Lake Superior Changes Mystify Scientists

MARQUETTE, Mich. -- Deep enough to hold the combined water in all the other Great Lakes and with a surface area as large as South Carolina, Lake Superior's size has lent it an aura of invulnerability. But the mighty Superior is losing water and getting warmer, worrying those who live near its shores, scientists and companies that rely on the lake for business.

The changes to the lake could be signs of climate change, although scientists aren't sure.

Superior's level is at its lowest point in eight decades and will set a record this fall if, as expected, it dips three more inches. Meanwhile, the average water temperature has surged 4.5 degrees since 1979, significantly above the 2.7-degree rise in the region's air temperature during the same period.

That's no small deal for a freshwater sea that was created from glacial melt as the Ice Age ended and remains chilly in all seasons.

A weather buoy on the western side recently recorded an "amazing" 75 degrees, "as warm a surface temperature as we've ever seen in this lake," said Jay Austin, assistant professor at the University of Minnesota at Duluth's Large Lakes Observatory.

Water levels also have receded on the other Great Lakes since the late 1990s. But the suddenness and severity of Superior's changes worry many in the region. Shorelines are dozens of yards wider than usual, giving sunbathers wider beaches but also exposing mucky bottomlands and rotting vegetation.
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