‘A normal year in the Southwest is now drier than it once was’
A subtle long-term shift in atmospheric patterns driven by global warming could lead to longer and more intense droughts in the southwestern U.S. and other semi-arid regions. Most climate models suggest that that a belt of higher average pressure that now sits closer to the equator will move north. This high-pressure belt is created as air that rises over the equator moves poleward and then descends back toward the surface.
That shift may already be affecting the climate of the Southwest, as moisture-bearing weather patterns have become more rare in the region, according to a new study. Previous research has suggested that the region’s forests and fish and birds are in big trouble. In Australia, researchers are nearly certain that global warming was a factor in a record-breaking 2013 heatwave. A federal climate assessment released in 2013 also identified similar concerns for the Southwest.
“A normal year in the Southwest is now drier than it once was,” said Andreas Prein, a postdoctoral researcher at the National Center for Atmospheric Research who led the study. “If you have a drought nowadays, it will be more severe because our base state is drier.” Continue reading