Southern Hemisphere westerly winds and possible links to CO2 outgassing

Some model studies suggested that the current strengthening and poleward shift of the Southern Hemisphere (SH) westerly winds brought carbon-rich Circumpolar Deep Water (CDW) to the surface and reduced ΔpCO₂, weakening the anthropocentric carbon sink (e.g., Mikaloff-Fletcher, 2015). A new study, which appeared in Nature Geoscience,  presented a 12,300-year reconstruction of SH westerly winds based on three independent proxies to show that from 12.1 thousand years ago (ka) to 11.2 ka (i.e., early Holocene), the SH westerly winds were above their long-term mean and corresponded with increasing atmospheric CO₂, and vice versa from 11.2 to 7.2 ka (i.e., middle and late Holocene). These results are consistent with model inferences of enhanced SH westerly winds contributing to the long-term outgassing of CO₂ from the Southern Ocean.

https://www.nature.com/articles/s41561-018-0186-5

http://science.sciencemag.org/content/349/6253/1165

Image Credit: Lee, S.-K., D. Volkov, H. Lopez, W. G. Cheon, A. L. Gordon, Y. Liu, and R. Wanninkhof, 2017: Wind-driven ocean dynamics impact on the contrasting sea-ice trends around West Antarctica. J. Geophys. Res. Oceans, 122, 4413-4430, https://doi.org/10.1002/2016JC012416.