Losing the Cold Season
By Carolyn Rumery Betz
Ice fishing, skiing, snowmobiling and other outdoor activities help us enjoy ─ rather than endure ─ Wisconsin's long winters.
"We don't dread winter," says Kathy Kline, who, with her husband Jeff, have skied the American Birkebeiner and Kortelopet cross-country races ten times. "We look forward to being outside, especially when we can ski."
Training for the "Birkie" may become more challenging in the future -- not because the Klines have two small children, but because Wisconsin winters are likely to be warmer with less snow.
WICCI climate scientists project that our winters will see the most warming of any season by mid-century. Northwestern Wisconsin, where the ski race occurs, is expected to warm the most—by as much as 8°F.
Ned Zuelsdorff, executive director of the American Birkebeiner Ski Foundation, sits on WICCI's advisory committee. He says the warmer winters mean reduced training time for skiers leading up to race day.
"Most of our race participants come from the near Midwest – Minneapolis to Milwaukee," says Zuelsdorff, "and if they can't train, they don't want to race."
Since the race began in 1973, the race course has had to be adjusted six times due to warmer weather, including shortening its distance, moving snow around, and changing the location of the finish line. In 2000, the race was canceled due to unseasonably warm weather and rain. Altering the race course is manageable, but it's impossible to change whether or not people can train for the event.
Wisconsin's average annual snowfall is expected to decrease by as much as 13 inches by mid-century, according to Michael Notaro, associate director of UW's Nelson Institute Center for Climatic Research, and the snow season is projected to shorten by about 24 days. By late century, an average Wisconsin winter could see snow cover for only about 96 days, from early December through late March, compared to today's span of 140 days from mid-November to mid-April.
Race officials could need to reschedule the late-February race. They have already moved the finish line to avoid having more than 8,000 participants ski across Hayward Lake due to worries that the ice might not be safe.
All lakes in Wisconsin have seen a reduction in the number of days they are frozen over, according to John Magnuson, an emeritus professor of limnology at the University of Wisconsin-Madison and former co-chair of WICCI's science council.
Shorter length of ice cover results from a combination of later freeze dates due to warmer fall air temperatures, and earlier breakup dates caused by higher winter and spring temperatures.
Ice cover on Lake Mendota has declined by 25 days since the mid-1800s, when records were first kept. Instead of being frozen for four months, the lake is now only frozen for an average of three. Long-term records also show that ice cover on Shell Lake in northwestern Wisconsin and on Lake Geneva in southeastern Wisconsin have shortened by 10 to 40 days.
Recreational opportunities associated with frozen lakes aren't confined to ice fishing and ice boating. A community event, Madison's "Kites on Ice," is no longer held, in part due to the liability associated with having more than 80,000 people tromp around on thin ice.
Fans of winter activities are likely to lose even more opportunities in the future. Spring weather arrives six to 20 days earlier than it did in 1950, and this trend is expected to continue, with temperatures projected to warm from 3-9°F by mid-century, particularly in the northern and central parts of the state.
Wisconsinites may eventually find it difficult to identify our state as a place of four seasons. "We've lost 25% of winter as measured in ice cover," says Magnuson. "If you value winter, as many of us do, that's not a good thing."