How anthropogenic climate change will impact the arid regions of Southwestern North America has implications for the allocation of water resources and the course of regional development. The findings of a new study, appearing in Science, show that there is a broad consensus amongst climate models that this region will dry significantly in the 21st Century and that the transition to a more arid climate may already be underway. If these models are correct, the levels of aridity of the recent multiyear drought, or the Dust Bowl and 1950s droughts, will, within the coming years to decades, become the new climatology of the American Southwest.
Lake Powell's "Slow, No Wake" sign...
... “'The arid lands of southwestern North America will imminently become even more arid as a result of human-induced climate change just at the time that population growth is increasing demand for water, most of which is still used by agriculture,” said Richard Seager, Senior Research Scientist at the Lamont-Doherty Earth Observatory and one of the lead authors of the study. “The West, and in particular, the United States and Mexico, need to plan for this right now, coming up with new, well-informed and fair deals for allocation of declining water resources.”Projections of anthropogenic, or man-made, climate change conducted by 19 different climate modeling groups around the world, using different climate models, show widespread agreement that Southwestern North America—and the subtropics in general—are heading toward a climate even more arid than now.
... “Our study emphasizes the fact that global warming not only causes water shortage through early snow melt, which leads to significant water shortage in the summer over the Southwest, but it also aggregates the problem by reducing precipitation,"...
The study also shows that, in addition to the Southwestern North America other land regions to be hit hard by subtropical drying include southern Europe, North Africa and the Middle East as well as parts of South America. - Columbia University
