Climate in the southwest may suffer sustained drought

Looking ahead, it’s possible the U.S. Southwests climate 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.

Join EarthSky in celebrating The International Year of Planet Earth. Thanks to the National Science Foundation and US Geological Survey.

Our thanks to:
Edward Cook
Director, Tree-Ring Laboratory
Lamont-Doherty Earth Observatory
Palisades, NY