Hurricane frequency dropped during 17th century ‘Little Ice Age’
Shipwreck data tell tale of lull in heat-fueled ocean storms
SAVAGE STORMS The history of Spanish ships wrecked by Atlantic hurricanes suggests that hurricane activity stagnated between 1645 and 1715, a time when the sun dimmed. Hurricane-wrecked ships, such as the British Lord Ashburton (illustrated) sunk in 1857, litter the Atlantic Ocean seafloor.
Joseph Heard/Wikimedia Commons
Using records of ships wrecked by Atlantic hurricanes dating as far back as the days of Christopher Columbus, researchers have extended the hurricane record by hundreds of years. The work reveals that hurricane frequency plummeted 75 percent between 1645 and 1715, a time called the Maunder Minimum when the sun dimmed to its lowest recorded brightness.
“We didn’t go looking for the Maunder Minimum; it just popped out of the data,” says study coauthor Valerie Trouet, a paleoclimate scientist at the University of Arizona in Tucson.
The findings should help scientists better predict how hurricanes will behave under climate change, the researchers report in a paper to appear in the Proceedings of the National Academy of Sciences.
Detailed hurricane observational records go back to 1851. Scouring an Atlantic shipwreck catalog, Trouet and colleagues identified more than 650 Spanish ships sunk by hurricanes from 1495 through 1825. The researchers bridged the shipwreck and observational records using tree rings from slash pines (Pinus elliottii) collected along the Florida coast and dating to as early as 1707. Hurricane damage stunts tree growth, narrowing the annual rings. All three records agreed, allowing the researchers to stitch together one long hurricane frequency record.
The number of hurricane-caused shipwrecks during the Maunder Minimum, which makes up a large portion of a period nicknamed the “Little Ice Age,” was less than a third the number of wrecks in the preceding decades. A hurricane slowdown during the solar dim period makes sense, Trouet says. Warm seawater fuels hurricanes. As temperatures dropped around the Maunder Minimum, less heat was available to power storms.
The finding doesn’t mean that global warming will increase hurricane frequency, says Gabriel Vecchi, an oceanographer at the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory in Princeton, N.J. While both solar brightness and heat-trapping greenhouse gases cause warming, their effects on hurricanes “aren’t perfect analogs,” he says.
Still, the new data can provide a test for climate simulations, Vecchi says. “We can ask a model, ‘When we give you less sun, what do you do?’ If it doesn’t give us fewer hurricanes, we can then ask why. This gives us something to aim at.”
