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The reversibility of sea ice loss in a state-of-the-art climate model

Armour, K. C. and Eisenman, I. and Blanchard-Wrigglesworth, E. and McCusker, K. E. and Bitz, C. M. (2011) The reversibility of sea ice loss in a state-of-the-art climate model. Geophysical Research Letters, 38 . Art. No. L16705. ISSN 0094-8276.

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Rapid Arctic sea ice retreat has fueled speculation about the possibility of threshold (or ‘tipping point’) behavior and irreversible loss of the sea ice cover. We test sea ice reversibility within a state-of-the-art atmosphere–ocean global climate model by increasing atmospheric carbon dioxide until the Arctic Ocean becomes ice-free throughout the year and subsequently decreasing it until the initial ice cover returns. Evidence for irreversibility in the form of hysteresis outside the envelope of natural variability is explored for the loss of summer and winter ice in both hemispheres. We find no evidence of irreversibility or multiple ice-cover states over the full range of simulated sea ice conditions between the modern climate and that with an annually ice-free Arctic Ocean. Summer sea ice area recovers as hemispheric temperature cools along a trajectory that is indistinguishable from the trajectory of summer sea ice loss, while the recovery of winter ice area appears to be slowed due to the long response times of the ocean near the modern winter ice edge. The results are discussed in the context of previous studies that assess the plausibility of sea ice tipping points by other methods. The findings serve as evidence against the existence of threshold behavior in the summer or winter ice cover in either hemisphere.

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Additional Information:© 2011 American Geophysical Union. Received 29 June 2011; accepted 15 July 2011; published 20 August 2011. We gratefully acknowledge support from National Science Foundation grants OCE-0256011 and ARC-0909313, the Davidow Discovery Fund, and a NOAA Climate and Global Change Postdoctoral Fellowship to IE administered by the University Corporation for Atmospheric Research. We thank Dorian Abbot, Gerard Roe, Brian Rose and Michael Winton for valuable discussions, and Eric Rignot, the editor. The Editor thanks an anonymous reviewer for his assistance in evaluating this paper.
Funding AgencyGrant Number
Davidow Discovery FundUNSPECIFIED
NOAA Climate and Global Change Postdoctoral FellowshipUNSPECIFIED
Subject Keywords:reversibility; sea ice; tipping point
Record Number:CaltechAUTHORS:20110909-111834029
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Official Citation:Armour, K. C., I. Eisenman, E. Blanchard-Wrigglesworth, K. E. McCusker, and C. M. Bitz (2011), The reversibility of sea ice loss in a state-of-the-art climate model, Geophys. Res. Lett., 38, L16705, doi:10.1029/2011GL048739.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25273
Deposited By: Tony Diaz
Deposited On:09 Sep 2011 18:39
Last Modified:03 Oct 2019 03:04

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