If global warming continues, the world’s blue lakes are at risk of turning a brownish-green color, according to a new study that provides the first global inventory of lake color.
According to the research paper published in Geophysical Research Letters, a change in the color of the water in the lake can indicate a loss of ecosystem health.
While materials such as algae and sediment can affect the color of lakes, the new study found that air temperature, precipitation, depth and elevation of the lake also play an important role in determining the most common water color of the lake. Lake.
Representing less than a third of the world’s lakes, blue lakes tend to deepen and are found in cold high latitudes where there is heavy rainfall and the winter ice sheet.
The study found that brown and green lakes, which represent 69% of all lakes, are more common and are found in drier regions, inland and along coasts.
Researchers used 5.14 million satellite images of 85,360 lakes and reservoirs worldwide from 2013 to 2020 to determine the most common water colors.
“No one has studied the color of lakes on a global scale,” said Xiao Yang, a remote sensing hydrologist at Southern Methodist University and the study’s author. The number of lakes also includes the area of small lakes. We try to cover every lake in the world one by one, a large and representative sample of the lakes we have.”
A lake’s color can change seasonally, in part due to changes in algae growth, so the authors determined the lake’s color by analyzing its most common color over a seven-year period. The results can be explored through an interactive map drawn by the authors.
Additionally, the new study explores how different levels of warming may affect the color of water if the climate continues to change. The study found that climate change could reduce the proportion of blue lakes, many of which are found in the Rocky Mountains, northeastern Canada, northern Europe and New Zealand.
Catherine O’Reilly, a water ecologist at Illinois State University and author of the new study, explains: “Warm water that produces more algae tends to turn lakes green. There are many examples of places where people have seen it…” .
For example, O’Reilly said North America’s Great Lakes are experiencing an increase in algal blooms and are also among the fastest warming lakes.
Yang said previous research has also shown that lakes are “greener” in remote Arctic regions.
While previous studies have used more complex and precise measurements to understand the overall health of a lake’s ecosystem, scientists say water color is a simple but convenient measurement for assessing water quality. seen around the world from satellites.
This approach provides a way to study how remote lakes change with climate change.
“If you use the lakes for fishing or drinking water, the changes in water quality as the lakes turn green will likely mean that the water will be more expensive to treat,” O’Reilly said. The fish may not be there, so we’re not going to get the same ecosystem services from these lakes when they turn green from blue.”
source: phys.org
Source: Arabic RT
