A regime change of almost incredible scale has occurred in the natural world, reflecting humanity’s growing dominance over one of the most essential resources on our planet. : fresh water.
In what researchers say is the first global study of human effects on the water cycle, scientists have used NASA satellite measurements to measure distance in the amount of water held in water. incredible number of water bodies: 227,386 ponds, lakes, and the world. reservoirs, whether small or large.
Although human-controlled reservoirs such as artificial dams make up only 3.9 percent of this large planetary system of surface-level water storage, that tiny fraction hides the intriguing reality that in terms of how much control humanity has over freshwater variables.
When the total amount of change in water levels is measured across both natural and human-managed systems, it turns out that the human-controlled reservoirs represent 57 per cent of surface water variability – more than half of the ebb and flow in freshwater systems.
“We tend to think of the water cycle as a completely natural system: Water and avalanches flow into rivers, which flow into the ocean where evacuation begins. ‘the whole circle again, “explained geologist Sarah Cooley of Stanford University.
“But people are very much involved in that cycle. Our work shows that people are responsible for most of the variability of seasonal surface water storage on Earth.”
The results, obtained from 22 months of data collected by NASA’s Ice, Cloud and Land Elevation Satellite 2 (ICESat-2), paint a picture of the world’s first type of water storage, capture and ‘body size of water as small as a football field within the study.
“Satellites before could not have come close to that place,” Cooley says, but while the scientific achievements are commendable, the takeaways are not.
“There are many ways in which this is bad for the environment.”
Threats range from negative impacts on natural ecosystems due to water scarcity, to micro-emissions of greenhouse gas emissions from artificial reservoirs.
Of course, there are other benefits of man-made reservoirs as well: as well as simply controlling water supplies, they enable things like hydroelectric systems, and dams can provide protection from floods.
But still, it’s hard to understand that we’ve largely taken control of something as natural as ebb and flow of fresh water.
Another strong reminder of just how our species affects the environment around us – with such huge consequences, we can only hope to see them from space.
“Of the major changes in freshwater bodies around the planet – all the floods, droughts and snow that push lake levels up and down – people have exceeded almost 60 percent of that variability, ”says environmental scientist Laurence Smith of Brown University.
“That has a huge impact on the water cycle. In terms of human impact on the planet, this is okay with an impact on ground cover and atmospheric chemistry.”
The results are reported in Nature.