Lake Superior, one of the world’s largest bodies of fresh water, is not only at its shallowest point in 81 years, it’s also warming at twice the rate of the air around it, according to an interesting story in the October issue of Minnesota Monthly. The piece quotes scientist Jay Austin, of the Large Lakes Observatory in Duluth, who says average water temperatures have increased 4.5 degrees since 1979. He relates the change to a significant decline in winter ice cover, which ordinarily reflects heat-making sunlight back toward the sky. The ice decline is, it seems, related to global warming.
With the lake’s summer season lengthening from 130 to 160 days, some sections of water recently reached a balmy 75 degrees (barely breaking 60 is more the norm). A warmer Lake Superior could mean dramatic changes in aquatic-life, and could open the door to dread invaders like sea lampreys and Quagga mussels. On the brighter side, with a lessening of Superior’s bone-chilling “lake effect,” Duluth, perhaps, will no longer be known as “the air-conditioned city.”
Austin explains that it’s hard to anticipate exactly how Superior will change in the coming decades. Predicting the effects of global warming, he says, is “like turning all these knobs at the same time. It’s anyone’s guess whether Lake Superior will turn into a big bass-fishing lake or a big desert.”