The Warming of Canadian Lakes

“Canadian lakes are in hot water over climate change, a new research survey has concluded.

“Canadian lakes are warming twice as fast as the rest of the lakes globally,” said York University biologist Sapna Sharma, a co-author of a paper published in the journal Bioscience.

Sharma and her colleagues pored over 143 studies from around the world to try to summarize how climate change is affecting the globe’s 100 million lakes.

Lakes that have been ice-covered at least part of the year are experiencing the biggest changes, they found.

Warming air temperatures have reduced ice cover an average of 31 days over the past 165 years, with ice cover disappearing six times faster in the past 25 years. About 15,000 Northern Hemisphere lakes that once froze every winter are now experiencing ice-free years and 6,000 of those lakes may never freeze again.

Water temperatures are rising as they absorb more sunlight, with the upper layers of lakes warming up even more quickly.

Lakes around the world are already warming by a third of a degree Celsius per decade, with ice-covered lakes warming twice as fast as the global average. By the end of the century, average global lake temperatures are expected to rise anywhere from one degree, to 4.

That increases water loss from evaporation and encourages blooms of toxic algae.

“In Canada, as well as other places in the world, we’re seeing increased incidence of these algal blooms much later in the season,” Ms. Sharma said.

Lake Superior, the world’s largest lake by surface area, now experiences algae blooms. In 2014, a secluded lake in Ontario’s Algonquin Park was closed to camping because of algal blooms – the first such bloom in more than a century.“