachloride (CCl₄) or certain chlorofluorocarbons (CFCs) are no longer used in refrigerators and foams, they continue to serve as feedstocks in industrial processes for the production of modern refrigerants and plastics. Until now, these so-called feedstock chemicals have flown under the radar of international agreements because the quantities produced and leakage rates were significantly underestimated.

Working with international research groups, Empa researchers have now used global measurements to show that during the production and processing of these substances, approximately three to four percent escapes into the atmosphere through leaks. Furthermore, their use has increased significantly in recent decades. In a study published in Nature Communications, they have now calculated that, as a result, the ozone layer is likely to recover about seven years later than previously assumed – unless emissions are reduced. “These substances are not only ozone-depleting but also highly harmful to the climate. Lower emissions would thus benefit both the ozone layer and the climate,” says Stefan Reimann, an atmospheric scientist at Empa and lead author of the study.

Measurements show higher emissions

When the Montreal Protocol was negotiated in the 1980s and later strengthened, it led to a global ban on ozone-depleting substances in everyday products. Feedstock chemicals, however, were exempt from this ban. At the time, industry assumed that only about 0.5 percent of the quantities produced would escape into the atmosphere and that the use of these substances would decline in the long term. “But this assessment has not been accurate anymore for quite some time,” says Reimann. “Feedstock chemicals are now being released in increased quantities during production, transport, and further processing, and the volumes currently being produced are significantly larger than was assumed 30 years ago.”

These new findings are based on global atmospheric measurements from international networks such as the Advanced Global Atmospheric Gases Experiment (AGAGE), which includes the Empa research station on the Jungfraujoch. Since many ozone-depleting substances remain in the atmosphere for decades, their concentrations allow conclusions to be drawn about global emissions. “We measure the concentrations of these substances in the atmosphere. Based on their lifetimes, we can calculate how much they should actually be decreasing. If they aren’t, emissions must still be occurring,” explains Martin Vollmer, an Empa researcher and co-author of the study.

A comparison of these measurements with the production figures officially reported by individual countries shows that today, an average of three to four percent of the feedstock produced enters the atmosphere – several times the originally assumed values. For carbon tetrachloride, which is particularly harmful to the ozone layer, emission rates are even above four percent.

Why usage is increasing

However, emissions are rising not only because of higher production losses, but also because the overall use of feedstock chemicals is increasing – by about 160 percent since the year 2000. Some of these feedstocks were initially used to produce hydrofluorocarbons (HFCs), which were introduced as refrigerant substitutes following the ban on CFCs. Since these substitutes later proved to be potent greenhouse gases, they are now being phased out under the so-called Kigali Amendment. They are increasingly being replaced by hydrofluoroolefins (HFOs), which have little impact on the climate but whose production again relies heavily on ozone-depleting feedstock chemicals.

Added to this is a rapidly growing use in the polymer industry – for example, in the production of fluoropolymers such as Teflon (PTFE) or polyvinylidene fluoride (PVDF), an important material in lithium-ion batteries for electric cars. “The quantities of feedstock are not decreasing but will continue to grow, at least in the coming years,” says Reimann.

Both the ozone layer and the climate are affected

Based on these developments, the international research team calculated various future scenarios. They compared, for example, the originally assumed, very low emission rates with the values measured today from the use of feedstock chemicals. The established benchmark from 1980, when global ozone depletion was first observed, serves as a reference. Until now, it was assumed that this original state of the ozone layer would be reached again around the year 2066. However, the new calculations show that if feedstock emissions remain at current levels, this timeline will shift by about seven years. The stratospheric ozone layer would therefore not fully recover until around 2073. The margin of uncertainty for this estimate ranges from six to eleven years.

However, the feedstock chemicals released not only damage the ozone layer but also act as powerful greenhouse gases. If nothing changes, these additional climate-damaging emissions will reach around 300 million metric tons of CO₂ equivalents per year by mid-century – comparable to the current annual CO₂ emissions of a country like England or France. Reducing these emissions would therefore have a dual benefit.

Whether these emissions will be reduced in the future through binding emission limits or a targeted restriction of particularly problematic substances is, according to Stefan Reimann, ultimately a political decision. Even though the Montreal Protocol continues to be regarded as one of the greatest successes of international environmental policy, it should be regularly reviewed and, if necessary, adapted in light of new scientific findings. “The Montreal Protocol was successful because science, politics, and industry worked closely together. Such cooperation is crucial again today to address new challenges,” says Reimann.

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Journal

Nature Communications

DOI

10.1038/s41467-026-70533-w 

Method of Research

Computational simulation/modeling

Article Title

Continuing Industrial Emissions Are Delaying the Recovery of the Stratospheric Ozone Layer

Article Publication Date

16-Apr-2026

A regulatory loophole could delay ozone recovery by years

Scientists say an exception in the Montreal Protocol for the use of ozone-depleting feedstocks could set the ozone recovery back seven years.

Massachusetts Institute of Technology

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Often hailed as the most successful international environmental agreement of all time, the 1987 Montreal Protocol continues to successfully phase out the global production of chemicals that were creating a growing hole in the ozone layer, causing skin cancer and other adverse health effects.

MIT-led studies have since shown the subsequent reduction in ozone-depleting substances is helping stratospheric ozone to recover. (It could return to 1980 levels by as early as 2040, according to some estimates.) But the Montreal Protocol made an exception in its rules for the use of ozone-depleting substances as feedstocks in the production of other materials. That’s because it was thought that only a small amount — just 0.5 percent — of the ozone-depleting substances used for this purpose would leak into the atmosphere.

In recent years, however, scientists have observed more ozone-depleting substances in the atmosphere than expected, and have increased their estimates of leakage from feedstocks.

Now an international group of scientists, including researchers from MIT, has calculated the impact of different feedstock leakage rates on the ozone’s fragile recovery. They find the higher leakage rates, if not addressed by the Montreal Protocol, could delay ozone recovery by about seven years.

“We’ve realized in the last few years that these feedstock chemicals are a bug in the system,” says author Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies and Chemistry, who was part of the original research team that linked the chemicals to the ozone hole. “Production of ozone-depleting substances has pretty much ceased around the world except for this one use, which is when you have a chemical you convert into something else.”

The paper, which will be published in Nature Communications, is the first to comprehensively quantify the impact of leaked feedstocks, which are currently used to make plastics and nonstick chemicals. They are also used to make substitute chemicals for the ones regulated under the Montreal Protocol. The researchers say it shows the importance of curbing use and preventing leakage of such feedstocks, especially as the production of their end products, like plastic, is projected to grow.

“We’ve gotten to the point where, if we want the protocol to be as successful in the future as it has been in the past, the parties really need to think about how to tighten up the emissions of these industrial processes,” says first author Stefan Reimann of the Swiss Federal Laboratories for Materials Science and Technology.

“To me, it’s only fair, because so many other things have already been completely discontinued. So why should this exemption exist if it’s going to be damaging?” says Solomon.

Joining Reimann on the paper are his colleagues Martin K. Vollmer and Lukas Emmenegger; Luke Western and Susan Solomon of the MIT Center for Sustainability Science and Strategy and the Department of Earth, Atmospheric and Planetary Sciences; David Sherry of Nolan-Sherry and Associates Ltd; Megan Lickley of Georgetown University; Lambert Kuijpers of the A/gent Consultancy b.v.; Stephen A. Montzka and John Daniel of the National Oceanic and Atmospheric Administration; Matthew Rigby of the University of Bristol; Guus J.M. Velders of Utrecht University; Qing Liang of the NASA Goddard Space Flight Center; and Sunyoung Park of Kyungpook National University.

Repairing the ozone

In 1985, scientists discovered a growing hole in the ozone layer over Antarctica that was allowing more of the sun’s harmful ultraviolet radiation to reach Earth’s surface. The following year, researchers including Solomon traveled to Antarctica and discovered the cause of the ozone deterioration: a class of chemicals called chlorofluorocarbons, or CFCs, which were then used in refrigeration, air conditioning, and aerosols.

The revelations led to the Montreal Protocol, an international treaty involving 197 countries and the European Union restricting the use of CFCs. The subsequent decision to exempt the use of ozone-depleting substances for use as feedstocks was based partially on industry estimates of how much of their feedstocks leaked.

“It was thought that the emissions of these substances as a feedstock were minor compared to things like refrigerants and foams,” Western says. “It was also believed that leakage from these sources was minor — around half a percent of what went in — because people would essentially be leaking their profits if their feedstocks were released into the atmosphere.”

Unfortunately, some of those assumptions are no longer true. Western and Reimann are part of the Advanced Global Atmospheric Gases Experiment (AGAGE), a global monitoring network co-founded by Ronald Prinn, MIT’s TEPCO Professor of Atmospheric Science. AGAGE monitors emissions of ozone-depleting substances around the world, and in recent years researchers have revised their estimates of feedstock leakage upwards, to about 3.6 percent. For some chemicals, the number was even higher.

In the new paper, the researchers estimated a 3.6 percent feedstock leakage as the baseline for most chemicals. They compared that with a scenario where 0.5 percent of feedstocks are leaked from 2025 onward and a scenario with zero feedstock-related emissions. The researchers also looked at production trends between 2014 and 2024 to project how much of each specific ozone-depleting chemical would be used as feedstock between 2025 and 2100.

The analysis shows that until 2050, total ozone-depleting chemical emissions decrease in all scenarios as rising feedstock emissions are offset by declining uses enforced by the Montreal Protocol. In the scenario with continued 3.6 percent leakage, however, emissions level off around 2045, and total emissions only decrease by 50 percent overall by 2100.

The researchers then evaluated the impact of feedstock-related emissions on stratospheric ozone depletion. In the scenario where feedstock leakage is 0.5 percent, the ozone returns to its 1980 status by 2066. In the scenario with zero feedstock leakage, the ozone reclaims its 1980 health in 2065. But in the baseline scenario, the recovery is delayed about seven years, to 2073.

“This paper sends an important message that these emissions are too high and we have to find a way to reduce them,” Reimann says. “Either that means no longer using these substances as feedstocks, swapping out chemicals, or reducing the leakage emissions when they are used.”

A global response

Solomon is confident industries will be able to adjust to the latest findings.

“There are a lot of innovators in the chemical industry,” Solomon says. “They make new chemicals and improve chemicals for a living. It’s true they can perhaps get too entrenched with certain chemicals, but it doesn’t happen that often. Actually, they’re usually quite willing to consider alternatives. There are thousands of other chemicals that could be used instead, so why not switch? That’s been the attitude.”

Solomon says the fact that AGAGE can detect the impact of feedstock emissions is a testament to the progress the world has made in reducing emissions from other sources up to this point. She believes raising awareness of the feedstock problem is the first step. 

“This isn't the first time that the AGAGE Network has made measurements that have allowed the world to see we need to do a little better here or there,” Western says. “Often, it’s just a mistake. Sometimes all it takes is making people more aware of these things to tighten up some processes.”

Members of the Montreal Protocol meet every year. In those meetings, they split into working groups around different topics. Feedstock emissions are already one of those topics, so participants will review the evidence together. Typically, they release a statement about mitigation strategies if needed.

“We wanted to raise the warning flag that something is wrong here,” Reimann says. “We could reduce the period of ozone depletion by years. It might not sound like a long time, but if you could count the skin cancer cases you’d avoid in that time, it would seem quite significant.”

The work was supported in part by the National Science Foundation, NASA, the Swiss Federal Office for the Environment, the VoLo Foundation, the United Kingdom Natural Environment Research Council, and the Korea Meteorological Administration Research and Development Program.

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Journal

Nature Communications

Article Title

“Continuing industrial emissions are delaying the recovery of the stratospheric ozone layer”