Humans have completely transformed the way water is stored on Earth


A light mineral bathtub ring shows the reservoir's high water mark that has dropped to its lowest point in the Colorado River, as seen from the Hoover Dam.

A light mineral bathtub ring shows the reservoir’s high water mark that has dropped to its lowest point in the Colorado River, as seen from the Hoover Dam.
Photo: Richard Vogel (AP)

Human fingerprints are all over the fresh water in the world. A new study published Wednesday in the journal Nature shows that while human-controlled freshwater sources make up a minimal portion of the world’s ponds, lakes, and rivers, 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 monitor their water levels at different stations. Using NASA’s ICESat-2 satellite, the researchers monitored more than 227,000 bodies of freshwater, ranging in size from the Great Lakes to small ponds. over a period of about a year and a half. The researchers found that 57% of the global seasonal water storage variability occurs in human-controlled reservoirs.

“This large proportion is even more surprising when you consider that reservoirs only represent 3.9% of the 227,386 lakes analyzed in this study,” said Sarah Cooley, lead author of the study who is currently at the University of California, Berkeley. , but started work while at Brownhe said by email. “While the water cycle is generally described 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 key regulator of the water cycle.”

Before the launch of this satellite in 2018, what was it originally designed In order to observe the ice sheets and be able to collect extraordinarily detailed data, it was actually difficult to understand how bodies of fresh water moved over time. Cooley said that most human-controlled reservoirs have meters to measure water levels, but there is no global database for these measurements. Meanwhile, few lakes and ponds that are not reservoirs have meters.

Satellites prior to ICESat-2 could only monitor a couple hundred of the world’s largest lakes, so the data collected here is very interesting to people who spend their time thinking about freshwater cycles. “This study provides the first global quantification of surface water level variability and human influence on surface water storage,” Cooley said.

Now that we can see how water cycles behave around the world:and how much impact humans have on freshwater reserves: it can tell us a lot about the future and how to improve management. That’s especially vital as the climate crisis progresses. disrupts the water cycle.

“For humans to exert strong control over surface water variability is not inherently a bad thing,” Cooley said, explaining that a human hand in freshwater management is essential to sustaining our life in Eart, including powering hydroelectric dams, watering farms, and, you know, giving us water to drink. But “amplifying seasonal variability in water storage can certainly have detrimental impacts on the environment by increasing evapotranspiration and greenhouse gas emissions, degrading water quality, negatively impacting ecosystems, and enhancing downstream erosion.” .

CClimate change is already looming over the world’s fresh water supply. The main sources of drinking water, such as Colorado River, have less water and flow more slowly due to climate change—even as they face increasing demand from our water-starved farms and cities. Rainfall itself is increasingly erratic in some places, like california, leading to years with too much water for the infrastructure to handle and others in which the reservoirs are almost dry. In December, Wall Street began betting on water as a commodityas the money vultures see water scarcity as a new opportunity to make a profit in the coming decades. With these changes and the risk of profiting from a vital natural resource for lifemonitoring what is actually happening with the water supply will be even more important.

“To ensure the sustainability of freshwater resources around the world, it is valuable, though, to understand where humans are exerting more control over surface water storage, as these may be areas that are more vulnerable in the future, “said Cooley.

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