Stephen J. Vavrus

Senior Scientist

Ph.D., Atmospheric Sciences, University of Wisconsin-Madison, 1997

Center for Climatic Research
1105 Atmospheric, Oceanic & Space Science Bldg.
1225 W. Dayton St.
Madison, Wisconsin 53706-1695

Phone: (608) 265-5279
Fax: (608) 263-4190

Research Interests

Climate change has emerged as one of the premier environmental concerns of our time and is motivating climatologists to investigate how future climatic trends will unfold. My research addresses several key aspects of climate change, including the role of Polar Regions, the behavior of extreme weather, regional impacts around the Great Lakes, and the origin of human-induced climate change. I address these questions mostly with computer climate models, which provide both quantitative estimates of future change and insights into the physical causes. My primary modeling tool is the Community Earth System Model (CESM), whose Science Steering Committee I serve on.

The Arctic

The Arctic is known to be the Earth's most climatically sensitive region, but climate models differ on how rapidly the Arctic will change in the future and what societal impacts will result. I am researching these questions, including how extreme storms will respond to a reduction in sea ice and how the amplified greenhouse warming in the Arctic might affect atmospheric circulation patterns and weather remotely in middle latitudes. This research is closely aligned with the goals of the Study of Environmental Arctic Change (SEARCH), an interagency program designed to improve understanding of the processes and consequences surrounding Arctic change. I currently serve on its Science Steering Committee.

Extreme Weather

Global climate change is likely to affect extreme weather globally. Some of my research focuses on how heat waves, cold spells, floods, and drought will respond to a changing climate, especially in the U.S. I am studying how bird populations are affected by extreme heat, cold snaps, and droughts and what sorts of mitigations strategies would most effectively protect avian species. A related project explores the impact of floods on stormwater management in Wisconsin, because heavy precipitation is projected to become more common and intense in a warmer climate. My research team is also analyzing how extreme lake-effect snowstorms across the Great Lakes region will change as both ice cover and cold air masses diminish in the future, in addition to investigating the cause of the rapid warming of the Great Lakes in recent years. These regional climate change topics dovetail with my participation in the Wisconsin Initiative on Climate Change Impacts (WICCI), a partnership between UW's Nelson Institute for Environmental Studies and the Wisconsin Department of Natural Resources.

Origin of Human Impact on Climate

A revolutionary idea proposed by Dr. William Ruddiman argues that the origin of anthropogenic climate change reaches back much further in time (thousands of years ago) than the conventional starting point of the Industrial Revolution. The “Early Anthropogenic Hypothesis” posits that widespread deforestation and rice cultivation with the emergence of agriculture several thousand years ago led to a gradual but significant rise in atmospheric CO2 and CH4 and thus greenhouse warming. I am involved in a collaborative research project to test this hypothesis, using global climate models to simulate the present-day climatic conditions expected in the absence of early human land-cover modification.

Madison Climate Change

I have long been interested in local weather and climate variability around Madison, aided by the long records kept by the Wisconsin State Climatology Office. In particular, Lake Mendota's record of freeze-up and thaw dates extend to the early 1850s and serves as an indirect thermometer of past local weather conditions. I use these data to test models that simulate the behavior of ice cover on Mendota, including when ice forms and melts off each winter, as well as how thick the ice grows during the winter.


Publications from my research can be found here: Steve's Papers.

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