http://rochesterareaflyers.com

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2063

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). During the
same period, Lake Michigan warmed by about 3.3°F (1.7°C), Lake Huron by 4.3°F
(2.4°C), and Lake Erie showed almost no warming.

The amount of warming of the waters in Lakes Superior, Huron, and Michigan is
higher than one might expect, because of a process called the ice-albedo
feedback: when ice melts, it exposes darker water, which absorbs more sunlight,
warming the water, forcing even more ice to melt. This sort of vicious cycle is
also responsible for the recent extreme loss of Arctic sea ice.

The increase in temperature of the lakes could be due to a combination of global
warming and natural cycles, the researchers said. They noted a pronounced 4-year
and 8-year oscillation in ice coverage, which could be caused by the El Niño/La
Niña and Arctic Oscillation (AO), respectively.