The low number for China correlates with a vegetarian diet, the researchers point out, noting that most people in China eat essentially a vegetarian diet. Water Resources Goodland and Pimentel believe that the present and future availability of adequate supplies of fresh water is frequently taken for granted. Natural collectors of water such as rivers and lakes vary in distribution throughout the world and are frequently shared within and between countries. All surface water supplies, but especially those in arid regions, are diminished by evaporation. For insance, reservoir water experiences an average yearly loss of about 24 percent.
All vegetation requires and transpires massive amounts of water during the growing season.
To supply this much water to the crop, not only must 855,119 gallons of rain fall per acre, but also a significant portion must fall during the growing season. The renowned scientists state that perhaps the greatest threat to maintaining freshwater supplies is overdraft of surface and groundwater resources used to supply the needs of the rapidly growing human population and the agriculture that provides its food. In the U.S., this figure is about 85 percent. About 80 nations in the world are already experiencing significant water shortages. For instance, in China, more than three hundred cities are short of water and the problem is intensifying.