Collapse, Jared Diamond ISBN 0739455354
page 152:
"The final blow for Chacoans was a drought that tree rings show to have begun around A.D. 1130. There had been similar droughts previously, around A.D. 1090 and 1040, but the difference this time was that Chaco Canyon now held more people, ..., and with no land left unoccupied."
On Thursday, August 28, 2014 11:08:13 AM you wrote:
> This specific thing has been on my mind much this year.... wondering if we
> are already into one and just don't realize it yet... and wondering what
> the Anasazi and other groups were thinking as Year One went to Year Two
> into Year Three and so on until they finally realized the game had changed
> and they were going to have to walk away from their civilization.
>
>
> On Thu, Aug 28, 2014 at 11:04 AM, Lin Kerns linkerns@gmail.com
>
> [californiadisasters] <californiadisasters@yahoogroups.com> wrote:
> > Date:
> > August 27, 2014
> > Source:
> > Cornell University
> >
> > Summary:
> > Due to global warming, scientists say, the chances of the southwestern
> >
> > United States experiencing a decade long drought is at least 50 percent,
> > and the chances of a "megadrought" – one that lasts over 30 years – ranges
> > from 20 to 50 percent over the next century.
> >
> > ------------------------------
> >
> > Risk of megadrought in Southwestern U.S.
> >
> > *Credit: Toby Ault, Cornell University; From "Assessing the risk of
> > persistent drought using climate model simulations and paleoclimate data"*
> >
> >
> >
> >
> > Due to global warming, scientists say, the chances of the southwestern
> > United States experiencing a decade long drought is at least 50 percent,
> > and the chances of a "megadrought" -- one that lasts over 30 years --
> > ranges from 20 to 50 percent over the next century.
> >
> > The study by Cornell University, 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 greenhouse
> > gases into the atmosphere -- and we haven't put the brakes on stopping
> > this
> > -- we are weighting the dice for megadrought conditions."
> >
> > As of mid-August, most of California sits in a D4 "exceptional drought,"
> > which is in the most severe category. Oregon, Arizona, New Mexico,
> > Oklahoma
> > and Texas also loiter between moderate and exceptional drought. Ault says
> > climatologists don't know whether the severe western and southwestern
> > drought will continue, but he said, "With ongoing climate change, this is
> > a
> > glimpse of things to come. It's a preview of our future."
> >
> > 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 California, Arizona and New Mexico will likely
> > face drought, the researchers show the chances for drought in parts of
> > Washington, Montana and Idaho may decrease.
> >
> > 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 will likely worsen, "implying that our
> > results should be viewed as conservative," the study reports.
> >
> > "These results help us take the long view of future drought risk in the
> > Southwest -- and the picture is not pretty. We hope this opens up new
> > discussions about how to best use and conserve the precious water that we
> > have," said Julia Cole, UA professor of geosciences and of atmospheric
> > sciences.
> >
> > The study, "Assessing the Risk of Persistent Drought Using Climate Model
> > Simulations and Paleoclimate Data," was also co-authored by Julia E. Cole,
> > David M. Meko and Jonathan T. Overpeck of University of Arizona; and
> > Gregory T. Pederson of the U.S. Geological Survey.
> >
> > The National Science Foundation, National Center for Atmospheric Research,
> > the U.S. Geological Survey and the National Oceanic and Atmospheric
> > Administration funded the research.
> >
> > ------------------------------
> >
> > *Story Source:*
> >
> > The above story is based on materials
> > <http://mediarelations.cornell.edu/2014/08/27/southwest-may-face-megadroug
> > ht-this-century/> provided by *Cornell University*
> > <http://www.cornell.edu>. The original article was written by Melissa
> > Osgood. *Note: Materials may be edited for content and length.*
> >
> > ------------------------------
> >
> > *Journal Reference*:
> > 1. Toby R. Ault, Julia E. Cole, Jonathan T. Overpeck, Gregory T.
> > Pederson, David M. Meko. *Assessing the risk of persistent drought
> > using climate model simulations and paleoclimate data*. *Journal of
> > Climate*, 2014; 140122102410007 DOI: 10.1175/JCLI-D-12-00282.1
> > <http://dx.doi.org/10.1175/JCLI-D-12-00282.1>
> >
> > ------------------------------
> >
> > Cornell University. "Southwest U. S. may face 'megadrought' this century."
> > ScienceDaily. ScienceDaily, 27 August 2014. <
> > www.sciencedaily.com/releases/2014/08/140827122505.htm>.
> > --
> >
> >
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