Intense New England Hurricanes Much More Numerous 340 to 1800 Years Ago

Numerous Category 3 and 4 hurricanes frequently pounded New England during the first millennium, from the peak of the Roman Empire into the height of the Middle Ages, said a study accepted for publication this month in the open-access journal Earth’s Future, Climate Forcing of Unprecedented Intense-Hurricane Activity in the Last 2,000 Years. These prehistoric hurricanes were stronger than any hurricane documented to hit the region since the mid-1800s, and would be catastrophic if they hit the region today, according to Jeff Donnelly, a scientist at Woods Hole Oceanographic Institution (WHOI) in Massachusetts and lead author of the new paper. In a press release, Donnelly said, “We hope this study broadens our sense of what is possible and what we should expect in a warmer climate. We may need to begin planning for a category 3 hurricane landfall every decade or so rather than every 100 or 200 years.”


Figure 1. The storm surge from Category 2 Hurricane Carol in 1954 batters New England's Edgewood Yacht Club near Providence, Rhode Island. Image credit: NOAA Photo Library.

The paper is the latest contribution to the field of paleotempestology--the study of past tropical cyclone activity by means sediment deposits, cave speleothems, tree rings, coral deposits, as well as historical documentary records. In this case, the researchers took sediment cores from Salt Pond near Falmouth on Cape Cod, Massachusetts. The pond is separated from the ocean by a 1.3- to 1.8-meter (4.3- to 5.9-foot) high sand barrier. Over hundreds of years, storm surges from Category 2 and stronger hurricanes have deposited sediment over the barrier and into the pond. The scientists were able to calibrate the timing of the intense hurricane strikes by dating the layers from Category 2 Hurricane Bob of 1991, the 1675 (September 7) New England hurricane, and the Great Colonial Hurricane of 1635, which passed across southeastern New England and caused widespread damage consistent with a category 3 hurricane.


Figure 2. Scientists collect a sediment core from Salt Pond in Falmouth, Massachusetts, to study hurricane overwash deposits placed there by storm surges from intense hurricanes. The aluminum tube was vibrated into the muddy sediment at the bottom of the pond and then extracted with a hoist. Image Credit: WHOI

The prehistoric sediments showed that there were two periods of elevated intense hurricane activity on Cape Cod--from 150 to 1150, and from 1400 to 1675. Previous paleotempestology studies also found evidence of high hurricane activity during 150 - 1150 A.D. from the Caribbean to the Gulf Coast. Both time periods had unusually warm sea surface temperatures (SSTs) in the Main Development Region for hurricanes, from the Caribbean to the coast of Africa. Warm ocean temperatures in this region have been linked to increased intense hurricane activity by a number of recent research papers. In recent decades, ocean temperatures in the Main Development Region have surpassed the warmth of prehistoric levels, and these waters are expected to warm further over the next century as the climate heats up, suggesting that intense hurricane activity in New England may return to the levels of 340 to 1800 years ago. However, other factors besides warming SSTs will also shape what happens in the North Atlantic. For example, the pattern of ocean warming could bring more El Niño-style wind shear to the Atlantic, reducing hurricane activity. Still, New England would be wise to take heed of Donnelly's advice that we may need to begin planning for a category 3 hurricane landfall every decade or so rather than every 100 or 200 years.

Jeff Masters