Winkler, Tyler Scott (2021-07). Near-Annual History of Subtropical North Atlantic Hurricane Activity Recorded in Blue Hole Successions. Doctoral Dissertation.
Thesis
The year 2020 Common Era (CE) observed the highest number of named tropical cyclone events since the instrumental record began in 1850 CE. Most downscaled models suggest that the frequency and destructive potential of major hurricanes in the Atlantic will increase in response to Anthropogenic climate change over the next century. Problematically, it is difficult to ascertain if recent high activity levels are unprecedented over longer-time scales due to the short instrumental record. To extend this record, I have produced four near-annual resolution stratigraphic paleohurricane archives using sediment successions from blue holes across the northern Bahamas. These individual reconstructions archive hurricane passage within a 50-115 km radius over the last 600 to 1700 years, and document dramatic multidecadal and centennial scale variability in local hurricane frequency. They also reveal multiple 50 to 150 yearlong intervals in which hurricane frequency was significantly higher than it has been over the last 100 years. However, substantial significant inter-island spatial heterogeneity in hurricane frequency suggests that a single-site reconstruction may not always reflect broader regional climatology. Based on this, these four reconstructions and three others from across the Bahamian Archipelago have been statistically merged into a two different 1500 to 1600-year compilations. These Bahamian Hurricane compilations observe sustained higher frequency in the subtropical North Atlantic during the Little Ice Age (LIA) from 1300 to 1850 CE relative to lower frequency the prior millennium as well as the last 170 years. The US Eastern Seaboard also experienced heightened hurricane activity during LIA, whereas the Gulf of Mexico and southern Caribbean were inactive. This suggests that despite globally cooler climate, regional ocean/climate conditions during the LIA remained favorable for cyclogenesis and intensification along specific hurricane pathways in the northern Bahamas and US East Coast.
