A recent study by a Toronto professor and colleagues analyzed 60 lakes in the Northern Hemisphere and the results should trigger real concern.
They found lakes warmed six times as fast in the past 25 years compared with any other period in the past century.
Kasha Patel of The Washington Post writes that the Great Lakes, which account for one fifth of the world's supply of surface fresh water, were among the fastest warming lakes:
Since October, the water temperatures on all five of the Great Lakes have hovered at record-high autumn levels, about five to six degrees above average. This comes after abnormally large spikes in temperature over the summer, as well.
The record-warm water temperatures over the Great Lakes fit into a pattern of warming lakes all over the planet, forced upward as human-caused climate change pushes air temperatures to record highs.
“I’m not surprised at all that the water temperatures are so warm,” said Sapna Sharma, an associate professor at York University in Toronto who has studied ice for more than a decade. “Lakes are experiencing more extreme warm years.”
Four of five Great Lakes border Michigan. Only Lake Ontario does not. In all, the lakes border eight states and Canada.
Warmer water can mean ice on the lakes form later than before and melt sooner. That can have dire consequences, The Post explains:
Today, researchers study ice cover to help track the health of the ecosystem. Less ice cover means more lake water can evaporate, reducing the amount of freshwater available to aquatic organisms and people. Less ice also allows the surface of the lake to warm earlier and more intensely, resulting in more algal blooms that can sometimes contaminate the water for humans. Changes in ice cover also have an economic effect on those who use the lake for fishing, sports and transportation for goods.
