Abstract
Anthropogenic induced climate change is thought to be influencing natural disasters like hurricanes. Hurricanes are the costliest natural disaster in the United States, with record breaking seasons becoming more common, costs are forecasted to increase. A warming climate can have many impacts on hurricane drivers such as sea surface temperatures, shifts in high pressure zones, El Niño Southern Oscillation, and Atlantic Multidecadal Oscillation. The key to understanding future of hurricanes is looking into the past through a field called paleotempestology. Paleotempestology utilizes geologic proxies and geochronology to identify tropical systems through time. These reconstructions allow us to understand how climate has impacted long-term tropical system activity. The goal of this study was to reconstruct hurricane history for the east coast of Florida where there have been no published long-term hurricane records. This study focuses on two central east coast of Florida field sites. Blind Creek, located behind Hutchinson Island and Peck Lake located behind Jupiter Island. Four sediment cores were collected from Blind Creek and used to reconstruct historic hurricanes going back to 1871. This record was created using grain size analysis, loss-on-ignition (LOI) and moisture content, along with radiometric dating. This short record was chronologically dated using 210Pb and 137Cs and the record contains evidence of five historic hurricanes. These tempestites likely represented hurricanes: Jeanne (2004), Delray Beach (1949), Treasure Coast (1933), Okeechobee (1928), and an unnamed storm (1871). These overwash layers consisted of fine to coarse grained quartz sand, shell hash, low moisture and high LOI content.
Two sediment cores were collected from Peck Lake, in order to reconstruct the hurricane history. The core samples were analyzed using grain size analysis, loss-on-ignition (LOI), moisture contents, and were radiometrically dated. Similar to Blind Creek core, these cores were dated using 210Pb and 137Cs along with 14C dating methods in deeper sediments. With the older 14C dates, this record allowed us to reconstruct major, tail risk, hurricane (category 3-5) history over the last two thousand years. One core preserved two overwash layers while the other recorded three. There was one major historic hurricane preserved in the core tops which likely represents 1928 Okeechobee Hurricane. The other two paleotempestites had age ranges of 1333-1270 AD and 543-432 AD. All three overwash layers consisted of fine to medium grained sand and coarse shell hash resulting in low moisture content and high LOI.
Short observational records like the one from Blind Creek, helps to understand the types of hurricanes that produce significant storm surge to overtop barrier islands. Being able to identify these hurricanes aids in better storm predictions, evacuation plans, and flood zoning. This is crucial in low-lying populous areas such as the central east coast of Florida. Longer records like Peck Lake gives us a deeper understanding of return periods for tail risk storms that produce storm surge over four meters (13.1 ft). Due to the height of the Peck Lake barrier dune this back-barrier lagoon offers insight into the periodicity of tail risk storms that can produce massive storm surge inundation.