"IPCC climate models do not capture Arctic sea ice drift acceleration: Consequences in terms of projected sea ice thinning and decline" by P. Rampal et al.,

Journal of Geophysical Research 116, C00D07, 2011; doi:10.1029/2011JC007110

IPCC climate models do not capture Arctic sea ice drift acceleration: Consequences in terms of projected sea ice thinning and decline

Key points:

• IPCC climate models underestimate Arctic sea ice thinning
• IPCC climate models fail to capture the recent sea ice kinematics acceleration
• Ice export may play a stronger role in the sea ice mass balance in the Arctic

P. Rampal

Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA, and 

Laboratoire de Glaciologie et Géophysique de l'Environnement, CNRS/Université Joseph Fourier, St Martin d'Hères, France

J. Weiss

Laboratoire de Glaciologie et Géophysique de l'Environnement, CNRS/Université Joseph Fourier, St Martin d'Hères, France

C. Dubois

Centre National de Recherches Météorologiques, Toulouse, France

J.-M. Campin

Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA

IPCC climate models underestimate the decrease of the Arctic sea ice extent. The recent Arctic sea ice decline is also characterized by a rapid thinning and by an increase of sea ice kinematics (velocities and deformation rates), with both processes being coupled through positive feedbacks. In this study we show that IPCC climate models underestimate the observed thinning trend by a factor of almost 4 on average and fail to capture the associated accelerated motion. The coupling between the ice state (thickness and concentration) and ice velocity is unexpectedly weak in most models. In particular, sea ice drifts faster during the months when it is thick and packed than when it is thin, contrary to what is observed; also models with larger long-term thinning trends do not show higher drift acceleration. This weak coupling behavior (1) suggests that the positive feedbacks mentioned above are underestimated and (2) can partly explain the models' underestimation of the recent sea ice area, thickness, and velocity trends. Due partly to this weak coupling, ice export does not play an important role in the simulated negative balance of Arctic sea ice mass between 1950 and 2050. If we assume a positive trend on ice speeds at straits equivalent to the one observed since 1979 within the Arctic basin, first-order estimations give shrinking and thinning trends that become significantly closer to the observations.

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Received 7 March 2011; accepted 30 June 2011; published 29 September 2011.

Citation: Rampal, P., J. Weiss, C. Dubois, and J.-M. Campin (2011), IPCC climate models do not capture Arctic sea ice drift acceleration: Consequences in terms of projected sea ice thinning and decline, J. Geophys. Res., 116, C00D07, doi:10.1029/2011JC007110.

http://www.agu.org/pubs/crossref/2011/2011JC007110.shtml