Scientists: Less ice on Great Lakes during winter

Mar 23, 2009

(AP) -- Ice cover on the Great Lakes has declined more than 30 percent since the 1970s, leaving the world's largest system of freshwater lakes open to evaporation and lower water levels, according to scientists associated with the National Oceanic and Atmospheric Administration.

They're concerned about how the milder winter freeze may affect the environment. But they're also trying to come to terms with a contradiction - the same climate factors that might keep lake from freezing might make freezing more likely if lake levels drop due to evaporation.

Scientists at the Laboratory in Ann Arbor, Mich., say can be at odds with regional climate patterns. Accurately measuring across a lake system that spans 94,000 square miles in two countries is no small task, they say.

Their studies show that although the amount of ice cover can vary substantially from year to year, the overall coverage on the world's largest system of freshwater lakes is diminishing, especially in the deepest, middle portions of Erie, Huron, Michigan, Ontario and Superior.

"The deeper the water, the greater the heat storage from summer, and it freezes later than the shallow areas," research Ray Assel told The Plain Dealer. "Now, increase the air temperature and the lake takes in more heat and stores it longer, to the point that many of the midlake areas are freezing over less."

Assel's records indicate that ice formation at nearshore areas has decreased less than on the deepest parts.

Evaporation from open water can cause heavy lake-effect snow inland.

Researcher Jia Wang said ice loss can cause other problems, including the destruction of the eggs of fall-spawning fish by winter waves from an open lake, erosion of coastal areas unprotected by shore ice and less winter recreation on the lakes such as snowmobiling or ice fishing.

The Coast Guard has estimated it cost more than $245,000 to rescue 134 fishermen from a huge ice floe off Ohio last month. The fishermen became stranded Feb. 7 when a miles-wide chunk of ice broke away in Lake Erie.

There might be one short-term advantage to decreased ice: Shipping may someday be more possible in the winter months. The locks at Sault Ste. Marie now close each year in mid-January and reopen in late March. But shipping companies might haul less cargo to pass through low-water areas.

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On the Net

GLERL: http://www.glerl.noaa.gov/

©2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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Velanarris
3 / 5 (2) Mar 24, 2009
Couldn't have anything to do with the salt mining that started in the 70's in the area, not at all.
lengould100
2.5 / 5 (2) Mar 25, 2009
Salt mining "started in the 1970's"? Salt has been mined at Windsor Ont. since at LEAST 1893. Typical of your fact-less nonsense.

"The Windsor Salt Mine currently operates two locations in Windsor, Ontario, Canada. The first is on 200 Morton Drive in Windsor, and was established in 1955 and is officially owned by The Canadian Salt Company, Limited. At this location, there are currently 250 employees, and the location earns roughly $75-99 million a year. They produce road and mining salt [ Scott%u2019s Directories, 2007 Manufacturer 50th Anniversary Edition (2007, Toronto, Division Big Directories) pg 2-876] The second location is the Windsor Facility of the Canadian Salt Company, and it is located at 30 Prospect Ave. in Windsor. This facility employs 110 people and estimates their sales at $25-50 million a year. It was established much earlier than the first, in 1893."

http://dic.academ.../7453758
Velanarris
5 / 5 (1) Mar 25, 2009
That's great Len, when did mining underneathe the lakes begin, rather than in the general area?

http://www.wcpn.o...ine.html

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