They measured the surface temperatures of 167 lakes, with an area of 193 square miles (500 square kilometers) or larger, around the world using thermal infrared imagery from satellites of the National Oceanic and Atmospheric Administration (NOAA) and the European Space Agency (ESA).
The inland water bodies were studied from-July-to-September (summer in the Northern Hemisphere) and from-September-to-January (summer in the Southern Hemisphere), from 1985 to 2009.
Data was taken during the night time hours.
For example, in North America the Great Lakes, the largest group of freshwater lakes on Earth with regards to total surface area and volume, were measured with nine buoys that relayed data up to satellites in orbit around the planet.
Drs. Schneider and Hook reported ''¦ an average warming rate of 0.81 degrees Fahrenheit per decade, with some lakes warming as much as 1.8 degrees Fahrenheit per decade. The warming trend was global, and the greatest increases were in the mid- to high-latitudes of the Northern Hemisphere. '
Page two continues with comments from Dr. Schneider on his and Dr. Hook's results pertaining to global climate change.