Emergence of the ocean CO2 uptake hole under global warming

Abstract Understanding the carbon cycle is crucial for an accurate assessment of emission allowances, which requires to mitigate climate change within the limits of human tolerance. The oceanic carbon system is an important reservoir for anthropogenic CO2 emissions, yet uncertainties persist regarding its future changes. Here, we employ the state-of-the-art model with different CO2 emission rates to systematically investigate the response of ocean CO2 uptake. We reveal the possibility of a pronounced weakening of the uptake–CO2 uptake hole–in the Subpolar North Atlantic (SPNA), where it is currently one of the most effective oceanic carbon sinks. Explosive accumulation of the surface dissolved inorganic carbon initiates the uptake hole, resulting from the collapse of local deep convection. The emergence of the uptake hole underscores the role of dynamical feedback in the carbon cycle, hence worthy of consideration in regional strategies for carbon dioxide removal.