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Sudden emergence of a shallow aragonite saturation horizon in the Southern Ocean

Nature Climate Change volume 9, pages 313–317 (2019)Cite this article

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Abstract

Models project that with current CO2 emission rates, the Southern Ocean surface will be undersaturated with respect to aragonite by the end of this century1,2,3,4. This will result in widespread impacts on biogeochemistry and ocean ecosystems5,6,7, particularly the health of aragonitic organisms, such as pteropods7, which can dominate polar surface water communities6. Here, we quantify the depth of the present-day Southern Ocean aragonite saturation horizon using hydrographic and ocean carbon chemistry observations, and use a large ensemble of simulations from the Community Earth System Model (CESM)8,9 to track its evolution. A new, shallow aragonite saturation horizon emerges in many Southern Ocean locations between now and the end of the century. While all ensemble members capture the emergence, internal climate variability may affect the year of emergence; thus, its detection may have been overlooked by ensemble average analysis in the past. The emergence of the new horizon is driven by the slow accumulation of anthropogenic CO2 in the Southern Ocean thermocline, where the carbonate ion concentration exhibits a local minimum and approaches undersaturation. The new horizon is also apparent under an emission-stabilizing scenario indicating an inevitable, sudden decrease in the volume of suitable habitat for aragonitic organisms.

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Fig. 1: Depth of aragonite saturation horizon.
Fig. 2: Emergence of shallow aragonite saturation horizon.
Fig. 3: Drivers of the sudden emergence of the shallow horizon.
Fig. 4: Year of emergence of shallow saturation horizon.

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Data availability

CESM ensemble output is available from the Earth System Grid (http://www.cesm.ucar.edu/projects/community-projects/LENS/data-sets.html). GLODAPv2 data can be accessed from the project webpage (https://www.glodap.info/). WOA data are provided by the National Oceanographic Data Center (https://www.nodc.noaa.gov/OC5/WOA09/pr_woa09.html).

References

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

    Article  CAS  Google Scholar 

  2. Hauri, C., Friedrich, T. & Timmermann, A. Abrupt onset and prolongation of aragonite undersaturation events in the Southern Ocean. Nat. Clim. Change 6, 172–176 (2016).

    Article  CAS  Google Scholar 

  3. Fabry, V. J., McClintock, J. B., Mathis, J. T. & Grebmeier, J. M. Ocean acidification at high latitudes: the bellwether. Oceanography 22, 160–171 (2009).

    Article  Google Scholar 

  4. 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).

    Article  CAS  Google Scholar 

  5. Moy, A. D., Howard, W. R., Bray, S. G. & Trull, T. W. Reduced calcification in modern Southern Ocean planktonic foraminifera. Nat. Geosci. 2, 276–280 (2009).

    Article  CAS  Google Scholar 

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

    Article  Google Scholar 

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

    Article  Google Scholar 

  8. Kay, J. E. et al. The Community Earth System Model (CESM) Large Ensemble project: A community resource for studying climate change in the presence of internal climate variability. Bull. Am. Meteorol. Soc. 96, 1333–1349 (2015).

    Article  Google Scholar 

  9. Lovenduski, N. S., McKinley, G. A., Fay, A. R., Lindsey, K. & Long, M. C. Partitioning uncertainty in ocean carbon uptake projections: Internal variability, emission scenario, and model structure. Global Biogeochem. Cycles 30, 1276–1287 (2016).

    Article  CAS  Google Scholar 

  10. Feely, R. A. et al. Impact of anthropogenic CO2 on the CaCO3 system in the oceans. Science 305, 362–366 (2004).

    Article  CAS  Google Scholar 

  11. Ciais, P. et al. in Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) Ch. 6 (IPCC, Cambridge Univ. Press, 2013).

  12. Le Quere, C. et al. Global carbon budget 2017. Earth Syst. Sci. Data 10, 405–448 (2018).

    Article  Google Scholar 

  13. Kroeker, K. J. et al. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biol. 19, 1884–1896 (2013).

    Article  Google Scholar 

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

    Article  CAS  Google Scholar 

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

    Article  Google Scholar 

  16. Sanderson, B. M., Oleson, K. W., Strand, W. G., Lehner, F. & O’Neill, B. C. A new ensemble of GCM simulations to assess avoided impacts in a climate mitigation scenario. Clim. Change 146, 303–318 (2015).

    Article  Google Scholar 

  17. Lovenduski, N. S., Gruber, N. & Doney, S. C. Toward a mechanistic understanding of the decadal trends in the Southern Ocean carbon sink. Global Biogeochem. Cycles 22, GB3016 (2008).

    Article  Google Scholar 

  18. Marshall, J. & Speer, K. Closure of the meridional overturning circulation through Southern Ocean upwelling. Nat. Geosci. 5, 171–180 (2012).

    Article  CAS  Google Scholar 

  19. Olsen, A. et al. The Global Ocean Data Analysis Project version 2 (GLODAPv2)—an internally consistent data product for the world ocean. Earth Syst. Sci. Data 8, 297–323 (2016).

    Article  Google Scholar 

  20. Lauvset, S. K. et al. A new global interior ocean mapped climatology: the 1° × 1° GLODAP version 2. Earth Syst. Sci. Data 8, 325–340 (2016).

    Article  Google Scholar 

  21. Conrad, C. J. & Lovenduski, N. S. Climate-driven variability in the Southern Ocean carbonate system. J. Clim. 28, 5335–5350 (2015).

    Article  Google Scholar 

  22. Xue, L. et al. Climatic modulation of surface acidification rates through summertime wind forcing in the southern ocean. Nat. Commun. 9, 3240 (2018).

    Article  Google Scholar 

  23. Sarmiento, J. L. & Gruber, N. Ocean Biogeochemical Dynamics (Princeton Univ. Press, Princeton, 2006).

    Google Scholar 

  24. Freiwald, A., Fossa, J. H., Grehan, A., Koslow, T. & Roberts, J. Cold-water Coral Reefs: Out of Sight—No Longer Out of Mind (UNEP-WCMC, 2004).

  25. Honjo, S., Francois, R., Manganini, S. J., Dymond, J. R. & Collier, R. W. Particle flux in the Pacific sector of the Southern Ocean. PANGAEA https://doi.org/10.1594/PANGAEA.787552 (2000) .

  26. Honjo, S. Particle export and the biological pump in the Southern Ocean. Antarct. Sci. 16, 501–516 (2004).

    Article  Google Scholar 

  27. Dadon, J. R. & de Cidre, L. L. The reproductive cycle of the thecosomatous pteropod limacina retroversa in the western South Atlantic. Marine Biol. 114, 439–442 (1992).

    Article  Google Scholar 

  28. Franco, A. C., Gruber, N., Frölicher, T. L. & Kropuenske Artman, L. Contrasting impact of future CO2 emission scenarios on the extent of the CaCO3 mineral undersaturation in the Humboldt current system. J. Geophys. Res. Oceans 123, 2018–2036 (2018).

    Article  CAS  Google Scholar 

  29. Lovenduski, N. S., Long, M. C. & Lindsay, K. Natural variability in the surface ocean carbonate ion concentration. Biogeosciences 12, 6321–6335 (2015).

    Article  Google Scholar 

  30. Williams, N. L. et al. Assessment of the carbonate chemistry seasonal cycles in the Southern Ocean from persistent observational platforms. J. Geophys. Res. Oceans 123, 4833–4852 (2018).

    Article  CAS  Google Scholar 

  31. Locarnini, R. A. et al. World Ocean Atlas 2009 Vol. 1 (ed. S. Levitus) (NOAA Atlas NESDIS 68, 2010).

  32. Antonov, J. I. et al. World Ocean Atlas 2009 Vol. 2 (ed. S. Levitus) (NOAA Atlas NESDIS 69, 2010).

  33. Garcia, H. E. et al. World Ocean Atlas 2009 Vol. 4 (ed. S. Levitus) (NOAA Atlas NESDIS 71, 2010).

  34. Orr, J. C. & Epitalon, J.-M. Improved routines to model the ocean carbonate system: mocsy 2.0. Geosci. Model Dev. 8, 485–499 (2015).

    Article  CAS  Google Scholar 

  35. Lee, K. et al. The universal ratio of boron to chlorinity for the North Pacific and North Atlantic oceans. Geochim. Cosmochim. Acta 74, 1801–1811 (2010).

    Article  CAS  Google Scholar 

  36. Lueker, T. J., Dickson, A. G. & Keeling, C. D. Ocean cCO2 calculated from dissolved inorganic carbon, alkalinity, and equations for k1 and k2: validation based on laboratory measurements of CO2 in gas and seawater at equilibrium. Marine Chem. 70, 105–119 (2000).

    Article  CAS  Google Scholar 

  37. Dickson, A. G. & Riley, J. P. The estimation of acid dissociation constants in seawater media from potentiometric titrations with strong base. I. The iconic product of water -- k w.Marine Chem. 7, 89–99 (1979).

    Article  CAS  Google Scholar 

  38. Hurrell, J. W. et al. The Community Earth System Model: A framework for collaborative research. Bull. Am. Meteorol. Soc. 94, 1339–1360 (2013).

    Article  Google Scholar 

  39. Long, M. C., Lindsay, K., Peacock, S., Moore, J. K. & Doney, S. C. Twentieth-century oceanic carbon uptake and storage in CESM1(BGC). J. Clim. 26, 6775–6800 (2013).

    Article  Google Scholar 

  40. Landrum, L., Holland, M. M., Schneider, D. P. & Hunke, E. Antarctic sea ice climatology, variability, and late twentieth-century change in CCSM4. J. Clim. 25, 4817–4838 (2012).

    Article  Google Scholar 

  41. Jiang, L.-Q. et al. Climatological distribution of aragonite saturation state in the global oceans. Global Biogeochem. Cycles 29, 1656–1673 (2015).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

N.S.L., G.N.-G. and K.M.K. are grateful for support from the National Science Foundation (grant nos. OCE-1558225 and PLR-1543457). G.N.-G. was supported, in part, by the Significant Opportunities in Atmospheric Research and Science (SOARS) programme, NSF grant no. AGS-1641177. C.H. acknowledges support from the National Science Foundation (grant no. OCE-1459834). CESM computing resources were provided by CISL at NCAR. We thank B. Medeiros for providing model re-gridding scripts and N. Freeman for helpful comments on an earlier version of the manuscript.

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Author notes

  1. Gabriela Negrete-García

    Present address: Integrative Oceanography Division, Scripps Institution of Oceanography, La Jolla, CA, USA

  2. Kristen M. Krumhardt

    Present address: Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO, USA

Authors and Affiliations

  1. Department of Atmospheric and Oceanic Sciences and Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, CO, USA

    Gabriela Negrete-García & Nicole S. Lovenduski

  2. International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, AK, USA

    Claudine Hauri

  3. Environmental Studies Program and Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, CO, USA

    Kristen M. Krumhardt

  4. NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway

    Siv K. Lauvset

  5. Geophysical Institute, University of Bergen and Bjerknes Centre for Climate Research, Bergen, Norway

    Siv K. Lauvset

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Contributions

N.S.L. and K.M.K. re-gridded the CESM-LE and CESM-ME DIC output to the GLODAP/WOA grid, corrected the model DIC bias and calculated the aragonite saturation state from the bias-corrected model DIC projections. S.K.L. provided the modified GLODAPv2 mapped climatologies and expertise. G.N.-G. analysed the bias-corrected projections and wrote the manuscript. All authors were involved in the study design, discussed the results and helped write the manuscript.

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Correspondence to Nicole S. Lovenduski.

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Journal Peer Review information: Nature Climate Change thanks Nancy Williams and other anonymous reviewer(s) for their contribution to the peer review of this work.

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Negrete-García, G., Lovenduski, N.S., Hauri, C. et al. Sudden emergence of a shallow aragonite saturation horizon in the Southern Ocean. Nat. Clim. Chang. 9, 313–317 (2019). https://doi.org/10.1038/s41558-019-0418-8

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