Humans are causing massive changes in water throughout the Earth, says NASA

Humans are causing massive changes in water throughout the Earth, says NASA
A 14-year mission from NASA has confirmed that a massive redistribution of fresh water is occurring across the Earth, with mid-latitude belts drying and the tropics and latitudes getting higher water supplies.
The results, which are probably a combination of the effects of climate change, huge human extractions of groundwater and simple natural changes, could have profound consequences if they continue, pointing to a situation in which some highly populated regions may have difficulty finding sufficient water. “For me, the fact that we can see this strong fingerprint of human activities in the global redistribution of water should be cause for alarm,” said Jay Famiglietti, a researcher at NASA’s Jet Propulsion Laboratory and one of the authors of a new study published in Nature on Wednesday.
The results arise from the 2002-2016 GRACE mission, which is short for Gravity Recovery and Climate Experiment, supplemented by additional data sources. The GRACE mission, which recently ended but will soon be replaced by a “Follow-On” effort, consisted of two twin satellites in orbit that detected the pull of Earth’s gravity beneath them and monitored mass changes based on small differences in the measurements of the two satellites.
Among all the massive characteristics of the Earth, water and ice are the ones that change most frequently. Therefore, the GRACE data has been used to detect from the large ice losses in Greenland, Antarctica and Alaska, to changes in ocean currents, to the scale of the California drought.
The new research, led by NASA’s Matthew Rodell, brings together these and other findings to identify 34 global regions that gained or lost more than 32 billion tons of water between 2002 and 2016. As the study notes, 32 billion tons equal to the amount of water contained in Lake Mead. Then the 34 areas saw very big changes.
The resulting map of the findings shows a general pattern, in which ice sheets and glaciers lose much mass at the poles, but at the same time, mid-latitudes show multiple areas of increasing dryness even when the highest latitudes see increases in water
The study emphasizes that the 34 separate changes it detects do not have the same cause, they are not even close.
There is a strong suspicion that the melting of glaciers and ice sheets is linked to climate change. On land, there may also be some droughts and increases in rainfall, although the study is cautious about it, noting that natural variability can also be an important factor here.
Even so, the idea of ​​mid-latitude drying and humidification at high and low latitudes is a common feature of climate change models. “We only have 15 years of GRACE data, but I’m sure that as the devils coincide with that pattern, now it equals it,” said Famiglietti. “That is cause for concern.”
More data from a new launch of the GRACE mission “Follow-On” will contribute to a longer data record that can help to better identify trends, Famiglietti said.
And then there are other changes induced by the human being, which are related not to climate change, but to the direct withdrawal of water from the landscape.
Therefore, in northern India, the plain of northern China, the Caspian and Aral Seas, among other regions, human retreats for agriculture have subtracted huge amounts of water mass from Earth. The changes in the Aral Sea region, previously documented by NASA, have been particularly intense.
There are also some important cases of humans that increase the storage of water in the landscape, particularly in China, where the massive construction of dams has created huge deposits.
Mainly, however, the surprising thing about the map is the way in which a combination of water withdrawals and human-driven droughts seem to be punishing the central latitudes of the northern hemisphere in particular, but also the southern hemisphere to a large extent.
“I think we have forgotten, society has forgotten, how much water is needed to produce food,” said Famiglietti. “We have taken their availability for granted, and you know, we are now at one point in many of these aquifers where we can no longer take it for granted, the population is too large, the groundwater levels are too low. inflection “.
Even so, it is important to bear in mind that, although the GRACE data has given a new panoptic view of the changing distribution of water throughout the world,

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Rajbir Mangat

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