Some nations are depleting their groundwater reserves faster than they can be renewed, according to Canadian researchers writing in the journal Nature. Globally, the groundwater "footprint"--the above ground area that relies on underground water--is about 3.5 times larger than the aquifers themselves. The research shows that as many as 1.7 billion people, mostly in Asia, live in areas with groundwater reserves that are under threat after overuse. Though some 80 percent of the world's aquifers are being treated sustainably, said one of the researchers, some reserves, such as one in the Upper Ganges and one in western Mexico, are being treated as non-renewable resources with as much as 54 times the amount of water coming out as going in. "The relatively few aquifers that are being heavily exploited are unfortunately critical to agriculture in a number of different countries," said Tom Gleeson, the researcher who led the study. Gleeson said that more efficient irrigation, limits on extraction, and promotion of diets with less meat could make the water resources more sustainable. For the full story, see http://uk.reuters.com/article/2012/08/09/us-science-environment-water-idUKBRE87713B20120809. For a map of the hardest-hit areas, see http://www.npr.org/blogs/thesalt/2012/08/08/158417396/heres-where-farms-are-sucking-the-planet-dry.