Climate Change and Drought in the U.S.

Over the past five years the entire southern half of the United States has had to deal with record droughts, though the circumstances have varied by region. The Southwest has experienced a nearly continuous dry spell. Texas went through one of its worst droughts on record in 2005 and 2006 only to be inundated this year; and the Southeast, which was drenched by a record hurricane season in 2005, is now experiencing an exceptional drought that has left many areas with only a few months of water supply on hand. All of these droughts are aggravated by the population growth that the sunbelt has experienced in recent decades.

Unlike the Southwest, which where a desert conditions have always required water planning, the Southeast now finds itself with dangerously low water supplies and no backup plan should the drought continue. Only Florida has passed a water plan. Atlanta's population has tripled since 1960; Georgia's water use increased by 30 percent between 1990 and 2000 alone--but its response to the worst drought on record has been surprisingly slow, typified by the plans at one outdoor theme park to build a 1.2 million gallon mountain of snow on a day when temperatures reached 81 degrees.

The American Southwest, more accustomed to dry conditions, has a better track record of water management; but this region finds changing weather patterns rendering their old assumptions obsolete.

The great dam and reservoir projects of the twentieth century gave the region a half century of surplus capacity, allowing agriculture to flourish and cities to expand. Now that surplus is gone--every drop is already allocated--and a persistent drought is threatening to deplete existing supplies. At the same time global warming is melting the mountain snow packs that provide a major source of fresh water.

Cities in the Southwest are now scrambling to find ways to conserve and reuse water supplies. The city of Aurora, Colorado has pioneered a method of installing wells downstream from their wastewater plants to retrieve the water, purify it and reuse it the first such closed loop in the U.S.

In the long run, however, there is little that can be done to support ever increasing populations in the U.S. South especially when one considers that the South lies astride the 30th parallel, where many of the Earth's deserts exist, due to air currents that rise at the equator and descend at the tropics of Cancer and Capricorn. Climate models project that these areas will get even dryer. What we are seeing now may be the leading edge of that trend. In any event, the rapid population growth of the sunbelt states is likely to hit a roadblock in the imminent future.