The Drought In The West: Here To Stay, So Time To Move
The 2000-2004 drought in the US West was apparently the most sever drought of the past 800 years. But don’t think that means we are headed into a wet period:
Christopher Schwalm, Christopher Williams, and Kevin Schaefer, Extreme Weather and Drought Are Here to Stay
Future precipitation trends, based on climate model projections for the coming fifth assessment from theIntergovernmental Panel on Climate Change, indicate that droughts of this length and severity will be commonplace through the end of the century unless human-induced carbon emissions are significantly reduced. Indeed, assuming business as usual, each of the next 80 years in the American West is expected to see less rainfall than the average of the five years of the drought that hit the region from 2000 to 2004.
That extreme drought (which we have analyzed in a new study in the journal Nature-Geoscience) had profound consequences for carbon sequestration, agricultural productivity and water resources: plants, for example, took in only half the carbon dioxide they do normally, thanks to a drought-induced drop in photosynthesis.
In the drought’s worst year, Western crop yields were down by 13 percent, with many local cases of complete crop failure. Major river basins showed 5 percent to 50 percent reductions in flow. These reductions persisted up to three years after the drought ended, because the lakes and reservoirs that feed them needed several years of average rainfall to return to predrought levels.
In terms of severity and geographic extent, the 2000-4 drought in the West exceeded such legendary events as the Dust Bowl of the 1930s. While that drought saw intervening years of normal rainfall, the years of the turn-of-the-century drought were consecutive. More seriously still, long-term climate records from tree-ring chronologies show that this drought was the most severe event of its kind in the western United States in the past 800 years. Though there have been many extreme droughts over the last 1,200 years, only three other events have been of similar magnitude, all during periods of “megadroughts.”
Most frightening is that this extreme event could become the new normal: climate models point to a warmer planet, largely because of greenhouse gas emissions. Planetary warming, in turn, is expected to create drier conditions across western North America, because of the way global-wind and atmospheric-pressure patterns shift in response.
Indeed, scientists see signs of the relationship between warming and drought in western North America by analyzing trends over the last 100 years; evidence suggests that the more frequent drought and low precipitation events observed for the West during the 20th century are associated with increasing temperatures across the Northern Hemisphere.
Our life in the US West is headed for an abrupt end. There will be no cotton crops from Texas worth talking about, and our collective wish that the American ‘breadbasket’ will revert to 1970s norms is a fairy tale.
We won’t necessarily have to force people to move out of this area: they will do so on their own. Farms will cease to be productive, water will become scarce then expensive then impossible. People will start to move away, back to Ohio, Georgia, and Kentucky. The Hudson River valley will become an important agricultural region again, as will the Willamette. All those tobacco farms in the Carolinas will be growing corns and peas, instead.
And the great interior of the US will become a desert, a sere, empty region, with under 10 inches of rain a year, supporting tumbleweeds and dry savannah, and 30 million or more American will leave it behind. One of the largest ecological migrations in history, but there are bigger yet to come.
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buffleheadcabin reblogged this from underpaidgenius and added:
Just in time for the Ogallala Aquifer to completely dry out.
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