Climate change is causing lakes to become less blue, with many at risk of permanently turning green-brown, a new examination have found.
Conducted by the American Geophysical Union, the study presents the first “global lake color inventory” and takes into account changes in water color to determine water quality.
While a specific time frame was not offered, researchers said one in 10 lakes can expect to change color in the “future.”
Blue lakes are generally found in cooler regions of the Earth and are not very common, representing only 31 percent of the world’s lakes. Compared to lakes with greener or browner water, they are typically deeper and more likely to be covered in ice in the winter.
The study, published Thursday in the journal Geophysical Research Letters, found that rising temperatures leading to a decline in ice is the main culprit behind the blue lakes’ color change.
“No one has ever studied the color of lakes on a global scale,” Xiao Yang, co-author of the study, said in a release.
“There were previous studies of maybe 200 lakes across the globe, but the scale we’re trying here is much, much larger in terms of the number of lakes and also the coverage of small lakes. Although we’re not studying every single lake on Earth , we try to cover a large and representative sample of the lakes we have.”
The study’s researchers used 5.14 million satellite images covering the nuances of 85,360 lakes and reservoirs worldwide from 2013 to 2020.
Generally, a lake’s color change is attributed to algae and other sediments, but the new research now suggests that varying degrees of warming may also affect the color of the water due to climate change.
The lakes likely to be affected are in northeastern Canada, New Zealand, the Rocky Mountains and northern Europe, the study says.
The color change in lakes has already begun, according to Catherine O’Reilly, co-author of the study, who pointed to the North American Great Lakes that have “increased algal blooms” and are also “among the fastest warming lakes.”
Yang also said that a similar trend can be seen in the Arctic regions, which are beginning to have lakes with “more intense greenness.”
The changes in lake colors can mean devastating consequences for those who depend on lakes for drinking water, food or fishing.
“There may be periods when the water is not usable and fish species may no longer be present, so we’re not going to get essentially the same ecosystem services from those lakes when they go from being blue to being green, ” O’Reilly said.
It may also mean that the lakes will no longer be used for recreational purposes.
“No one wants to swim in a green lake,” O’Reilly said.
“So aesthetically, some of the lakes that we may have always thought of as places of refuge or spiritual places, those places may be disappearing.”