April 06, 2007
The trend toward a drier, hotter southwestern U.S., including all of Texas, probably has already begun and could become strikingly noticeable within about 15 years. Drought conditions are expected to resemble the Dust Bowl years of the 1930s and Texas' worst-ever drought of the 1950s. Unlike those droughts, however, the new conditions won't be temporary. "This time, once it's in, it's in for good." Atmospheric concentrations of carbon dioxide, the chief greenhouse gas, are HIGHER THAN AT ANY TIME IN THE PAST 650,000 years, and probably higher than in the past 800,000 years. All of Texas would receive significantly less rain, with conditions generally becoming drier toward West and southwest Texas. Parts of New Mexico, Arizona, western Mexico, the Yucatan peninsula and nearly all of Central America would see extreme drought. Past droughts such as the Dust Bowl and the 1950s drought were driven by identifiable and natural short-term temperature variations in the Pacific Ocean and sometimes in the Atlantic. The perpetual drought conditions foreseen in the Columbia study, by contrast, result from planetary-scale changes driven by higher temperatures around the globe. During 2006-07, a massive switch in Texas from growing cotton to growing corn for ethanol in gasoline is boosting irrigation needs by the equivalent of "a large lake."
Adapting to the damaging effects of climate change, plants are gradually moving to where temperatures are cooler, rainfall is greater, f...