Current understanding and challenges for oceans in a higher-CO2 world


Ocean acidification is a global phenomenon, but it is overlaid by pronounced regional variability modulated by local physics, chemistry and biology. Recognition of its multifaceted nature and the interplay of acidification with other ocean drivers has led to international and regional initiatives to establish observation networks and develop unifying principles for biological responses. There is growing awareness of the threat presented by ocean acidification to ecosystem services and the socio-economic consequences are becoming increasingly apparent and quantifiable. In this higher-CO2 world, future challenges involve better design and rigorous testing of adaptation, mitigation and intervention options to offset the effects of ocean acidification at scales ranging from local to regional.

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Fig. 1: Projections of atmospheric CO2 and associated marine carbonate chemistry changes.
Fig. 2: Temporal trends in confidence in our understanding for key themes across OA research.
Fig. 3: Comparison of variability in seawater pH across a range of locations and scales.
Fig. 4: Ecosystems, OA and global ocean change.
Fig. 5: Annual average climatology of the aragonite saturation state for open-ocean surface waters.


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We acknowledge the sponsors and participants of the 4th International Symposium on the Ocean in a High CO2 World and the 3rd Global Ocean Acidification Observing Network workshop that helped define the research needs and directions. This project was supported under Australian Research Council’s Special Research Initiative for Antarctic Gateway Partnership (Project ID SR140300001). P.W.B. acknowledges support from the Australian Research Council (Laureate Fellowship FL160100131). B.T. and P.W.B were supported by Antarctic Climate and Ecosystem Co-operative Research Centre.

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Correspondence to Catriona L. Hurd.

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Hurd, C.L., Lenton, A., Tilbrook, B. et al. Current understanding and challenges for oceans in a higher-CO2 world. Nature Clim Change 8, 686–694 (2018).

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