If the planet continues to warm at its current trajectory, and human populations rise on-pace, well over 1 billion people will face new or increased water scarcity by the end of this century, a series of studies from the Potsdam Institute for the Germany-based Climate Impact Research (PIK) reveals.

"If population growth continues, by the end of our century under a business-as-usual scenario these figures would equate to well over one billion lives touched," Gerten points out. "And this is on top of the more than one billion people already living in water-scarce regions today."

Researchers warn that the planet is headed for severe scarcity in which the global poor, as well as people living in parts of Asia and North Africa, the Mediterranean, and the Middle East, will be hardest hit. "Now this is not a question of ducks and daisies, but of our unique natural heritage, the very basis of life," said Hans Joachim Schellnhuber, one of the co-authors and director of PIK, in a Tuesday announcement about the the studies.

The current pledges of the international community to reduce greenhouse gas emissions are not aggressive enough to curb the spiraling problem of water scarcity, researchers found in a series of modeling studies.

"Mean global warming of 2 degrees, the target set by the international community, is projected to expose an additional 8 percent of humankind to new or increased water scarcity," says Dieter Gerten, lead-author of one of the studies. "3.5 degrees – likely to occur if national emissions reductions remain at currently pledged levels – would affect 11 percent of the world population."

If the globe warms 5 degrees Celsius, which PIK says it is on-target to do by the end of the century if "business-as-usual" continues, the number of people directly affected by new or increased water scarcity will reach well over 1 billion, a stunning 13 percent of the global human population.

"Our findings support the assertion that we are fundamentally destabilizing our natural systems," says Wolfgang Lucht, one of the authors and co-chair of PIK's Research Domain of Earth System Analysis. "[W]e are leaving the world as we know it."

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