U.S. Great Lakes thawing earlier.

The Great Lakes region of the United States, home to the largest concentration of fresh water on Earth, is thawing earlier each spring, according to findings reported in the August 20 issue of New Scientist. Scientists with the University of Wisconsin-Madison (UW-M) found that on 56 of 61 lakes studied the spring thaw showed an earlier trend, occurring two days sooner on average each decade between 1975 and 2004.

The date of ice break-up has "marched northward 100 kilometers per decade" since the mid-1970s, said Barbara Benson of UW-M's Center for Limnology. The team studied the timing of break-up on lakes in Minnesota, Wisconsin, Michigan, New York, and Ontario, gathering information from government databases, newspapers, lake associations, and local residents.

The study notes that although the earlier thaw has been happening since 1846, the rate of change has accelerated and is now more than three times as fast as before 1975. Since the mid-1970s, the average global air temperature has risen by 0.4 degrees Celsius, suggesting a link to a wider warming trend. "What's happening around us is big enough and so far out of our control that it is affecting the whole Great Lakes region," team member John Magnuson said.

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As the U.S. Northeast feels the effects of rising temperatures, officials in New York and eight other states have taken region-wide steps to regulate the greenhouse gases that contribute to global warming. In August, according to a confidential draft proposal, the states came to a preliminary agreement to freeze power plant emissions at their current levels and then reduce them by 10 percent by 2020. This cooperative regional action, the first of its kind in the United States, would set up a market-driven system to control carbon dioxide emissions from more than 600 electric generators in the nine states.