Ice on U.S. Great Lakes Has Decreased by 71 Percent Since 1973

The average amount of ice covering the U.S. Great Lakes has dropped by 71 percent over the past 40 winters, with ice coverage on the largest of the lakes, Superior, dropping by 79 percent, according to a report

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NASA Sea Ice 1980 2012

Lake Superior, 2012
from the American Meteorological Society. Researchers used satellite photographs and Coast Guard reports to document the decline of ice coverage in the Great Lakes from 1973 to 2010. The lake with the most precipitous loss of ice has been Lake Ontario, where ice coverage has fallen by 88 percent, according to the report, published in the Journal of Climate. The report does not include the current winter, which has been extraordinarily mild, resulting in only five percent of the Great Lakes’ surface being covered in ice. Lead researcher Jia Wang of the National Oceanic and Atmospheric Administration said the large loss of ice could speed the evaporation of the lakes and accelerate shoreline erosion because of the increase in open water.