Simulation of glacial-interglacial cycles by simple relaxation models: consistency with observational results.

The model of Paillard and Parrenin (Earth Planet Sci Lett 227:263-271, ) was modified to obtain a closer fit to δO and CO time series for the last 800 kyr. The model performance can be improved if its CO sensitivity to I insolation is eliminated and if different response times are assumed for ablation/accumulation of ice. Correlations between simulated and experimental time series for CO and ice volume V increase from 0.59 and 0.63 to 0.79 and 0.88, respectively. According to these models, terminations are produced by I amplification through CO-T and T-CO feedbacks, in synergy with an extra CO contribution from the deep ocean. This contribution is strongly dependent on ice-sheet extent and ice volume (or alternatively, CO concentration, which is a good proxy of Antarctic temperature) but is insensitive to Southern Ocean (SO) insolation on 21 February (I). Change of deep SO state may be the 'order parameter' for nonlinear deglacial changes. According to these models, 100 kyr periodicity of glacial cycles arises from the characteristic time of Antarctic ice sheet advance to the continental slope. [ABSTRACT FROM AUTHOR]