El Niño, tropical Atlantic warmth, and Atlantic hurricanes over the past 1500 years

Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 460 (2009): 880-883, doi:10.1038/nature08219.Atlantic Tropical Cyclone (TC) activity, as measured by annual storm counts, reached anomalous levels over the past decade. The short nature of the historical record and potential issues with its reliability in earlier decades, however, has prompted an ongoing debate regarding the reality and significance of the recent rise. Here, we place recent activity in a longer-term context, by comparing two independent estimates of TC activity over the past 1500 years. The first estimate is based on a composite of regional sedimentary evidence of landfalling hurricanes, while the second estimate employs a previously published statistical model of Atlantic TC activity driven by proxy-reconstructions of past climate changes. Both approaches yield consistent evidence of a peak in Atlantic TC activity during Medieval times (around AD 1000) followed by a subsequent lull in activity. The Medieval peak, which rivals or even exceeds (within uncertainties) recent levels of activity, results in the statistical model from a ‘perfect storm’ of La Niña-like climate conditions and relative tropical Atlantic warmth.M.E.M. and Z.Z. acknowledge support from the ATM programme of the National Science Foundation (grant ATM-0542356). J.P.D. acknowledges support from the EAR and OCE programmes of the National Science Foundation (grants EAR-0519118 and OCE-0402746), the Risk Prediction Initiative at the Bermuda Institute for Ocean Sciences, and the Inter-American Institute for Global Change Research

Coastal flooding by tropical cyclones and sea-level rise

The future impacts of climate change on landfalling tropical cyclones are unclear. Regardless of this uncertainty, flooding by tropical cyclones will increase as a result of accelerated sea-level rise. Under similar rates of rapid sea-level rise during the early Holocene epoch most low-lying sedimentary coastlines were generally much less resilient to storm impacts. Society must learn to live with a rapidly evolving shoreline that is increasingly prone to flooding from tropical cyclones. These impacts can be mitigated partly with adaptive strategies, which include careful stewardship of sediments and reductions in human-induced land subsidence

Sedimentary coasts

The most popular of coastlines are beaches. Beaches are primary landforms bounding approximately 30% of the world’s coastlines and consist of sand or gravel (or a mixture of both). They have enormous recreational value but importantly act as buffers for wave energy delivered to the shore and shelter areas behind the beach from wave attack or flooding, especially during storms. Along many coastlines, beaches and the associated back-beach environments (lagoons, marshes, dune belts) have been intensively developed and are today among the most densely populated regions of the world and therefore particularly vulnerable to the impacts of marine natural hazards. A beach is a t hree-dimensional s ediment b ody a long a shoreline t hat e xtends f rom t he upper limits of wave run-up to the outer limits of wave action in the nearshore zone. In 124 images we demonstrate the diversity of beaches and associated often ephemeral features both on land and in the littoral zone: Dunes, spits, barriers, tombolos, beachrock, beach ridge systems and coastal landforms at the interface between rivers and the sea: different delta types of the world