Water scarcity is not a problem just for the developing world. In California, legislators are currently proposing a $7.5 billion emergency water plan to their voters; and U.S. federal officials last year warned residents of Arizona and Nevada that they could face cuts in Colorado River water deliveries in 2016. Irrigation techniques, industrial and residential habits combined with climate change lie at the root of the problem. But despite what appears to be an insurmountable（不能克服的） problem, according to researchers from McGill and Utrecht University it is possible to turn the situation around and significantly reduce water scarcity in just over 35 years.

In a new paper published in Nature Geoscience, the researchers outline strategies in six key areas that they believe can be combined in different ways in different parts of the world in order to effectively reduce water stress. (Water stress occurs in an area where more than 40 percent of the available water from rivers is unavailable because it is already being used -- a situation that currently affects about a third of the global population, and may affect as many as half the people in the world by the end of the century if the current pattern of water use continues).

The researchers separate six key strategy areas for reducing water stress into "hard path" measures, involving building more reservoirs and increasing desalination（脱盐作用） efforts of sea water, and "soft path" measures that focus on reducing water demand rather than increasing water supply thanks to community-scale efforts and decision-making, combining efficient technology and environmental protection. The researchers believe that while there are some economic, cultural and social factors that may make certain of the "soft path" measures such as population control difficult, the "soft path" measures offer the more realistic path forward in terms of reducing water stress.

"There is no single silver bullet to deal with the problem around the world," says Prof. Tom Gleeson, of McGill's Department of Civil Engineering and one of the authors of the paper. "But, by looking at the problem on a global scale, we have calculated that if four of these strategies are applied at the same time we could actually stabilize the number of people in the world who are facing water stress rather than continue to allow their numbers to grow, which is what will happen if we continue with business as usual."

"Significant reductions in water-stressed populations are possible by 2050," adds co-author Dr. Yoshihide Wada from the Department of Physical Geography at Utrecht University, "but a strong commitment and strategic efforts are required to make this happen."