Antarctic sea ice control on ocean circulation in present and glacial climates
In the modern climate, the ocean below 2 km is mainly filled by waters sinking into the abyss around Antarctica and in the North Atlantic. Paleoproxies indicate that waters of North Atlantic origin were instead absent below 2 km at the Last Glacial Maximum, resulting in an expansion of the volume oc...
| Published in: | Proceedings of the National Academy of Sciences |
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| Main Authors: | , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Published: |
National Academy of Sciences
2014
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| Subjects: | |
| Online Access: | https://doi.org/10.1073/pnas.1323922111 https://www.ncbi.nlm.nih.gov/pmc/PMC4066517 |
| Summary: | In the modern climate, the ocean below 2 km is mainly filled by waters sinking into the abyss around Antarctica and in the North Atlantic. Paleoproxies indicate that waters of North Atlantic origin were instead absent below 2 km at the Last Glacial Maximum, resulting in an expansion of the volume occupied by Antarctic origin waters. In this study we show that this rearrangement of deep water masses is dynamically linked to the expansion of summer sea ice around Antarctica. A simple theory further suggests that these deep waters only came to the surface under sea ice, which insulated them from atmospheric forcing, and were weakly mixed with overlying waters, thus being able to store carbon for long times. This unappreciated link between the expansion of sea ice and the appearance of a voluminous and insulated water mass may help quantify the ocean's role in regulating atmospheric carbon dioxide on glacial–interglacial timescales. Previous studies pointed to many independent changes in ocean physics to account for the observed swings in atmospheric carbon dioxide. Here it is shown that many of these changes are dynamically linked and therefore must co-occur. © 2014 National Academy of Sciences. Freely available online through the PNAS open access option. Published online before print June 2, 2014. Edited by Edward A. Boyle, Massachusetts Institute of Technology, Cambridge, MA, and approved April 16, 2014 (received for review December 31, 2013). L.P. Nadeau helped with figures. All authors acknowledge support from the National Science Foundation. R.F. acknowledges support from the Breene M. Kerr Chair. Author contributions: R.F. designed research; R.F., M.F.J., J.A., A.B., A.L.S., and A.F.T. performed research; R.F. and M.F.J. analyzed data; and R.F. wrote the paper. The authors declare no conflict of interest. This Direct Submission article had a prearranged editor. This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1323922111/-/DCSupplemental. Published - ... |
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