Abrupt onset and prolongation of aragonite undersaturation events in the Southern Ocean


Ocean acidification may lead to seasonal aragonite undersaturation in surface waters of the Southern Ocean as early as 2030 (ref. 1). These conditions are harmful to key organisms such as pteropods2, which contribute significantly to the pelagic foodweb and carbon export fluxes in this region3. Although the severity of ocean acidification impacts is mainly determined by the duration, intensity and spatial extent of aragonite undersaturation events, little is known about the nature of these events, their evolving attributes and the timing of their onset in the Southern Ocean. Using an ensemble of ten Earth system models, we show that starting around 2030, aragonite undersaturation events will spread rapidly, affecting 30% of Southern Ocean surface waters by 2060 and >70% by 2100, including the Patagonian Shelf. On their onset, the duration of these events will increase abruptly from 1 month to 6 months per year in less than 20 years in >75% of the area affected by end-of-century aragonite undersaturation. This is likely to decrease the ability of organisms to adapt to a quickly evolving environment4. The rapid equatorward progression of surface aragonite undersaturation can be explained by the uptake of anthropogenic CO2, whereas climate-driven physical or biological changes will play a minor role.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Duration of aragonite undersaturation events in months per year.
Figure 2: Spatial extent and regional progression of aragonite undersaturation events.
Figure 3: Transition time from short (1 month per year) to long (6 months per year) aragonite undersaturation events.


  1. 1

    McNeil, B. I. & Matear, R. J. Southern Ocean acidification: A tipping point at 450-ppm atmospheric CO2 . Proc. Natl Acad. Sci. USA 105, 18860–18864 (2008).

    CAS  Article  Google Scholar 

  2. 2

    Bednaršek, N. et al. Extensive dissolution of live pteropods in the Southern Ocean. Nature Geosci. 5, 881–885 (2012).

    Article  Google Scholar 

  3. 3

    Hunt, B. P. V. et al. Pteropods in Southern Ocean ecosystems. Prog. Oceanogr. 78, 193–221 (2008).

    Article  Google Scholar 

  4. 4

    Sunday, J. M. et al. Evolution in an acidifying ocean. Trends Ecol. Evol. 29, 117–125 (2014).

    Article  Google Scholar 

  5. 5

    Sarmiento, J. L., Gruber, N., Brzezinski, M. A. & Dunne, J. P. High-latitude controls of thermocline nutrients and low latitude biological productivity. Nature 427, 56–60 (2004).

    CAS  Article  Google Scholar 

  6. 6

    Gruber, N. et al. Oceanic sources, sinks, and transport of atmospheric CO2 . Glob. Biogeochem. Cycles 23, 1–21 (2009).

    Article  Google Scholar 

  7. 7

    Brooks, C. M. Competing values on the Antarctic high seas: CCAMLR and the challenge of marine-protected areas. Polar J. 3, 277–300 (2013).

    Article  Google Scholar 

  8. 8

    Schofield, O. et al. How do polar marine ecosystems respond to rapid climate change? Science 328, 1520–1523 (2010).

    CAS  Article  Google Scholar 

  9. 9

    Bromwich, D. H. et al. Central West Antarctica among the most rapidly warming regions on Earth. Nature Geosci. 6, 139–145 (2012).

    Article  Google Scholar 

  10. 10

    Kawaguchi, S. et al. Risk maps for Antarctic krill under projected Southern Ocean acidification. Nature Clim. Change 3, 843–847 (2013).

    CAS  Article  Google Scholar 

  11. 11

    Orr, J. C. et al. Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature 437, 681–686 (2005).

    CAS  Article  Google Scholar 

  12. 12

    Ries, J. B., Cohen, A. L. & McCorkle, D. C. Marine calcifiers exhibit mixed responses to CO2-induced ocean acidification. Geology 37, 1131–1134 (2009).

    CAS  Article  Google Scholar 

  13. 13

    Tebaldi, C. & Knutti, R. The use of the multi-model ensemble in probabilistic climate projections. Phil. Trans. R. Soc. A 365, 2053–2075 (2007).

    Article  Google Scholar 

  14. 14

    Friedrich, T. et al. Detecting regional anthropogenic trends in ocean acidification against natural variability. Nature Clim. Change 2, 167–171 (2012).

    CAS  Article  Google Scholar 

  15. 15

    Hauri, C., Gruber, N., McDonnell, A. M. P. & Vogt, M. The intensity, duration, and severity of low aragonite saturation state events on the California continental shelf. Geophys. Res. Lett. 40, 1–5 (2013).

    Article  Google Scholar 

  16. 16

    Orr, J. C. in Ocean Acidification Vol. 2 (eds Gattuso, J.-P. & Hansson, L.) 41–66 (Oxford Univ. Press, 2011).

    Google Scholar 

  17. 17

    Wood, H. L., Spicer, J. I. & Widdicombe, S. Ocean acidification may increase calcification rates, but at a cost. Proc. Biol. Sci. 275, 1767–1773 (2008).

    Article  Google Scholar 

  18. 18

    Seibel, B. A., Maas, A. E. & Dierssen, H. M. Energetic plasticity underlies a variable response to ocean acidification in the pteropod, Limacina helicina antarctica. PLoS ONE 7, e30464 (2012).

    CAS  Article  Google Scholar 

  19. 19

    IPCC Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) (Cambridge Univ. Press, 2013).

  20. 20

    Hauri, C. et al. Inorganic carbon dynamics along the Western Antarctic Peninsula from 1998 until 2013. Biogeosci. Discuss. 12, 6929–6969 (2015).

    Article  Google Scholar 

  21. 21

    McNeil, B. I., Sweeney, C. & Gibson, J. A. E. Short note: Natural seasonal variability of aragonite saturation state within two Antarctic coastal ocean sites. Antarct. Sci. 23, 411–412 (2011).

    Article  Google Scholar 

  22. 22

    Lewis, C. N., Brown, K. A., Edwards, L. A., Cooper, G. & Findlay, H. S. Sensitivity to ocean acidification parallels natural pCO2 gradients experienced by Arctic copepods under winter sea ice. Proc. Natl Acad. Sci. USA 110, E4960–E4967 (2013).

    CAS  Article  Google Scholar 

  23. 23

    Espinoza, P. & Bertrand, A. Revisiting Peruvian anchovy (Engraulis ringens) trophodynamics provides a new vision of the Humboldt Current system. Prog. Oceanogr. 79, 215–227 (2008).

    Article  Google Scholar 

  24. 24

    Montecino, V. & Lange, C. B. The Humboldt current system: Ecosystem components and processes, fisheries, and sediment studies. Prog. Oceanogr. 83, 65–79 (2009).

    Article  Google Scholar 

  25. 25

    Bisbal, G. A. The Southeast South American shelf large marine ecosystem. Mar. Policy 19, 21–38 (1995).

    Article  Google Scholar 

  26. 26

    Carrillo, C. J., Smith, R. C. & Karl, D. M. Processes regulating oxygen and carbon dioxide in surface waters west of the Antarctic Peninsula. Mar. Chem. 84, 161–179 (2004).

    CAS  Article  Google Scholar 

  27. 27

    Bednaršek, N., Tarling, G. A., Fielding, S. & Bakker, D. C. E. Population dynamics and biogeochemical significance of Limacina helicina antarctica in the Scotia Sea (Southern Ocean). Deep-Sea Res. II 59–60, 105–116 (2012).

    Article  Google Scholar 

  28. 28

    Meijers, A. J. S. The Southern Ocean in the coupled model intercomparison project phase 5. Phil. Trans. R. Soc. A 372, 20130296 (2014).

    CAS  Article  Google Scholar 

  29. 29

    Doney, S. C., Fabry, V. J., Feely, R. A. & Kleypas, J. A. Ocean acidification: The other CO2 problem. Ann. Rev. Mar. Sci. 1, 169–192 (2009).

    Article  Google Scholar 

  30. 30

    Hauck, J. et al. On the Southern Ocean CO2 uptake and the role of the biological carbon pump in the 21st century. Glob. Biogeochem. Cycles http://dx.doi.org/10.1002/2015GB005140 (2015).

  31. 31

    Montes-Hugo, M. et al. Recent changes in phytoplankton communities associated with rapid regional climate change along the western Antarctic Peninsula. Science 323, 1470–1473 (2009).

    CAS  Article  Google Scholar 

  32. 32

    Hoppe, C. J. M., Holtz, L.-M., Trimborn, S. & Rost, B. Ocean acidification decreases the light-use efficiency in an Antarctic diatom under dynamic but not constant light. New Phytol. http://dx.doi.org/10.1111/nph.13334 (2015).

  33. 33

    Midorikawa, T. et al. Decreasing pH trend estimated from 35-year time series of carbonate parameters in the Pacific sector of the Southern Ocean in summer. Deep-Sea Res. I 61, 131–139 (2012).

    CAS  Article  Google Scholar 

Download references


We acknowledge support from the National Science Foundation Ocean Acidification Program (OCE-1314209). This is IPRC publication no. 1152 and SOEST publication no. 9508.

Author information




T.F. prepared and analysed the model output. C.H. analysed the model output and wrote the paper. All authors were involved in the study design, discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Claudine Hauri.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Hauri, C., Friedrich, T. & Timmermann, A. Abrupt onset and prolongation of aragonite undersaturation events in the Southern Ocean. Nature Clim Change 6, 172–176 (2016). https://doi.org/10.1038/nclimate2844

Download citation

Further reading