Scientists Wary of Lake Superior Warming

[Doondoo]

For Jay Austin, who has made a career of studying the Great Lakes, the warming climate around Lake Superior is no mystery. But he was surprised to find the waters of the lake itself warming even more rapidly.

Austin, a Duluth professor and a researcher with the University of Minnesota-Duluth's Large Lakes Observatory, has studied decades of data. What he found was water temperatures rising almost twice as fast as air temperatures -- more than 4 degrees for the average surface temperature. The increase is having dramatic effects.

"The date of what we call the spring overturn has been getting earlier in the year," Austin said. "It's basically the start of the summer season in the lake. It's when you start to develop strong positive stratification: warm water sitting on top of cool water."

In two decades, the spring turnover has moved up two weeks from early July to mid-June. Part of that likely is due to a loss of ice cover. Since ice is reflective, when it's not there it makes it easier for the lake to absorb heat.



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[greenman3610]

1. Superior is vital to great lakes health