Schedule Jun 13, 2018
Megadrought, Extreme El Niño, and California's Climate Future
Sam Stevenson, UCSB

The tropical Pacific is one of the most important regions on the planet for generating year-to-year variations in climate. Interactions between the atmosphere and ocean lead to El Niño events, sudden warmings of the eastern and central Pacific, and their cold counterparts, La Nina events. These events, in turn, generate atmospheric patterns that alter weather extremes around the world - their effects are felt particularly strongly in the southwest US, where La Nina is associated with drought conditions. Evidence from tree ring-based climate reconstructions tells us that past droughts may have been much worse than anything observed in the 20th century. This makes it important to understand how future climate variability might amplify future drought; but although climate change is expected to alter the patterns of atmospheric and oceanic circulation in the future, even state-of-the-art computer models still disagree on what this will mean for El Niño and La Nina. I will describe recent work using 'ensemble' sets of model simulations to study the interaction between El Niño, La Nina, and drought in past and future climates, and what it might mean for the range of futures we may expect for California and the rest of the western US.

Sam Stevenson is an assistant professor at the Bren School of Environmental Science & Management at UCSB. Her research uses global climate and regional ocean models to understand the physics driving climate extremes, how they have changed in the past, and what we may expect in the future. Sam received her B.A. in Mathematics from Western CT State University and her M.A. in Astronomy from Wesleyan University, before earning her Ph.D. in Atmospheric & Oceanic Sciences from the University of Colorado at Boulder. She was then a National Science Foundation Ocean Sciences Postdoctoral Fellow at the University of Hawaii at Manoa, followed by work as a research scientist at the National Center for Atmospheric Research.

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