More than 50 percent of the world’s largest lakes are losing water mainly due to climate warming and unsustainable human consumptionaccording to a study published The science.

But lead author Fangfang Yao, a visiting researcher at the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder, says that the news is not all bleak.

With this new method of tracking lake water storage trends and their causes, scientists can give water professionals and communities ideas on how to better protect critical water sources and important regional ecosystems.

“This is the first comprehensive assessment of trends and causes of global variability in lake water supplies based on a series of satellites and models,” Yao said in a statement.

ecological crises of some of the largest bodies of water on the planetsuch as the drying up of the Aral Sea between Kazakhstan and Uzbekistan prompted him to undertake this study.

So he and his colleagues at the University of Colorado at Boulder, Kansas State University, France, and Saudi Arabia created a technique to measure water level changes in nearly 2,000 of the world’s largest lakes and reservoirswhich account for 95% of the total lake water supply of the Earth.

The team combined three decades of observations from set of satellites with models to quantify and describe trends in lake storage worldwide.

Worldwide freshwater lakes and reservoirs They store 87% of the planet’s water. making them a valuable resource for both humans and terrestrial ecosystems. Unlike rivers, lakes are poorly controlled, yet they provide water for a large proportion of humanity, even more than rivers.

But, despite its value, long-term trends and changes in water levels were largely unknown – until now.

“We have a lot of information about iconic lakes such as the Caspian Sea, the Aral Sea and the Salton Sea, but if we want to say something on a global scale, we need reliable estimates of lake levels and volume,” explains Balaji Rajagopalan, CIRES researcher , professor of engineering at UC Boulder and co-author of the study. With this new method, we can provide data about global lake level changes from a broader point of view.

For the new work, the team used 250,000 satellite images of the lake area between 1992 and 2020 to study the surface of 1972 of the largest lakes on Earth. They collected water levels from nine satellite altimeters and used long-term water levels to reduce any uncertainty.

For lakes without long-term level data, they used recent water measurements made by newer instruments on satellites. Combining recent level measurements with longer-term surface measurements has allowed scientists to restore the volume of lakes ten years ago.

The researchers got amazing results because In 53% of the world’s lakes there has been a reduction in water supplies. The authors compare this loss to a 17-point loss from Lake Meads, the largest reservoir in the United States.

To explain trends in natural lakes, the team took advantage of the latest advances in water use and climate modeling. Climate change and human water consumption dominate global net decline in natural lake volume and water loss in about 100 large lakes, Yao explains.

“And many of human footprints and climate change water losses from lakes were unknown until now, such as the drying up of Lake Gud-e-Zare in Afghanistan and Lake Mar Chiquita in Argentina,” he adds.

Lakes in dry and wet regions of the world are losing volume. Losses in humid tropical and arctic lakes point to trends desiccation is more common than previously thought.

Yao and colleagues also rated lreservoir storage trends. They found that nearly two-thirds of the major reservoirs on Earth experience significant water loss.