Poleward displacement of the Southern Hemisphere Westerlies in response to Early Holocene warming

Recent intensification of the Southern Hemisphere Westerlies has resulted in important changes to ocean circulation, Antarctic ice shelf stability and precipitation regimes in the continents abutting the Southern Ocean. Efforts to resolve the natural behaviour of the Westerlies over sub-millennial to millennial-timescales are critical to anticipating future changes with continued 21st Century warming. Here we present an ~11,000 year diatom-inferred sea salt aerosol and multiproxy geochemical record preserved in lake sediments from Cape Horn (56°S) which documents warm conditions and stronger-than-present Westerlies in the Early Holocene (10 000–7500 calibrated years before present) at this site. Combined with other regional records, we demonstrate that the Westerlies were poleward of their current position during the Early Holocene. This poleward migration of the Southern Hemisphere Westerlies in response to peak Holocene warmth provides an analogue for future warming and greater impacts on the southern high latitudes and global climate in the coming decades.

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