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The Southern Hemisphere westerly winds (SWW), a belt of strong zonal winds in the mid-latitudes, play a key role in Southern Hemisphere climate variability. Recent intensification and southwards migration of the SWW is projected to continue due to anthropogenic climate change and despite a recovering Antarctic ozone hole, impacting regional hydroclimate, ocean circulation and carbon cycling. Despite the importance of the SWW, our understanding of their behaviour on centennial to millennial timescales is limited by the inherently short observational record and limited palaeo-archive agreement on the wind belt's Holocene dynamics. Here we utilise dust flux, Itrax core scanning, rare earth element composition and HYSPLIT particle modelling to present a 8700-year (10,500–1700 cal yr BP) reconstruction of local SWW intensity from a Falkland Islands (Islas Malvinas) peat sediment core which, along with other reconstructions, we interpret in a regional South Atlantic and hemispheric context. We find increased dust deposition and variability from ca. 5700 cal yr BP, signalling an intensification and possible southwards shift of the SWW, though Patagonia likely remains the primary distal dust source throughout our record. Additionally, we identify asymmetric behaviour in the SWW belt from 3000 to 1700 cal yr BP over southern South America and the southwest Atlantic. In alignment with these findings, we propose a possible eastwards projection of the Amundsen Sea Low (ASL) into the South Atlantic during this period. Two volcanic eruptions, likely from Mt Burney (ca. 9700 cal yr BP) and Mt Hudson (ca. 4100 cal yr BP), are captured as cryptotephra deposits in the record. Our precisely dated, high-resolution multiproxy record of South Atlantic wind-blown transport provides an important new dataset that accurately constrains SWW Holocene variability over the Falkland Islands.

The timing and duration of the coldest period in the last glacial stage, often referred to as the last glacial maximum (LGM), has been observed to vary spatially and temporally. In Australia, this period is characterised by colder, and in some places more arid, climates than today. We applied Monte-Carlo change point analysis to all available continuous proxy records covering this period, primarily pollen records, from across Australia (n = 37) to assess this change. We find a significant change point occurred (within uncertainty) at 28.6 ± 2.8 ka in 25 records. We interpret this change as a shift to cooler climates, associated with a widespread decline in biological productivity. An additional change point occurred at 17.7 ± 2.2 ka in 24 records. We interpret this change as a shift towards warmer climates, associated with increased biological productivity. We broadly characterise the period between 28.6 (± 2.8) – 17.7 (± 2.2) ka as an extended period of maximum cooling, with low productivity vegetation that may have occurred as a combined response to reduced temperatures, lower moisture availability and atmospheric CO2. These results have implications for how the spatial and temporal coherence of climate change, in this case during the LGM, can be best interrogated and interpreted.

The Southern Ocean occupies 14% of the Earth’s surface and plays a fundamental role in the global carbon cycle and climate. It provides a direct connection to the deep ocean carbon reservoir through biogeochemical processes that include surface primary productivity, remineralization at depth and the upwelling of carbon-rich water masses. However, the role of these different processes in modulating past and future air–sea carbon flux remains poorly understood. A key period in this regard is the Antarctic Cold Reversal (ACR, 14.6–12.7 kyr bp), when mid- to high-latitude Southern Hemisphere cooling coincided with a sustained plateau in the global deglacial increase in atmospheric CO2. Here we reconstruct high-latitude Southern Ocean surface productivity from marine-derived aerosols captured in a highly resolved horizontal ice core. Our multiproxy reconstruction reveals a sustained signal of enhanced marine productivity across the ACR. Transient climate modelling indicates this period coincided with maximum seasonal variability in sea-ice extent, implying that sea-ice biological feedbacks enhanced CO2 sequestration and created a substantial regional marine carbon sink, which contributed to the plateau in CO2 during the ACR. Our results highlight the role Antarctic sea ice plays in controlling global CO2, and demonstrate the need to incorporate such feedbacks into climate–carbon models.

The Southern Ocean occupies 14% of the Earth’s surface and plays a fundamental role in the global carbon cycle and climate. It provides a direct connection to the deep ocean carbon reservoir through biogeochemical processes that include surface primary productivity, remineralization at depth and the upwelling of carbon-rich water masses. However, the role of these different processes in modulating past and future air–sea carbon flux remains poorly understood. A key period in this regard is the Antarctic Cold Reversal (ACR, 14.6–12.7 kyr bp), when mid- to high-latitude Southern Hemisphere cooling coincided with a sustained plateau in the global deglacial increase in atmospheric CO2. Here we reconstruct high-latitude Southern Ocean surface productivity from marine-derived aerosols captured in a highly resolved horizontal ice core. Our multiproxy reconstruction reveals a sustained signal of enhanced marine productivity across the ACR. Transient climate modelling indicates this period coincided with maximum seasonal variability in sea-ice extent, implying that sea-ice biological feedbacks enhanced CO2 sequestration and created a substantial regional marine carbon sink, which contributed to the plateau in CO2 during the ACR. Our results highlight the role Antarctic sea ice plays in controlling global CO2, and demonstrate the need to incorporate such feedbacks into climate–carbon models.