Fig. 9

Obliquity and associated temperature and mass balance model inputs for the past 26 Myr. a Obliquity (black line) determined by Laskar et al. (2004) and the average surface temperature in the accumulation (red line) and ablation zones (blue line). If ice is accumulating in the specified accumulation zone, the surface albedo in the zone is changed from 0.3 to 0.4 resulting in a ~ 10 K drop in temperature. b The ablation rate changes with local temperature (Eq. 5), and ablation occurs everywhere at obliquity less than roughly 44^°. The rate of accumulation depends on obliquity using the assumed relationship shown in Fig. 5