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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.



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.

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.