earth & Climate ScienceS
Understanding Tree Growth in a Warming World
Authors: Gabriel Katul and international collaborators
The context: To grow, plants take in water from soil and process sunlight and carbon dioxide from the air through photosynthesis. Although rising atmospheric CO2 levels might suggest increasing tree growth, research has instead documented varied growth with no central explanation.
The method: Using data from field experiments, researchers developed a mathematical model linking photosynthesis and transpiration 鈥 a plant-cooling process that releases water vapor 鈥 and the activity of stomata, which are tiny leaf pores that open and close in response to various plant needs.
The findings: The model suggests that stomata adjust based on a tradeoff between the need for CO2 and the availability of water in soil. In warmer and drier environments, stomata shrink to conserve water. As a result, trees absorb less CO2, leading to reduced growth.
The takeaway: The potential of forests to reduce atmospheric CO2 requires consideration of how water moves from the soil to the leaves and of local climatic conditions.
The paper: , published Nov. 24, 2025, in Nature Climate Change.
environmental natural sciences
When Fires Burn Near Urban Areas, Do Air PurifieRS Protect Against Smoke EXPOSURE?
Authors: Ph.D. student Ruoxue (Rory) Chen, Yan Lin, Yihui Ge, Ph.D.鈥25, Junfeng (Jim) Zhang and Mike Bergin (Pratt School of Engineering), in collaboration with colleagues from the University of Southern California
The context: Little research exists on how well portable air purifiers protect people inside their homes from smoke tied to fires burning in the transition zone between undeveloped and developed areas, also called the wildland-urban interface.
The method: The researchers analyzed data on outdoor and indoor air quality from 27 Los Angeles homes, some of which were equipped with HEPA (high-efficiency particulate air) purifiers. They compared data collected before, during and after the Eaton Fire, California鈥檚 second most destructive fire, which broke out in January 2025.
The findings: Outdoor levels of particulate matter 鈥 fine particles of air pollution 鈥 were similar across homes at all stages of the study. During the fire, HEPA purifiers were associated with a modest 15% reduction in indoor particulate matter.
The takeaway: Portable HEPA purifiers provide limited indoor protection against exposure to pollutants in smoke from fires at the wildland-urban interface. Complementary strategies, such as reducing drafts and providing guidance for optimal purifier use, could further improve indoor air quality during wildfires.
The paper: , published Jan. 14, 2026, in npj Clean Air.
Environmental social systems
Co-Designing a Sensor for Tribal Stewardship of Wild Rice
Authors: Kimberly Marion Suiseeya and Ojibwe Tribal and academic partners
The context: For Ojibwe Tribes living around the Western Great Lakes, native wild rice called Manoomin is essential to culture, ecology and diet. Technology that monitors Manoomin habitat could help Ojibwe Tribes to conserve the species, which has declined by 40% over the last century.
The method: Through a partnership called the , academic researchers and Ojibwe Tribal partners built and deployed the first affordable, wireless sensor for collecting environmental data in wetlands where Manoomin grows. The researchers later interviewed Tribal partners about device development and deployment.
The findings: Partner feedback was generally positive and included suggestions for improving how sensor data is accessed and visualized, among other constructive ideas.
The takeaway: The findings can inform future work by the STRONG Manoomin Collective, and may also provide insights to other researchers working with Indigenous scientists and partners and on Indigenous lands.
The paper: , published July 2025, in COMPASS 鈥25: Proceedings of the ACM SIGCAS/SIGCHI Conference on Computing and Sustainable Societies.
Marine Science & Conservation
Simulated Military Sonar Affects Goose-Beaked Whale Behavior
Authors: Brandon Southall, Robert Schick, William Cioffi, Ph.D.鈥20, former research analyst Heather Foley, Ph.D. student Anne Harshbarger, Doug Nowacek, Zach Swaim, Jillian Wisse, Ph.D.鈥23, Danielle Waples, Andy Read and colleagues
The context: In some cases, naval sonar used to detect submarine threats has been linked to strandings of deep-diving beaked whales. These strandings could stem from a behavioral response to a perceived threat.
The method: The team equipped 53 goose-beaked whales off Cape Hatteras, North Carolina, with two types of tags. Using data obtained from the tags, the research team monitored how whales responded to signals simulating military sonar.
The findings: When receiving signals above 120 decibels 鈥 the threshold between 鈥渕edium鈥 and 鈥渉igh鈥 exposure levels 鈥 whales changed their diving behavior, moved away from the source of the signals and stopped using echolocation, a process they rely on to forage. These effects were temporary and not associated with habitat abandonment.
The takeaway: The study adds to growing evidence suggesting that deep-diving whales react to human disturbances as they would to the sounds of a predator. These findings can inform conservation and management of the species.
The paper: , published Jan. 7, 2026, in Ecosphere.
In the Media
Recent articles and interviews featuring Nicholas School faculty and students:
- (Drew Shindell and Gordon Williams in Sierra magazine)
- (Dimitris Floros in Duke Today)
- (Brian Murray in The Hill)
- (Nishad Jayasundara in NPR)
- (Jessica Maher, MEM鈥03, in Salazar Center for North American Conservation)
Summaries by Julie Leibach, Senior Science Writer
Nicholas School Communications & Marketing