Oral

IAPSO

P01 - General Topics in Oceanography (physics and boiogeochemistry)

Emergence of an oceanic CO2 uptake hole under global warming

The ocean serves as an important sink for anthropogenic CO2 emissions, yet uncertainties persist regarding its future changes. Here, we employ the Community Earth System Model (CESM2), conducting scenarios with different CO2 emission rates, to investigate the response of ocean CO2 uptake. We find the pronounced weakening of CO2 uptake in the Subpolar North Atlantic (SPNA), which is distinct from the global ocean response. In the beginning of the scenarios, the SPNA is an effective CO2 sink, but this uptake decreases due to the weakening of deep convection around the Labrador?Irminger Seas region and the rising of its oceanic pCO2 beyond the global average. Given the critical influence of regional ocean circulation on CO2 uptake, we find a nonlinear relationship between the surrounding environment and the uptake response, establishing consistent thresholds for the emergence of the uptake weakening. Furthermore, these findings are generally reproduced in the Coupled Model Intercomparison Project Phase 6, supporting the reliability of the phenomena. Overall, the distinct uptake response reflects a notable role of the regional dynamics in regulating CO2 budget and geochemical environment, which is worthy of consideration in regional CO2 mitigation strategies.