Fig. 1. Global oceanic oxygenation reconstructions compared with global climate and ocean circulation records.

(A) Atmospheric CO₂ concentrations from the Antarctic composite ice core records (54). ppm, parts per million. (B) authigenic sedimentary ε²⁰⁵Tl record from the core TN041-8PG/8JPC with the LOESS fit (Materials and Methods) shown in the solid red curve and the bootstrapped 2-SD envelope shown in the dashed red curve. Error bars are in 2 SD. When the measurement 2 SD is smaller than 0.3, the error bar was set to 0.3 (the long-term reproducibility of ε²⁰⁵Tl analyses, see Materials and Methods). ¹⁴C dates were shown in the yellow triangles. (C) Opal fluxes of TN057-13PC as an upwelling proxy in the Southern Ocean (28). (D) ²³¹Pa/²³⁰Th activity ratios from the Bermuda Rise as an indicator of AMOC strength from the core OCE326 GGC-5 (green) (43) and ODP Site 1063 (blue) (44). The error bar represents 2 SE. The production ratio of ²³¹Pa/²³⁰Th in the water columns is shown in the horizontal dashed line. (E) Radiocarbon age offsets between benthic foraminifera and the atmosphere (B-Atm) as a proxy for subsurface water mass ventilation from the Indian Ocean core SS172/4040 (42). The error bar is 2 SD. (F) The relative deviation (δ¹⁴R) between the deep water and the atmospheric Δ¹⁴C as an indicator for deep water ventilation from the Pacific Ocean at core MD97-2106 (47). Error bars are 1 SD. The HS1 and YD are shaded in light blue, whereas B-A/ACR is shaded in light red.