Climate change puts forty percent more people at risk of absolute water scarcity

A press release from the Potsdam Institute for Climate Impact Research: Water scarcity impacts people’s lives in many countries already today. Future population growth will increase the demand for freshwater even further. Yet in addition to this, on the supply side, water resources will be affected by projected changes in rainfall and evaporation. Climate change due to unabated greenhouse-gas emissions within our century is likely to put 40 percent more people at risk of absolute water scarcity than would be without climate change, a new study shows by using an unprecedented number of impact models. The analysis is to be published in a special issue of the Proceedings of the National Academy of Sciences that assembles first results of the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP), a unique community-driven effort to bring research on climate change impacts to a new level.

“The steepest increase of global water scarcity might happen between 2 and 3 degrees global warming above pre-industrial levels, and this is something to be experienced within the next few decades unless emissions get cut soon,” says lead-author Jacob Schewe of the Potsdam Institute for Climate Impact Research. “It is well-known that water scarcity increases, but our study is the first to quantify the relative share that climate change has in that, compared to – and adding to – the increase that is simply due to population growth.”

Today, between one and two people out of a hundred live in countries with absolute water scarcity. Population growth and climate change combined would increase this to about ten in a hundred at roughly 3 degrees global warming. Absolute water scarcity is defined as less than 500 cubic meters available per year and person – a level requiring extremely efficient water use techniques and management in order to be sufficient, which in many countries are not in place. For a comparison, the global average water consumption per person and year is roughly 1200 cubic meters, and significantly more in many industrialized countries....

Women carrying water in Afghanistan, near Bamiyan, in 1976, shot by Ian Alexander, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license