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Climate Change

Science Supporting Policy in California and Beyond

Photo: Isabel P. Montanez and Steve Fairchild

Isabel P. Montañez and Steve Fairchild climbing to the stalagmite (top right) to drill cores used to reconstruct rainfall patterns in the Sierras over the past 20,000 years.  » READ MORE

Ancient Climate Change

How does past climate change on the California coast help us understand and predict future climate scenarios?

Tessa Hill, Bodega Marine Lab and geology, is a paleo-oceanographer examining California climate change on glacial timescales over the past 50,000 years. She collects coral skeletons and deep sea sediments as records of past climate events. Corals can live for hundred of years, preserving a high-resolution record of environmental conditions, including processes like El Nino and anthropogenic warming. Deep sea sediments provide an even longer record, going back tens of thousands of years. For example, Hill investigated whether undersea emissions of methane increased during periods of global warming from 14,000 to 16,000 and from 10,000 to 11,000 years ago. These are the most dramatic warming periods in Earth's recent history, when glacial eras gave way to more moderate temperatures. Her examinations of tar deposits from sediment cores taken off the Santa Barbara coast suggest that global warming may have melted undersea methane ice, disturbing the sea floor and opening new cracks that allowed petroleum and methane to bubble to the surface.

Does climate change affect all freshwater lakes in the same way?

Geoff Schladow, director, Tahoe Environmental Research Center, has commenced its Pacific Rim Initiative. By working with collaborators in Chile, Japan and Pacific Rim nations, Schladow is investigating the differences in historic lakes due to climate forcing . By focusing on the Pacific Rim, the project can investigate the impacts of a broad range of latitudinal and altitudinal gradients on both sides of the Pacific to explore differences and commonalities. The project uses both water column data and sediment data, allowing for the investigation of responses dating back tens to hundreds of thousands of years.

How do reactions in snow affect our understanding of ice core records?

Cort Anastasio; land, air & water resources; is examining the reactions that occur in polar snows. In the past it was thought that most of the material deposited in snow was preserved without significant changes. However, more recent work has shown that reactions in surface snow can change the composition of the snow grains as well as the surrounding air. Anastasio's research group is characterizing these changes for several important tracers, such as hydrogen peroxide and nitrate, that will help other researchers more accurately read ice core records of past atmospheres.

What are the latest methods for reconstructing the history of the Earth's climate?

Jim Rustad, geology, uses the distribution of stable isotopes among minerals, water, and the atmosphere as important indicators of climate change. This allows him to see back in time much further than is possible from data obtained from ice cores. His research uses a cross between computer science and chemistry--called computational chemistry--to improve the reliability of these isotopic methods in soil minerals and ocean sediments. Rustad's group is carrying out calculations that start at the level of established laws of quantum mechanics to determine isotope distributions for the ratio of boric acid to borate, which serves as a "paleo-pH meter." He also uses dissolved aqueous carbonates and trace carbonate components in soil minerals. These molecular-level tools have the capability of transforming our understanding of how isotopes can be used to unravel the history of Earth's climate.