Ocean acidification has the potential to amplify climate warming through the decreased production of a biogenic sulphur compound. A study online in Nature Climate Change this week reports that decreased seawater pH results in lower concentrations of dimethylsulphide. Marine emissions are the largest natural source of atmospheric sulphur - which increases the reflectivity of the atmosphere to incoming radiation, reducing surface temperatures.
Katharina Six and colleagues used knowledge of pH changes and dimethylsulphide concentrations in seawater to estimate changes in future marine biogenic sulphur emissions under different climate scenarios. They project that a reduction in marine biogenic sulphur emissions of around 18% by 2100 will induce significant extra radiative forcing, equivalent to 0.23-0.48 °C of warming.
The study emphasizes that a reduction of anthropogenic carbon dioxide emissions is not only necessary to limit the negative effects of ocean acidification on marine life, but also to avoid amplified climate warming from changes in biogenic sulphur production.