Global Study Shows Large Lakes Are Warming

If you cover climate change, and happen to have an audience in an area that is home to one of 104 large lakes around the world, a new study provides a news hook for localizing climate change effects.

NASA researchers have found that the surface warming pattern in the selected lakes generally emulates what has been seen in many other data sets. The lakes are warming by an average of 0.81 degrees Fahrenheit each decade (with some lakes increasing by up to 1.8 degrees F), and the temperature increase tends to be larger as you work toward the North Pole. The warming waters can contribute to problems such as algal blooms and shifts in species composition. The authors say this is the first comprehensive study of temperature trends in large lakes.

The researchers used thermal infrared satellite data from 1985-2009 for their measurements, and used temperatures from an area farthest from shore in order to reduce the effect of land temperatures. They started with 167 lakes, and found 104 that had suitable satellite data. Of these, 41 had a statistically significant trend. When just these 41 lakes are included, the average warming trend is about 50% higher than for all 104 lakes in the study.

In the US, the 8 lakes with viable temperature data included Great Salt Lake, Lake Michigan, Lake Okeechobee, Lake Tahoe, Lake Winnebago, Pyramid Lake, Upper and Lower Red Lake, and Selawik Lake. Also included are four of the Great Lakes shared with Canada — Erie, Huron, Ontario, and Superior. The lakes in the Southwest tended to warm about 40% more than did the Great Lakes.

Among the 18 other Canadian lakes are Great Bear Lake, Great Slave Lake, Lake of the Woods, Lake St. Clair, Lake St. Jean, Lake Winnipeg, Reindeer Lake, and Simcoe Lake.

There is one Mexican Lake (Chapala), and two Nicaraguan lakes (Managua and Nicaragua). Other lakes are in Europe, Asia, the Middle East, Africa, South America, and Australia.

The authors can provide the full list of lakes and data specific to each lake upon request. The study was published online Nov. 24, 2010, in the journal Geophysical Research Letters.

• "Space Observations of Inland Water Bodies Show Rapid Surface Warming Since 1985"; for a copy of the full study, contact co-author Simon Hook, 818-354-0974. Nov. 23, 2010, press release.