Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

No signature of abyssal carbon in intermediate waters off Chile during deglaciation


At the end of the Last Glacial Maximum (19,000 to 11,000 years ago), atmospheric carbon dioxide concentrations rose while the Δ14C of atmospheric carbon dioxide declined1,2. These changes have been attributed to an injection of carbon dioxide with low radiocarbon activity from an oceanic abyssal reservoir that was isolated from the atmosphere for several thousand years before deglaciation3. The current understanding points to the Southern Ocean as the main area of exchange between these reservoirs4. Intermediate water formed in the Southern Ocean surrounding Antarctica would have then carried the old carbon dioxide signature to the lower-latitude oceans5,6. Here we reconstruct the Δ14C signature of Antarctic Intermediate Water off the coast of Chile for the past 20,000 years, using paired 14C ages of benthic and planktonic foraminifera. In contrast to the above scenario, we find that the Δ14C signature of the Antarctic Intermediate Water closely matches the modelled surface ocean Δ14C, precluding the influence of an old carbon source. We suggest that if the abyssal ocean is indeed the source of the radiocarbon-depleted carbon dioxide, an alternative path for the mixing and propagation of its carbon dioxide may be required to explain the observed changes in atmospheric carbon dioxide concentration and radiocarbon activity.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: The study area and core locations.
Figure 2: Apparent age difference between paired benthic and planktonic foraminifera in core SO161-SL22.
Figure 3: Deglacial radiocarbon activity of Pacific intermediate waters.


  1. Monnin, E. et al. Atmospheric CO2 concentrations over the last glacial termination. Science 291, 112–114 (2001).

    Article  Google Scholar 

  2. Hughen, K., Southon, J., Lehman, S., Bertrand, C. & Turnbull, J. Marine-derived 14C calibration and activity record for the past 50,000 years updated from the Cariaco Basin. Quat. Sci. Rev. 25, 3216–3227 (2006).

    Article  Google Scholar 

  3. Broecker, W. & Barker, S. A 190‰ drop in atmosphere’s Δ14C during the ‘Mystery Interval’ (17.5–14.5 kyr). Earth Planet. Sci. Lett. 256, 90–99 (2007).

    Article  Google Scholar 

  4. Fischer, H. et al. The role of Southern Ocean processes in orbital and millennial CO2 variations— A synthesis. Quat. Sci. Rev. 10.1016/j.quascirev.2009.06.007 (2009).

  5. Marchitto, T., Lehman, S., Ortiz, J., Fluckiger, J. & van Geen, A. Marine radiocarbon evidence for the mechanism of deglacial atmospheric CO2 rise. Science 316, 1456–1459 (2007).

    Article  Google Scholar 

  6. Spero, H. & Lea, D. The cause of carbon isotope minimum events on glacial terminations. Science 296, 522–525 (2002).

    Article  Google Scholar 

  7. Fairbanks, R. et al. Radiocarbon calibration curve spanning 0–50,000 years BP based on paired Th-230/U-234/U-238 and C-14 dates on pristine corals. Quat. Sci. Rev. 24, 1781–1796 (2005).

    Article  Google Scholar 

  8. Beck, J. et al. Extremely large variations of atmospheric 14C concentration during the last glacial period. Science 292, 2453–2458 (2001).

    Article  Google Scholar 

  9. Stephens, B. & Keeling, R. The influence of Antarctic sea ice on glacial–interglacial CO2 variations. Nature 404, 171–174 (2000).

    Article  Google Scholar 

  10. Francois, R. et al. Contribution of Southern Ocean surface-water stratification to low atmospheric CO2 concentrations during the last glacial period. Nature 389, 929–935 (1997).

    Article  Google Scholar 

  11. Adkins, J., McIntyre, K. & Schrag, D. The salinity, temperature, and δ18O of the glacial deep ocean. Science 298, 1769–1773 (2002).

    Article  Google Scholar 

  12. Sikes, E. L., Samson, C. R., Guilderson, T. P. & Howard, W. R. Old radiocarbon ages in the southwest Pacific Ocean during the last glacial period and deglaciation. Nature 405, 555–559 (2000).

    Article  Google Scholar 

  13. Stott, L., Southon, J., Timmermann, A. & Koutavas, A. Radiocarbon age anomaly at intermediate water depth in the Pacific Ocean during the last deglaciation. Paleoceanography 24, PA2223 (2009).

    Article  Google Scholar 

  14. Anderson, R. et al. Wind-driven upwelling in the southern ocean and the deglacial rise in atmospheric CO2 . Science 323, 1443–1448 (2009).

    Article  Google Scholar 

  15. Toggweiler, J. Shifting westerlies. Science 323, 1434–1435 (2009).

    Article  Google Scholar 

  16. Sloyan, B. & Rintoul, S. Circulation, renewal, and modification of Antarctic mode and intermediate water. J. Phys. Oceanogr. 31, 1005–1030 (2001).

    Article  Google Scholar 

  17. Iudicone, D., Rodgers, K., Schopp, R. & Madec, G. An exchange window for the injection of Antarctic Intermediate Water into the South Pacific. J. Phys. Oceanogr. 37, 31–49 (2007).

    Article  Google Scholar 

  18. Schneider, W. & Bravo, L. Argo profiling floats document Subantarctic Mode Water formation west of Drake Passage. Geophys. Res. Lett. 33, L16609 (2006).

    Article  Google Scholar 

  19. Butzin, M., Prange, M. & Lohmann, G. Radiocarbon simulations for the glacial ocean: The effects of wind stress, Southern Ocean sea ice and Heinrich events. Earth Planet. Sci. Lett. 235, 45–61 (2005).

    Article  Google Scholar 

  20. Key, R. et al. A global ocean carbon climatology: Results from Global Data Analysis Project (GLODAP). Glob. Biogeochem. Cycles 18, GB4031 (2004).

    Article  Google Scholar 

  21. Pahnke, K., Goldstein, S. & Hemming, S. Abrupt changes in Antarctic Intermediate water circulation over the past 25,000 years. Nature Geosci. 1, 870–874 (2008).

    Article  Google Scholar 

  22. Toggweiler, J., Russell, J. & Carson, S. Midlatitude westerlies, atmospheric CO2, and climate change during the ice ages. Paleoceanography 21, PA2005 (2006).

    Article  Google Scholar 

  23. Knorr, G. & Lohmann, G. Southern Ocean origin for the resumption of Atlantic thermohaline circulation during deglaciation. Nature 424, 532–536 (2003).

    Article  Google Scholar 

  24. Pahnke, K. & Zahn, R. Southern Hemisphere water mass conversion linked with North Atlantic climate variability. Science 307, 1741–1746 (2005).

    Article  Google Scholar 

  25. Bostock, H., Opdyke, B., Gagan, M. & Fifield, L. Carbon isotope evidence for changes in Antarctic Intermediate Water circulation and ocean ventilation in the southwest Pacific during the last deglaciation. Paleoceanography 19, PA4013 (2004).

    Article  Google Scholar 

  26. Broecker, W. The mysterious C-14 decline. Radiocarbon 51, 109–119 (2009).

    Article  Google Scholar 

  27. Mohtadi, M. et al. Deglacial pattern of circulation and marine productivity in the upwelling region off central-south Chile. Earth Planet. Sci. Lett. 272, 221–230 (2008).

    Article  Google Scholar 

Download references


We thank M. Carman and the National Ocean Science Accelerator Mass Spectrometer Facility and Keck Carbon Cycle Accelerator Mass Spectrometer staff for technical support. Financial support for this work came from the NSF grant OCE-0751643. R.D.P.-H. was supported by the Cooperative Institute for Climate and Ocean Research (CICOR) postdoctoral fellowship at the Woods Hole Oceanographic Institution.

Author information

Authors and Affiliations



R.D.P.-H. and L.K. conceived the study. R.D.P.-H. collected the foraminifera and wrote the paper with the help of all the co-authors. J.S. supplied ideas that shaped the final version. D.H. and M.M. collected the core material and provided the samples. Core SO161-SL22 was retrieved for M.M. doctoral thesis work. All authors contributed to the writing of this manuscript.

Corresponding author

Correspondence to Ricardo De Pol-Holz.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 432 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

De Pol-Holz, R., Keigwin, L., Southon, J. et al. No signature of abyssal carbon in intermediate waters off Chile during deglaciation. Nature Geosci 3, 192–195 (2010).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing