Cow manure digesters really cut methane — unless they leak

Study finds rare failures can have enormous consequences

University of California - Riverside

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Methane plume over a cow manure lagoon in California on June 22, 2023.

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Credit: Alyssa Valdez/Google/UCR

A new study shows that systems designed to capture methane from cow manure, called dairy digesters, are highly effective. But on the rare occasions they fail, the leaks are large enough to offset their climate benefits.

“I think manure emissions on dairies are underestimated. These digesters seem to be a solution that captures a lot of methane,” said Alyssa Valdez, a University of California, Riverside climate scientist and lead study author. “But I wanted to make sure they were working properly.”

The findings of her study, published in Environmental Research Letters, draw on eight years of satellite and airborne observations of 98 dairies across California. By tracking emissions before, during, and after digester installation, Valdez and her research team were able to see how these systems perform over time and at scale.

Digesters are widely seen as a key climate solution. By sealing manure ponds and capturing the gas they produce, these systems convert methane into usable fuel instead of allowing it to escape into the atmosphere where it has a tremendous effect on the climate.

Methane is shorter lived than carbon dioxide, but it is 80 times more powerful at trapping heat in the atmosphere, making even small releases significant.

A previous study led by UCR climate scientist Francesca Hopkins examined emissions at a single dairy using ground-based measurements. Hopkins found that a well-managed digester can cut methane emissions by as much as 80%. This new research builds on that work by showing how digesters perform across dozens of farms, including what happens when things go wrong.

Across the dairies studied, the number of strong methane plumes declined after digesters were installed, suggesting the systems are effective overall. However, the researchers also detected occasional leaks that were far more intense than emissions from traditional manure storage.

“For the most part, the digesters are working well,” Valdez said. “But the few leaks that happen, they make a huge impact.”

In some cases, the team observed methane escaping at rates around 1,000 kilograms per hour. By comparison, typical emissions from open manure lagoons ranged from 20 to 100 kilograms per hour.

The contrast highlights a central challenge: digesters concentrate methane in one place, making it easier to capture, but they also increase the risk of powerful releases if something goes wrong.

Those large releases are not limited to system failures. The study also captured spikes in emissions during digester construction and installation, a phase that is rarely measured but can produce substantial short-term increases.

To capture these patterns, the researchers relied on satellite and aircraft data. Satellite images allowed them to track changes across dozens of dairies over long periods, which is not possible with traditional ground-based monitoring. Aircraft measurements were then used to identify concentrated methane plumes over specific infrastructure locations, making the approach especially useful for spotting leaks.

“A farmer might not know their digester is leaking,” Valdez said. “This gives us a way to detect issues early and prevent them from becoming long-term problems.”

However, this method does not capture all emissions. It cannot measure more diffuse methane releases from sources such as lagoons or fields. For that reason, the researchers say satellite and airborne observations are most effective when combined with on-the-ground measurements, which provide a fuller picture.

This need for comprehensive monitoring comes as California continues to invest in digesters as part of its strategy to reduce emissions of heat-trapping gases. Hundreds of these systems are already operating or in development across the state.

In some cases, methane releases are not accidental. Operators may vent gas when it cannot be flared due to air quality regulations or when systems require maintenance. These process-related emissions add another layer of complexity to managing digester performance.

Even so, the study shows that most systems are working well and that large leaks are relatively uncommon. But for Valdez, who spent years living in California’s Central Valley, and whose family lives there, the work is about ensuring that climate solutions deliver real benefits in a region critical to the nation’s food system.

“This region is the backbone of our food supply, but people there also carry a lot of fear about air quality,” she said. “And they have good reasons for that.”

More broadly, the study highlights the need to pay closer attention to agricultural waste.

“We need to start caring about poop,” Valdez said. “And we need to keep verifying that these solutions are actually working. If we monitor them carefully, we can make sure they deliver on their promise.”

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Journal

Environmental Research Letters

DOI

10.1088/1748-9326/ae4fe4 

Article Title

Evaluating the impact of anaerobic digesters on point source methane emissions from California dairies from remote sensing

Article Publication Date

24-Mar-2026

 

Towards smarter agriculture: Durable nanofilm electrodes for monitoring leaf health

Researchers develop non-invasive devices for the long-term measurement of bioelectric potentials in plants

Institute of Science Tokyo

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This is the first transparent, durable, and water-resistant electrode that does not compromise the natural functions of leaf hairs. It could enable real-time monitoring of plant health status and help secure higher crop yields.

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Credit: Institute of Science Tokyo

Nanofilm electrodes capable of detecting stress in plants through bioelectric potentials could pave the way for more resilient agriculture, report researchers from Institute of Science Tokyo. Thanks to the electrode’s small thickness, leaf surface hairs can easily pierce through it, enabling stable and long-term electrical contact without compromising the leaf’s natural processes. This work could help improve crop yields by enabling early detection of stress in plants.

Food security is becoming a major global concern as climate change and growing pesticide resistance put crops under pressure. One promising strategy to tackle these issues and improve yields is catching health problems in crops early, before they cause irreversible damage. Interestingly, much like animals, plants produce electrical signals when under stress, and measuring these bioelectric potentials directly from leaves can provide timely warnings of diseases or harmful conditions. If developed into practical sensors, such technology could become a key component of smart agriculture systems.

However, despite many research efforts over the past decade, existing leaf electrodes are not yet suitable for widespread adoption. Some electrodes are not transparent, which interferes with photosynthesis. Others are not fully water-resistant, making them unsuitable for long-term use. One particularly tricky obstacle is the presence of trichomes—the tiny hair-like structures found on the leaves of many economically important crops, including soybeans, tomatoes, and eggplants. Existing thin-film electrodes are designed to simply cover trichomes, disrupting their function and damaging the leaf over time.

To address these issues, a research team led by Professor Toshinori Fujie, graduate student Yusuke Hori, and Assistant Professor Tatsuhiro Horii from the Department of Life Science and Technology, School of Life Science and Technology, Institute of Science Tokyo (Science Tokyo), Japan, in collaboration with Professor Shinji Masuda from the same institute, developed a new type of durable thin-film electrode compatible with trichome-rich leaves. Their latest paper, published online in Advanced Science on March 23, 2026, describes transparent nanofilm electrodes made from conductive, single-walled carbon nanotubes deposited onto a flexible elastomer layer. Only 70 to 320 nanometers thick, the nanofilms are extremely thin and can conform closely to complex leaf surfaces without the need for adhesives.

One key discovery was that the 70-nm-thick electrodes could be pierced by trichomes, settling directly onto the leaf’s epidermis while leaving the hairs largely undisturbed. This “trichome-piercing” mechanism—consistent across several crop species—enabled stable electrical contact without damaging plant tissues or compromising key biological processes. The electrodes also proved highly transparent, transmitting over 80% of incoming light and allowing photosynthesis to continue normally.

Tests showed that the nanofilm electrodes could record bioelectric signals continuously for several weeks. In some experiments, the devices remained attached and functional for up to 10 months without causing apparent damage. The research team also confirmed the electrodes’ durability in simulated rainfall conditions; unlike hydrogel-based sensors, which fail after exposure to water, the proposed carbon nanotube electrodes remained attached and continued to record electrical signals without issue.   

The researchers also showcased how their electrodes could be used to monitor physiological stress in plants. “When the electrode was attached to leaves under herbicide damage, chemical stress was successfully detected through changes in the bioelectric potential waveform associated with light irradiation,” explains Fujie.

Because electrical signals often change before visible symptoms appear, the proposed devices could enable early detection of plant stress in real-world settings. “Our findings make it possible to non-destructively capture physiological changes that occur before stress levels reach the stage that leads to yield reduction,” remarks Fujie. “In the future, we expect this technology to be applied for crop health monitoring in agricultural fields.”

By enabling long-term monitoring of plant electrical activity, these new nanofilm electrodes could become a valuable tool for precision agriculture. With further development, networks of these sensors could help farmers respond more quickly to environmental stressors, marking an important step toward more resilient food production systems.

 

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About Institute of Science Tokyo (Science Tokyo)
Institute of Science Tokyo (Science Tokyo) was established on October 1, 2024, following the merger between Tokyo Medical and Dental University (TMDU) and Tokyo Institute of Technology (Tokyo Tech), with the mission of “Advancing science and human wellbeing to create value for and with society.”

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Journal

Advanced Science

DOI

10.1002/advs.202522824 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Pierceable, Water-Resistant, and Transparent Nanofilm Electrodes Comprising Carbon Nanotubes for Long-Term Monitoring of Plant Electrophysiology

Article Publication Date

23-Mar-2026

COI Statement

This work relates to the patent to be pended: JP2024-131682.

 

Climate change could make unhealthy air a routine reality by 2100

New modelling shows a dramatic rise in air quality alerts, with vulnerable populations facing the greatest risks

University of Waterloo

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New modelling shows almost one in three Americans will routinely breathe air considered unhealthy for sensitive people by the year 2100 due to climate change, a sevenfold increase compared to the turn of the century. 

The international study, led by the University of Waterloo, found that about 100 million people in the United States will live in areas where average air quality during smog season is poor enough to trigger alerts advising vulnerable people to stay indoors. 

That is up from an estimated 14 million people in 2000, with most of the increase coming in California and the eastern United States. Smog season runs from the beginning of May to the end of September. 

“Climate change could cause days with poor air quality to shift from rare to commonplace,” said Dr. Rebecca Saari, a professor of civil and environmental engineering and the Canada Research Chair in Global Change, Atmosphere and Health at Waterloo. 

“People who are especially sensitive to air pollution, including the elderly, children with asthma and those with health conditions, could face a daily coin flip, with nearly even odds of an alert every day asking them to change their behaviour to reduce exposure.” 

The study built on previous research that estimated the number of air quality alerts in the  United States will quadruple, and that staying indoors to avoid the health risks posed by worsening air pollution due to climate change would require an additional 142 days per year by the end of the century. 

The new study broadens the picture by including the impact of both ozone and particulate matter pollution, which together cause almost all air quality alerts and are the primary environmental contributors to sickness and premature death. 

The research team also examined the economic costs of intensifying air pollution and the potential mitigating impacts of policies to limit it over the next 75 years. 

Saari said a significant finding is that seniors benefit much, much more than other vulnerable people from steps to limit their exposure to poor air, such as staying indoors, wearing masks, and improved building filtration. 

“We were surprised by how widespread and common it could be for sensitive groups to experience air that is considered unhealthy on average,” said Saari. “We hope our work helps inform more targeted guidance and reinforces the need for pollution reductions and long-term adaptations such as access to clean indoor spaces.” 

Collaborators included researchers at Harvard University, North Carolina State University and the University of California, Davis. 

Their study, Air Quality Alerts, Health Impacts and Adaptation Implications Under Varying Climate Policy, appears in Environmental Science and Technology. 

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Journal

Environmental Science & Technology

DOI

10.1021/acs.est.5c12522 

 

Preparing Canada’s health system for military conflicts

Canadian Medical Association Journal

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To prepare for major armed conflict involving Canada or its North Atlantic Treaty Organization (NATO) allies, the country must create a national framework for civilian–military medical integration, as the public health system would bear the burden of medical care, argue authors in a commentary in CMAJ (Canadian Medical Association Journal) https://www.cmaj.ca/lookup/doi/10.1503/cmaj.252067.

“Canada’s vulnerability in the context of military conflict lies in its lack of a national framework that would coordinate large-scale evacuation of casualties, allocate scarce resources, and integrate provincial and federal surge capacity,” writes Dr. Jeremy Grushka, assistant professor of surgery, McGill University, Trauma Surgery Fellowship Program director, McGill University, co-director MUHC Centre for Global Surgery, Montréal, Quebec, with coauthors. “The country also lacks a standing command structure linking Canadian Forces Health Services, provincial and territorial ministries of health, the Public Health Agency of Canada, and Canadian Blood Services during national emergencies.” 

“Civilian hospitals would carry any additional clinical burden of caring for injured service members, repatriated casualties, and affected civilians.”

The authors describe several scenarios in which Canada’s various health systems may need to respond, from providing clinical health care and rehabilitation services to repatriated casualties, responding to domestic mass casualty attacks, and addressing cyber attacks that would disrupt health information systems and delivery. Military operations to support sovereignty in Canada’s north could put additional strains on health systems and infrastructure. 

“In each scenario, the limiting resources would be trauma surgery, intensive care beds, blood supply, transport coordination, and real-time situational awareness,” writes Dr. Andrew Beckett, medical director, Trauma Program, St. Michael’s Hospital, Unity Health, Toronto and lieutenant-colonel, Canadian Forces Health Services. “All these resources depend on digital infrastructure enabling patient tracking, hospital capacity management, and interfacility communication, which may themselves be disrupted during cyber attacks.”

To help Canada prepare, a viable national framework should include 3 foundational pillars: sustained clinical readiness, dual-use capacity that can be expanded when necessary, and formal coordination between the Canadian Forces Health Services, Health Canada, and the Public Health Agency of Canada, in partnership with the provinces and territories. 

This is not unprecedented, as Canada has had coordinated civilian–military medical governance in past war times.

“During World War II, federal authorities established mechanisms to balance military and civilian physician allocation and procurement at scale,” they write. “The contemporary context is more complex, but the principle endures. National emergencies require coherent medical governance that transcends institutional silos.”

“[W]e do not argue for militarizing health care but for structural coherence. Civilian hospitals will bear the clinical burden of sustained casualty events involving Canada’s people. Institutionalizing civilian–military medical integration now is a prudent investment in national resilience and the stability of Canadian health care,” the authors conclude. 

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Journal

Canadian Medical Association Journal

DOI

10.1503/cmaj.252067 

Method of Research

Commentary/editorial

Subject of Research

Not applicable

Article Title

Preparing Canada’s health system for conflict: a framework for civilian–military medical readiness

Article Publication Date

30-Mar-2026

 

Developing a new predictive model to assess chemical risks in cetaceans

Assessing the impact of chemical contaminants on finless porpoises using in vitro data and mass distribution modeling

Ehime University

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A conceptual diagram of the risk assessment framework evaluating the health risks of harmful chemicals (POPs) by comparing data from finless porpoise biological samples (blood and blubber) with cultured cell data.

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Credit: Environ. Sci. Technol. 2026, 60, 11, 8353-8362

[Background] Cetaceans, as apex predators in the marine ecosystem, accumulate persistent organic pollutants (POPs) at high concentrations. However, due to ethical constraints, toxicity testing using live animals is impossible, leaving a long-standing challenge of how to link the results of in vitro experiments (using cultured cells) to actual "in vivo risk assessments." Conventionally, the "nominal concentrations" in cell experiments were directly compared with the "measured total concentrations" in actual organisms. However, this method carries high uncertainty because it does not account for the binding of chemicals to proteins and lipids within the body.

[Methodology] Using the finless porpoise as a model species, this study introduced a quantitative approach to predict actual in vivo effects from cell experiment results by using the "freely dissolved concentration" (the concentration of free chemicals not bound to proteins or lipids), which is directly responsible for triggering toxicity, as a common metric. We measured the protein and lipid contents of finless porpoise blood and blubber, as well as the culture media used in the cell experiments, and constructed a mass distribution model for 15 types of POPs.

[Results] The mass distribution modeling revealed that the freely dissolved concentrations of POPs in the bioassay media, blood, and blubber were 2-3, 4-6, and 6-8 orders of magnitude lower than their nominal and measured total concentrations, respectively. Using this freely dissolved concentration as a baseline, we calculated the "QIVIVE ratio" (risk prediction ratio) to compare actual exposure concentrations in vivo with the effect concentrations in cell experiments. The results indicated that mixed exposure to POPs at current environmental levels poses a low risk of reducing cell viability or inducing apoptosis (cell death).

[Future Outlook] This predictive approach, based on mass distribution modeling and freely dissolved concentrations, enables a realistic and mechanistically grounded risk assessment of chemicals in cetaceans. In the future, by incorporating chronic endpoints such as endocrine disruption and immunotoxicity into this framework, it is expected to be applied to more comprehensive health risk assessments for marine mammals.

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Journal

Environmental Science & Technology

DOI

10.1021/acs.est.5c13935