Climate-Altering Effects

Tony Wexler

UC Davis scientists are looking for players in global climate change in unusual places: seashores, dead plankton and pine trees.

All are thought to be natural sources of tiny airborne particles that may have unexpectedly large effects on the Earth’s surface temperatures. Those temperatures have shot up in recent years because people have released climate-altering gases into the atmosphere. Scientists know much more about those “anthropogenic emissions” than they do about the natural, background emissions; UC Davis researchers are urgently trying to help fill in the gaps.

UC Davis engineering professor Tony Wexler was the first scientist to find extremely tiny particles forming in the air above the ocean along the Pacific coast. The particles, called aerosols, are known to foster cloud formation. Because aerosols and clouds reflect sunlight, both have the potential to cool Earth’s surface and mediate global warming.

UC Davis atmospheric scientist Ian Faloona is also at the seashore, looking at phytoplankton—microscopic plants that grow in wild abundance in the cold waters that well up along the California coast. As phytoplankton decompose, dimethyl sulfide (DMS) gas is released into the atmosphere, where it forms aerosols. Faloona is measuring DMS emissions to try to understand their contribution to background aerosol levels and their effects on coastal air quality.

Faloona also is heading into the forests of the Sierra Nevada to measure yet another precursor of aerosols and clouds—the gases given off naturally by pine and fir trees. Using a state-of-the-art quantum cascade laser loaned to him by NASA, Faloona will try to help UC Berkeley scientists gauge the trees’ emission rates of volatile organic compounds. He will have to act fast: The measurements must be taken in the first minutes after the compounds emerge. Then they swirl away into the atmosphere, mingling with other natural and unnatural particles to affect climate in ways no one yet fully understands.

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Links to more information:

Air Quality Research Center

John Muir Institute of the Environment

Institute of Transportation Studies

UC Davis–Caltrans Air Quality Project

Atmospheric Aerosols & Health program for graduate students

Stories and photos by Sylvia Wright, who writes about the environmental sciences for UC Davis.