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(CNN) -- More than half of the world's largest lakes and reservoirs have lost significant amounts of water over the past three decades, according to a new study, which largely blames climate change and excessive water use.

About a quarter of the world's population lives in a lake basin that is drying up, according to the study by an international team of scientists, published Thursday in the journal Science.

Although lakes only cover about 3% of the planet, they contain nearly 90% of its surface liquid freshwater and are essential sources of drinking water, irrigation and energy, as well as providing vital habitats for animals and plants.

But they have problems.

Lake water levels fluctuate in response to natural climatic variations of rain and snow, but are increasingly affected by human action.

Around the world, major lakes are experiencing steep declines. Lake Mead of the Colorado River in the southwestern U.S. has regressed dramatically amid a megadrought and decades of overexploitation. The Caspian Sea, between Asia and Europe, the world's largest inland body of water, has been declining for some time due to climate change and water use.

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The decline in size of many lakes is well documented, but the extent of the change and the reasons behind it haven't been examined as thoroughly, explains Fangfang Yao, lead author of the study and a visiting professor at the Cooperative Research Institute in Environmental Sciences at the University of Colorado at Boulder.

The Caspian Sea is rapidly receding due to climate change and human activity. Credit: NASA

The researchers used satellite measurements of nearly 2,000 of the world's largest lakes and reservoirs, which together account for 95% of Earth's total lake water storage.

By examining more than 250,000 satellite images spanning from 1992 to 2020, along with climate models, they were able to reconstruct the history of the lakes going back decades.

The results were "shocking," according to the report's authors.

They found that 53% of lakes and reservoirs had lost significant amounts of water, with a net decrease of about 22 billion metric tons a year, an amount the report's authors compared to the volume of 000 times Lake Mead.

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According to the report, more than half of the net loss of water volume in natural lakes can be attributed to human activities and climate change.

A boat submerged in the dry bed of Lake Mead on June 14, 2022. Credit: Roger Kisby/The Washington Post/Getty Images

The report detected losses in lake water storage everywhere, including the wet tropics and cold Arctic. This suggests that "desiccation trends around the world are broader than previously thought," Yao said.

Different lakes have been affected by different causes.

According to the report, unsustainable water consumption is the predominant reason for the wilting of the Aral Sea in Uzbekistan and California's Salton Sea, while changes in rainfall and runoff have driven the decline of Utah's Great Salt Lake.

In the Arctic, lakes have been shrinking due to a combination of changes in temperature, precipitation, evaporation and runoff.

"Many of the human and climate change footprints of lake water losses were unknown until now," Yao said, "such as the desiccations of Lake Good-e-Zareh in Afghanistan and Mar Chiquita in Argentina."

Dust rising from Mar Chiquita, Argentina, in July 2022. Water levels are now consistently lower than in the 1980s and 1990s, due to drought and water withdrawals. Credit: NASA

Climate change can have a variety of impacts on lakes. The most obvious, according to Yao, is increased evaporation.

According to the study, shrinking lakes may contribute to the "aridification" of the surrounding basin, which in turn increases evaporation and accelerates its decline.

In lakes in the coldest areas of the world, winter evaporation is a growing problem, as warmer temperatures melt the ice that usually covers them and leave water exposed to the atmosphere.

These changes can have cascading effects, such as decreased water quality, increased toxic algal blooms, and loss of aquatic life.

"An important aspect that is often overlooked is the degradation of lake water quality due to a warmer climate, which places a burden on the water supply of lake-dependent communities," Yao explained.

The exposed bed of the Aral Sea on May 5, 2018 near Muynak, Uzbekistan, which used to be the fourth largest lake in the world. Credit: The Asahi Shimbun/Getty Images

In the case of reservoirs, the report notes that the main factor in their decline is sedimentation, which causes sediments to flow into the water, obstructing it and reducing its space. This is a "progressive disaster," Yao explains, occurring over years and decades.

Lake Powell, for example, the second-largest man-made reservoir in the United States, has lost nearly 7% of its storage capacity due to sediment accumulation.

Sedimentation may be affected by climate change, he added. Forest fires, for example, are becoming more intense as the world warms, burning forests and destabilizing soil, contributing to increased sediment flow into lakes and reservoirs.

"The result of sedimentation will be that reservoirs will be able to store less water, making them less reliable for freshwater supply and hydropower, especially for us here in the U.S., since our nation's reservoirs are quite old," Yao says.

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According to the report, not all lakes are declining, with about a third of the declines offset by increases elsewhere.

Some lakes have grown, with a 24% significant increase in water storage. According to the report, these are usually lakes located in less populated regions, such as the Great Plains of North America and the interior of the Tibetan Plateau.

Traces of climate change are present in some of these increases, as melting glaciers fill the lakes, posing a potential risk to people living downstream.

As for reservoirs, although nearly two-thirds experienced significant water loss, overall there was a net increase because more than 180 reservoirs were recently filled, according to the report.

Catherine O'Reilly, a geology professor at Illinois State University who was not involved in the study, said this new research provides a useful set of long-term data that helps unravel the relative importance of the factors driving lake decline.

"This study highlights the impact of climate in a very close way: how much water do we have access to and what are the options for increasing its storage?" he told CNN.

"It's a little scary to see how many freshwater systems are unable to store as much water as before," he added.

As many parts of the world become warmer and drier, lakes need to be properly managed.

Otherwise, climate change and human activities "may cause them to desiccate sooner than we think," Yao said.

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