Drought debates muddy the waters

Differences in location, and definition, mask long-term issues

Drought has been the standard forecast in the southwestern United States for the past decade, and as global warming dries out this and other regions around the world, and booming populations cause more water shortages, the word is likely to be tossed around even more.

"There is no single definition for drought," according to the National Drought Mitigation Center’s website. It is one of the planet’s most complex natural hazards, and exactly when a drought begins and ends is difficult to determine because it tends to develop gradually.

Bigger changes coming

Water shortages will affect many areas of the United States and the world, leading to “water wars” between states and countries if global temperatures continue to rise throughout the next century, as predicted in reports issued by the Intergovernmental Panel on Climate Change..

Droughts will especially increase in subtropical areas, like the U.S. Southwest, Australia and parts of Africa and Europe, as Earth’s warming causes more evaporation and shifts weather patterns, pushing the paths of storms that bring thirst-quenching rains further north.

According to a recent study, over the coming century the Southwest will essentially transition into a state of “perpetual drought” due to the effects of global warming. This prediction leads to the questions of whether the worsening arid conditions of the Southwest should be called a drought or whether the regional climate is changing.

“The climate has changed and it’s become even a little more arid than it was,” said Trenberth, the NCAR researcher.

Other scientists disagree. According to Garfin, records of the region’s past climate show that multi-decade droughts have occurred many times before.

“I think the fact that we have multi-decade drought and that we’re in one now is not unusual, but maybe the character of [drought] is changing,” he said, referring to massive die-offs of trees and earlier snowmelts (which the parched soil can’t absorb, reducing a critical source of water supplies).

http://www.msnbc.msn.com/id/18232281/