The Global Circulation: A Paleoclimate Perspective (Invited Presentation)

Observations allow us to look at relationships in the climate system. Numerical models let us explore more deeply the mechanisms explaining these observations. In 1972, Don Johnson took me the first step from my love of synoptic meteorology to my lifelong journey in understanding the climate system.

In this talk I will discuss uses of increasingly sophisticated climate models and paleoclimate data to assess and evaluate what we know about the forcings and feedbacks that determined the large-scale circulation features of past climates. The first models applied to paleoclimate questions generally only simulated the atmospheric responses with the oceans and land surface set to either present or reconstructed conditions. Subsequent developments have allowed for prediction of the ocean, land surface, and even recently ice sheets. These capabilities allow us to more comprehensively simulate changes on time scales of centuries to millennia. A paleoclimate perspective not only provides tests of our understanding as incorporated in numerical models but also allows assessments of future outcomes of our actions as we approach a world that the Earth has not seen for millions of years.