Dendrology indicates future droughts likely

dwheeler at dwheeler at
Fri Dec 18 21:43:30 EST 1998

The following article appeared in The Oregonian on Dec. 16, 1998, p A5

Scientists say Earth will have megadroughts

By JEFF NEWSMITH, Cox News Service

	WASHINGTON - The costly Dust Bowl drought of the 1930s was little
more than a bad dry spell, compared to the kind of weather that lies ahead,
government scientists warned Tuesday.	  It has happened before.	 
Evidence in lakes and ancient trees shows that in the late 1300s and the late
1500s, "megadroughts" lasting at least 25 years descended on western North
America, said Connie A. Woodhouse and Jonathn T. Overpeck, climatologists at
the National Oceanic and Atmospheric Administration.	  The droughts
occurred because of natural climate variations and therefore undoubtedly will
occur again, the scientists said.    "These abrupt shifts appear more likely
when the climate is changing," Overpeck said. "As the Earth warms in the
future, we could get sudden, surprising shifts."       Growth rings in trees
reflect the two megadroughts, Woodhouse said.	  In addition, lake sediments
show corresponding shifts in the kind of diatoms - microscopic plants - that
lived in the lakes. With less rainfall, lakes became more saline, and the
change caused diatoms that thrive on saltier water to increase.     
Scientists have tracked similar changes in aquatic plant life in response to
modern fluctuations in rainfall, Woodhouse said.   The report was published
in the Bulletin of the American Meteorological Society.

Comment by poster: Another reason to grow more trees.

This article was posted as a courtesy by:
Daniel B. Wheeler

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