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Meltdown: Ice is Vanishing As Lakes, Rivers Freeze Later

Posted on: Monday, 14 January 2008, 12:00 CST

Forty years ago, Buckeye Lake was covered in thick ice from late November to early March.

"It used to be frozen so solid that people could drive their cars on it," said J-me Braig-Bogden, director of the Greater Buckeye Lake Historical Society.

"We'd have ice-boat races and motorcycle races. People would have fires on the ice and skating parties."

Those fond childhood memories might not come again.

Three University of Wisconsin researchers who studied northern lakes, rivers and bays found there now are 16 fewer days of ice cover than in 1975. And some lakes in states including Wisconsin and Michigan no longer freeze over at all, they report.

The study, sponsored by the National Science Foundation, offers the latest indicator of global warming, said Barbara Benson, a co-author and an ecology professor.

"People are aware of what's happening," she said. "I think there is probably concern about the effect this will have on the economy and other things that depend on real winter conditions."

The researchers studied ice formation and thaw data for 65 lakes, rivers and bays and found a steady decline in the number of days each would stay frozen during the past 30 years.

The researchers used newspaper archives, transportation ledgers and even religious-observance logs to gather ice records across the Northern Hemisphere.

Today, higher temperatures delay lake freezes by an average of 10 days and speed up thaws by six days compared with 1975, the study found.

The average fall-through-spring temperatures also rose about 3.6 degrees since 1975.

The quality and thickness of the ice on the lakes have diminished over time, said George Leshkevich, a researcher at the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Laboratory.

"A lot of (recent) years, we wanted to go out and make measurements, but there wasn't enough ice," Leshkevich said. "The ice was decaying, had water on it and melt holes."

David Bromwich, a professor of atmospheric sciences at Ohio State University, said the earlier spring thaws mirror rapid declines in arctic sea ice north of Alaska.

A lack of ice can throw off the ecological balance of lakes, said Olaf Jensen, a co-author of the Wisconsin study.

Ice can help balance fish populations, he said. For example, ice can kill off larger fish that prey on smaller fish, such as minnows. A warmer lake makes it tougher for the smaller fish to survive.

This warming trend also can throw off the timing between fish hatchings and the peak growth times for the plankton they eat.

"If you hatch too early or too late, you miss out on your food," Jensen said.

At Buckeye Lake these days, ice forms and melts several times during the winter, Braig-Bogden said. That's made ice fishing a lot more difficult.

"They get their little huts out there and then they have to haul them right back."

Source: The Columbus Dispatch, Ohio

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