Mid-Pleistocene transition in glacial cycles explained by declining CO₂ and regolith removal.

ABSTRACT: Variations in Earth's orbit pace the glacial-interglacial cycles of the Quaternary, but the mechanisms that transform regional and seasonal variations in solar insolation into glacial-interglacial cycles are still elusive. Here, we present transient simulations of coevolution of climate, ice sheets, and carbon cycle over the past 3 million years. We show that a gradual lowering of atmospheric CO₂ and regolith removal are essential to reproduce the evolution of climate variability over the Quaternary. The long-term CO₂ decrease leads to the initiation of Northern Hemisphere glaciation and an increase in the amplitude of glacial-interglacial variations, while the combined effect of CO₂ decline and regolith removal controls the timing of the transition from a 41,000- to 100,000-year world. Our results suggest that the current CO₂ concentration is unprecedented over the past 3 million years and that global temperature never exceeded the preindustrial value by more than 2°C during the Quaternary.

SUBMITTER: Willeit M 

PROVIDER: S-EPMC6447376 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature