Cold brings icy silver lining to Lake Superior

By John Michaelson
Minnesota News Connection

It may not soothe the sore backs of shovelers or help cover high heating bills, but this cold and snowy Minnesota winter does have a silver lining for the Great Lakes. The bitter temperatures that have been common have led to Lake Superior being nearly entirely covered in ice for the first time in 20 years, according to climatologist Jeff Andresen.

“Having ice over the cover of the lake inhibits — or prohibits, even —evaporation of free water, so this should help reduce the amount of evaporation, and of course that would help our lake levels a little bit,” he said.

Since the late 1990s, Andresen said, water levels have mostly been below normal, negatively affecting the Great Lakes’ $35 billion shipping industry. The latest figures show Lake Superior is currently 91 percent ice covered, while the Great Lakes as a whole are more than 80 percent ice covered.

It’s also likely, said Andresen, that the deep freeze of this winter will help slow the spread of certain invasive insects in Minnesota, such as the destructive emerald ash borer.

“If they had the bad fortune of overwintering on a tree or on bark, or on a location that was exposed and above the snow line, odds are that — well, there are going to be many fewer of them.”

The emerald ash borer was first detected in Minnesota in 2009 and is now confirmed in four counties: Hennepin, Ramsey, Houston and Winona. There are an estimated 900 million ash trees in the state, the second-highest number in the country.

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