The Last Drop.
Andre
Willers
13
Feb 2015
Hi,
Civilization ending drought in
Western America expected before the end of the 21st century.
Note Mexico and meso-america in
picture below .
Expect massive volkewanderungs
from the South to the North .
It will take more than a wall to
keep desperate families out .
Another reason for the Occupy
Ukraine movement . (See http://andreswhy.blogspot.com/2015/02/yellowstone-catastrophe-and-us.html
)
Or else they could copy Almeria
. (See http://andreswhy.blogspot.com/2014/06/the-quiet-revolution.html
)
Although a similar type of
approach didn't end well for the Anazazi . Desperate neighbours overwhelmed
them .
The Maya simply imploded in
resources wars.
Revolution is just one harvest
away .
Andre
xxxxxxxxxxxxxx
Warming
pushes Western U.S. toward driest period in 1,000 years: Unprecedented risk of
drought in 21st century
Date:
February 12, 2015
Source:
The Earth Institute at
Columbia University
Summary:
During the second half
of the 21st century, the US 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.
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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
[Click to enlarge image]
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.
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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 soil moisture 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 American
Association for the Advancement of Science, which also publishes the leading
journal Science.
Today, 11 of the past
14 years have been drought 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 than64 million people in the Southwest and Southern
Plains, according to NASA, and many more are indirectly affected because of the
impacts on agricultural regions.
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.
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 global
warming; and a second scenario in which emissions are moderated.
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 CO2on
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.
Toby R. Ault of
Cornell University is a co-author of the study. Funding was provided by the
NASA Modeling, Analysis and Prediction Program, NASA Strategic Science, and the
U.S. National Science Foundation.
Story Source:
The above story is
based on materials provided
by The Earth
Institute at Columbia University. Note: Materials may be
edited for content and length.
Journal Reference:
- Benjamin I. Cook, Toby R. Ault, Jason E. Smerdon. Unprecedented
21st century drought risk in the American Southwest and Central Plains. Science
Advances, 12 February 2015 DOI: 10.1126/sciadv.1400082
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