Abstract: Ocean acidification (OA) has been an important research topic for a decade. Given that 30%—40% of ocean uptake of anthropogenic CO₂ occurs in the Southern Ocean (SO), and that the SO consists of high-latitude waters with low buffering capacity, a greater understanding of OA and the factors that affect it is particularly necessary. The OA-mediated decline in the seawater carbonate ion concentration and the carbonate saturation state, which dramatically impairs the ability of calcifying organisms to form calcium carbonate (including aragonite and calcite), will eventually have an adverse impact on the marine ecosystem. It is critical to understand the OA responses and predict their resulting impact on the carbonate system and ecosystem of the SO. In this article, we review studies of the acidification of SO surface waters and provide an overview of the acidification of the open ocean and representative marginal seas and bays of the SO. Additionally, we identify future trends in OA research, as well as some urgent problems.

Key words: Southern Ocean, Ocean acidification, Carbonate chemistry, pH, Aragonite saturation state