Global water supplies are shrinking, even as rainfall is rising, because of drying soils due to climate change.
A global study has found a paradox: our water supplies are shrinking at the same time as climate change is generating more intense rain. And the culprit is the drying of soils, say researchers, pointing to a world where drought-like conditions will become the new normal, especially in regions that are already dry.
The study – the most exhaustive global analysis of rainfall and rivers – was conducted by a team led by Professor Ashish Sharma at Australia’s UNSW (University of New South Wales) in Sydney. It relied on actual data from 43,000 rainfall stations and 5300 river monitoring sites in 160 countries, instead of basing its findings on model simulations of a future climate, which can be uncertain and at times questionable.
“This is something that has been missed,” said Sharma, an ARC Future Fellow at UNSW’s School of Civil and Environmental Engineering. “We expected rainfall to increase, since warmer air stores more moisture – and that is what climate models predicted too. What we did not expect is that, despite all the extra rain everywhere in the world, the large rivers are drying out.
“We believe the cause is the drying of soils in our catchments. Where once these were moist before a storm event – allowing excess rainfall to run off into rivers – they are now drier and soak up more of the rain, so less water makes it as flow.”
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