Atlantic tropical cyclones are a persistent threat to Countries surrounding the tropical Atlantic Ocean and Caribbean Sea. The recent devastation on the Island of Dominica is a case in point where Tropical Storm Erica caused flooding and landslides and killed at least 20 people and left more than 50 missing. While these storms are often perceived as a threat to the economies of the Small Island Developing States of the Caribbean Region (primarily because of their potential devastating impacts on life, agricultural productivity and food security), hurricanes also contribute significantly to the water budget across the region by replenishing water reserves and buffering national economies from the threat of drought.
Despite recent advances in our understanding of how climatic change may control tropical cyclone activity on a global scale, there is still no consensus on the extent to which activity in the Atlantic basin is influenced by human activity. Indeed, the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC; Christensen et al. 2013) concluded that there is low confidence in region-specific projections of tropical cyclone activity and that it remains uncertain whether recent changes in Atlantic tropical cyclone activity lie outside the range of natural variability. In order to determine the long-term variability of hurricane activity over the last 1000 years, we have developed an index of long-term hurricane activity known as the Extended Hurricane Activity (EHA) index.
We present the new reconstruction of hurricane activity in a recent paper published by the Nature Publishing Group in the Open Access journal Scientific Reports and show that a strong correlation exists between the EHA index (developed from the published Jamaican lake level record), the Accumulated Cyclone Energy index (ACE) and sea surface temperature variability within the Main Development Region (MDR) of tropical cyclone activity for the modern historical period (Fig. 1).
When extended further back in time (Figure 4 (original article)) hurricane activity appears muted during the Medieval Climate Anomaly (~900–1350 CE) and becomes more variable (and extreme) during the so-called Little Ice Age (~1450–1850 CE), a period of cooler temperatures recorded in the Northern Hemisphere and thought to be associated with a combination of lower solar and enhanced volcanic activity. The index supports evidence for a gradual increase in Atlantic hurricane activity during the industrial period (ca. 1870-present), however, we show that contemporary activity has not exceeded its longer-term natural variability exhibited over last 1000 years.
Christensen, J. H. et al. in Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (eds. Stocker, T.F., Qin, D., Plattner, G.-K., Tignor, M., Allen, S.K., Boschung, J., Nauels, A., Xia, Y., V., B. & P. M., M.) (Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2013) Chapter 14.