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.

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.

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.”