Abstract
Most Atlantic hurricanes form in the Main Development Region between 9°N to 20°N along the northern edge of the Intertropical Convergence Zone (ITCZ). Previous research has suggested that meridional shifts in the ITCZ position on geologic timescales can modulate hurricane activity, but continuous and long-term storm records are needed from multiple sites to assess this hypothesis. Here we present a 3000 year record of intense hurricane strikes in the northern Bahamas (Abaco Island) based on overwash deposits in a coastal sinkhole, which indicates that the ITCZ has likely helped modulate intense hurricane strikes on the western North Atlantic margin on millennial to centennial-scales. The new reconstruction closely matches a previous reconstruction from Puerto Rico, and documents a period of elevated intense hurricane activity on the western North Atlantic margin from 2500 to 1000 years ago when paleo precipitation proxies suggest that the ITCZ occupied a more northern position. Considering that anthropogenic warming is predicted to be focused in the northern hemisphere in the coming century, these results provide a prehistoric analog that an attendant northern ITCZ shift in the future may again return the western North Atlantic margin to an active hurricane interval.
Highlights
Landscape, and these develop from the subsurface dissolution and subsequent collapse of limestone bedrock[10]
The most significant result of the Blackwood reconstruction is the contrast between pronounced active versus quiescent intervals of intense hurricane landfalls based on event bed deposition, which closely matches previous evidence for intense hurricane strikes at Laguna Playa Grande in Puerto Rico (LPG, 18.09°N, 65.49°W, compare Fig. 4A,B)[8]
Relying on historical intense hurricane climatology for the last 164 years[18], both LPG and Blackwood are predominantly vulnerable to storms forming in the central MDR
Summary
B reef-dwelling foraminifera (e.g., Archaias) and marine bioclasts hurricane tree damage sea level. Based on the uppermost event, it appears that intense hurricane strikes with surge and flooding exceeding 2 m above sea level are responsible for event bed deposition (> 20 mg cm−3) at this core locale. The magnitude of coarse fraction sedimentation from one core alone cannot be used to infer hurricane intensity as multiple parameters (e.g., radius of maximum winds, storm translational velocity, local sediment budget and coastal geometry) can influence the lateral variability of a tempestite in the subsurface[27]. At the core site of BLWD-C2, varying coarse-grained sedimentation into Blackwood Sinkhole can be used to indicate active versus quiescent intervals of hurricane activity through time. The current geometry of the site was likely similar over the time that this sediment archive was accumulating, given the modest rates of regional sea-level rise during the late Holocene[28] and the sinkhole’s structural geology
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