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Tree Ring Weather

September 13, 2005

Are hurricanes increasing in number? Scientists have now found a way to ask the trees.

Transcript

BOB HIRSHON (host):

How trees can tell the weather. I’m Bob Hirshon and this is Science Update.

You probably have heard of tree-ring dating, the method of reading the age of a tree in its growth rings. Now scientists have also found a history of hurricanes written in the rings of Georgia pine trees. Water from hurricanes contains less oxygen-18 than normal rainwater, so trees should have less of it in the rings they grow during hurricane years. Geologist Claudia Mora and geographer Henri Grissino-Mayer of the University of Tenessee saw this signature drop in oxygen-18 in the rings of some old pines.

CLAUDIA MORA (University of Tenessee):
What we have we feel is a very good record for hurricane occurrence in this one area through about 1770, and we’re starting to fill that record in back to about 1580.

HIRSHON:
The method could help scientists discover whether hurricanes are becoming more frequent due to global climate change.

I’m Bob Hirshon, for AAAS, the science society.