Carbon cycle instability as a cause of the Late Pleistocene Ice Age Oscillations: Modeling the asymmetric response

A dynamical model of the Pleistocene ice ages, incorporating many of the qualitative ideas advanced recently regarding the possible role of ocean circulation, chemistry, temperature, and productivity in regulating long‐term atmospheric carbon dioxide variations, has been constructed. This model involves one additional term (and free parameter) beyond that included in a previous model (B. Saltzman and A. Sutera, 1987), providing the capacity for an asymmetic (for example, “saw‐toothed”) response. It is shown that many of the main features exhibited by the δ 18 O‐derived ice record and the Vostok core/δ 13 C‐derived carbon dioxide record in the late Pleistocene can be deduced as a free oscillatory solution of the model, including a rapid déglaciation during which a spike of high CO 2 and a rapid surge in North Atlantic deep water production occurs. It is expected that the addition of reasonable levels of external (for example, Earth orbital) forcing will enable the model to account for a significant amount of the remaining observed variance and covariance of the slow response climatic variables over the full Pleistocene including the mid‐Pleistocene transition.