As the Great Lakes warm, researchers say more winter science is crucial

CBC

23-05-2025

The climate is changing. Weather patterns are shifting. The globe is warming — and that includes the Great Lakes.
The five interconnected freshwater North American lakes attract significant study in the summer, but they are not such a magnet in the winter — and a group of scientists says that needs to change as air and water temperatures rise, resulting in a shorter winter season.
As it stands, almost all monitoring on the lakes is done during the spring, summer and early fall months when there's easier access to research vessels and equipment like buoys.
But no matter the season, one researcher says it's been her experience that studying the Great Lakes is treated like a second-class science.
"It is a little more complicated to study the Great Lakes because they are so large and they are underfunded compared to the oceans," said Marguerite Xenopoulos, one of the authors of a new report about addressing research gaps and enhancing winter science on the Great Lakes.
The report released earlier in May outlines to Canadian and U.S. governments what a group of environmental scientists say needs to happen next for winter research on the Great Lakes.
An advisory board within the International Joint Commission (IJC) — a binational organization that helps provide science-based advice to governments over transboundary waterways — penned the document after two years of study.
It offers a look at why winter science is needed, and the barriers to it.
"Without winter science, we cannot get a complete picture of Great Lakes water quality. Winter data, especially long-term time series data, is necessary to better understand the impacts of changing winter conditions on the health of the Great Lakes," authors note in part of the IJC report.
Drew Gronewold is an associate professor with the University of Michigan's school for environment and sustainability.
He says winter measurements of the lakes are critical to saving human lives and protecting the ecosystem.
There are some resources devoted to the issue currently: satellite information and the use of underwater temperature readers called thermistors anchored to the bottom of lakes.
But, he says, more year-round monitoring is needed because of "dramatic" changes from January until the summer months.
"A lot of large lakes around the world don't undergo the sort of same seasonal changes in terms of temperature, ice formation, even what we would call heat content — that's like temperature integrated across the depths," said Gronewold.
He points to ice cover in the winter and its impact on evaporation that happens in the spring and summer, saying: "That can then affect how much water levels decline in the following fall."
Referring to it as a "master variable" of the Great Lakes, Xenopoulos, a professor of biology at Trent University and member of the IJC, says ice cover controls a number of factors, such as oxygen in the water.
Less ice can also result in warmer water and the greater chance of low levels of dissolved oxygen, known as hypoxia.
"Of course, fish don't like not [having] any oxygen. This is one of the reasons why we need to keep studying winter and connect it to the summer conditions."
Warmer winters are not only affecting the amount of ice on the lakes, but they're also impacting the amount of water that's flowing in — bringing in more phosphorus, the most bio-available nutrient, she says.
"Although it hasn't been directly linked yet, it could be one reason why we are now seeing more algae blooms on Lake Superior, which is really unexpected," she said. "It's a very pristine lake."
New winter science study
Xenopoulos says it's expensive to capture the Great Lakes' spatial variability and the lakes require a lot of complicated infrastructure — even more so in the wintertime.
"The infrastructure is not necessarily there so we do need ice-breaking capabilities to sample ... It's unsafe, it requires special training."
The heightened danger of winter science is another obstacle in the way of expanding surveillance, said Xenopoulos.
"Some of the early data that we're looking [at] right now that we're going to hopefully publish soon is showing that there [are] more winter drownings than there are summer drownings. And it's because ice maybe looks safe, but it's not. Ice is a beautiful thing, but it's very dangerous."
According to Xenopoulos, over the past five years or so there's also been a surge in winter limnology — the study of lakes and other bodies of fresh water.
"For the longest time we actually thought lakes were dormant in the winter. Life was still or sleeping. I think [partly] for that reason, winter was understudied."
Tracking lake health, climate variation
Mike McKay says winter is the season we know the least about, yet it's the season changing most rapidly.
However, the University of Windsor environmental researcher — who also sat on the IJC's advisory panel for winter science — says there are some examples of winter sampling already taking place, including with the utilization of coast guard icebreakers in the Windsor, Ont., area.
He says that's been going on since 2009 and gives a glimpse into what the lake may look like in the future.
"We get this extreme variability and with those record low ice years which are happening at higher frequency now we're starting to see … a window into what many think will be a future ice-free Lake Erie," McKay told Windsor Morning host Amy Dodge.
When lakes such as Erie don't consistently freeze like they used to, Xenopoulos says it can also result in more moisture in the air, resulting in lake-effect snow.
"This can cause big ice snowfalls. Especially in areas like Buffalo … so there's that to worry about, too."
When lakes freeze over, Gronewold says they also serve as a barrier, protecting the shorelines of coastal communities.
"When there is less ice in the wintertime, when these storms come in, it can greatly exacerbate erosion."
According to Gronewold, the ice cover can also serve as a stabilizer to protect spawning habitats for whitefish and other organisms.
Government science funding
Canadians re-elected a Liberal government in the recent federal election, albeit a minority one, though as of yet it's unclear what, if anything, that could mean for Great Lakes research funding.
On the U.S. side of the Great Lakes, hundreds of weather forecasters and other National Ocean and Atmospheric Administration (NOAA) employees were let go in late February.
McKay says the moves make him concerned about other potential science-related cutbacks from the Trump administration.
"Unfortunately, monitoring surveillance is often one of the first things to be cut when budgets are tight, especially when there's not a big problem, a crisis, that you're dealing with," McKay said.
Gronewold says the science information in the IJC's report largely relies on existing funding through federal agencies.
Xenopoulos says she's trying to remain optimistic about future funding and winter monitoring: "We want to do it and we want to collaborate."
IJC physical scientist Matthew Child is also holding out hope when it comes to longer term progress on winter science.
"Awareness is up," he said. "The project itself is sort of boring, but the intellectual output … Both on the agency and the academic side, the personnel capacity is being developed and I think many of us thought that was quite encouraging."