Wednesday, February 10, 2016

The Dust-Bowlification of the U.S.


A new study shows that the Southwest is going to get drier.  There's a little hope for the Pacific Northwest, but the Southwest has serious problems with water going into the future.
[T]he semi-arid U.S. Southwest has begun to enter the “drier climate state” that had been long-predicted from climate models. These findings match ones from September documenting an expansion of the entire world’s dry and semi-arid climate regions in recent decades because of human-caused climate change.
The new study from the National Center for Atmospheric Research (NCAR) concludes that “The weather patterns that typically bring moisture to the southwestern United States are becoming more rare, an indication that the region is sliding into the drier climate state predicted by global models.”



Drying Map
Weather systems that bring moisture to the southwest U.S. are forming less often, which is drying out resulting in a drier climate. This map depicts the changes in precipitation that can be attributed to these weather changes. The gray dots are areas where the results are statistically significant. Via NCAR.


In the long run it's going to get a lot worse.
Here, for instance, is a 2015 NASA projection of what the normal climate of North America will look like unless we keep taking stronger and stronger measures to slash carbon pollution. The darkest areas have soil moisture comparable to that seen during the 1930s Dust Bowl.

rcp8.5_soilmoisture-1


I called this prolonged, multi-decadal warming and drying “Dust-Bowlification” in a 2011 Nature review article, “The Next Dust Bowl,” because the 1930s Dust Bowl seems to be the best analogy to what’s coming. But in fact, the coming multidecadal megadroughts will be much worse than the Dust Bowl of the 1930s — “worse than anything seen during the last 2000 years,” as explained in a major 2014 study, “Assessing the risk of persistent drought using climate model simulations and paleoclimate data.” They will be the kind of megadroughts that in the past destroyed entire civilizations. 
By the end of this century, it's going to be really, really dry all over the lower 48.  Alaska looks ok.