In a first of its kind survey of the planet’s largest lakes, NASA has found that the temperatures have been steadily warming over the past 25 years in response to climate change. The researchers from NASA’s Jet Propulsion Laboratory in Pasadena, California, reported an average warming rate of 0.45 degrees Celsius (0.81 degrees Fahrenheit) per decade, with some lakes warming as much as 1 degree Celsius (1.8 degrees Fahrenheit) per decade.
“Our analysis provides a new, independent data source for assessing the impact of climate change over land around the world,” said Phillipp Schneider, lead author of the study published this week in the journal Geophysical Research Letters. “The results have implications for lake ecosystems, which can be adversely affected by even small water temperature changes.”
The adverse effects Schneider refers to include algal blooms, which can make a lake uninhabitable to fish, and the introduction of non-native species that end up driving the natural ecosystem away.
Using thermal infrared imagery from National Oceanic and Atmospheric Administration and European Space Agency satellites, the researchers focused on summer temperatures, at night, in bodies of water that were typically at least 500 square kilometres (193 square miles), at the point farthest from the shore to ensure the greatest accuracy without interference from thick ice, sunlight, and land influences.
The largest and most consistent area of warming was in northern Europe, though it was slightly weaker in southeastern Europe around the Black and Caspian seas and in Kazakhstan. The farther east they went the trends increased slightly in Siberia, Mongolia and northern China. In North America the warming trends were slightly higher in the southwest than in the Great Lakes region, and warming was weaker in the tropics and in the mid-latitudes of the Southern Hemisphere.
The satellite data gathered by the JPL researchers was mostly in agreement with trends measured by nine buoys in the Great Lakes, as well as independent surface air temperature data from NASA’s Goddard Institute for Space Studies in New York.