Warming pushes Western US toward driest period in 1,000 years

Warming pushes Western US toward driest period in 1,000 years
A representation of the summer moisture in the US Central Plains and Southwest is shown. The brown line represents the variation in dryness since the year 1000; the lower the line on the graph, the drier the conditions. Colored lines to the right side of the graph represent what climate models see ahead: a trend toward dryness not seen in the previous millennium. As the authors describe it: Regional average time series of the summer season moisture balance metrics from the NADA and CMIP5models.The observational NADA PDSI series (brown) is smoothed using a 50-year loess spline to emphasize the low-frequency variability in the paleo-record. Model time series (PDSI, SM-30cm, and SM-2m) are the multimodel means averaged across the 17 CMIP5models, and the gray shaded area is the multimodel interquartile range for model PDSI. Credit: Cook et al., Science Advances, 2015

During the second half of the 21st century, the U.S. Southwest and Great Plains will face persistent drought worse than anything seen in times ancient or modern, with the drying conditions "driven primarily" by human-induced global warming, a new study predicts.

The research says the drying would surpass in severity any of the decades-long "megadroughts" that occurred much earlier during the past 1,000 years—one of which has been tied by some researchers to the decline of the Anasazi or Ancient Pueblo Peoples in the Colorado Plateau in the late 13th century. Many studies have already predicted that the Southwest could dry due to global warming, but this is the first to say that such drying could exceed the worst conditions of the distant past. The impacts today would be devastating, given the region's much larger population and use of resources.

"We are the first to do this kind of quantitative comparison between the projections and the distant past, and the story is a bit bleak," said Jason E. Smerdon, a co-author and climate scientist at the Lamont-Doherty Earth Observatory, part of the Earth Institute at Columbia University. "Even when selecting for the worst megadrought-dominated period, the 21st century projections make the megadroughts seem like quaint walks through the Garden of Eden."

"The surprising thing to us was really how consistent the response was over these regions, nearly regardless of what model we used or what metric we looked at," said lead author Benjamin I. Cook of the NASA Goddard Institute for Space Studies and the Lamont-Doherty Earth Observatory. "It all showed this really, really significant drying."

The new study, "Unprecedented 21st-Century Drought Risk in the American Southwest and Central Plains," will be featured in the inaugural edition of the new online journal Science Advances, produced by the AAAS, which also publishes the leading journal Science.

Today, 11 of the past 14 years have been years in much of the American West, including California, Nevada, New Mexico and Arizona and across the Southern Plains to Texas and Oklahoma, according to the U.S. Drought Monitor, a collaboration of U.S. government agencies.

The current drought directly affects more than 64 million people in the Southwest and Southern Plains, according to NASA, and many more are indirectly affected because of the impacts on agricultural regions.

NASA study finds carbon emissions could dramatically increase risk of U.S. megadroughts
Soil moisture 30 cm below ground projected through 2100 for high emissions scenario RCP 8.5. The soil moisture data are standardized to the Palmer Drought Severity Index and are deviations from the 20th century average. Credit: NASA's Goddard Space Flight Center

Shrinking water supplies have forced western states to impose water use restrictions; aquifers are being drawn down to unsustainable levels, and major surface reservoirs such as Lake Mead and Lake Powell are at historically low levels. This winter's snowpack in the Sierras, a major water source for Los Angeles and other cities, is less than a quarter of what authorities call a "normal" level, according to a February report from the Los Angeles Department of Water and Power. California water officials last year cut off the flow of water from the northern part of the state to the south, forcing farmers in the Central Valley to leave hundreds of thousands of acres unplanted.

"Changes in precipitation, temperature and drought, and the consequences it has for our society—which is critically dependent on our freshwater resources for food, electricity and industry—are likely to be the most immediate climate impacts we experience as a result of greenhouse gas emissions," said Kevin Anchukaitis, a climate researcher at the Woods Hole Oceanographic Institution. Anchukaitis said the findings "require us to think rather immediately about how we could and would adapt."

Much of our knowledge about past droughts comes from extensive study of tree rings conducted by Lamont-Doherty scientist Edward Cook (Benjamin's father) and others, who in 2009 created the North American Drought Atlas. The atlas recreates the history of drought over the previous 2,005 years, based on hundreds of tree-ring chronologies, gleaned in turn from tens of thousands of tree samples across the United States, Mexico and parts of Canada.

NASA scientists used tree rings to understand past droughts and climate models incorporating soil moisture data to estimate future drought risk in the 21st century. Credit: NASA's Goddard Space Flight Center

For the current study, researchers used data from the atlas to represent past climate, and applied three different measures for drought—two soil moisture measurements at varying depths, and a version of the Palmer Drought Severity Index, which gauges precipitation and evaporation and transpiration—the net input of water into the land. While some have questioned how accurately the Palmer drought index truly reflects soil moisture, the researchers found it matched well with other measures, and that it "provides a bridge between the [climate] models and drought in observations," Cook said.

The researchers applied 17 different climate models to analyze the future impact of rising average temperatures on the regions. And, they compared two different global warming scenarios—one with "business as usual," projecting a continued rise in emissions of the greenhouse gases that contribute to ; and a second scenario in which emissions are moderated.

NASA study finds carbon emissions could dramatically increase risk of U.S. megadroughts
Soil moisture 30 cm below ground projected through 2100 for moderate emissions scenario RCP 4.5. The soil moisture data are standardized to the Palmer Drought Severity Index and are deviations from the 20th century average. Credit: NASA's Goddard Space Flight Center

By most of those measures, they came to the same conclusions.

"The results ... are extremely unfavorable for the continuation of agricultural and water resource management as they are currently practiced in the Great Plains and southwestern United States," said David Stahle, professor in the Department of Geosciences at the University of Arkansas and director of the Tree-Ring Laboratory there. Stahle was not involved in the study, though he worked on the North American Drought Atlas.

Smerdon said he and his colleagues are confident in their results. The effects of CO2 on higher average temperature and the subsequent connection to drying in the Southwest and Great Plains emerge as a "strong signal" across the majority of the models, regardless of the drought metrics that are used, he said. And, he added, they are consistent with many previous studies.

Anchukaitis said the paper "provides an elegant and convincing connection" between reconstructions of past climate and the models pointing to the risk of future drought.


Explore further

Evidence suggests California's drought is the worst in 1,200 years

More information: "Unprecedented 21st century drought risk in the American Southwest and Central Plains Drought risk in Western North America," Science Advances, DOI: 10.1126/sciadv.1400082
Journal information: Science

Citation: Warming pushes Western US toward driest period in 1,000 years (2015, February 12) retrieved 21 July 2019 from https://phys.org/news/2015-02-western-driest-period-years.html
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RWT
Feb 12, 2015
More bad science, which unfortunately is just business as usual for climate science.

Feb 12, 2015
♫When you want pseudo science in the neighborhood
Who ya gonna call????????
Physics.Org, Columbia, and the GloBULLsters!!!!!!♫


Feb 12, 2015
USA chops down trees everywhere then complains about arid conditions. The Sahara desert offers a lesson to such morons but they are too busy not thinking to notice

Feb 12, 2015
"USA chops down trees everywhere then complains about arid conditions. The Sahara desert offers a lesson to such morons but they are too busy not thinking to notice"

A great example of the Dunning-Kruger effect at work.

Feb 12, 2015
Why did they steal that Colorado River again? Oh right. Never mind.

Feb 12, 2015
The sky is falling.. The sky is falling... I think I have heard this one before from the same group. They must employ a battery of writers just to keep pumping this stuff out every week. 'Bull semen is on the decline due to climate change." " Polar bears are losing their toe nails due to overheating." "Climate scientists have greater than normal brain tumors because of common sense deficiencies due to rising temperatures... Hey, anyone can pump this stuff out!

Feb 13, 2015
We'll see what song you clowns sing when all yer relatives and friends from the south and west come to live with you, after they're dried out of town.

Idiots.

Feb 13, 2015
@RWT, @Ghost, @SamB,

If the scientists are correct they will be validated, if not they will be corrected. That is why scientists publish.

Why is it that deniers are so incoherently negative and quick to respond without any insight or specifics from the original paper they think they are commenting on? Why do they undermine their own credibility by posting inarticulate angst? Because they have no idea how to do science themselves or even what it is.

It took tens of thousands of years for civilization to invent processes for coss-checking and validating theory's based on published evidence and methods. A lot of people's DNA isn't up to that. Their brains cannot get past their treasured biases.

For them science is just another religion to be cherry picked for desirable beliefs.

Feb 13, 2015
@Tektrix,

A great example of the Dunning-Kruger effect at work.


I would be interested to know if a similar effect takes place, where someone who has great expertise in one subject is more likely to judge their expertise in other areas more realistically, vs. people who have no special expertise at all thinking they are experts at everything.

Feb 13, 2015
USA chops down trees everywhere then complains about arid conditions. The Sahara desert offers a lesson to such morons but they are too busy not thinking to notice


Where do you get this stuff? Really? Do you know the Saharan history even? The US? I know of more planting going on than deforestation in the US. We have many very large groups who work to preserve our forests, wetlands and prairies. I personally know many people who are using their own money to buy forest a hedge against their contribution to the carbon cycle. What country do you live in? I am really curious.

Feb 13, 2015
Nevermark,

I always laugh at these people who throw these cute little prepackaged dialogue benders out there.

A professor at Yale just released a paper that found that people who are skeptical of the magnitude of humans impact on climate, ie skeptics, generally know more about the science than people who are "warmists". The suggestion was that the warmists just need to explain the science to the "skeptics". It am sure you will see it floating around soon. I think the authors last name was Haran, and it was Yale. Psychology. For Boolean operators you know.

Feb 13, 2015
It is Kahan, not Haran.

Feb 13, 2015
@Tektrix,

A great example of the Dunning-Kruger effect at work.


I would be interested to know if a similar effect takes place, where someone who has great expertise in one subject is more likely to judge their expertise in other areas more realistically, vs. people who have no special expertise at all thinking they are experts at everything.


I wouldn't be at all surprised to learn something like that is the case. Also skirting the edges of D-K are the "The Belligerently Ignorant" - the one's who bloviate with angered self-righteousness even though they are utterly clueless.

Feb 13, 2015
A professor at Yale just released a paper that found that people who are skeptical of the magnitude of humans impact on climate, ie skeptics, generally know more about the science than people who are "warmists". The suggestion was that the warmists just need to explain the science to the "skeptics". It am sure you will see it floating around soon. I think the authors last name was Haran, and it was Yale. Psychology. For Boolean operators you know.

Hogwash!! A good example of D-K syndrome right there. Most denialists argue the fact (yes FACT) of CO2 caused global warming because the UN wants to institute a world government. They have no bloody clue about the science!

And talk about flinging about talking points! "Warmists" for gawd's sake. A real skeptic looks at the evidence, not the delusional meanderings of anti-science, climate denying bloggers. You should try that.

Feb 13, 2015
Just because you are incompetent and are incapable of actually using google to find a study referenced by a Yale professor, does not mean that it is not true. Your true colors are being perfectly exposed. I have never seen you post anything but rhetoric. Not one single scientific statement. You are the perfect example of the the D-K effect and the belligerent ignoramus effect. My God dude, go look in the mirror. While you are at it, call yourself stupid, and scream ignorant whilst spitting, be sure and wash the froth off every once Ina awhile, you wouldn't want to look like a lunatic.

Feb 13, 2015
USA chops down trees everywhere then complains about arid conditions. The Sahara desert offers a lesson to such morons but they are too busy not thinking to notice


I know of more planting going on than deforestation in the US. We have many very large groups who work to preserve our forests, wetlands and prairies. I personally know many people who are using their own money to buy forest a hedge against their contribution to the carbon cycle. What country do you live in? I am really curious.
Russia. Every place I stayed In South California has it's trees cut down. The mayor cut down 200 trees to park a space shuttle. Trees which provided cool shade in South Central for people who could no afford air conditioning. I see Americans cut square blocks of trees to make a black asphalt parking lot for their fat trucks into which their fat asses are not spatially challenged. South America is suffering drought now from burning rain forest

Feb 13, 2015

I know of more planting going on than deforestation in the US. We have many very large groups who work to preserve our forests, wetlands and prairies. I personally know many people who are using their own money to buy forest a hedge against their contribution to the carbon cycle. What country do you live in? I am really curious.
Russia. Every place I stayed In South California has it's trees cut down. The mayor cut down 200 trees to park a space shuttle. Trees which provided cool shade in South Central for people who could no afford air conditioning. I see Americans cut square blocks of trees to make a black asphalt parking lot for their fat trucks into which their fat asses are not spatially challenged. South America is suffering drought now from burning rain forest


And no trees are being cut down in Russia right?

Feb 13, 2015
Just because you are incompetent and are incapable of actually using google to find a study referenced by a Yale professor, does not mean that it is not true. Your true colors are being perfectly exposed. I have never seen you post anything but rhetoric. Not one single scientific statement. You are the perfect example of the the D-K effect and the belligerent ignoramus effect. My God dude, go look in the mirror. While you are at it, call yourself stupid, and scream ignorant whilst spitting, be sure and wash the froth off every once Ina awhile, you wouldn't want to look like a lunatic.


Suggest you seek immediate psychological assistance.

You are very sick in the head my friend.

Feb 13, 2015
Just because you are incompetent and are incapable of actually using google to find a study referenced by a Yale professor, does not mean that it is not true.
Oh, you mean this one? (http://papers.ssr...2216469) Where Dan Kahan (the LAWYER!) talks about using evidence in the discussion of climate science? That's the 2nd or 3rd time I've provided a cite you couldn't reference.
Your true colors are being perfectly exposed. I have never seen you post anything but rhetoric.
Really. Yet I seem to be able to post those items you reference but can't cite yourself. So show me the rhetoric McDooffy.
While you are at it, call yourself stupid, and scream ignorant...
Do you know what ignorant means? I only call those that make stupid comments, get corrected, then move to another article and make the same stupid comments stupid.

Aww poor little, did you not like the word nonsensical? Look it up; it doesn't mean anything bad.

Feb 13, 2015

I know of more planting going on than deforestation in the US. We have many very large groups who work to preserve our forests, wetlands and prairies. I personally know many people who are using their own money to buy forest a hedge against their contribution to the carbon cycle. What country do you live in? I am really curious.
Russia. Every place I stayed In South California has it's trees cut down. The mayor cut down 200 trees to park a space shuttle. Trees which provided cool shade in South Central for people who could no afford air conditioning. I see Americans cut square blocks of trees to make a black asphalt parking lot for their fat trucks into which their fat asses are not spatially challenged. South America is suffering drought now from burning rain forest


And no trees are being cut down in Russia right?
Overall, no. Of course more trees are needed. Protests were staged near the Moscow airport over swaths of forest being cut

Feb 14, 2015
More bad science, which unfortunately is just business as usual for climate science.


Agreed.

Only about 20% of that graph is scientific and only 10% is "good science" the remainder of it is "indefinite extrapolation" on the right side, and bad proxy data with no written historical record to provide anecdotal context on the left side.

This is literally as bad as divining through animal entrails and feces for clues about one's future.

Tree rings don't track climate. They track weather and forest fires.

Feb 14, 2015
California's droughts are caused by micro-climates induced from draining entire lake-beds and rivers for water for it's cities and farms, not "global climate change" per se.

The solution to this is solar powered desalination both to replace draining the water table,a nd to replenish the crippled water table, and re-fill those drained lake beds which humans literally pumped dry whilst watering cities.

It's not that I'm denying climate change happens, but worrying about any alleged "AGW" while ignoring the first, most direct water management problems is sort of stupid.

Finally, geologic records show that inland lakes and seas in the southwest from California to the 4 corners region or so have been evaporating for several million years, moreover, the Earth's albedo is actually increased when an inland lake or sea evaporates because water is much darker than sand and salt dunes.

Death Valley would likely be hotter if flooded by several feet of water.

Feb 14, 2015
I just hope the kids scientifically illiterate clowns grow up smart enough to care, they don't really have an option. Hot potato

Feb 14, 2015
I was reading a bit of stuff from Dan Kahan, and I must state how impressed I am by his treatise of the issues surrounding the illogical rejection of climate change and the disconnect between the scientific findings and cultural cognition of those findings. He has some very well considered talking points (as much as mndaffy seems to dislike those) and his review of the problems and suggestions for overcoming those cognitive biases that those who reject the science display is very well articulated.

Thank you mndaffy for pointing him out. You should read some of his stuff here: http://papers.ssr...id=45442

Especially, you should read this one: Kahan, D M. and Braman, Donald and Slovic, Paul and Gastil, John and Cohen, Geoffrey L., The Second National Risk and Culture Study: Making Sense of - and Making Progress In - The American Culture War of Fact (October 3, 2007). GWU Legal Studies Research Paper No. 370.

Feb 14, 2015
The mayor cut down 200 trees to park a space shuttle....I see Americans cut square blocks of trees to make a black asphalt parking lot

.
So from those ad hoc observations you conclude that the US is deforesting? Prior to a century ago, you might have had a point. I haven't gone to original source material, but here are two excerpts from Wikipedia:
.
"the forest resources of the United States have remained relatively constant through the entire 20th century." http://en.wikiped...d_States
.
"According to the Center for Russian Environmental Policy, 16 million hectares of forest are lost each year to a variety of causes, including logging, pollution and fires." http://en.wikiped...estation
.
I've lived in or near the Pacific Northwest for most of my 60 years, and I can tell you we aren't felling forests pell mell without replanting.
.
.

Feb 15, 2015
USA chops down trees everywhere then complains about arid conditions. The Sahara desert offers a lesson to such morons but they are too busy not thinking to notice


USA plants more trees than it cuts down. (Capitalism! Yay!)
Also, how do all those prehistoric whale skeletons on the surface in certain parts of the Sahara fit into the lesson plan?

PS: There hasn't been any warming, so the whole point of this article is bunk.

Feb 15, 2015
What the western US doesn't get will be made up for by what Boston gets.......GO BOSTON, two more feet this coming week. Any roof collapse reports on the MIT Campus yet?

Feb 15, 2015
RWT, @Ghost, @SamB,

If the scientists are correct they will be validated, if not they will be corrected. That is why scientists publish.

Why is it that deniers are so incoherently negative and quick to respond without any insight or specifics from the original paper they think they are commenting on? Why do they undermine their own credibility by posting inarticulate angst? Because they have no idea how to do science themselves or even what it is.


actually it is because they truly are dumb, so much so that they can't see how badly it hurts their campaign, they're still cranking lame one liners from old politics 101 taken from the 80s, which states to be qualified as a true politician one must try and dismiss the topic at hand by stating it is false, and most peoplewill only read the first 3 comments on a given topic, what they don't realise is that back then, the average population were more uneducated whereas cont...

Feb 15, 2015
people today are much more aware, much more intelligent, read a lot more, and can tell the difference between a stupid dumb political answer and a good science one, moreover they read all of the comments because they don't take the first 4 answers as fact, they want to listen to scientific answers and look at evidence, not listen to some clown and his sockpuppets cranking dumb one liners without ny sense or logic backing it.

Feb 15, 2015
hence the reason i'm having so much fun seeing political clowns insulting themselves, every single time... and the past dozen or so climate topics really made the world see how foolish they truly are.... more i could not have asked for hence i'm enjoying this site so much... :D

Feb 15, 2015
USA chops down trees everywhere then complains about arid conditions. The Sahara desert offers a lesson to such morons but they are too busy not thinking to notice


I used to work in forestry and this just isn't true, even though that might be surprising.
Although we did fell large forests, especially the eastern half of the country, we still actually have more trees than this country does historically. The main reason for this is that as we colonized the west, it became prudent to protect the rail roads and old mining communities from forest fires.
But many forest ecosystems in the US are rely on fire, fire clears the canopy and allows new young plants to get sunlight and grow, and the pine cones of a few common trees only open when they get really hot.

But because we don't let fires burn anymore, we have lots of old giant trees that otherwise probably wouldn't be here, plus lots of people plant trees in their property all over the country, including the deserts.

Feb 15, 2015
So in USA there are trees where nobody needs them, and black asphalt and concrete in the hotspot cities so that grotesquely obese, who would outweigh a circus freak from the 1900s, waddle from their oversize minivans without fear of bird crap and tree sap on the windshield

Feb 16, 2015
From the article:
During the second half of the 21st century, the U.S. Southwest and Great Plains will face persistent drought worse than anything seen in times ancient or modern, with the drying conditions "driven primarily" by human-induced global warming, a new study predicts.

Computer modeling has gotten very good, and I don't doubt the analysis. Given global warming, it presents a frightening future for the southwest and central US.

We have already seen the effects from the sever drought on the Russian permafrost an that blanked Moscow with smoke. In the USA south and SW, you can imagine how bad droughts could be on crops, water and recreation. It's a nightmare scenario.

Feb 16, 2015
Kochevnik
Lay off the vodka

Feb 16, 2015
Kochevnik
Lay off the vodka
Steve - clean up your filthy cities

Feb 17, 2015
So in USA there are trees where nobody needs them, and black asphalt and concrete in the hotspot cities so that grotesquely obese, who would outweigh a circus freak from the 1900s, waddle from their oversize minivans without fear of bird crap and tree sap on the windshield


Is an oversize minivan bigger than a regular van?

Methinks you have a chip on your shoulder.

Is that due to an underlying inferiority complex which so many Russians are known to suffer from?

Lot's of people would happily immigrate from Russia to USA.
Very few would immigrate from USA to Russia - unless of course they had just stolen a bunch of secret documents from their employer to dump on Wikileaks.

What do these facts tell you? Perhaps American cities are not as filthy as you had hoped?

Feb 17, 2015
USA vs. Russia?

Going way off course. Where did the article say anything about Russia? O_o

Can't we all agree that they both suffer from a nationalistic and inflated sense of ego, that both could actually do much much better socially and environmentally and that a good part of the world would be better off if they'd both control their imperialist tendencies a bit better?

Feb 25, 2015
people who are skeptical of the magnitude of humans impact on climate, ie skeptics, generally know more about the science than people who are "warmists"
@mndaffy
I came to PO a skeptic... then i took some great advice from runrig, Thermodynamics and Maggnus

i read the science

now i know what it says
and the "AGW/warming debate" is proven to be just exactly what it is: the big oil/$$$ companies trying to ignore the reality of the situation so that they can make uber big profits while the climate goes to pot

If you would read the SCIENCE, you would come to the same conclusion
not the blogs
not the religion
not the extremist sites
not even just the articles
READ THE SCIENCE
as in the STUDIES (which prove the conclusions with empirical evidence)

This is also a very cogent study regarding deniers (and pseudoscience/conspiracy theorists, like Zeph): http://www.ploson...tion=PDF

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