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Maximum Great Lakes Ice Cover on Decline

By Climate Central

On the Great Lakes, the maximum ice cover this year is down substantially from 2014 and 2015, which were the 2nd and 4th highest percentages on record, respectively. Despite its large season-to-season variability, the maximum winter ice cover has been trending downward in recent decades. In addition to curtailing recreational activities such as ice fishing, less ice can alter the lake-effect snow season. Our recent report highlighted how more open water may be responsible for the recent increase in the amount of lake-effect snow. But as the atmosphere continues to warm, the longer term outlook is for a snow season that will eventually be shorter and start later.

Less ice cover also has environmental impacts on the lakes. According to the Environmental Protection Agency, plankton, an important link in the food web, are better protected beneath the ice. Similarly, ice also shelters the eggs for some types of native fish. That’s bad news for local fish like lake trout and whitefish. Less ice also means warmer surface water, which tends to not mix as well with the colder water below. This leads to a concentration of pollutants such as nitrogen and phosphorus and lower levels of oxygen in the upper part of the water column. Those conditions can lead to more widespread algae blooms, which present a threat to drinking water and native species that call the lakes home.

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