Recent declining ice trends could be headed for a rebound, but that doesn't mean the lakes and the winter activities they support will escape the consequences of climate change
Study: Century-long data reveals complex trends in ice cover in the Laurentian Great Lakes (DOI: 10.1038/s43247-026-03866-5)
There's good news and bad news for folks who love a good coat of ice on the Great Lakes for the activities and businesses it supports.
The good news is that, after decades of dipping annual average ice cover, there's reason to believe that trend could slow or even, temporarily, turn around. That's according to new research from the Cooperative Institute for Great Lakes Research, or CIGLR, at the University of Michigan.
"We may anticipate a pause in ice cover decline, or even a moderate (short-lived) increase in average ice cover," the team wrote in its study. "This contradicts most existing literature on this subject."
The research suggests that the Great Lakes' ice cover is synced to strong but slow-churning natural global cycles that drive regional weather patterns. Currently, we're in a trough, but we could be heading out of that toward a crest that would mean more ice cover, even against a backdrop of global warming. Which is not to say the lakes are out of hot water with respect to climate change.
"It is important that we do not interpret these changes as climate recovery, but rather a temporary respite from the background warming that has continued over the last 125 years," the authors wrote.
The researchers also found further concerning news in that, especially with warmer temperatures, the year-to-year swings in ice cover can be massive. This makes forecasting ice cover for future coming winters more challenging. That, in turn, makes it more difficult for Great Lakes residents, businesses and the shipping industry to prepare for and adapt to what may be in store.
"If you look at the last 50 years, the highest ice year and the lowest ice year we have on record are back to back," said David Cannon, senior author of the new study and an assistant research scientist with CIGLR. "So as we continue seeing these changes in the lakes, maintaining our observations and long-term records is really important."
A song of data and ice
Building a better long-term record of ice cover was actually the basis for this new study, published in the journal Communications Earth & Environment, which began as part of the Great Lakes Summer Fellows Program.
In partnership with the National Oceanic and Atmospheric Administration Great Lakes Environmental Research Laboratory, or NOAA GLERL, the fellows program offers undergraduate students hands-on, real-world research experience while strengthening our scientific understanding of the lakes. This particular opportunity appealed to Elleanna Viere.
"I have always loved Lake Superior growing up in Minnesota," Viere said. "By the time I was off to undergrad, I knew that I wanted to go to Northland College on the south shore of Lake Superior, where I further fell in love with snow and the Great Lakes. When I was looking for summer internships, I stumbled upon CIGLR and got very excited to have the opportunity to expand my knowledge and skills in the region."
During her time at Northland, she noticed the ice bridge to nearby islands in Superior forming later and later each season. In 2024, poor ice conditions forced Ashland's "Book Across the Bay" 10K ski and snowshoe crossing of the frozen Chequamegon Bay to reroute closer to the shore to boost safety.
10.1038/s43247-026-03866-5 (Used under a creative commons license)
"With changes in ice cover and major events in the region, many people stated how the ice has been becoming more unpredictable in recent years," Viere said.
Her project with CIGLR aimed to assess one metric of those changes-the average annual ice cover of each lake-not just in recent years, but diving much further into their history to plumb for new insights. Researchers have access to satellite data to determine Great Lakes ice cover going back to the 1970s. Prior to that, though, they have to rely on estimates and simulations that have known limitations.
Viere, Cannon and their colleagues coupled this ice cover data with air temperature records to develop a model that linked the two observables. With air temperature data stretching back more than a century, they then used the model to look backward and "hindcast" the lakes' average annual ice cover back to 1898. The team also dug up newspaper articles and captains' logs from the pre-satellite era to help vet their model's outputs.
The model showed that, for about the first 40 years of the 20th century, average annual ice cover experienced a downward trend, similar to what the lakes have been experiencing since the late 1970s. But for the better part of four decades between those two declines, ice cover rose. That means, if history repeats itself, we could see increasing average annual ice cover within the next decade or so.
"I think this is a reminder that our memories are pretty short," Cannon said. "Our parents and grandparents can tell us that there used to be more ice on the lakes, and there definitely was. But we've kind of lost what happened before that, and that timescale is important."
Moving forward, Cannon said it would be helpful to build models to hindcast other ice attributes on the Great Lakes, such as its thickness and spatial patterns, over time. Both he and Viere also stressed the importance of measuring and preserving this data now to help current and future generations of researchers better forecast Great Lakes ice.
"The Great Lakes are a precious resource and ecosystem to the region," said Viere, who has started a graduate program at Northern Michigan University. "Knowing how factors such as annual average ice cover have been fluctuating can eventually help us understand how future years can be influenced, and how to adapt to these changes."
CIGLR is a partnership between NOAA and regional universities, businesses and nongovernmental organizations and is housed in the U-M School for Environment and Sustainability, or SEAS. The research team also included Hazem Abdelhady, an assistant professor at Texas A&M University; Meena Raju, a CIGLR postdoctoral fellow; Ayumi Fujisaki-Manome, an associate research scientist with CIGLR and SEAS; Jia Wang, a NOAA GLERL climatologist; James Kessler, a physical scientist with NOAA GLERL; and Khush Bafna, a CIGLR undergraduate researcher.
