Alumni Association

Two UMD Scientists Discover Surprisingly Rapid Warming

Lake Superior is warming at a rate faster than the climate around it, according to a study conducted by two UMD scientists. "It is a remarkably rapid rate of change, and it is very surprising," said Jay Austin, assistant professor with the UMD Department of Physics and Large Lakes Observatory. Professor Austin co-authored the study with UMD geology professor and Large Lakes Observatory director Steve Colman. Their study has garnered national and international attention from the major TV and radio networks, as well as newspapers and prestigious scientific publications.

The two scientists found that Lake Superior's summer surface temperatures have increased about 4.5°F since 1979 compared with an increase of 2.7°F in the region's annual average summer air temperature. Their study is based on data collected by the National Oceanic and Atmospheric Administration buoys on Lake Superior. Their paper, "Lake Superior Summer Water Temperatures are increasing more rapidly than Regional Air Temperatures: a positive ice-albedo feedback", was published March 23 by the American Geophysical Union in the journal "Geophysical Research Letters".

Dr. Austin said the findings are significant because they show that the primary factor in determining summer temperatures is winter ice cover. A trend towards warmer winters means less winter ice cover, which allows more solar radiation and an earlier summer season. The summer season of Lake Superior is now beginning about two weeks earlier than it did 27 years ago. This, combined with warmer summer air temperatures, leads to an accelerated rate of summer warming.

"What was most startling," said Dr. Austin, "was not just the rapid rate of warming--but that a system we thought was fairly well understood would have such an unexpected response to climate change."

Currently Dr. Austin is working on understanding the implications of this rapid change in Lake Superior, and is studying computer models of how the lake, lake ice, and the atmosphere interact and respond to changes in regional climate. Austin and Colman are interested in exploring what can be learned from better understandings of how these processes work in Lake Superior--and applying them to more complex systems such as the Artic Ocean.

FOR MORE INFORMATION SEE

http://www.d.umn.edu/~jaustin/ICE.html