Extended Data Fig. 4: Deglacial records of Southern Ocean CO₂ chemistry and opal fluxes, and climate over Antarctica and Greenland.

Data are plotted as in Figs. 2, 3, but with opal flux²³, a proxy for upwelling, surface ocean-atmosphere CO₂ difference, based on δ¹¹B in planktic foraminifera²⁶, and radiocarbon data^4,25 from corals within these sample groupings, shown as ¹⁴C age offsets compared to the contemporaneous atmosphere. Intervals of rising CO₂ in the atmosphere are associated with input of waters rich in CO₂ and nutrients to the upper reaches of the Southern Ocean. Radiocarbon ages reflect the competing influences of upwelling of ¹⁴C-depleted waters and improved ventilation over the deglaciation.