Fifty years ago, winter didn’t just visit the Great Lakes — it took up residence. If you blinked too slowly, your eyelashes froze together. Standing on the ice at the edge of Lake Superior, just after an early January snowstorm, everything was white and still, except for the lake. The wind had swept across it revealing ice cracked along thunderous fractures.

Usually by Christmas, Lake Huron’s Saginaw Bay would be locked in — thick enough for trucks, ice shanties dotting the horizon like little wooden cities. People hauled augers and bait out before dawn, thermoses of black coffee steaming in the cold.

But in 2019-20, the ice never came.

The air, wet and gray, hovered above freezing. The ground was muddy. Kids tried sledding on dead grass. Businesses that rented shanties stayed shuttered and people wondered if this is how winters would be going forward.

The environmental and social consequences of warming winters are impacting lakes globally. Despite these clear signs, most Great Lakes monitoring occurs during warmer, calmer weather.

As professors researching winter and members of the International Joint Commission Great Lakes Science Advisory Board, we’ve developed evidence-based advice for policymakers in Canada and the United States on water quality priorities and co-ordination. To strengthen international monitoring co-operation, we recommend adding winter monitoring to fully understand what ails the lakes.

Warming winter syndrome

Diagnosed with “warming winter syndrome,” the Great Lakes’ surface water temperatures are increasing, especially during the cold season.

Winters in the Great Lakes region are trending warmer and wetter, and annual maximum ice cover is significantly declining. Winter conditions are getting much shorter — by about two weeks fewer each decade since 1995.

In the Great Lakes region, businesses, visitors and more than 35 million residents see winter warming symptoms year-round. Shifting seasons increase nutrient runoff, fuelling algal blooms that foul summer beach days.

Changing food webs affect commercially and culturally important species like lake whitefish. Shrinking ice cover makes recreation and transportation less safe, altering the region’s identity and culture.

Winter is changing the most, but studied the least

We are losing winter on the Great Lakes before fully understanding how the season affects the ecosystem and communities. Our review of recent literature shows winter is understudied.

Researchers have limited understanding of the physical, biological and biogeochemical processes at play. Changes to these processes can affect water quality, ecosystem and human health, and the region’s social, cultural and economic well-being, yet understanding them is difficult without the necessary background.

Under the Great Lakes Water Quality Agreement, Canadian and American agencies monitor and report water quality and health indicators. The agreement establishes objectives for Great Lakes water quality, including keeping them safe for drinking, recreation and consumption of fish and wildlife. However, current efforts focus on warm months.

Expanding to winter would address key data gaps. Ad-hoc studies already show winter warrants systematic monitoring. In 2022, a dozen Canadian and U.S. universities and agencies collected under-ice samples across the basin in the Great Lakes Winter Grab.

Teams travelled by foot or snowmobiles and drilled through the ice to collaboratively gather a snapshot of lake life and water quality conditions across all five Great Lakes.

What followed was a grassroots Great Lakes Winter Network of academics and government researchers to better understand how rapidly winter conditions are changing, with the aim to improve data sharing, resource co-ordination and knowledge exchange.

Annual maximum ice coverage on the Great Lakes from 1973 to 2025. Despite significant variance year to year, ice coverage on the lakes has declined by roughly 0.5 per cent annually since 1973. (NOAA Great Lakes Environmental Research Laboratory)

Impacts on communities

Warmer winters are linked to increased drownings from unstable ice. Greater nutrient runoff fuels harmful algal blooms and complicates drinking water treatment.

Reduced ice cover may extend the shipping season but can harm the US$5.1 billion fishery sector by altering habitats, increasing invasive species pressures and degrading water quality.

Winter also shapes cultural identity and recreation. From snowshoeing to skating on frozen lake waters, residents and visitors to the Great Lakes region can share happy memories of wintertime activities. Its loss can erode community ties, traditions and livelihoods.

Changing winter conditions also present threats to the traditions and cultural practices of Indigenous Peoples in the region. Many Indigenous Peoples express their cultural relationships to their ancestral lands through hunting, fishing, gathering and farming.

For example, lower total snowfall and more frequent freeze-thaw events remove nutrients from soil and may result in changes in the seasonal timing and availability of culturally important plant species. Unstable ice limits fishing and reduces opportunities to pass on skills, language and cultural practices to future generations.

a man in winter clothing standing on a frozen lake with instruments for taking samples.
Collecting samples on Lake Erie to study wintertime conditions in the lake. This research was conducted as part of the 2022 Great Lakes Winter Grab. (Paul Glyshaw/NOAA)

Strengthening Great Lakes winter science

Data collection in cold-weather conditions poses logistical challenges. Researchers need specialized equipment, trained personnel and co-ordinated approaches for safe, efficient observations. Expanding Great Lakes winter science requires more resources.

Our new report highlights knowledge gaps in winter processes, socioeconomic and cultural impacts of changing conditions, and how to strengthen Great Lakes winter science.

The report also cites infrastructure limits, calling for more training so scientists can work safely in cold conditions, such as the 2024 Winter Limnology Network training workshop. Better data management and sharing are also needed to maximize the value of collected information.

Great Lakes winter science is growing, but improved capacity and co-ordination are essential to keep pace with changing conditions. These changes affect not only ecosystems but also communities. Strengthening winter science will help safeguard the health and well-being of those who live, work and play across the Great Lakes basin.

This article is republished from The Conversation, a nonprofit, independent news organization bringing you facts and trustworthy analysis to help you make sense of our complex world. It was written by: Marguerite Xenopoulos, Trent University and Michael R. Twiss, Algoma University

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Marguerite Xenopoulos receives funding from Canada Research Chairs and the Natural Sciences and Engineering Research Council.

Michael R. Twiss is affiliated with the International Association for Great Lakes Research.