Great Lakes tops 90% ice cover, zeroes in on record

(Detroit Free Press) -- The Great Lakes are now more than 90.5% ice-covered — not just a Great Lake; all of them. That's the most ice cover in 34 years. In 1979, there was 94.7% ice cover, the largest ever recorded by scientists.

"This year we will pass that, because in the next few days it will be another 5%, easy," said Jia Wang, a research ice climatologist for the Great Lakes Environmental Research Laboratory in Ann Arbor.

A science degree isn't required to understand what's driving this: bitterly cold air.

"I look at the weather forecast and it looks like another week or so of freezing," Wang said. A forecast warm-up — and we use that term loosely — by the end of this work week should inch temperatures over the freezing mark.

Scientists only have data on Great Lakes ice cover levels going back to 1963, when airplanes were used to help measure it for the first time, Wang said. But even in anecdotes and the historic record it appears a total Great Lakes freeze-over has never occurred — at least since people have been around.

A key reason is Lake Ontario, at the far east end of the Great Lakes chain. With its warmer water temperatures from a slightly more temperate climate, the lake generally doesn't freeze. But this brutal winter has it nearing 50% ice cover, which also is extremely unusual, according to Wang.

"It's nice to see this kind of level after 20-some years," he said. "We need more research to study what happens when the lakes are this covered, and why it looks like this only after decades."


Contact Keith Matheny: 313-222-5021 or kmatheny@freepress.com. Follow on Twitter


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