Humans have completely transformed the way water is stored on Earth

Human fingerprints can be found all over the fresh water of the world. A new study Published Wednesday in the journal Nature shows that while human-controlled freshwater sources make up a minimal part of the world’s ponds, lakes, and rivers, they are responsible for more than half of all changes on Earth water system

The study used new satellite laser technology to take a closer look at freshwater sources around the world and track their water levels over the different seasons. Using NASA’s ICESat-2 satellite, researchers tracked more than 227,000 freshwater bodies, ranging in size from the Great Lakes to small ponds over a period of about eighteen months. Researchers found that 57% of the global seasonal variability in water storage occurs in human-controlled reservoirs.

“This large proportion is even more striking when you consider that reservoirs make up only 3.9% of the 227,386 lakes analyzed in this study,” Sarah Cooley, lead author of the study currently at the University of California, Berkeley, but started work while at Brown, said via email. “Although the water cycle is generally portrayed as a natural process, our finding that humans are responsible for most of the seasonal variability of surface water storage shows that we are now a major regulator of the water cycle.”

For the launch of this satellite in 2018, which was originally designed In fact, in order to observe ice sheets and collect extraordinarily detailed data, it was actually difficult to get a handle on how freshwater bodies shifted over time. Cooley said most human-controlled reservoirs have meters to measure water levels, but there is no global database for these measurements. There are now few lakes and ponds without reservoirs.

Satellites before ICESat-2 could track only a few hundred of the world’s largest lakes, so the data being collected here is quite exciting for people who spend their time thinking about freshwater cycles. “This study provides the first global quantification of variability in surface water levels and human impact on surface water storage,” said Cooley.

Now that we can see how water cycles behave around the world –and how people impact freshwater resources – it can tell us a lot about the future and how we can improve management. That’s especially vital as the climate crisis continues changes the water cycle.

“People who have a strong control over surface water variability is not necessarily a bad thing,” Cooley said, explaining that a human hand in freshwater management is essential to keep our lives on Earth, including powering hydropower plants, irrigating farms and, you know, giving us water to drink. But “enhancing seasonal variability in water storage can certainly have detrimental effects on the environment through increased evaporation and greenhouse gas emissions, deterioration of water quality, negative impact on ecosystems and enhancing downstream erosion.”

C.limate change is already emerging in the world’s freshwater supply. Important sources of drinking water, such as the Colorado River, have less water and flow more slowly due to climate changeeven though they are faced with an increasing demand from our water-hungry farms and cities. The rainfall itself becomes more erratic in some locations, like California, leading to years with too much water for the infrastructure to process and others in which reservoirs are running dry. Wall Street started in December betting on water as a commodityas money vultures see water scarcity as a new opportunity to capitalize on the coming decades. With these changes – and the risk of seeking profit from a natural resource vital to lifemonitoring what is really going on with the water supply becomes even more important.

“To ensure the sustainability of freshwater supplies worldwide, it is valuable, although, to understand where humans most control surface water storage, as this may be more vulnerable in the future, ”said Cooley.