February 10, 2016--Drying out of the American Southwest (Mountain Town News)

Peering through a window on a flight from Denver to Los Angeles, you first see the Rocky Mountains, rich with forests and snow, here and there a ski area. Then, for the majority of the trip you see aridity, the soft greens of sagebrush steppes at higher elevations dissolving to harsh pigments of the Mojave Desert until you get to the exurbs of LA. This is the American Southwest. Apart from its few rivers, it’s inherently dry, even parched—and, according to a new study conducted by scientists at the National Center for Atmospheric Research, getting drier as a result of less frequent storms. “A normal year in the Southwest is now drier than it once was,” said Andreas Prein, an NCAR postdoctoral researcher who led a study published last week in the journal Geophysical Research Letters. “If you have a drought nowadays, it will be more severe because our base state is drier.” With less rain and higher temperatures, droughts will lengthen, they say. “As temperatures increase, the ground becomes drier and the transition into drought happens more rapidly,” said NCAR scientist Greg Holland, a study co-author. Water policy officials in both California and Colorado said the study provides further evidence of the challenges they had already understood. Unlike other areas of North America, emerald green from plentiful rain, the American Southwest walks on a narrowing razor’s edge between supply and demand. This study finds evidence of less supply, even as climate models predict rapidly increasing temperatures—heat that will likely further reduce available water supplies. Eric Kuhn, general manager of the Colorado River Water Conservation District, which is based in Glenwood Springs, Colo., echoed Holland’s emphasis on the twin drivers of drought: precipitation and heat. “Even if your precipitation goes up in winter months, like some of the studies have suggested, the overall net impacts of the increased warming in places like Lake Powell or (in the Colorado River) at Lee’s Ferry will be less water,” he told Mountain Town News. To view the full article visit the Mountain Town News.