Holocene dynamics of the Southern Hemisphere westerly winds and possible links to CO2 outgassing

The Southern Hemisphere westerly winds (SHW) play a significant role in regulating the capacity of the Southern Ocean carbon sink. They modulate upwelling of carbon-rich deep water and, with sea ice, determine the ocean surface area available for air-sea gas exchange. Some models suggest the current strengthening and poleward shift of the SHW will weaken the carbon sink. If correct, centennial- to millennial-scale reconstructions of SHW intensity should be linked with past changes in atmospheric CO2, temperature, and sea ice. Here, we present a 12,300-year reconstruction of wind strength based on three independent proxies that track inputs of sea salt aerosols and minerogenic particles accumulating in lake sediments on sub-Antarctic Macquarie Island. Between c. 12.1–11.2 ka BP and since c. 7 ka BP, wind intensities were above their long-term mean, and corresponded with increasing atmospheric CO2. Conversely, from c. 11.2–7.2 ka BP, wind intensities were below their long term mean and corresponded with decreasing atmospheric CO2. These observations are consistent with model inferences of enhanced SHW contributing to the long-term outgassing of CO2 from the Southern Ocean.