World's Lakes Have Lost Water Equivalent to 17 Lake Meads

More than half of the world's largest lakes and reservoirs have lost substantial amounts of water—the equivalent of 17 Lake Meads—in recent decades, according to a large-scale study that largely blames climate change and human behavior. While climate change is bringing warmer temperatures that increase evaporation, per Axios, humans are cited for excessive water use. Water levels in lakes naturally fluctuate with "variations in rain and snowfall," as CNN points out. But the study—which looked at some 250,000 satellite images in the vicinity of 1,972 freshwater bodies, representing 95% of Earth's total lake water storage, from 1992 to 2020—found 53% of major water bodies experienced significant drops in water levels across the three decades.

The net decline in water storage is "equivalent to the total water use in the US for the entire year of 2015 or 17 times the volume of Lake Mead, the largest reservoir in the United States," according to the study published Thursday in Science. The losses extend to dry and wet areas, from the tropics to the Arctic, and indicate "drying trends worldwide are more extensive than previously thought." More than half of the net loss in natural lakes is tied to climate change and human activities, according to lead study author Fangfang Yao, a former CIRES fellow at the University of Colorado Boulder, now at the University of Virginia. The report blames unsustainable water consumption for the shrinking of California's Salton Sea and Uzbekistan's Aral Sea.

Only "a third of lake declines were offset by increases elsewhere," CNN reports. Some 24% of major water bodies experienced significant increases, with these typically found in less-populated regions. Some of these gains are tied to climate change through the melting of glaciers. The biggest factor in water loss in reservoirs was the flow of sediment into water, which can also be linked to climate change through the destabilization of soil by wildfires. Yao calls sedimentation a "creeping disaster," responsible for a 7% reduction in storage capacity of California's Lake Powell, per CNN. Nearly two-thirds of reservoirs experienced significant water loss, with Lake Mead losing 66% of its water, per the AP. Overall, however, there was a net increase in reservoir water levels with more than 180 newly filled. (More lakes stories.)