A 250-year periodicity in Southern Hemisphere westerly winds over the last 2600 years
- 1School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, Australia
- 2Climate Change Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, Australia
- 3Department of Geography, Exeter University, Exeter EX4 4RJ, UK
- 4Archaeological & Heritage Management Solutions Pty Ltd, 2/729 Elizabeth Street, Waterloo, NSW 2017, Australia
- 5Waikato Radiocarbon Laboratory, University of Waikato, Private Bag 3105, Hamilton, New Zealand
- 6School of Geography, Archaeology and Palaeoecology, Queen's University Belfast, Belfast BT7 1NN, UK
Abstract. Southern Hemisphere westerly airflow has a significant influence on the ocean–atmosphere system of the mid- to high latitudes with potentially global climate implications. Unfortunately, historic observations only extend back to the late 19th century, limiting our understanding of multi-decadal to centennial change. Here we present a highly resolved (30-year) record of past westerly wind strength from a Falkland Islands peat sequence spanning the last 2600 years. Situated within the core latitude of Southern Hemisphere westerly airflow (the so-called furious fifties), we identify highly variable changes in exotic pollen and charcoal derived from South America which can be used to inform on past westerly air strength. We find a period of high charcoal content between 2000 and 1000 cal. years BP, associated with increased burning in Patagonia, most probably as a result of higher temperatures and stronger westerly airflow. Spectral analysis of the charcoal record identifies a pervasive ca. 250-year periodicity that is coherent with radiocarbon production rates, suggesting that solar variability has a modulating influence on Southern Hemisphere westerly airflow. Our results have important implications for understanding global climate change through the late Holocene.