The transient versus the equilibrium response of sea ice to global warming

Li, C., Notz, D., Tietsche, S. and Marotzke, J. (2013) The transient versus the equilibrium response of sea ice to global warming. Journal of Climate, 26 (15). pp. 5624-5636. ISSN 0894-8755 doi: 10.1175/JCLI-D-12-00492.1

Abstract/Summary

To examine the long-term stability of Arctic and Antarctic sea ice, idealized simulations are carried out with the climate model ECHAM5/MPIOM. Atmospheric CO2 concentration is increased over 2000 years from pre-industrial levels to quadrupling, is then kept constant for 5940 years, is afterwards decreased over 2000 years to pre-industrial levels, and finally kept constant for 3940 years.Despite these very slow changes, the sea-ice response significantly lags behind the CO2 concentration change. This lag, which is caused by the ocean’s thermal inertia, implies that the sea-ice equilibrium response to increasing CO2 concentration is substantially underestimated by transient simulations. The sea-ice response to CO2 concentration change is not truly hysteretic and in principle reversible.We find no lag in the evolution of Arctic sea ice relative to changes in annual-mean northern-hemisphere surface temperature. The summer sea-ice cover changes linearly with respect to both CO2 concentration and temper...