Global warming brings earlier thaw to Great Lakes

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.