Canada’s lakes—including the Great Lakes—are some of the fastest-warming in the world, according to a new study.
The more than 200 lakes studied may only be a small fraction of the world’s total number, but they account for more than half of the world’s freshwater supply. And as it turns out, the mighty Lake Superior isn’t faring well. Although it’s the largest of the Great Lakes, it was the second-fastest warming lake studied following Sweden’s Lake Fracksjon.
The warming of Lake Superior came as a shock to some of the researchers involved, since the lakes studied varied in depth, location, and other characteristics that would lead one to believe that other, much smaller lakes would warm faster.
But the ice that normally covers Canada’s lakes in winter is melting earlier each spring, and that exposes them to warmer air temperatures and prolonged solar radiation. This causes the lakes to warm faster than what’s generally expected from climate change, Sapna Sharma, lead author of the study and an assistant professor at York University, told CBC.
The team of international scientists found that the lakes’ summer surface temperatures rose by more than twice the rate of oceans. On average, that’s about 0.34 degrees C per decade.
And while that might not sound like much, if the lakes continue to warm at the rate they did during the 25-year study, algae blooms could increase by 20 percent over the next century.
Toxic blue-green algae prefers and thrives in warm water, creating a more hostile environment for native fish, who become choked-out by the lack of oxygen in the water. It also makes it easier for invasive species to survive, which can have devastating effects on the ecosystem.
With these changes, we also have to consider the state of our drinking water: last year, algae blooms in Lake Erie made tap water undrinkable in Toledo, Ohio, for days at a time.
The study, which examined data from 236 lakes, is the largest of its kind. Published in Geophysical Research Letters on Wednesday, it was funded by NASA and the National Science Foundation. It combined long-term hand measurements with temperature measurements made from satellites to offset any errors in each method.
