Lake effect: World's lakes warming due to climate change

The world's lakes are warming because of climate change, according to a study published last week in the journalGeophysical Research Letters, a publication of the American Geophysical Union.

In the first worldwide survey of how lake temperatures are changing due to greenhouse gas emissions, scientists report that the Earth's largest lakes have warmed at an average rate of 0.81 degree (F) per decade during the past 25 years. Some lakes warmed as much as 1.8 degrees per decade. The warming trend was global.

NASA scientists Philipp Schneider and Simon Hook used thermal infrared imagery from satellites to measure the surface temperatures of 167 large lakes worldwide.

In the USA, the warming was slightly higher in the Southwest than in the Great Lakes.

The largest and most consistent area of warming was northern Europe. The warming trend was slightly weaker in southeastern Europe, near the Black and Caspian seas and Kazakhstan. The trends increased slightly in Siberia, Mongolia and northern China.

"Our analysis provides a new, independent data source for assessing the impact of climate change over land around the world," says Schneider. "The results have implications for lake ecosystems, which can be adversely affected by even small water temperature changes."

Fresh water lakes make up only a tiny fraction of the water on Earth, when compared to the oceans: Oceans hold 97 percent of surface water, glaciers and polar ice caps 2.4 percent, and other land surface water such as rivers, lakes and ponds 0.6 percent.

According to the study, even small changes in water temperature can result in algal blooms that can make a lake toxic to fish or result in the introduction of non-native species that change the lake's natural ecosystem.