Abstract

In spite of significant progress achieved in recent decades in understanding of Quaternary climate dynamics, there are still a number of important questions remained to be answered. Among them is the cause of Mid-Pleistocene transition (MPT). To address this questions we used the Earth system model of intermediate complexity CLIMBER -2 which incorporates all major components of the Earth system – atmosphere, ocean, land surface, northern hemisphere ice sheets, terrestrial biota and soil carbon, aeolian dust and marine biogeochemistry. We performed a set of simulations covering the entire Quaternary using as the only forcing variations in Earth orbital parameters and gradually evolving in time land-ocean distribution and terrestrial sediment cover. We found that a gradual removal of terrestrial sediment from the Northern Hemisphere continent by glacial processes is sufficient to explain transition from 40-ka to 100-ka worlds around the MPT . Gradual change in volcanic outgassing or weathering rate during Quaternary is required to explain early Pleistocene climate dynamics. Our results strongly suggest that Quaternary glacial cycles are externally forced and almost deterministic.

Quaternary Discussion Group seminar