Global water supplies shrinking due to climate change: Study

December 19, 2018 12:00 am | Updated 03:32 am IST - Melbourne:

Global water supplies shrinking

Climate change will drive our water supplies to shrink due to drying soils, while generating more intense rain, according to a study which warns that drought-like conditions will soon become the new normal in our world. The study relied on actual data from 43,000 rainfall stations and 5,300 river monitoring sites in 160 countries.

“We expected rainfall to increase, since warmer air stores more moisture – and that is what climate models predicted too. Despite all the extra rain everywhere in the world, the large rivers are drying out,” say researchers.

They 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.

Less water into our rivers means less water for cities and farms. And drier soils means farmers need more water to grow the same crops. Worse, this pattern is repeated all over the world, assuming serious proportions in places that were already dry. It is extremely concerning.

For every 100 raindrops that fall on land, only 36 drops are ‘blue water’ -- the rainfall that enters lakes, rivers and aquifers -- and therefore, all the water extracted for human needs.

The remaining two thirds of rainfall is mostly retained as soil moisture -- known as ‘green water’ -- and used by the landscape and the ecosystem.

As warming temperatures cause more water to evaporate from soils, those dry soils are absorbing more of the rainfall when it does occur -- leaving less ‘blue water’ for human use. PTI

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