Great Lakes temperature extremes intensifying due to climate change

Peer-reviewed research out of the University of Michigan indicates that Great Lakes temperature extremes have changed across all five Great Lakes over the last 80 years.

Borrowing computer modeling concepts that have been used to study the oceans, the researchers refined them to work with the Great Lakes.

Drew Gronewold is an associate professor at UM’s School of Environment and Sustainability. He said when we talk about heat waves on land, people understand.

“So this paper is taking that idea that we’re very familiar with on land and applying it to temperatures in the lakes.”

The problem to overcome was that we don’t have all the data needed across eight decades to look at water temperatures during the most extreme heat waves or cold periods.

“There are periods in time or locations on the lake either at the surface or at depth that we just don’t have a measurement for. So, this is where developing high-powered computer models comes in. And that’s a huge part of this study,” said Gronewold.

Lead author of the study, postdoctoral research fellow Hazem Abdelhady, said the study analyzed how extremes have affected the lakes over the last 80 years and found they’ve intensified sharply in their strength, more than doubling.

That is in keeping with climate change predictions.

The findings are not just about colder colds and hotter heat waves. They have real world consequences.

“Stronger extremes can disrupt ecosystems, threaten fisheries, degrade water quality, and stress coastal infrastructure like drinking water intakes and nuclear power plant cooling systems,” Abdelhady said.

Past studies have shown that of the large lakes in the world, Lake Superior was among those warming fastest.

“Lake Superior continues to warm rapidly and, based on our findings, now shows the largest increase in heatwave intensity among all the Great Lakes,” Abdelhady said.

That does not mean Lake Superior is the warmest lake; it means it is warming the most quickly.

The research was published in the journal Communications Earth and Environment.

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Featured image: Lake Superior on a windy day. Photo by Lester Graham