By comparing the rings of pine trees growing in the Florida Keys to historical records of Spanish shipwrecks in the Caribbean Sea, researchers from the University of Arizona (UA) devised a new way to study hurricane activity.
Using this innovative approach, researchers found there was a dramatic 75 percent drop in the number of Caribbean hurricanes from 1645 to 1715, when the planet went through what is known as the Maunder Minimum. This time period is associated with very low sunspot activity and relatively cooler temperatures in the Northern Hemisphere.
"We're the first to use shipwrecks to study hurricanes in the past," said lead author Valerie Trouet, an associate professor in the UA Laboratory of Tree-Ring Research. "By combining shipwreck data and tree ring data, we are extending the Caribbean hurricane record back in time and that improves our understanding of hurricane variability."
Hurricanes gain energy from heat stored in tropical oceans. Therefore, current global climate models indicate hurricanes will be more intense as temperatures continue to rise.
The hope, researchers said, is to improve hurricane forecasts and better predict how tropical cyclones will behave under future climate changes, specifically on a regional scale.
"We're providing information that can help those models become more precise," Trouet added.
Previously, lake sediments were studied to develop a record of hurricanes. This data alone could only provide hurricane information on a century level.
The new study, however, provides a more detailed annual record of Caribbean hurricanes, dating as far back as the year 1500 - the days of Christopher Columbus.
As trading between Spain and the Caribbean became increasingly popular during the 17th and 18th centuries, Spain was diligent in its record-keeping of ship traffic. Therefore, if a ship did not make it to its destination, or was wrecked at sea, it was duly noted.
Furthermore, strong winds and surging seas associated with hurricanes stunt the growth of pine trees, which is reflected in the rings inside their trunks. This evidence combined with ship records confirms the occurrence of hurricanes.
The UA study has vast implications, as learning more about how climate change impacts hurricane activity is imperative to developing better emergency management strategies.
Their findings were recently published in the Proceedings of the National Academy of Sciences.
