Study: Planet's lakes warming faster than ocean, atmosphere

PULLMAN, Wash., Dec. 17 (UPI) -- The world's lakes are heating up at an average rate of 0.61 degrees Fahrenheit per decade, outpacing the rise in ocean and atmosphere temperatures.

The new findings are the result of a first-of-its-kind international survey, combining satellite and ground-based temperature data on 235 lakes, comprising more than half the planet's freshwater supply.

The results were published in the journal Geophysical Research Letters, and presented on Wednesday to attendees of the American Geophysical Union meeting in San Francisco.

At risk are lake-based ecosystems and freshwater drinking supplies. If warming trends continue at the current rate, researchers expect oxygen-sucking algae blooms to increase by 20 percent over the next century. Blooms that give off fish-killing toxins will grow by 5 percent.

"Society depends on surface water for the vast majority of human uses," study co-author Stephanie Hampton, a researcher at Washington State University, said in a press release. "Not just for drinking water, but manufacturing, for energy production, for irrigation of our crops. Protein from freshwater fish is especially important in the developing world."

Some of the ground-based records stretch back more than a century. Modern satellites are incredibly accurate and precise, but they can only measure surface temperatures; ground work offers temperature records at varying depths.

"Combining the ground and satellite measurements provides the most comprehensive view of how lake temperatures are changing around the world," explained study co-author Simon Hook, the science division manager at NASA's Jet Propulsion Laboratory.

Though warmer, tropical lakes aren't heating up quite as fast as cooler lakes, and scientists say even small changes can have significant effects. Dramatic swings in lake temperatures can drastically alter the animals that live there. Researchers say changes are likely already underway.

Researchers say the new study is a reminder that global warming is affecting all types of ecosystems, and further emphasizes the need for rapid action to slow the release of greenhouse gases.