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A new research found an interesting way to estimate date of occurrence of ancient hurricanes. This new source is shipwreck, which is being added to source such as coastal lake sediments or coral isotopes. Scientists even compare the data collected through Spanish shipwrecks to tree rings data to come to precise results.
The research was done by scientists at Arizona State University. It included analyzing 657 shipwrecks that were recorded between 1495 and 1825 by Spanish government. The study was undertaken to predict potential periods of increased cyclonic activity in Caribbean. The data collected through shipwreck was combined with data from tree rings as hurricanes commonly strip the trees of limbs and leaves, stunting growth.
“We found that in the years when many ships wrecked in the Caribbean, the trees in the Florida Keys showed the same signal that trees show during hurricanes. So, that gave an indication that we could use shipwreck records as a proxy for hurricane activity”, said Valerie Trouet, study author from the University of Arizona.
Using both tree ring and shipwreck data, it became feasible to come to precise periods. It is also a fact that tree rings data cannot be used alone to discover about ancient storms as there exist other conditions which influence rate of tree growth. Now with new markers, hurricane activity that occurred between a periods of 10 to 15 years and in some cases annually can be determined. This wasn’t the case earlier as lake sediments can only estimate hurricane activity for a century long period.
The new study revealed that hurricane activities reduced by 75% between 1645 and 1715, this period is also known for cooler sea surface temperatures in response to reduced sunspot activity. The lower sea surface temperatures are generally believed to suppress hurricane activity.