The colors of the planet are no longer the same due to climate change

The colors of the planet are changing, like the characteristic blue of the lakes which could disappear and turn a greenish brown, according to a new study.

Climate change continues its progression on the planet, and with it unimaginable changes are occurring on life and its ecosystems. New study warns of lake health due to unexpected color change.

Blue lakes around the world (such as Lake McKenzie on Frase Island, Blue Lagoon in Iceland, Blue Lake in New Zealand, and Crater Lake in Oregon) could lose their beautiful, crystal-clear blue hue to because of rising global temperatures, which are turning blue lakes into cloudy green-brown bodies of water.

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The scourge of climate change affects the colors of the planet

A team of scientists from the University of North Carolina at Chapel Hill examined 5.14 million satellite images of freshwater reservoirs taken between 2013 and 2020. They represent 85,360 lakes and reservoirs scattered around the world.

The main objective was to know the dominant color of the water. Scientists examined more than 5 million Landsat-8 satellite images, closely monitoring their color changes. It turned out that the pure blue color is already present in less than a third of them. Thus, 69% of all lakes on Earth have a greenish-brown color.

The new study showed that it is not the transport of sediment and algae that determines whether the lake stays blue for most of the year or takes on a less pleasing color as the months pass. Satellite images have proven that the main factors to take into account in the change of colors of the planet are: air temperature, precipitation, altitude above sea level and depth of the reservoir.

No one has ever studied the color of lakes on a global scale.al,” says Xiao Yang, a remote sensing hydrologist at Southern Methodist University and co-author of the study published in the journal Geophysical Research Letters.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. Although we do not study all existing lakes on Earth, we try to cover a large and representative sample of the lakes that we have.“.

lakes, blue lakes, algae, planet colors, biodiversity, ecosystems, climate change, temperatureBlue Lagoon of Iceland

The algae problem

Bluer lakes tend to be deeper and are found in colder, high-latitude regions with heavy precipitation and winter ice cover, while greenish-brown lakes are found in drier continental interior regions and the along the coasts.

Climate change is transforming these blue lakes by making them increasingly rare. The researchers modeled the different warming scenarios, concluding that, first, lakes at high latitudes, such as those in Canada, northern Europe and New Zealand, could stop being blue. In fact, microscopic algae already exist in all of these lakes. If the air begins to get warmer, they will also “bloom”, and it will be impossible to fight them.

Warmer water, which produces more algal blooms, will tend to change the colors of the lakes towards greensaid Catherine O’Reilly, an aquatic ecologist at Illinois State University and co-author of the study. “There are many examples of researchers seeing this happen when studying an individual lake.“.

Blue lakes lose their color

Blue lakes are in decline. But the cosmetic changes are only the beginning of the problem. The change in color is also an indication of how much these ecosystems are changing, which will affect the wildlife and humans that depend on them.

If you use lakes for fishing, livelihoods, or drinking water, the changes in water quality that may occur as lakes become greener will likely mean that it will be more expensive to treat that water. There may be times when the water is not usable and fish species are no longer present, so we will not get essentially the same ecosystem services from these lakes when they turn from blue to green. .“, conclude the researchers.

Reference: Xiao Yang, Catherine M. O’Reilly, John R. Gardner, Matthew RV Ross, Simon N. Topp, Jida Wang, Tamlin M. Pavelsky. The color of the Earth’s lakes. Geophysical Research Letters, 2022; 49 (18) DOI: 10.1029/2022GL098925

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