Warming temps mean many Michigan lakes won’t freeze in coming years

As the earth warms, more Michigan lakes will see ice-free winters, and “extensive loss of lake ice will occur within the next generation,” according to a study recently published in the journal Nature Climate Change.

The trend bodes poorly for the state’s cold water ecosystems and those who enjoy ice fishing, skating and other winter recreation, experts say.

The study examined ice cover across 1.4 million lakes of a certain size in a swath of the Northern Hemisphere from Michigan to South Korea. Researchers found 14,800 lakes now freeze only intermittently, but that number could surge to 35,300 in a few decades, even if the world limits average temperature increases to 2 degrees Celsius (3.6 degrees Fahrenheit), the goal of the Paris Agreement reached by the United Nations.

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In Michigan, whose average monthly temperatures have warmed 1.78 degrees Fahrenheit over the past 30 years, more than 1,100 lakes as far north as Muskegon now freeze only intermittently, according to the researchers’ data.

That line could extend to Traverse City if temperatures rise 2 degrees Celsius, encompassing about 700 more lakes, including Houghton Lake in Roscommon County and Benzie County’s Crystal Lake.

“Lake ice is a really good index of what’s happening to weather and climate change variation,” John Magnuson, an aquatic ecologist at the University of Wisconsin in Madison, and a co-author on the Nature study, told Bridge Magazine. “It’s very sensitive.”

Ice trends on lakes can vary wildly year to year, Magnuson said. One lake he has extensively studied — 15 square-mile Lake Mendota in Madison, roughly the same latitude as Grand Rapids — has been frozen as long as six months and as short as 21 days since 1855.

But the average ice window has shrunk significantly, from four months to three over that same period. And the lake this winter saw its third-latest freeze in that history.

The loss of lake ice could have widespread implications for the ecosystems that live in them, though scientists are still studying exactly what might happen.

Ice typically acts as an ecological “reset” button in lakes, and an ice-free winter sets up a wildly different “mixing regime” that could harm fish, Magnuson said.

No ice also means lakes would warm up more quickly during the spring and summer, which could harm cold water fish like walleye and fuel more harmful algal blooms.

And don’t overlook the effects on fishing, skating, ice festivals and other outdoor activities integral to the culture of the Midwest, Magnuson said.

In the summertime, folks might need a dock, boat or property front to enjoy a lake, the scientist said.

“In the winter time, once the ice is safe, you can go out on it — and the lake is open to everybody.”