Browsing by Author "Hodgson, D"

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    A northward shift of the southern westerlies during the Antarctic cold reversal: evidence from Tasmania
    (Australasian Quaternary Association, 2018-12-10) Alexander, J; Fletcher, MS; Pedro, JB; Mariani, M; Beck, KK; Blaauw, M; Hodgson, D; Heijnis, H; Gadd, PS; Lisé-Pronovost, A
    The Last Glacial Termination (LGT) was interrupted in the Southern Hemisphere by the Antarctic Cold Reversal (ACR; 14.7 to 13 ka), a millennial-scale cooling event that coincided with the Bølling– Allerød warm phase in the North Atlantic (14.7 to 12.7 ka). This inter-hemispheric asynchrony of climate change through the LGT, the bipolar seesaw, has been theoretically linked to latitudinal shifts in the southern westerly wind belt (SWW) and their proposed influence over the global carbon cycle via wind-driven upwelling of CO2 rich deep waters in the Southern Ocean (SO). However, while climate models and theory predict a northward shift of the SWW during the ACR in response to ocean-atmosphere heat dynamics, proxy-based reconstructions disagree on the behaviour of the SWW through this interval, and the role of the SWW during the LGT remains contested. Here we present terrestrial proxy palaeoclimate data (pollen, μXRF geochemistry, charcoal) from multiple lakes across Tasmania (40-44⁰S), an island located at the northern edge of the SWW. Our data reveal a clear SWW increase over Tasmania during the ACR, synchronous with reduced SWW-driven upwelling in the SO at the southern edge of the SWW. When combined with evidence from Antarctic ice cores and terrestrial records from New Zealand and Patagonia our results suggest a hemisphere-wide migration of the SWW during the LGT, lending support to the hypothesis that changes in wind-driven ventilation of CO2 from the Southern Ocean were a key driver of the global carbon cycle during the LGT. © The Authors.