Southwest may face 'megadrought' within century, study finds

Aug 26, 2014 by Blaine Friedlander
A photograph of a farmer showing his affected plot due to drought in Karnataka, India, 2012. Credit: Pushkarv/Wikipedia

(Phys.org) —Due to global warming, scientists say, the chances of the southwestern United States experiencing a decadelong drought is at least 50 percent, and the chances of a "megadrought" – one that lasts up to 35 years – ranges from 20 to 50 percent over the next century.

The study by Cornell, University of Arizona and U.S. Geological Survey researchers will be published in a forthcoming issue of the American Meteorological Society's Journal of Climate.

"For the southwestern U.S., I'm not optimistic about avoiding real megadroughts," said Toby Ault, Cornell assistant professor of earth and atmospheric sciences and lead author of the paper. "As we add into the atmosphere – and we haven't put the brakes on stopping this – we are weighting the dice for megadrought."

As of Aug. 12, most of California sits in a D4 "exceptional drought," which is in the most severe category. Oregon, Arizona, New Mexico, Oklahoma and Texas loiter in a substantially less severe D1 moderate . Ault says climatologists don't know whether the severe western and southwestern drought will continue, but "with ongoing climate change, this is a glimpse of things to come. It's a preview of our future," he said.

While the 1930s Dust Bowl in the Midwest lasted four to eight years, depending upon location, a megadrought can last more than three decades, which could lead to mass population migration on a scale never before seen in this country.

Ault said that the West and Southwest must look for mitigation strategies to cope with looming long-drought scenarios. "This will be worse than anything seen during the last 2,000 years and would pose unprecedented challenges to water resources in the region," he said.

In computer models, while the southern portions of the western United States (California, Arizona, New Mexico) will likely face drought, the researchers show the chances for drought in the northwestern states (Washington, Montana, Idaho) may decrease.

Prolonged droughts around the world have occurred throughout history. Ault points to the recent "Big Dry" in Australia and modern-era drought in sub-Saharan Africa. As evidenced by tree-ring studies, a megadrought occurred during the 1150s along the Colorado River. In natural history, they occur every 400 to 600 years. But by adding the influence of growing greenhouse gas in the atmosphere, the drought models – and their underlying statistics – are now in a state of flux.

Beyond the United States, southern Africa, Australia and the Amazon basin are also vulnerable to the possibility of a megadrought. With increases in temperatures, drought severity likely will worsen, "implying that our results should be viewed as conservative," the study reports.

Explore further: 'Severe' drought covers nearly 99.8% of California, report says

More information: "Assessing the Risk of Persistent Drought Using Climate Model Simulations and Paleoclimate Data." dx.doi.org/10.1175/JCLI-D-12-00282.1

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User comments : 25

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antialias_physorg
4 / 5 (16) Aug 26, 2014
Can we stop with the 'super' and 'mega' nonsense already? The situation is bad enough as it is without artificially hyping it with content-free media buzzwords.
Scroofinator
1.7 / 5 (15) Aug 26, 2014
In natural history, they occur every 400 to 600 years

Yes, the Earth has many different cycles, and the process of desertification is one of those. I'm glad they explain this simple fact without putting all the blame on AGW, which does have a currently undefined influence in our global climate.
antigoracle
1.5 / 5 (17) Aug 26, 2014
Yet, the US, which has led the world in GHG emissions, has cooled since the 1930s.
http://www.giss.n...nsen_07/
Scottingham
4 / 5 (5) Aug 26, 2014
Sounds like they're going to need still-suits a la Dune.
tim305
2.2 / 5 (10) Aug 26, 2014
In general, global warming will increase rainfall, so it would be interesting to hear why it will decrease in the Southwest, and where it will increase, other than the US Northwest as mentioned.
zorro6204
1.8 / 5 (9) Aug 26, 2014
There is a solution to this problem, look to the north. There are vast sources of fresh water flowing into Hudson's Bay that really don't matter to Canada, and the bay itself is unproductive. It wouldn't matter much if the salinity in the bay was increased, it's covered by ice most of the year. Build some pipelines from the inflowing rivers to Lake Mead, it's doable. Better than abandoning Southern Cal!
supamark23
3.9 / 5 (12) Aug 26, 2014
Yet, the US, which has led the world in GHG emissions, has cooled since the 1930s.
http://www.giss.n...nsen_07/


antigoricl, a lying pedophile.
full_disclosure
1.4 / 5 (9) Aug 26, 2014
supamark23

Yet, the US, which has led the world in GHG emissions, has cooled since the 1930s.
http://www.giss.n...nsen_07/


antigoricl, a lying pedophile.


Typical pseudoscience Phys.org contributor…..
antigoracle
1.3 / 5 (13) Aug 26, 2014
supaturd, the megaturd, strikes again with another gem from his cesspool of ignorance.
Liquid1474
4 / 5 (3) Aug 26, 2014
Oil-pipelines exist; what about water pipelines to keep water features at minimum levels?
supamark23
3.5 / 5 (11) Aug 26, 2014
supamark23

Yet, the US, which has led the world in GHG emissions, has cooled since the 1930s.
http://www.giss.n...nsen_07/


antigoricl, a lying pedophile.


Typical pseudoscience Phys.org contributor…..


Oh look, another retarded denier too stupid to understand actual science. You're an embarrassment to the human race.
antigoracle
1.4 / 5 (11) Aug 26, 2014
Oh look, supaturd with another gem from his cesspool of ignorance. You are a credit to your turd Cult.
supamark23
3.6 / 5 (10) Aug 26, 2014
Oh look, supaturd with another gem from his cesspool of ignorance. You are a credit to your turd Cult.


Your coprophilia, on top of your pedophilia, is rather disturbing. but then, you do have shit for brains so it shouldn't be surprising.
runrig
5 / 5 (8) Aug 26, 2014
Yet, the US, which has led the world in GHG emissions, has cooled since the 1930s.
http://www.giss.n...nsen_07/


So, are you saying those two things are related?
In what way?
antigoracle
1 / 5 (8) Aug 26, 2014
Oh, isn't CO2 responsible for global warming?
Unless the US is not in the globe and did not lead the world in GHG emissions.
t_d_lowe
5 / 5 (5) Aug 26, 2014
This is an international website, don't just say 'southwest' in the title and expect people to know where that is.
supamark23
4.5 / 5 (8) Aug 26, 2014
This is an international website, don't just say 'southwest' in the title and expect people to know where that is.


They say where in the first sentence of the article...
kochevnik
2.7 / 5 (7) Aug 26, 2014
Maybe I missed something, but isn't most of California a desert? How then does it experience a drought in places like Death Valley, which is the hottest place in the world?

California agriculture is based upon water imported from the Colorado River, which is not affected by droughts in the desert. Without imported water California would simply revert back to desert
thermodynamics
5 / 5 (11) Aug 26, 2014
Maybe I missed something, but isn't most of California a desert? How then does it experience a drought in places like Death Valley, which is the hottest place in the world?

California agriculture is based upon water imported from the Colorado River, which is not affected by droughts in the desert. Without imported water California would simply revert back to desert


Yes, you missed something. California is a large state with all types of terrains represented. At the present time the entire state is in exceptional drought, not just the desert areas.
howhot2
3.5 / 5 (8) Aug 26, 2014
@antigoracle says:
supaturd, the megaturd, strikes again with another gem from his cesspool of ignorance.


Sounds like tard, must be a tard. I guess you know what megatard is from personal experience. Does it take one to know one, or were you just born that way.
ViperSRT3g
5 / 5 (10) Aug 27, 2014
Maybe I missed something, but isn't most of California a desert? How then does it experience a drought in places like Death Valley, which is the hottest place in the world?

California agriculture is based upon water imported from the Colorado River, which is not affected by droughts in the desert. Without imported water California would simply revert back to desert

The fresh water pulled from the Colorado River is used almost exclusively in the LA/San Diego regions. Everything else to the north is still in a state of extreme drought and they rely on local sources for water. The local sources are all but drying up before our eyes, and the Colorado River is already almost completely tapped.
runrig
5 / 5 (9) Aug 28, 2014
Oh, isn't CO2 responsible for global warming?
Unless the US is not in the globe and did not lead the world in GHG emissions.


Err - in the same sentence you included the fact that the US is the world's biggest polluter (per capita).
It sounded awfully like you were using your cooling statement with the fact of that pollution.... to imply that CO2 does not obey empirical science?
howhot2
5 / 5 (5) Aug 31, 2014
The chances of the southwestern United States experiencing a decadelong drought is at least 50 percent
And a megadrought has between 20 - 50% chance. Hum this seems to be a perfect time for Democrats to build out some massive joint Government/Private funded desalination plants to provide fresh water to the southwest and mediate the droughts expected.
mooster75
4 / 5 (4) Aug 31, 2014
Can we stop with the 'super' and 'mega' nonsense already? The situation is bad enough as it is without artificially hyping it with content-free media buzzwords.

Content free? They explain the terms in the very first paragraph.
rockwolf1000
5 / 5 (1) Sep 05, 2014
@full disclosure

supamark23

Yet, the US, which has led the world in GHG emissions, has cooled since the 1930s.
http://www.giss.n...nsen_07/


antigoricl, a lying pedophile.


Typical pseudoscience Phys.org contributor…..


Not really. But I see you have submitted your typical post.

5 words strung together that are completely meaningless.

As usual, thanks for nothing. Nothing being the sum of your contributions and achievements.