title: Antarctic sea ice control on ocean circulation in present and glacial climates.
abstract: 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.
authors.affiliation: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139; rferrari@mit.edu.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Ferrari
authors.affiliation: Atmospheric and Oceanic Sciences Program, Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08544; and.
authors.forename: Malte F
authors.initials: MF
authors.lastname: Jansen
authors.affiliation: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.
authors.forename: Jess F
authors.initials: JF
authors.lastname: Adkins
authors.affiliation: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.
authors.forename: Andrea
authors.initials: A
authors.lastname: Burke
authors.affiliation: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Stewart
authors.affiliation: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125.
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Thompson
mesh_terms: D000465:Algorithms; D000864:Antarctic Regions; D057486:Carbon Cycle; D002980:Climate; D003198:Computer Simulation; D046448:Ice Cover; D008962:Models, Theoretical; D009791:Oceanography; D009792:Oceans and Seas; D012623:Seawater; D013997:Time Factors; D014872:Water Movements
keywords: Southern Ocean; carbon cycle; ice age; ocean circulation; paleoceanography