Global warming brings earlier thaw
to Great Lakes
By Margaret Neighbour
Published August 18, 2005
GLOBAL warming is bringing an earlier spring thaw to the
Great Lakes of North America, according to scientists.
Their study comes a week after news that Siberia's frozen
peat bog is melting for the first time since the Ice Age.
The Great Lakes contain the earth's largest concentration
of fresh water and are thawing earlier each spring, according
to an analysis of ice break-ups dating back to 1846.
A team from the University of Wisconsin-Madison studied
the timing of ice break-ups on 61 lakes in Minnesota,
Wisconsin, Michigan, New York and Ontario between 1975
and 2004, during which time the average global air temperature
rose by 0.4C.
The team gathered the dates from government databases,
lake associations, newspapers and local residents, reports
New Scientist today. On 56 of the lakes, the spring thaw
occurred, on average, two days earlier each decade.
Although the thaw has been happening ever earlier since
1846, the rate of change is now more than three times
as fast as it was before 1975.