Water levels plunge in half of Earth’s largest lakes

Water levels are declining in more than half of the world’s largest lakes, according to analysis of nearly three decades of satellite data.

Climate change and unsustainable human consumption are to blame, say climate researchers from the universities of Virginia and Colorado Boulder in the US.

The assessment published in Science is the first comprehensive review of global trends and drivers of lake water storage, its authors say.

“We have pretty good information on iconic lakes like [the] Caspian Sea, Aral Sea and Salton Sea, but if you want to say something on a global scale, you need reliable estimates of lake levels and volume,” says co-author Balaji Rajagopalan, professor of engineering at Colorado Boulder.

The analysis draws on satellite data for 1,972 of the world’s largest lakes between 1992 and 2020, available data on long-term water levels, as well as water use and climate modelling. 

The lakes in the study represent 95% of total lake water storage on Earth and the authors estimate around 2 billion people live in areas affected by drying lakes.

The assessment found 53% of lakes globally experienced a decline in water storage, and that lakes located in both wet and dry areas of the world are losing volume.

Nearly two-thirds of large water reservoirs experienced significant water losses, with sedimentation the main driver.

In around a quarter of the lakes assessed, water levels increased. These were mainly located in underpopulated areas in the inner Tibetan Plateau, the northern Great Plains of North America and areas with new reservoirs such as the Yangtze, Mekong and Nile River basins.

The authors say their findings can assist water managers and communities in better managing and protecting local water resources. 

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