Ice cover on the Great Lakes is vanishing:
“Ice cover on North America’s Great Lakes–Superior, Michigan, Huron, Ontario, and Erie–has declined 71% since 1973, says a new study published in the Journal of Climate by researchers at NOAA’s Great Lakes Environmental Research Laboratory.”
"The biggest loser of ice during the 1973 – 2010 time period was Lake Ontario, which saw an 88% decline in ice cover. During the same time period, Superior lost 79% of its ice, Michigan lost 77%, Huron lost 62%, and Erie lost 50%. The loss of ice is due to warming of the lake waters. Winter air temperatures over the lower Great Lake increased by about 2.7°F (1.5°C) from 1973 – 2010, and by 4 – 5°F (2.3 – 2.7°C) over the northern Lakes, including Lake Superior. Lake Superior’s summer surface water temperature warmed 4.5°F (2.5°C) over the period 1979 – 2006 (Austin and Colman 2007)."
Source: Climate Progress