30 Jul 2012:
Recent Historic Drought
May Be the ‘New Normal,’ Study Says
A multi-year drought from 2000 to 2004 that lowered crop productivity and reduced water levels across western North America may become “the new normal” over the next century
as the climate warms, a new
study says. In an analysis of climate models and precipitation projections, a team of scientists predicts that 80 of the 95 years between 2006 and 2100 will have precipitation levels as low, or lower, than levels experienced during the recent historic drought. That drought — which, based on tree ring data, was worse than any other experienced by the western U.S. in many centuries — caused crop productivity to drop by 5 percent, reduced runoff in the upper Colorado River basin by half, and triggered increased mortality in forests. In addition, the dry conditions cut the carbon sequestration capacity of forests across the western U.S., Canada, and Mexico by 51 percent, said Beverly Law, a scientist at Oregon State University and co-author of the study, published in the journal Nature Geoscience
. As forest vegetation wilted, it caused more CO2 emissions into the atmosphere, amplifying global warming, according to the study. The researchers said it is unclear whether the drought conditions now crippling the midwestern U.S. have been caused by the same forces.