The presence of the Tibetan Plateau lowers atmospheric CO2 levels via the Atlantic-Pacific carbon seesaw

Abstract

The presence of the Tibetan Plateau is believed to lower pCO₂^atm by stimulating weathering carbon sink, during which the global ocean is considered a passive carbon reservoir despite the tremendous marine carbon inventory. Yet, recent studies reveal that the orographic forcing of the Tibetan Plateau could lead to drastic changes in ocean circulation, which would substantially affect basin-scale carbon storage and hence pCO₂^atm. However, this connection between the presence of the Tibetan Plateau and changes in the oceanic carbon inventory remains insufficiently investigated. Here, by employing a state-of-the-art ocean-biogeochemical model, we explore the role of the Tibetan Plateau in determining basin-scale carbon storage patterns based on an idealized experimental design. We find that the presence of the Tibetan Plateau substantially enhances deep Pacific carbon storage and hence lowers pCO₂^atm via essential reorganization of the meridional overturning circulation, particularly associated with the development of the Pacific halocline. Moreover, the presence of the Tibetan Plateau greatly affects the oceanic carbon uptake in the Northern Hemisphere, which is likely controlled by the variations in surface alkalinity.