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If global warming continues, blue lakes around the world are at risk of turning brownish green. The new study presents the world's first global lake color inventory.

A shift in the color of lake water can indicate a loss of ecosystem health. The research was published in the journal Geophysical Research Letters.

It is well known that substances such as algae and sediment can affect the color of lakes. This latest study found that air temperature, rainfall, depth, and elevation of the lake also determine the color of the lake water.

Researchers used 5.14 million satellite images for 85,360 lakes and reservoirs worldwide. They analyzed data from 2013 to 2020 to determine the most common water colors.

"No one has ever studied lake color on a global scale," said Xiao Yang, a remote-sensing hydrologist at Southern Methodist University, United States, and the study's author.

"There have been previous studies of maybe 200 lakes around the world, 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," he said. /2022).

"Although we didn't study every lake on Earth, we tried to cover the large and representative sample of the lakes that we have," Yang said.

The author characterizes the color of the lake by assessing the color of the lake that appears most frequently for seven years according to seasonal algae growth. The results can be explored through an interactive map developed by the author.

In addition, different degrees of warming could affect the color of the water if climate change continues. The study found climate change could reduce the percentage of blue lakes, such as those found in northern Europe and New Zealand.

"Warmer water, which produces more algae, will tend to turn the lake green," said Catherine O'Reilly, an aquatic ecologist at Illinois State University, US, and author of the study.

"If you use a lake for fishing or for food or drinking water, the changes in water quality that may occur when the lake becomes greener may mean it will cost more to treat that water," O'Reilly said.

In addition, changes in water color may have implications for recreational and cultural behavior in locations such as Sweden and Finland. As warming continues, lakes in northern Europe may lose their winter ice sheets. This can affect winter activity and culture in the region.

"No one wants to swim in a green lake," O'Reilly said.

"So aesthetically, some of the lakes that we might always think of as a sanctuary or spiritual place, those places might disappear when the color changes," he said. (RRI)