Clues from hurricane 'fingerprints'
Scientists decode hurricane 'records' left in trees and rocks to try to predict the strength of future storms.
Hard hats and head lamps are not tools one usually associates with hurricane hunters. But for Amy Frappier they are indispensable.
The Boston College geochemist and her colleagues have been searching for signs of hurricanes in stalagmites that rise like jagged stone fangs from the floors of caves in Latin America. In the formations' tree-ringlike growth layers, she and her colleagues have shown that stalagmites record individual hurricanes by the unique chemical fingerprints the storms leave on the rain they dump. Buoyed by results published last April from a field trip to Belize in 2001, the team this summer has been focusing its hunt on caves on Mexico's Yucatan peninsula.
Meanwhile, a group of scientists at the University of Tennessee has been looking for similar signatures hidden in tree rings. The samples gathered in 2001 from a region of woods near Valdosta, Ga., have yielded a record of hurricane activity reaching back 220 years. Colleagues at the University of South Carolina say they have conducted similar work that pushes the record there back to the 1400s.
These are among the latest efforts at trying to build a record of Atlantic tropical-cyclone activity reaching as far into the past as these "proxies" for written records will take them. The approaches range from teasing out the chemistry of tree rings and stalagmites to pulling long cores of muck from beneath coastal lakes and lagoons.
The results feed more than academic curiosity. Insurance companies want to know how often major storms strike parts of the coast where the firms have sold large numbers of policies. More broadly, tropical-cyclone specialists have been embroiled over the past two years in a debate over whether global warming's fingerprints are appearing in the recent cyclone record for the Atlantic and globally.
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