The researchers monitored 25 years of lake data from 236 lakes worldwide. Lead author Sapna Sharma, an assistant professor at York University, told York media relations that the lakes studied were a small fraction of the world’s lakes, but they contained more than half the world’s freshwater supply.


This isn’t the first we’ve been warned about the rapidity of lake warming. In 2013, Dr. James Kitchell of the University of Wisconsin in Madison said that Lake Superior was the fastest warming lake of any on the planet (Sharma et. al.’s study says it is the second-fastest of 236 studied.) He reported to Public International Radio that in the last 30 years, Superior has warmed about six degrees Fahrenheit, “a rate that actually exceeds the melting rate of the ice caps in the Antarctic and the Arctic oceans.” Sharma’s study confirmed this, stating that on average, lakes were warming at a rate of 0.34 celsius per decade. This is faster than either the ocean (increasing 0.12 C per decade) or the air (warming by 0.25 C per decade).


Kitchell’s findings were a bit more balanced in its outlook. He said that warmer temperatures favoured increased walleye populations, good news for commercial and recreational fisheries. However, he said it also meant a resurgence of the sea lamprey, an invasive species known for decimating lake trout numbers.