NOAA/WDS Paleoclimatology - New Zealand and Australia Pacific Region d18O and d13C data for the last 30,000 years

Changes in ocean circulation are thought to have contributed to lowering glacial atmospheric CO2 levels by enhancing deep ocean sequestration of carbon that was returned to the atmosphere during glacial terminations. High-resolution benthic foraminiferal d13C and d18O records from a depth transect of cores in the Southwest Pacific Ocean presented here provide evidence that both wind-and thermohaline-driven circulation drove CO2from the ocean during the last deglaciation. Shallow geochemical stratification in the glacial Southern Ocean was followed by a short pulse of rapid d13C enrichment to intermediate water depths during Heinrich Stadial1, indicative of better-ventilated intermediate waters co-occurring with documented wind-driven upwelling in the Southern Ocean. Intermediate depth d13C enrichment paused at the start of the Antarctic Cold Reversal (~14.7ka), implying a brief shallow restratification, while deeper layers were progressively flushed of d13C-depleted and d18O-enriched waters, likely caused by the increasing influence of deep waters sourced from the North Atlantic. The coincidence of atmospheric CO2increases with these geochemical shifts in both shallow and deep cores suggests that shifts in both atmospheric and oceanic circulation contributed to the deglacial rise of CO2.