Fifty years ago, when there were fewer than half the current number of people on the planet, the common perception was that water was an infinite resource. People were not as wealthy then as they are today, consumed fewer calories and ate less meat, so less water was needed to produce their food. They required a third of the volume of water we presently take from rivers. Today, the competition for water resources is much more intense. This is because there are now over seven billion people on the planet, their consumption of water-thirsty meat and vegetables are rising, and there is increasing competition for water from industry, urbanisation and biofuel crops.
The total amount of available freshwater supply is also decreasing because of climate change, which has caused receding glaciers, reduced stream and river flow, and shrinking lakes. Many aquifers have been over-pumped and are not recharging quickly. Although the total fresh water supply is not used up, much has become polluted, salted, unsuitable or otherwise unavailable for drinking, industry and agriculture. To avoid a global water crisis, farmers will have to strive to increase productivity to meet growing demands for food, while industry and cities find ways to use water more efficiently.[7]
The New York Times article, "Southeast Drought Study Ties Water Shortage to Population, Not Global Warming", summarises the findings of Columbia University researcher on the subject of the droughts in the American Southeast between 2005 and 2007. The findings were published in the Journal of Climate. They say the water shortages resulted from population size more than rainfall. Census figures show that Georgia’s population rose from 6.48 to 9.54 million between 1990 and 2007.[8] After studying data from weather instruments, computer models and measurements of tree rings which reflect rainfall, they found that the droughts were not unprecedented and result from normal climate patterns and random weather events. "Similar droughts unfolded over the last thousand years", the researchers wrote, "Regardless of climate change, they added, similar weather patterns can be expected regularly in the future, with similar results."[8] As the temperature increases, rainfall in the Southeast will increase but because of evaporation the area may get even drier. The researchers concluded with a statement saying that any rainfall comes from complicated internal processes in the atmosphere and are very hard to predict because of the large amount of variables.