On Sun, Apr 6, 2008 at 6:38 PM, David B. Benson <[EMAIL PROTECTED]> wrote:
> > On Apr 6, 1:54 pm, "Michael Tobis" <[EMAIL PROTECTED]> wrote: > > ... > > Food is largely provided through extractive use of ground water. > World-wide? I doubt this. Data? The magnitude of the aquifer depletion problem has only recently become evident. Although comprehensive data do not exist, it is believed that global groundwater over-pumping (i.e., beyond the rate at which groundwater is recharged) totals at least 160 billion cubic meters a year, equal to twice the annual flow of the Nile rivers. For example, the rate at which groundwater is extracted in India is more than twice the rate of recharge, with some water tables now falling by one to three meters per year. As a result, India could lose 25% or more of its current crop production during the next 25 years due to unsustainable aquifer usage rates. Similarly, Mexico is depleting ground water reserves in some agriculturally important regions at rates exceeding 3 meters per year. The implications for global food security<http://www.usaid.gov/our_work/environment/water/food_security.html>are enormous. It is estimated that nearly 10% of the global food supply (160 million tons of grain) is currently based on the unsustainable practice of depleting groundwater. http://www.usaid.gov/our_work/environment/water/groundwater_mgmt.html mt --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/globalchange -~----------~----~----~----~------~----~------~--~---
