Speaker

Dr. Harriet Lau, Assistant Professor, Brown University

Evolving Solid Earth Dynamics as a Trigger for the Mid Pleistocene Transition

Abstract

Milankovitch cycles—orbital modulations in Earth’s insolation—are thought to pace ice ages over the last 2.6 million years, with dominant periods associated with changes in precession (~20,000 years) and obliquity (~40,000 years). While Milankovitch cycles have not changed over tens of millions of years, Earth’s climatic response has. In particular, the Mid Pleistocene Transition (MPT), ~1 million years ago, is defined by an enigmatic shift between ice ages paced every ~40,000 to ~100,000~years. In this talk, we will explore solid Earth feedbacks (i.e., crustal rebound/subsidence) on the ice age system using a climate model that accounts for variation in the timescale of crustal deformation associated with changes to the length-scale of ice ages and duration of ice loading. I will demonstrate that the impact of the feedback mechanism is significantly larger in the late Pleistocene relative to the early Pleistocene, and hypothesize that this sensitivity played a crucial role in driving the MPT.