Editorial: Role of the Southern Ocean in atmospheric pCO2 change: observations, simulations and paleorecords

The Southern Ocean plays a key role in atmospheric CO2 sequestration, accounting for ~40-50% of the anthropogenic CO2 absorbed by the modern ocean (Landschützer et al., 2015; Gruber et al., 2019). The Southern Ocean also played a critical role in modulating variation in the atmospheric partial pressure of carbon dioxide (pCO2) in the geologic past on both orbital and millennial timescales (Anderson et al., 2009; Sigman et al., 2010; Gottschalk et al., 2016). Moreover, the Southern Ocean influences atmospheric and oceanic circulation in the tropics remotely, including low-latitude atmospheric CO2 exchange (Sarmiento et al., 2004; Hendry and Brzezinski, 2014; Sigman et al., 2021). Thus, the Southern Ocean is a key component of the global climate system through its influence on atmospheric CO2 variations at a range of timescales (Fischer et al., 2010; Rae et al., 2018; Dong et al., 2024). However, the processes and mechanisms of Southern Ocean influence on atmospheric pCO2 and global climate changes are still not well understood. To fill this gap, this Research Topic integrates the results of modern observations, paleoclimate data, and model simulations to promote a comprehensive understanding of the significance of the Southern Ocean in global climate change from the perspective of the carbon cycle. This Research Topic collected 12 articles, including 11 original research articles and 1 perspective article. The articles focus on in-situ analyses of carbon and other nutrients and watermass factors, recent advances in simulation of the effects of overturning circulation on atmospheric pCO2, and palaeoceanographic reconstructions of carbon cycle (-related) processes. These articles can be classified into the three themes explored below