Why are the lakes less and less blue?

Climate change is causing lakes to become less blue, and many are at risk of turning permanently green-brown, a new to study has 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 no specific time frame was offered, the researchers said one in 10 lakes can expect to change color “in the future.”

Blue lakes are generally found in the coldest regions of the Earth and are not very common, accounting for only 31 percent of the world’s lakes. Compared to lakes with greener or browner waters, they are generally deeper and more likely to be covered with ice during the winter.

The study, published Thursday in the journal Geophysical Research Letters, found that rising temperatures, which lead to less ice, are the main culprit behind the color change of blue lakes.

“No one has ever studied the color of lakes on a global scale,” Xiao Yang, a co-author of the study, said in a statement. release.

“There have been previous studies of maybe 200 lakes around the world, but the scale we are trying here is much, much larger in terms of the number of lakes and also the coverage of small lakes. Although we are not studying all the lakes on Earth, we are trying to cover a large and representative sample of the lakes that we have.”

Covering the hues of 85,360 lakes and reservoirs around the world from 2013 to 2020, the study researchers used 5.14 million satellite images.

Generally, a lake’s color change is attributed to algae and other sediments, but the new research now suggests that various degrees of warming could 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 the lakes has already begun, according to study co-author Catherine O’Reilly, who noted that the North American Great Lakes have “increased algal blooms” and are also “among the lakes that are They heat up faster.

Yang also said a similar trend can be seen in arctic regions that are starting to see lakes with “increasingly intense greenness.”

Changes in the colors of the lakes could mean devastating impacts for those who depend on the lakes for drinking water, livelihoods or fishing.

“There may be periods when the water is not usable and fish species are no longer present, so we’re not going to get essentially the same ecosystem services from those lakes when they go from blue to green,” he said. O’Reilly.

It could 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 always thought were a haven or spiritual places, those places might be disappearing.”

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