More Than Half of the World’s Large Lakes Are Drying Up, a New Study Finds

A new study finds that more than half of the world’s large lakes are drying up, intensifying concerns about water for agriculture, hydropower, and human consumption. The findings from a team of international researchers were published on Thursday in the journal Science. Reuters reports that they used satellite measurements and climate and hydrological models to evaluate more than 2,000 large lakes worldwide. The authors found that some of the world’s most important freshwater sources – from the Caspian Sea between Europe and Asia to South Americas Lake Titicaca – lost water at a cumulative rate of around 22 gigatonnes per year. The study said that that’s the equivalent of 17 refills of the US reservoir Lake Mead. Even lakes in regions with more rainfall were losing water as warmer air sucked the liquid up into the sky through evaporation, and thirsty societies diverted some of it for irrigation, power plants, and drinking supplies.

The study found that the net loss of lake water storage across the globe was caused by unsustainable human consumption, changes in precipitation and runoff, sedimentation, and rising temperatures. In addition, the researchers say around a quarter of the global population lives in the basins of lakes that are shrinking.

According to the scientists behind this study, lakes are crucial for sustaining crops through irrigation, providing fish and freshwater for people to eat, and powering hydroelectricity. They also help to control erosion, reduce wildfire risk and mitigate the impact of insalubrious dust storms. But these vital habitats are vanishing at an alarming rate, with human consumption and climate change to blame, the report finds.

Researchers estimate that 56% of the decline in natural lakes was driven by climate warming and human consumption, with the former accounting for a larger share. While climate scientists generally think that arid areas will get drier and wet areas wetter, the study found significant water loss even in humid regions. This “should not be overlooked,” said lead researcher Fangfang Yao, a surface hydrologist at the University of Virginia.

As the number of people living with water scarcity increases, dwindling lake levels will likely have far-reaching impacts. They could increase the concentration of toxic pollutants in rivers and streams, contaminating drinking water supplies. They could also raise the risks of conflict between humans and wildlife, making it harder for migrating birds to find food.

And they may even directly affect the health of humans, who can develop dangerous diseases from drinking water from polluted lakes and rivers. The study found that roughly two-thirds of the world’s population drinks water directly from rivers and lakes. The study authors warned that a continuing trend of shrinking lakes could have devastating consequences. They concluded that water shortages can trigger conflict, aggravate social and economic inequalities, and contribute to climate change. The study’s authors urged that policymakers focus on changing human water use and conservation policies. They said this is one of the most effective ways to slow the loss of freshwater resources.