A low-order theory of Arctic sea ice stability
Department of Geology & Geophysics - Yale University - New Haven, CT 06520-8109, USA
2 Department of Physics & Program in Applied Mathematics - Yale University - New Haven, CT 06520-8109, USA
3 NORDITA - Roslagstullsbacken 23, SE-10691 Stockholm, Sweden, EU
Accepted: 7 September 2011
We analyze the stability of a low-order coupled sea ice and climate model and extract the essential physics governing the time scales of response as a function of greenhouse gas forcing. Under present climate conditions the stability is controlled by longwave radiation driven heat conduction. However, as greenhouse gas forcing increases and the ice cover decays, the destabilizing influence of ice-albedo feedback acts on equal footing with longwave stabilization. Both are seasonally out of phase and as the system warms towards a seasonal ice state these effects, which underlie the bifurcations between climate states, combine exhibiting a “slowing-down” to extend the intrinsic relaxation time scale from ∼2 yr to 5 yr.
PACS: 92.10.Rw – Sea ice (mechanics and air/sea/ice exchange processes) / 92.70.Gt – Climate dynamics / 02.30.Oz – Bifurcation theory
© EPLA, 2011