Minneapolis, Minn. — John Magnuson is a retired zoology professor and past director of a center for lake studies at the University of Wisconsin at Madison. He's watched the dates of ice formation and ice break up on Lake Mendota for decades, and in that time, it seemed that the ice season was getting shorter.
A study of newspaper records beginning in the 1850's confirmed his suspicion. It showed that in the past 150 years, the length of time the lake has remained frozen each winter has declined from around four months to three.
Magnuson says in an era of global climate change, the study of such past climate records is becoming increasingly important.
"It's turned out that, a rather recent realization I think, that the things that are worrisome to us, the most worrisome to us, are things that happen very slowly, and these are only apparent in these longer term records," Magnuson said. "So people like myself and others have been digging back into these records with much more vigor than they did."
Magnuson was the keynote speaker at a symposium attended by around 80 people, mostly Minnesota scientists along with staff from the state Pollution Control Agency and Department of Natural Resources.
He urged them to do more research into Minnesota's past climate records. Those records include year by year observations on such things as flowering times and bird migrations. They also include technical records, such as data kept by the U.S. Geological Service on water flows and water levels.
Scientists expect the state's rivers and lakes to get warmer. That would mean cold water fish, such as walleye, could decline. Warm water fish might move north into Minnesota. Magnuson says the state DNR may have to decide whether to try to preserve some Minnesota lakes for walleye, or let them give way to warm water fish.
"I think that one of the things that's got to be happening is the agencies have to think through, what are the consequences of doing nothing, and what's the best they can do in the worst case scenarios to preserve the diversity of resources and values that Minnesotans care about, such as 'I want to fish for walleye," Magnuson said.
Minnesota Pollution Control Agency research scientist Peter Ciborowski says that agency also faces decisions.
"It's very hard to predict exactly what will happen. We think generally we're looking at increased flooding events but we don't know how the variablity of precipitation will change," Ciborowski said. "So what we think we're going to have to do, given this uncertain future, is broaden out our design parameters, for waste water treatment plants, and for pollution loading of streams, to account for a much more uncertain future."
The MPCA and the State Department of Natural Resources were both sponsors of the symposium. The agencies hope to encourage more monitoring efforts to track climate change effects on the state's forests, water, and wildlife.