Pacific Ocean Climate Variability: Effects on North American Precipitation Patterns
Positive PDO in the North Pacific results in either increased (blue) or decreased (red) winter precipitation in North America. Our projects assesses the strength and variability of PDO-precipitation relationships over the last ~7,000 years.
This project aims to reconstruct patterns of climate variability along the Pacific coasts of North America during the last 15,000 years through analysis of diatoms, foraminifers, silicoflagellates, pollen, charcoal, geochemistry, isotopes, and other proxies from marine, estuarine, and lacustrine sediment cores. We produce high-resolution records of marine sea-surface temperature and surface water productivity from the Pacific margins between southeastern Alaska and Mexico. These decadal scale records of the past 1,200 years can be used in regional and global reconstructions of the Medieval Climate Anomaly (~AD 950-1250), Little Ice Age (~AD 1350-1850). We also produce high-resolution proxy records of precipitation and moisture availability from terrestrial environments, primarily lake sediments from California, Nevada, and Oregon, as well as Guatemala. These records are integrated with instrumental climate records of the past 100+ years to document impacts of both naturally occurring climate cycles and anthropogenic forcings. We also aim to assess (on a regional basis) the links between extensive drought and offshore sea surface temperatures. Our efforts will aid resource managers in their efforts to understand the variability of surface processes in the West and to mitigate the effects of climate change on ecosystems.
Why is this research important?
Modern climate of the Pacific coasts of North America and much of the western US is largely dictated by the sea surface temperatures and atmospheric conditions in the eastern North Pacific (i.e., El Nino/La Nina, Pacific Decadal Oscillation). Understanding patterns of natural climate variability is critical to understand the impacts of anthropogenic changes. In the West, water availability is the issue of greatest concern both presently and in projected future (global warming) climate scenarios.