Looking ahead, it’s possible the U.S. Southwest will suffer persistent drought. The region has a history of drought. Global warming may increase this trend.
Edward Cook: Over the past thousand years in the West, there have been profound periods of drought lasting decades to a century or more. So we know that the natural climate system, independent of human activities, is capable of locking itself into long-term dry episodes.
That’s Edward Cook, of the Lamont-Doherty Earth Observatory. Cook reconstructed the Southwest’s past climate using tree ring records. Scientists can determine a dry or wet period by measuring the size and density of tree rings.
Edward Cook: So we can actually tie certain variability in the tree ring records, that indicate periods of drought happening, with changes in early culture.
Cook said that tree ring records link periods of severe drought with the disappearance of certain Native American civilizations. Today’s American cities are better insulated from the immediate impacts of drought, but a drier climate has major implications for regional water supplies
Edward Cook: That tells us something about the vulnerability in human systems.
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Our thanks to:
Edward Cook
Director, Tree-Ring Laboratory
Lamont-Doherty Earth Observatory
Palisades, NY
When I lived in Phoenix, it was always short of water.0t has been parched in the Phoenix area for the last 100,000 years and global warming has nothing to do with it. Those Dinos and their Hummers.
Edward Cook’s comment: “Over the past thousand years in the West, there have been profound periods of drought lasting decades to a century or more. So we know that the natural climate system, independent of human activities, is capable of locking itself into long-term dry episodes†seems to close the case that the decade long drought seen in America’s desert Southwest isn’t out of the normal.
Regarding the comment on global warming increasing the trend… If droughts lasting a century or more are recorded in the geological history of the region prior to man, where is the tie-in? Now that we are in a period of global cooling that may last for several decades longer, would the decrease in temperatures potentially move the region towards a wetter climate system or is the relationship too disconnected or complex to make such a prediction?
Edward Cook’s best work is his email to Keith Briffa September 3, 2003
source ‘Climate-Gate email leaks’