Global warming amplified by reduced sulphur fluxes as a result of ocean acidification

Abstract

Using computer simulations, this study quantifies the potential effect of ocean acidification on marine biogenic sulphur emissions and the resulting feedback mechanisms on future climate. It 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 due to changes in biogenic sulphur production. Climate change and decreasing seawater pH (ocean acidification)1 have widely been considered as uncoupled consequences of the anthropogenic CO2 perturbation2,3. Recently, experiments in seawater enclosures (mesocosms) showed that concentrations of dimethylsulphide (DMS), a biogenic sulphur compound, were markedly lower in a low-pH environment4. Marine DMS emissions are the largest natural source of atmospheric sulphur5 and changes in their strength have the potential to alter the Earth’s radiation budget6. Here we establish observational-based relationships between pH changes and DMS concentrations to estimate changes in future DMS emissions with Earth system model7 climate simulations. Global DMS emissions decrease by about 18(±3)% in 2100 compared with pre-industrial times as a result of the combined effects of ocean acidification and climate change. The reduced DMS emissions induce a significant additional radiative forcing, of which 83% is attributed to the impact of ocean acidification, tantamount to an equilibrium temperature response between 0.23 and 0.48 K. Our results indicate that ocean acidification has the potential to exacerbate anthropogenic warming through a mechanism that is not considered at present in projections of future climate change.

Cite this article

Six, K., Kloster, S., Ilyina, T. et al. Global warming amplified by reduced sulphur fluxes as a result of ocean acidification. Nature Clim Change 3, 975–978 (2013). https://doi.org/10.1038/nclimate1981

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