Humankind’s water use greater than thought

New analysis quantifies global impact of evaporation, runoff

rice fields

WATER LOSS  Humans water crops, like the rice fields shown here, using methods such as irrigation. Water management practices like these are taking a toll on water sources, a new study finds.


Humans’ global water footprint is up to 18 percent greater than previous estimates, researchers from Sweden report in a new study.

An analysis of water and climate data from 1901 to 2008 from 100 large water basins around the world revealed more water loss to the atmosphere and less water runoff compared with conclusions from earlier studies. The researchers link both water impacts to human activities. Water management techniques such as irrigation and damming rivers to create reservoirs, rather than climate conditions or geographic location, better explain the findings, they say.

On a global scale, the new results suggest that humans use about 10,700 cubic kilometers of water­­ per year, more than all the water in Lakes Michigan, Huron, Ontario and Erie combined. That’s about 18 percent more than a 2012 estimate for current water use. The level is increasingly unsustainable, the scientists report December 4 in Science

WATER, WATER Half of the 100 water basins studied were heavily impacted (dark blue) by such human activities as irrigation and building dams for flood control, storing water or creating hydropower. Only a few locations weren’t affected at all (light blue). F. Jaramillo and G. Destouni/Science 2015

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