Sea Ice–Albedo Feedback and Nonlinear Arctic Climate Change - Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications - page 128

The stabilization of sea ice through opposing heating or
cooling of the surrounding ocean was shown to have sub-
stantial impact on the overturning circulation and deep
ventilation. This effect may provide a partial answer to an
outstanding question raised by the Coupled Model Inter-
comparison Project group experiments [ Gregory et al .,
2002]. These experiments separate MOC weakening under
CO 2 increase into freshwater and thermally induced compo-
nents by using two auxiliary experiments: control radiation
with CO 2 -induced increase in ocean freshwater forcing and
the reverse. These experiments show that the two effects ba-
sically add linearly and that thermal forcing dominates the
MOC response. The mechanisms for this thermal impact are
yet to be explored, but ice-albedo feedback, and polar ampli-
fication more generally, may be one of them.

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Acknowledgments. The author thanks Isaac held, Ron Stouffer,
Ian Eisenman, Eric deWeaver, Gerald North, and an anonymous
reviewer for helpful comments on the manuscript. The author also
acknowledges the international modeling groups for providing
their data for analysis, the Program for Climate Model diagnosis
and Intercomparison (PCMdI) for collecting and archiving the
model data, the JSC/CLIVAR Working Group on Coupled Mod-
eling (WGCM) and their Coupled Model Intercomparison Project
(CMIP) and Climate Simulation Panel for organizing the model
data analysis activity, and the IPCC WG1 TSu for technical sup-
port. The IPCC Data Archive at Lawrence Livermore National
Laboratory is supported by the Office of Science, U.S. Department
of Energy.

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M. Winton, Geophysical Fluid dynamics laboratory, NOAA,
P.O. Box 308, Princeton University Forrestal Campus, Princeton,
NJ 08542, USA. ([e-mail])