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. 

About this series: The Chemical Oceanography, Geology, Geochemistry, and Geobiology Seminar [COG3] is a student-run seminar series. Topics include chemical oceanography, geology, geochemistry, and geobiology. Contact cog3_seminar_organizers@mit.edu for more information and Zoom password.