Unseasonable winter temperatures decimate Great Lakes ice coverage

A cyclist travels around Lake Michigan near the Adler Planetarium in Chicago on Feb. 26. Springlike weather during much of the past winter reduced the ice coverage on the lake. Associated Press
Sunlight reflects off Lake Michigan at Montrose Harbor in Chicago on an unseasonably warm day Feb. 27. Associated Press
A man walks along the shore of Lake Michigan at Lighthouse Beach in Evanston on Jan. 16. Unseasonably warm temperatures throughout the winter led to historic lows of ice coverage this year. Associated Press
A lone man walking in dense fog pauses to take a photograph along Lake Michigan near Chicago’s Shedd Aquarium in Chicago on Jan. 25. Associated Press

With unseasonably warm temperatures dominating weather forecasts this winter, communities and visitors of the Great Lakes may have noticed the iconic bodies of water were strangely low on one cold weather staple — ice.

Ice coverage on the lakes stood at historic lows in late February — the time of year ice typically reaches its annual peak, NASA’s Earth Observatory reported.

Owing to warmer winter weather and above-average surface water temperatures, Great Lakes ice coverage has been trending down since 1973, with annual maximum coverage decreasing by about 5% each decade.

Experts say the declining levels are raising red flags toward greater shoreline erosion, lake effect snow, invasive species and toxic algal blooms. While less ice also can mean more shipping days, the trade-off is ecologically expensive, said Nancy Tuchman, founding dean of Loyola University’s School of Environmental Sustainability.

“It does increase commerce, but it also increases the scouring of the shoreline and the introduction of invasive species, because most invasive species have come in through the shipping industry,” said Tuchman, who is an aquatic ecologist with a focus on coastal Great Lakes ecosystems.

High shipping traffic leads to a constant wake crashing against the shore, causing damaging erosion. And with ice coverage declining in the winter, the shorelines don’t get a break during shipping off-season because they lose the protection the huge frozen sheets offer.

“When you decrease ice cover and that's coupled with an increased frequency and intensity of storm events, we see increased shoreline erosion and flooding,” Tuchman said. “There are a lot of really important Great Lakes coastal wetlands that serve as nursery grounds for fish, but also for many of the mollusks and insects and even the water birds and shorebirds.”

Less ice also can have effects farther from the lakes themselves — primarily greater lake effect snowfall, which occurs when cold, Canadian air moves across the open waters of the Great Lakes.

As the cold air passes over, moisture from the warmer waters is transferred into the atmosphere, producing snow on the other end of the wind current. The effect happens more and more when there’s no ice cover, leaving open water for the wind to pick up warmth and moisture from.

Richard Rood, professor emeritus of climate and space science and engineering at the University of Michigan, added this year’s nearly nonexistent ice cover is a harbinger of what is yet to come.

“This is a vision of our future, and we need to be thinking about how we're going to live in that,” Rood said. “It's not the end of the world, but it's different, and we need to be thinking about our adaptation. And we really need to be reducing our emissions to keep it from getting worse and worse. We still spend too much time thinking that we're going to go back to the way it used to be.”

• Jenny Whidden is a climate change and environment writer working with the Daily Herald through a partnership with Report For America supported by The Nature Conservancy. To help support her work with a tax-deductible donation, see

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