(Published Friday, March 30, 2007 11:26:22 PM CST)
A d v e r t i s e m e n t
By Chris Schultz Gazette staff
LAKE GENEVA-Scientists in Wisconsin and New York State say their research shows Geneva Lake is frozen about a month less each winter than years ago.
The air is getting warmer sooner and staying warmer longer, said Ted Peters, director of the Geneva Lake Environmental Agency.
"It's a way of telling us if we have global warming," Peters said.
Ken Schmaling of Walworth said he hasn't noticed anything unusual about the ice on Geneva Lake.
An occasional ice fisherman, Schmaling, a clerk at the Clear Water Sports shop in Lake Geneva, said he takes his bucket and line out when the ice is firm. The ice seems to come in time for him to get some fishing done, Schmaling said.
But the scientists say that like the caged canaries once carried into mines because they were sensitive to poisonous gases, Geneva Lake seems to be very sensitive to changes in global climate.
John J. Magnuson, professor of zoology and limnology at UW-Madison, said Geneva Lake is near the southern boundary of where lakes freeze in winter.
"Owing to its greater depth and its location at the southern boundary of where lakes are ice-covered, its ice cover is more sensitive than many other lakes," Magnuson wrote in an e-mail to The Janesville Gazette. Because of Geneva Lake's depth (144 feet at its deepest), it has to lose more heat to freeze than a more shallow lake.
That makes Geneva Lake's ice cover more sensitive to climate change, Magnuson said.
According to freeze and thaw data collected by the Wisconsin State Climatology Office, and recently published by The Milwaukee Journal-Sentinel, Lake Geneva's average days of ice cover dropped from 104 days in 1880 to 70 days in 2006, a loss of 33 percent.
Kenton M. Stewart, professor of limnology at the University of Buffalo, N.Y., also has been keeping an eye on freeze and thaw dates, including those of Geneva Lake.
Stewart, a graduate of UW-Madison, said changes in the freeze and thaw cycles of lakes are not noticed over two or three years. It takes decades of watching and recording freeze and thaw dates before conclusions can be reached, he said.
According to a 2000 paper on lake and river freezes and thaws around the world, co-authored by Stewart, Magnuson and others, by 1995 freeze dates were starting about six days later and thaw dates were occurring a little over six days earlier compared to 1895.
Shorter periods of ice will eventually change the ecology of the lake, but how that would happen is hard to predict, Stewart said.
Good ice cover stops wave action and allows sediments to settle, Peters said.
A snow cover over the ice also cuts off light and kills plants. Without the plant die-off, lake weeds seem to take bloom earlier in the spring.
Geneva Lake freeze and thaw
Earliest freeze date: Nov. 23 in 1880.
Earliest thaw date: Jan. 3 in 1886.
Latest freeze date: March 10 in 1932.
Latest thaw date: May 4 in 1881.
Longest period of freeze: 162 days in 1880-81.
Shortest period of freeze: 0 days in 1997-98. The lake never froze.
