Tree rings reveal hurricane history
With the help of oxygen isotopes, scientists could soon better understand past hurricane activity and thus make more reliable statements about the future development of hurricane strength in the Atlantic.
Until now, climatologists have relied on old records such as ship logs or newspaper reports to make statements about the number and category of hurricanes along the American coast - a rather unreliable source, such as Claudia Mora of the University of Tennessee in Knoxville and her colleagues point out. They, on the other hand, reconstructed the hurricanes of the last 220 years using different oxygen isotope ratios in the wood of swamp pines (Pinus palustris) from the southeastern United States.
The pines take up these isotopes via rainwater, but the content of 18O in the precipitation from hurricanes is reduced by up to ten percent, so that the trees are correspondingly depleted of liquid put away in the weeks after the storm. If the season was very active and the hurricanes involved were strong, the 18O values in the corresponding annual rings of the tree are well below the average of windless periods. For example, the 1770s and the decades between 1800 and 1830 and 1840 to 1860 were marked by numerous storms.
