Deglacial CO2 changes in the northwest Pacific (Shatsky Rise)

The deglacial is an important period for understanding the relationship between the weakened Atlantic Meridional Overturning Circulation and the global CO₂ outgassing. We examined how the change manifested itself in the northwest Pacific in an area where the subtropical and the subarctic gyres converge. At Shatsky Rise, the Kuroshio extension of the subtropical gyre and the Oyashio extension of the subarctic gyre come together. The Kuroshio advects water from the Western Pacific Warm Pool where strengthening of the monsoon led to surface water stratification (Partin et al., 2007) and which acted as a CO₂ source during the Heinrich Stadial 1 (Palmer and Pearson, 2003). The Oyashio advects water from the NW Pacific where formation of the North Pacific Intermediate Water was strengthened and intermediate-to-deep stratification was stronger during HS1 (Gong et al., 2019). The NW Pacific was also an area of CO₂ outgassing in the HS1 (Gray et al., 2018).

We measured the δ¹¹B of foraminifera in a giant piston core NPGP1302-1B (32°16′N, 158°13′E; 2514 m water depth) on the Shatsky Rise (Seo et al., 2018). Planktic (G. ruber, G. sacculifer, G. bulloides, O. universa, N. pachyderma) and benthic (C. wuellerstorfi) species were picked from 47 depth intervals and analyzed using NuPlasma 3 MC-ICPMS. Calculated pH was lower during the HS1 compared to both the LGM and the B/A. We will use this and the stable isotope data to discuss how the effects of HS1 played out in terms of water mass properties and carbon storage at Shatsky Rise.