Dansgaard‐Oeschger oscillations predicted in a comprehensive model of glacial climate: A “kicked” salt oscillator in the Atlantic

Abstract

Abstract During the period from 60,000 to 35,000 years ago, Summit‐Greenland ice core records of the oxygen isotopic ratio 18 O/ 16 O exhibit intense millennium time scale oscillations. These Dansgaard‐Oeschger oscillations have been interpreted to represent the variations in North Atlantic air temperature caused by correlative changes in the strength of North Atlantic Deep Water production. We apply a comprehensive model of glacial climate to unambiguously identify the mechanism responsible for this phenomenon. This is shown to involve a salt oscillation of relaxation oscillator form. This nonlinear oscillation does not require the existence of feedback due to freshwater release from grounded ice on the continents during the warm phase of the cycle.