CENOZOIC EVOLUTION OF ANTARCTIC CLIMATE, ICE SHEETS, AND SEA ICE: A MODELING PERSPECTIVE

Despite recent advances in understanding first principals and dynamics of the climate system, much of the variability in Cenozoic proxy climate records remains poorly understood. Numerous paleoclimate studies have applied sophisticated Global Climate Models (GCMs) to isolated “snapshots” at specific time points through the Cenozoic, but this approach fails to elucidate the time-continuous nature of climate change over geological timescales. In reality the climate state at any one time may not be in equilibrium with the given forcings, but may instead be dependent on the long-term inertia of the long-term components (ice sheets, deep ocean, geochemical cycles, etc.). To better understand the long-term trends, abrupt events, and sudden transitions recognized in Cenozoic proxy climate records, a new modeling approach is required, capable of accounting for the multi-million year evolution of the long-term components, while accounting for orbital forcing and changes in atmospheric composition. Recent applications of such “time-continuous” modeling techniques across the Eocene-Oligocene boundary and other intervals of global environmental change are leading toward new ideas concerning the relative importance of different forcings and internal feedbacks in the evolution of Cenozoic climate, and in particular, the evolution of the Antarctic cryosphere. More specifically, these studies explore the impact of changing atmospheric composition, paleogeography, mountain uplift, ocean heat transport, and the role of internal climate system feedbacks in the long-term evolution of Antarctic climate and ice volume. Recent model results emphasizing the fundamental importance of greenhouse gas concentration’s control on ice volume are discussed in the context of long standing, data-driven hypotheses of Cenozoic climate change.