Abstract

The North Atlantic is one of the most effective regions of the global ocean for atmospheric carbon uptake and long-term carbon storage. Understanding the mechanisms of carbon uptake and storage in the North Atlantic under a changing climate is crucial for studying the global carbon cycle. In this talk, I will present recent modelling studies investigating the drivers of changes in the North Atlantic carbon sink, conducted as part of the C-Streams project (https://c-streams.uk/). The first part of the presentation will introduce the project and the development of a model framework based on Estimating the Circulation and Climate of the Ocean version 4 release 2 (ECCOv4r2), coupled to an ocean biogeochemistry model (ECCOv4r2-DIC). The second part will present recent results from a suite of sensitivity experiments, highlighting the roles of rising atmospheric CO2 and warming using idealised 1% per year CO2 increase experiments with ECC Ov4r2-DIC. I will discuss both the direct effects of increasing atmospheric CO2 and ocean warming, and the indirect effects arising from warming-induced modifications to ocean circulation and transport, with a focus on the Gulf Stream and the subpolar North Atlantic. The idealised experiments show that the increase in atmospheric CO2 is the dominant driver of enhanced carbon uptake along the Gulf Stream and in the subpolar North Atlantic. However, the spatial pattern of warming can modulate carbon uptake in the subpolar region, reflecting both local and remote impacts of warming on ocean transport and mixing.