UMD researcher contributes to global lake temperature databse

by Allison Kronberg

When it comes to climate change research, even in the Land of 10,000 Lakes, researchers still know more about how oceans respond to air temperature changes than freshwater lakes.
But a new global database of lake temperature changes could help researchers learn more about the fragile ecosystems’ responses over time to a changing climate.
A global database of lake surface temperatures was published earlier this month with a contribution from a University of Minnesota-Duluth researcher. 
“I don’t know why oceans have been studied more and lakes haven’t been talked about as much,” said Sapna Sharma, the paper’s lead author and a professor at York University in Canada. “I find lakes really interesting to study because of the importance of them. We need fresh water to drink, and we need them to survive.”
Sharma said the study will serve as a baseline for how climate change around the world affects freshwater systems.
The dataset is the first to compile on-site research of smaller lakes from individual researchers alongside satellite-collected temperature data from NASA, with a total of 291 lakes measured altogether from 1985 to 2009. Previous global lake temperature data compilations have only included satellite data on large lakes.
Associate professor Jay Austin of the Large Lakes Observatory at the University of Minnesota-Duluth is one of about 70 researchers who contributed on-site research by gathering information through working directly at an individual lake.
Austin has been studying the surface temperature of Lake Superior for much of his career. He said the lake is so sensitive that even a change in a couple degrees in overall air temperature can greatly affect it.
Until the winter of 2014, Austin said, Lake Superior had been on a warming trend, which has led to less ice each year. Last year’s cold winter in the region threw off the warming trend with extremely high ice coverage.
Overall, however, the lake may still see less ice in the future if the warming trend continues, he said.
Austin is curious to know how Lake Superior’s temperature changes fit in with other lakes around the world, he said, and the database allows him to compare.
“One of the things that define living up here in Duluth is the presence of the big lake,” Austin said. “People are very interested in how it’s behaving. Climate change is just one part of that story.”
Throughout Minnesota, lakes influence people and their activities. And sometimes, their temperatures can be significant.
University of Minnesota alumnus Spencer Olson, who graduated with a degree in finance last May, has been ice fishing since he was about 8 years old.
Olson said he could walk on the ice on Potato Lake near Park Rapids, Minn., where he was able to fish by about Thanksgiving last year, which is very early. But during other years, the ice didn’t get thick enough until much later. 
“We’ve noticed more variability,” he said. “I think in the future, the variability in the weather will affect us eventually. But it hasn’t really affected us yet because the season hasn’t really shortened at all.”
Aside from ice fishing, changes in lake temperatures could have implications for human health and economies, as well as habitats for wildlife.
Sharma is in the process of analyzing the global set of lake temperature data to figure out if there are spatial patterns in how lakes respond to climate change and to learn what factors are influencing their temperature changes. Sharma’s analysis may be published within the next couple of months, she said.
“This data we put together is so important for illustrating what’s already happening,” Sharma said. “That way we can begin to understand what might happen in the future.”