Stephen Barker, Lorraine Lisiecki, Gregor Knorr, Sophie Nuber, Polychronis C Tzedakis

Identifying the specific roles of precession, obliquity and eccentricity in glacial/interglacial transitions is hindered by imprecise age control. We circumvent this problem by focussing on the morphology of deglaciation/inception, which we show depends strongly on the relative phasing of precession versus obliquity. We demonstrate that while both parameters are important, precession has more influence on deglacial onset, while obliquity is more important for attainment of peak interglacial conditions and glacial inception. We find that the set of precession peaks (minima) responsible for terminations since 0.9Ma is a subset of those ‘candidate peaks’ which begin (precession parameter starts decreasing) while obliquity is increasing. Specifically, termination occurs with the first candidate peak following each eccentricity minimum. Thus the gross morphology of 100kyr glacial cycles appears largely deterministic.