Mega-Droughts Stalk the Southwest

A few weeks ago, I mused that the American Southwest may be on borrowed time. Forget that.

The Southwest is toast.

A new paper in Nature spells doom. From the abstract:

The potential for increased drought frequency and severity linked to anthropogenic climate change in the semi-arid regions of the southwestern United States is a serious concern. Multi-year droughts during the instrumental period and decadal-length droughts of the past two millennia were shorter and climatically different from the future permanent, “˜dust-bowl-like’ megadrought conditions, lasting decades to a century, that are predicted as a consequence of warming.

Nature’s Quirin Schiermeier has an article on the study, and this eye-popping quote from Richard Seager, a Columbia University climate researcher:

The drying we expect for the twenty-first century is entirely the result of increased greenhouse forcing.

But we’re not there yet, Seager tells Nature:

A signal of anthropogenic drying is emerging, but it is still small. I’d expect that by mid-century the human signal will exceed the amplitude of natural climate variability. Then we can safely say that the Southwest has entered a new climate stage.

UPDATE: Prehistoric drought in the SW is a big interest of mine, so I’m going to provide all the relevant press coverage links, as they come in. John Fleck, a science writer for The Albuquerque Journal, has a story and a post at his blog.

8 Responses to “Mega-Droughts Stalk the Southwest”

  1. John Fleck says:

    Seager’s pretty clear, as you’ll see in my newspaper story tomorrow, in arguing that Fawcett’s droughts are different in mechanism from Seager’s greenhouse-fueled droughts, and that Fawcett’s work therefore can’t tell us much about what to expect going forward.

  2. Keith Kloor says:

    I look forward to that story tomorrow, John.

  3. Gaythia says:

    I think that it is important to remember (as you have pointed out previously) that ” the amplitude of natural climate variability” is already on a collision course with population growth and water use patterns.

    I doubt that many people elsewhere understand the intensive allocation of the water of the Colorado River.  For example, where I live, north of Denver and east of the Rockies, water is supplied via a pipeline that runs under Rocky Mountain National Park.  This water originates in reservoirs in the Colorado River drainage on the other side of the Continental Divide.   This means that water that was to drain into the Gulf of California now ultimately drains into the Mississippi and the Gulf of Mexico.

  4. Keith Kloor says:

    Very true, Gaythia. My intention was merely to play off the Nature paper and story in a headline newsy way (while still linking to my previous post drawing out some of those other factors).

    It’ll be interesting to see the coverage of it tomorrow, which I suspect will be widespread. (Nature News doesn’t have to abide by the same embargo rules, I suppose, since it appeared in their journal.)

  5. David Palmer says:

    Yes, maybe they are right but maybe not.

    That second quote from Seager is hardly compelling, more a whistful plea for the AGW storyline to be vindicated.

    We have had a 10-12 year drought in eastern/central Australia that was supposed to convince us all of AGW, but nature has responded in a most emphatic way in the past 6 months with this latest la nina event – rain, rain and yet more rain, dams filling, aquifers recharged, Lake Eyre in the red centre filling again, motor mowers going non stop in suburbia.

    Watchful vigilance, yes, but nothing more as yet.

  6. Keith Grubb says:

    This mid century crap has got to stop. Wouldn’t a ten year trend of significant cooling work better? How about a five year trend? I mean with the last ten year trend being flat, I would think five years of future cooling would seal the deal. There is no way we could have 15 years of no warming with CO2 being the driver, right? So, my take is, we will know for sure in five years. Much better than having to wait for mid century. I’ll be dead by then. I need to know if I’m right (like, most of the time) or wrong before I die. No fun at all otherwise.

  7. Paul in Sweden says:

    The latest United States Global Climate Change Impacts Report for the Southwest reminds us that the droughts of today are nothing compared to the mega-droughts of the past when CO2 was lower and population & anthropogenic land use burdens were not a factor.

    “Droughts are a long-standing feature of the Southwest’s climate. The droughts of the last 110 years pale in comparison to some of the decades-long “megadroughts” that the region has experienced over the last 2000 years. During the closing decades of the 1500s, for example, major droughts gripped parts of the Southwest.189 These droughts sharply reduced the flow of the Colorado River and the all-important Sierra Nevada headwaters for California, and dried out the region as a whole. As of 2009, much of the Southwest remains in a drought that began around 1999. This event is the most severe western drought of the last 110 years, and is being exacerbated by record warming”

    Of course the USGCRP did tack on the obligatory CO2 “belief” mantra at the end of that section…

    Yes, the arid & desert regions of the Southwest currently have drought conditions(what a surprise), they have in the past & the future as well. Money wasted on Windmills, Solar arrays & CO2 schemes would be better spent on better irrigation, reservoirs, conservation & population dispersement.

  8. Matt B says:

    This is the news we’ve been waiting for in Cleveland! We’re the Saudi Arabia of water!

    Time to kick back & watch our real estate prices rise……

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