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Nonlinear threshold behavior during the loss of Arctic sea ice

Eisenman, I. and Wettlaufer, J. S. (2009) Nonlinear threshold behavior during the loss of Arctic sea ice. Proceedings of the National Academy of Sciences of the United States of America, 106 (1). pp. 28-32. ISSN 0027-8424. PMCID PMC2629232. doi:10.1073/pnas.0806887106.

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In light of the rapid recent retreat of Arctic sea ice, a number of studies have discussed the possibility of a critical threshold (or “tipping point”) beyond which the ice–albedo feedback causes the ice cover to melt away in an irreversible process. The focus has typically been centered on the annual minimum (September) ice cover, which is often seen as particularly susceptible to destabilization by the ice–albedo feedback. Here, we examine the central physical processes associated with the transition from ice-covered to ice-free Arctic Ocean conditions. We show that although the ice–albedo feedback promotes the existence of multiple ice-cover states, the stabilizing thermodynamic effects of sea ice mitigate this when the Arctic Ocean is ice covered during a sufficiently large fraction of the year. These results suggest that critical threshold behavior is unlikely during the approach from current perennial sea-ice conditions to seasonally ice-free conditions. In a further warmed climate, however, we find that a critical threshold associated with the sudden loss of the remaining wintertime-only sea ice cover may be likely.

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Additional Information:© 2009 by The National Academy of Sciences of the USA. Edited by Carl Wunsch, Massachusetts Institute of Technology, Cambridge, MA, and approved November 14, 2008 (received for review July 25, 2008). Published online before print December 24, 2008, doi:10.1073/pnas.0806887106 We thank the Geophysical Fluid Dynamics summer program at Woods Hole Oceanographic Institution (WHOI) [National Science Foundation (NSF) Grant OCE0325296], where the development of the physical representations used in this study benefited from discussions with many visitors and staff including Norbert Untersteiner, John Walsh, Jamie Morison, Dick Moritz, Danny Feltham, Göran Björk, Bert Rudels, Doug Martinson, Andrew Fowler, George Veronis, Grae Worster, Neil Balmforth, Ed Spiegel, Joe Keller, and Alan Thorndike. I.E. thanks Eli Tziperman and Cecilia Bitz for helpful conversations during the course of this work. The authors thank Richard Goody, Tapio Schneider, and Eli Tziperman for comments on the manuscript. J.S.W. acknowledges support from NSF Grant OPP0440841 and Yale University, and the Wenner–Gren Foundation, the Royal Institute of Technology, and NORDITA in Stockholm. I.E. acknowledges support from a National Aeronautics and Space Administration Earth and Space Science Fellowship, a WHOI Geophysical Fluid Dynamics Fellowship, NSF Paleoclimate Program Grant ATM-0502482, the McDonnell Foundation, a prize postdoctoral fellowship through the California Institute of Technology Division of Geological and Planetary Sciences, and a National Oceanic and Atmospheric Administration Climate and Global Change Postdoctoral Fellowship administered by the University Corporation for Atmospheric Research. Author contributions: I.E. and J.S.W. designed research, performed research, and wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at
Funding AgencyGrant Number
Woods Hole Oceanographic InstituteUNSPECIFIED
Yale UniversityUNSPECIFIED
Wenner–Gren FoundationUNSPECIFIED
Royal Institute of Technology (Sweden)UNSPECIFIED
Nordic Institute for Theoretical PhysicsUNSPECIFIED
James S. McDonnell FoundationUNSPECIFIED
National Oceanic and Atmospheric Administration (NOAA)UNSPECIFIED
Subject Keywords:Arctic climate; bifurcation; climate change; tipping point
Issue or Number:1
PubMed Central ID:PMC2629232
Record Number:CaltechAUTHORS:EISpnas09
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12863
Deposited By: Archive Administrator
Deposited On:08 Jan 2009 22:34
Last Modified:08 Nov 2021 22:33

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