What over a century of ice data can tell us about the Great Lakes’ future
Michigan researchers have gone back in time to get a sense of how Great Lakes ice cover has changed since the late 19th century.
Using historical temperature records from weather stations in the region, researchers improved their understanding of where the ice might have formed, and for how long, over the past 120 years.
Their findings were published in the journal Scientific Data last month. The researchers said these new data records would help better understand the impact of climate change on the region over time and clarify what life under the ice is like for iconic declining species such as lake whitefish. The new data could also help improve the prediction of winter ice cover, making recreational activities and people getting out on the ice safer.
“Lake ice is truly part of the system, of our life. [for] our culture, regional weather, safety, everything,” said Ayumi Fujisaki-Manome, one of the study’s co-authors and associate director of the University of Michigan Cooperative Great Lakes Research Institute.
There is a “pretty good satellite record” of Great Lakes ice cover over the past 45 years, she said. But research into the region’s historical climate requires a longer time scale, and there are no reliable ice-specific data.
According to the researchers, there is a general gap in scientific knowledge about winter in the Great Lakes: data buoys are removed due to harsh conditions. There are, however, good historical weather observations. And air temperature is a good indicator of ice cover on lakes, because ice typically forms when there are several cold days in a row.
How thick is the ice on the Great Lakes? Scientists want your help.
To look into the past, the researchers examined temperature records from weather stations located all around the Great Lakes, limiting their study to stations with the most consistent data since 1897.
They calculated the ice cover using this information, and the end result was a data set that could be compared to current conditions. The researchers said this could inform future research into animal behavior during winter, for example.
“A lot of the biological conditions under the ice are very poorly understood,” said Katelyn King, a fisheries research biologist for the Michigan Department of Natural Resources and lead author of the study. King is using the dataset to study the historic decline of whitefish in the Great Lakes, a culturally and economically important regional species.
King said this dataset provides a useful benchmark as the region continues to evolve under climate change. Research shows that average temperatures in the region have risen over the past two decades, freezing seasons are shortening, and heavy snowfall and torrential rains are becoming more frequent.
Yet year-to-year variability is the new normal. Ice cover on the Great Lakes was relatively close to average last winter, but followed historic lows the previous season.
So far this winter, cold temperatures in recent weeks have contributed to some of the highest ice cover on the Great Lakes in years, according to data collected by the U.S. National Oceanic and Atmospheric Administration.
“These really extreme years, where we have very cold weather or very hot weather, are just a sign that the long-term climate is changing,” King said. “It really affects all of us in our daily lives.”
