No abstract

Anthropogenic climate change is expected to increase the frequency of drought events in the earth's subtropical regions. However, the climate dynamics of these regions are not fully understood and debate surrounds how external forcing factors such as solar and volcanic forcing influence long-term rainfall patterns in the subtropics. Here, we present the first high-resolution reconstruction of Caribbean drought events over the last millennium based on analyses of sediment geochemical data from a continuous high-resolution coastal lakesediment record in Jamaica. The record suggests extended episodes of drought occurred during the so-called Little Ice Age (1400-1850 CE), which were associated with El-Niño-like conditions in the eastern equatorial Pacific Ocean and controlled by low natural radiative forcing. Comparison of the Jamaican drought record with previously published palaeoclimatic archives from within the circum-Caribbean region suggests that dry conditions were associated with the southward migration of the Hadley Cell, a stronger North Atlantic High and the concomitant intensification of the north-east trade winds and the Caribbean Low Level Jet. We conclude that pre-industrial climatic change in the region was probably controlled by solar forcing and modulated by the combined influence of El Niño Southern Oscillation and the North Atlantic Oscillation.

No abstract

Hurricanes are a persistent socio-economic hazard for countries situated in and around the Main Development Region (MDR) of Atlantic tropical cyclones. Climate-model simulations have attributed their interdecadal variability to changes in solar and volcanic activity, Saharan dust flux, anthropogenic greenhouse gas and aerosol emissions and heat transport within the global ocean conveyor belt. However, the attribution of hurricane activity to specific forcing factors is hampered by the short observational record of Atlantic storms. Here, we present the Extended Hurricane Activity (EHA) index, the first empirical reconstruction of Atlantic tropical cyclone activity for the last millennium, derived from a high-resolution lake sediment geochemical record from Jamaica. The EHA correlates significantly with decadal changes in tropical Atlantic sea surface temperatures (SSTs; r = 0.68; 1854–2008), the Accumulated Cyclone Energy index (ACE; r = 0.90; 1851–2010), and two annually-resolved coral-based SST reconstructions (1773–2008) from within the MDR. Our results corroborate evidence for the increasing trend of hurricane activity during the Industrial Era; however, we show that contemporary activity has not exceeded the range of natural climate variability exhibited during the last millennium.