Ocean Carbon Sink Changes Following AMOC tipping

AMOC tipping is considered a low probability-high impact event. CMIP6 models show that AMOC is not likely to collapse in the 21^st century while several fingerprint studies show evidence for the opposite. Here, we assess the global carbon cycle response under SSP2-4.5 extended scenario with the GISS climate model, where an interesting case of AMOC bifurcation occurred: AMOC collapses in some ensemble members but not in others, even though all ensemble members are forced with the exact same forcing. Other studies of the response of the carbon cycle to AMOC collapsing have been carried out in hosing experiments where an external freshwater flux is applied in the North Atlantic subpolar gyre. Here, the AMOC collapse happens without the need to prescribe any such external forcing but arises from the model’s internal variability and in particular extreme freshening events in the Irminger Sea which is a site of deep water formation in the GISS modelE. We find that whereas the ocean global sink of carbon is similar in the AMOC-on and AMOC-off states, there are important regional differences in both the solubility and the biological component of the ocean carbon uptake.