Melt ponds play a major role in the absorption of solar radiation. Absorption by a water surface is a strong function of solar elevation and so it is solar elevation at high northern latitudes during the summer which determines albedo and melt rates rather than insolation itself. Furthermore, the stable stratification of melt ponds in the range 0
oC to 4
oC allows storage of heat from summer to summer while positive feedback between pond area and heat uptake leads to exponential growth followed, ultimately, by catastrophic collapse.
All five Terminations occurred at times of peak annual water surface absorption of solar radiation, a better match than previous models.
Chapter 11 of The Fluid Catastrophe by John Reid