TRACKING HURRICANE HISTORY IN THE BAHAMAS—FROM JOAQUIN AND BEYOND

On September 28, 2015, Hurricane Joaquin formed in the SW Atlantic, making landfall as a CAT 4 hurricane several days later, striking Acklins, Crooked Island, Long Island, Rum Cay and San Salvador Island, and causing at least $60million USD in damages. This event represented the third CAT 3 hurricane or higher striking the island of San Salvador in the past eleven years. San Salvador as well as Long Island experience a tropical cyclone every 2.23-2.47 years, with the average years between direct hits approximately 5 years. The historical records of hurricanes are significant, but longer-term records are needed to understand the true relationship between climate change and tropical cyclone formation.

We reconstructed the paleotempestological record of tropical cyclones in the Bahamas from coastal ponds on Eleuthera and San Salvador. Sediment cores from Shad Pond (Eleuthera), Salt Pond and Clear Pond (San Salvador), establish a >6,000 year record based on multi-proxy indicators of loss on ignition, grain size analysis and elemental concentrations of Ca, Br and Fe. Based upon these comparative records, we found a strong relationship between hurricanes and ENSO. Three major phases have been developed in the late Holocene beginning with a closing off of all three ponds at approximately 3700-3900 ybp. This was followed by a period of climatic variability. During the Medieval Climatic Optimum, storminess increased. In recent centuries, tropical cyclones have reached the levels of that time period.

As sea level increases at rates estimated between 20-80 cm in the next 50 years, and as global air and sea surface temperatures rise, it is anticipated that hurricane intensity and frequency will increase accordingly, especially in non-El Nino years. Further, with increased sea levels, coastal erosion also will likely increase, causing major property losses in the future.