Climbing GHGs may stop many lakes from freezing, say York researchers

Large bays in places such as Lake Superior, pictured, could be ice-free by 2055 if nothing is done to curb the planet’s greenhouse gas emissions. Credit: Tupungato, AdobeStock.

New research by Ontario’s York University suggests that if the planet’s greenhouse gas emissions aren’t drastically reduced, 179 lakes could permanently lose ice cover within the decade, then skyrocket to 5,700 iceless lakes by the end of the century.

The ice loss could even include portions of the Great Lakes, states the study, published this month in the journal Geophysical Research Letters. Large bays in Lake Superior and Lake Michigan, for instance, could be ice-free by 2055 if nothing is done to curb global emissions.

Ice is needed to curtail and minimize evaporation rates in the winter, ultimately preserving fresh water that could otherwise be lost or compromised in quality, says lead researcher Sapna Sharma, an associate professor in York’s Faculty of Science.

“In years where there isn’t ice cover or when the ice melts earlier, there have been observations that water temperatures are warmer in the summer, there are increased rates of primary production, plant growth, as well as an increased presence of algal blooms, some of which may be toxic,” Sharma explained.

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Researchers say that increased greenhouse gas emissions will lead to warmer winter temperatures that will even surpass increases in summer temperatures. Just a couple of degrees warmer will make the difference as far as the lakes gradually not getting cold enough in the winter for them to freeze.

The York team looked at 51,000 lakes in the Northern Hemisphere through the HydroLAKES dataset to forecast whether those lakes would become ice-free, using annual winter temperature projections from 2020 to 2098 with 12 climate change scenarios.

Researchers found that when air temperature was above -0.9°C, most lakes no longer froze. For shallow lakes, the air temperature could be zero or a bit higher. Larger and deeper lakes need colder temperatures to freeze – some as cold as -4.8°C – than shallow lakes, the research states.

“It’s pretty shocking to imagine a lake that would normally freeze no longer doing so,” said York postdoctoral researcher Alessandro Filazzola in a statement about the new paper.

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