Finding data on shipwrecks was no problem for the researchers since ship traffic between Spain and the Caribbean in the 17th and 18th centuries was bustling. And because the ships carried valuable goods such as gold, Spain was diligent in its record-keeping of their comings and goings. When a ship didn't reach its destination, records showed it.
Those records were also supported by a book commonly used by treasure hunters today - Robert F. Marx's "Shipwrecks in the Americas: a complete guide to every major shipwreck in the Western Hemisphere."
Hurricane Link To Climate Change Explained
Another clue to hurricane activity in this period is revealed in tree rings since tree growth slows during years with hurricanes. The University of Arizona team combined the two sets of data, shipwrecks and tree rings, and discovered the hurricane patterns from both overlapped from 1707-1825. The slowdown in storms revealed by both corresponded to a period known as the Maunder Minimum.
"We didn't go looking for the Maunder Minimum," Trouet said. "It just popped out of the data."