Climate change warming world’s lakes at alarming rate

The ongoing temperature change could be damaging to Michigan’s lake ecosystem and economy, says Donald Uzarski, director of the Institute for Great Lakes Research at Central Michigan University.

The study was released this week at the annual meeting of the American Geophysical Union and published in the AGU’s “Geophysical Research Letters” journal. “That has made forecasting the future of lakes – and the life and livelihoods they support – very challenging”.

The study determined that the Great Lakes have been warming at a rate of 0.61 degrees per decade, and while that does not seem like a large number, warming of even a degree can have cascading negative impacts on those habitats.

Among the potential impacts of warmer water are more large blooms of algae that can harm water quality and kill fish, said O’Reilly.

The study predicts that at the current rate, algal blooms, which rob water of oxygen, will increase 20 percent in lakes over the next century. Algal blooms that are toxic to fish and animals are expected to increase by 5 percent.

These rates also imply that emissions of methane, a greenhouse gas that is 25 times more powerful than carbon dioxide, will increase four percent over the next decade.

“Lakes are important because society depends on surface water for the vast majority of human uses – not just for drinking water, but manufacturing, energy production, irrigation and crops”, said paper co-author Stephanie Hampton of Washington State University. The study was the first global analysis of lake temperature trends, O’Reilly said.

The study used 25 years of satellite and on-scene measurements of 235 lakes representing more than half of the world’s freshwater supply. The blend of methods offsets the shortcomings of any individual technique used.

For starters, the warming of world’s lakes puts fresh water supplies in danger. In northern climates, lakes are losing their ice cover earlier. Due to this reason it gets more quickly warmed by the air and sun than a deeper lake, said researchers. Therefore, even these sectors are bound to be severely disrupted by this unprecedented rise in lake temperatures.

Warming causes a different problem for some lakes. Second, the warming of world’s lakes negatively affects the lush ecosystems dependent on the lakes’ water.

As for the lakes analyzed in the study, the temperature increase already translates into significant changes.

“We want to be careful that we don’t dismiss some of these lower rates of change, because in warmer lakes, those temperature changes can be really important”, Hampton said.