GEOCHEMICAL PROXIES IN COASTAL LAKE SEDIMENTS REVEAL 4500 YEARS OF HURRICANE ACTIVITY IN NORTH FLORIDA

Hurricane strikes can cause devastation to coastal communities. However, the relationship between hurricane patterns and climate change remains poorly understood because of the paucity of highly detailed long-term storm records. Here, we present a high-resolution proxy record of storm history over the last 4500 year based on organic geochemical proxies (OGPs) (i.e., δ13C, δ15N, C%, N% and C/N) preserved in sediment cores from a coastal sinkhole lake in North Florida. The record indicates that storm activity has varied significantly on multi-decadal, centennial and longer time scales. The storm frequency obtained from the sediment OGP record for the post-1850 CE era is congruous with the documented record of hurricanes that made landfall within 100 km of the study site. The OGP record reveals eight active periods with storm frequencies ≥ 3 hurricanes/century: 2016 CE-150 Cal yr BP, ~830-980 Cal yr BP, ~1120-1330 Cal yr BP, ~2800-2850 Cal yr BP, ~3010-3200 Cal yr BP, ~3670-3710 Cal yr BP, ~3825-3830 Cal yr BP, and ~4070-4330 Cal yr BP. No seawater flooding events were detected in the OGP record at ~200-720 Cal yr BP, ~1570-1660 Cal yr BP, and ~2650-2680 Cal yr BP. The OGP based reconstruction of storm activities suggest that storm activity peaked between 2016 CE and 150 yr BP and also between 1120 Cal yr BP and 1330 Cal yr BP, and the latter roughly coincides with the Medieval Warm Period (MWP). The MWP peak in the OGP record is comparable to (and slightly exceeded) the peak storm frequency in the post-1850 era, consistent with the statistical model predictions of past tropical cyclone activity based on instrumental and proxy-reconstructed climate indices. Our findings support the idea that the long-term hurricane activity is largely driven by variations in large-scale climate and oceanographic conditions.