North Atlantic Tropical Cyclone Activity over the last 2000 years: Patterns, Consequences and Potential Climatic Forcing
Abstract
With a series of high-resolution reconstructions of hurricane-induced overwash from high deposition rate sites from across the western North Atlantic, we document patterns of event occurrence dating back more than 2000 years. Some sites with interbedded overwash sediments preserve annual laminations, which provide exceptional chronologies of hurricanes. The records suggest that while the frequency of hurricane landfall in the region has not changed dramatically over the last two millennia, the frequency of intense hurricanes has varied considerably. Sedimentary evidence suggests the eastern seaboard of the United States experienced a period of elevated intense hurricane activity during the 15th, 16th and early 17th Centuries. Spanish document archives also suggest elevated tropical cyclone activity during the late 16th and early 17th Centuries. This interval of increased intense hurricane activity had significant impacts on coastal landforms and ecosystems including more frequent and widespread inlet formation, erosion of coastal wetlands, and forest disturbance. Similarly, an earlier active interval between 2500 and 1000 years ago may have had a dramatic impact on coastal pine and scrub oak forests in the northeastern United States. Pollen and charcoal analyses indicate more frequent forest disturbance with the highest concentration of charcoal occurring during the active period between 1900 and 1300 years ago. Many of the peaks in charcoal follow closely after storm-induced coarse grained deposits. The increase of large fires during the active hurricane regime between 1900 and 1300 years ago provides compelling evidence of hurricane/fire interactions. However drought, identified by a lake level lowstand in the region, may have contributed to increased fires during this interval. Fossil pollen preserved in the sediment provides evidence of significant changes in vegetation composition in most taxonomic groups during the active hurricane interval between 1900 and 1300 years ago. A reconstruction of intense hurricane landfalls from the Gulf coast documents some similar patterns that likely point to large scale climate forcing; however, some significant differences are evident. For example, the Gulf frequently experienced intense hurricanes during the 13th and 14th centuries, but a subsequent decline in activity has persisted through the historic period. This antiphasing of intense hurricane activity between the East and Gulf coasts may point to basin-wide changes in hurricane tracks, but regional controls on the frequency of intense hurricanes (e.g., loop current penetration in the Gulf of Mexico) may also have driven spatial variability in Atlantic paleohurricane records.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMOS43D..03D
- Keywords:
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- 0468 BIOGEOSCIENCES / Natural hazards;
- 1616 GLOBAL CHANGE / Climate variability;
- 1641 GLOBAL CHANGE / Sea level change;
- 4901 PALEOCEANOGRAPHY / Abrupt/rapid climate change