Human fingerprints are found all over the fresh water of the world. A new one to study published Wednesday in the journal Nature shows that, although human-controlled freshwater sources constitute a minimal portion of the world’s lakes, and rivers, are responsible for more than half of all changes that occur on Earth water system.
The study used new satellite laser technology to delve into freshwater sources around the world and monitor their water levels during different seasons. Using NASA’s ICESat-2 satellite, researchers monitored more than 227,000 bodies of freshwater, ranging from the Great Lakes to small ponds. for a period spanning about a year and a half. The researchers found that 57% of the world’s seasonal variability in water storage occurs in human-controlled reservoirs.
“This large proportion is even more surprising if we consider that reservoirs account for only 3.9% of the 227,386 lakes analyzed in this study,” said Sarah Cooley, lead author of the study currently at the University. of California, Berkeley, but who began work while at Brown, he said by email. “While the water cycle is generally represented as a natural process, our finding that humans are responsible for most of the seasonal variability in surface water storage demonstrates that we are now a key regulator of the cycle. of water “.
Before the launch of this satellite in 2018, which was originally designed to observe the ice sheets and to be able to collect extraordinarily detailed data, it was actually difficult to understand how freshwater bodies changed over time. Cooley said most human-controlled reservoirs have meters to measure water levels, but there is no global database for such measurements. Meanwhile, few lakes and ponds that are not reservoirs have calibers.
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Pre-ICESat-2 satellites could only control a couple of hundred of the world’s largest lakes. so the data 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 level and human influence on surface water storage,” Cooley said.
Now that we can see how water cycles behave around the world—and how many impacts humans have on freshwater reserves: it can tell us a lot about the future and how to improve management. This is especially vital as the climate crisis unfolds alters the water cycle.
“Humans exercising strong control over surface water variability is not inherently bad,” said Cooley, who explained that a human hand in freshwater management is essential to sustaining our lives in Earth, including the feeding of hydroelectric dams, the irrigation of farms and, as is well known, which gives us drinking water. But “amplifying the seasonal variability of water storage can certainly have detrimental impacts on the environment by increasing evapotranspiration and greenhouse gas emissions, degrading the quality of the water, negatively impacting ecosystems and increasing downstream erosion. “
Clime change already appears to a large extent on the world’s fresh water supply. Main sources of drinking water, such as the Colorado River, have less water and flow more slowly due to climate change—although they face a growing demand from our farms and cities that lack water. Rainfall itself is increasingly uneven in some places, like California, which leads to years with too much water for handling the infrastructure and others where the reservoirs are about to dry up. In December, Wall Street began betting on water as a commodity, as money vultures see water scarcity as a new opportunity for profit in the coming decades. With these changes and the risk of taking advantage of a vital natural resource for life–controlling what is really going on with the water supply will be even more important.
“To ensure the sustainability of freshwater resources around the world, it is valuable, But, understand where humans exercise maximum control over surface water storage, as they may be more vulnerable areas in the future, ”said Cooley.