Center for Coastal Physical Oceanography

Fall 2012 Seminar Series


Amelia Shevenell
College of Marine Science, University of South Florida

Monday, October 1, 2012
3:30 PM
Room 3200, Innovation Research Park Building I


The disintegration of ice shelves, reduced sea-ice and glacier extent, and shifting ecological zones observed around Antarctica highlight the impact of recent atmospheric and oceanic warming on the cryosphere. Observations and models suggest that oceanic and atmospheric temperature variations at Antarctica's margins affect global cryosphere stability, ocean circulation, sea levels and carbon cycling. In particular, recent climate changes on the Antarctic Peninsula have been dramatic, yet the Holocene climate variability of this region is largely unknown, limiting our ability to evaluate ongoing changes within the context of historical variability and underlying forcing mechanisms.

Here we show that surface ocean temperatures at the continental margin of the western Antarctic Peninsula cooled by 3-4°C over the past 12,000 years, tracking the Holocene decline of local (65°S) spring insolation. Our results, based on TEX86 sea surface temperature (SST) proxy evidence from a marine sediment core, indicate the importance of regional summer duration as a driver of Antarctic seasonal sea-ice fluctuations. On millenial timescales, abrupt SST fluctuations of 2-4°C coincide with globally recognized climate variablity.

Similarities between our SSTs, Southern Hemisphere westerly wind reconstructions and El Niño/Southern Oscillation variability indicate that present climate teleconnections between the tropical Pacific Ocean and the western Antarctic Peninsula strengthened late in the Holocene epoch. We conclude that during the Holocene, Southern Ocean temperatures at the western Antarctic Peninsula margin were tied to changes in the position of the westerlies, which have a critical role in global carbon cycling.


As an undergraduate at Hamilton College in 1995, Amelia Shevenell got her first taste of Antarctica and paleoceanographic research as an NSF REU participant. After a two-year "break" from academia, during which time she worked as an analytical chemist and environmental consultant in Juneau, Alaska, Dr. Shevenell moved south to sunny Santa Barbara, California to begin her graduate studies in Marine Science with Dr. Jim Kennett. Her M.Sc. and Ph.D. research at the University of California Santa Barbara examined the evolution of Antarctica and the Southern Ocean system on hundred year to million year timescales. After a Program on Climate Change post-doctoral fellowship at the University of Washington, Dr. Shevenell moved to University College London, in England, where she was an Assistant Professor in both the Earth Sciences and Geography Departments until 2011, when she began an Assistant Professorship at the University of South Florida's College of Marine Science. She uses a multiproxy geochemical approach to investigate processes occurring along Antarctica's margins, including trying to understand the past influence of Upper Circumpolar Deep Water on Antarctica's ice sheets. In recent years, Dr. Shevenell's research interests have expanded beyond the Southern Ocean and into the Northern Hemisphere high latitudes.

Reception before seminar at 3:00 PM

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