This summer, Canadian and US scientists will “cruise” the Great Lakes, conducting monitoring and sampling. They will gather essential data that helps track the status and trends of the lakes’ water quality and environmental health. While we don’t usually prefer to think about cold winters during the warm summer, recent winter conditions have a major impact on summer water quality conditions. From warming water temperatures to fish populations to algae blooms, all will be influenced by recent winter conditions.
In their May report, the IJC Great Lakes Science Advisory Board puts the focus on winter science. This is an “understudied season” as the report explains, as far fewer scientists conduct the frigid fieldwork to measure the Great Lakes during winter or the associated shoulder seasons. Like a puzzle with a quarter of the pieces missing, gaps in Great Lakes winter science mean we have an incomplete picture of the Great Lakes’ health. Without wintertime data, Great Lakes decision-makers and managers are missing critical pieces to understand the full picture of the Great Lakes ecosystem.
Speaking at the board’s May webinar that highlighted the report findings, former IJC Great Lakes Regional Office Director Heather Stirratt noted that cold weather observations are key to understanding a season that is not only ecologically important, but also impacted by increasingly unpredictable atmospheric conditions.
“While it is important to have a baseline knowledge of the impacts of winter on the Great Lakes, winter conditions are also changing rapidly. Since 1973, the lakes have seen an increase in water temperature and a decrease in ice cover... a roughly 0.5 percent annual decline in the case of ice cover. What this means is that we are losing winter on the Great Lakes before we fully understand it,” said Stirratt.
Winter has long been an overlooked season for Great Lakes science. Cold-weather data collection can be challenging, as it requires specialized equipment, highly trained personnel, and coordinated approaches to monitoring. Most monitoring happens from late spring to early fall when the lakes can be safely and reliably accessed using current monitoring tools.
Understanding and managing the Great Lakes ecosystem is based on sampling and monitoring from ice-free, warm-weather seasons. Increasing wintertime monitoring activities will help fill in the blanks and give a complete picture that will contribute to more effective policy and management decisions.
The Great Lakes Science Advisory Board’s May 2025 webinar about their report on the state of Great Lakes winter science.
Gaps in science and research infrastructure
The board’s report outlines the current gaps in the knowledge of physical, biogeochemical and biological factors at stake in the Great Lakes ecosystems in winter. The report also highlights gaps in the understanding of the socioeconomic and cultural impacts of changing winter conditions. Wintertime data is needed to better understand how changes in these areas will affect Great Lakes water quality and human well-being.
“Changes to winter conditions on the Great Lakes are expected to be wide reaching, with ecological, human health and socioeconomic and cultural impacts,” said Maggie Xenopoulos, report co-author and member of the Great Lakes Science Advisory Board-Science Priority Committee.
The report identifies key areas for research to better understand how changes will affect Great Lakes water quality.
“While we have some preliminary insights into the impacts of these changes, it is difficult to conclude anything definitive. We need more data to better understand how these observed and predicted changes affect the Great Lakes and influence our policy and decision making,” added Xenopoulos, also Canada Research Chair in Global Change of Freshwater Ecosystems at Trent University.
The report also identified gaps and needs in the research infrastructure that enables Great Lakes winter science. These gaps include enhanced support for monitoring and surveillance activities, developing cold-weather specific models to increase accuracy in forecasting efforts, and data management and sharing, so that the data that is collected can be used to its maximum potential. Addressing these needs is an essential step to eliminating barriers and enhancing our winter science capabilities.
“The top identified need was enhanced support for monitoring and surveillance activities,” said Michael Twiss, co-author of the report and professor at Algoma University.
“The ability of the Great Lakes science community to collect winter data is limited by our current winter science resources. Getting out on the lakes to collect samples and data is challenging to do safely, as it requires specialized equipment, like ice-hardened vessels, and training,” said Twiss, also a former member of the Science Advisory Board-Research Coordination Committee.
“Investments in new emerging technologies such as ice-capable buoys or autonomous underwater vehicles could enable in-lake data collection year-round. Not only would this provide valuable wintertime monitoring but would also provide data during the shoulder seasons in the early spring and late fall, when is to too cold to be on the water but not cold enough for ice to form,” said Twiss.
To support enhanced winter science efforts, the board recommends that the governments of Canada and the United States incorporate wintertime monitoring into the Cooperative Science and Monitoring Initiative (CSMI) sampling cycle. Through the CSMI program, the Canada and the United States coordinate research and monitoring activities on the Great Lakes. Efforts focus on sampling one lake per year, typically during the summer months, in a rotating five-year cycle. Incorporating wintertime monitoring into the program would ensure the routine cold-weather data collection. Currently, preparations are underway to sample Lake Michigan this summer.
"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," Xenopoulos told CBC Windsor.
The board reports that Great Lakes winter science is growing, such as through initial efforts to develop a Great Lakes Winter Network, or the 2022 “Winter Grab.” Scaling science efforts up to achieve routine, systematic observations integrated into existing monitoring are the missing pieces that will provide a complete picture of a Great Lakes ecosystem that is very much awake and alive all year long.
Rachel Wyatt is the communications officer at the IJC’s Great Lakes Regional Office.
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