Climatic precession forcing in early Pleistocene glacial cycles: implications for gradual ice-age transitions over the past 3 Ma

Seminar by Parker Liautaud from Harvard University

24 March 2020
10:00 — 11:00

The Seminar is being held in Room 1010 (Jasmin) – Intergrated mechanical engineering building. Click here for the campus map.

Despite having a large influence on summer insolation, climatic precession is thought to account for negligible variance in early Pleistocene proxies of ice volume and deep-water temperature. Various mechanisms have been suggested to account for the lack of precession variability, including meridional insolation gradients, interhemispheric cancellation of ice-volume changes, and antiphasing between the duration and intensity of summer insolation. I will discuss recent work to quantify precession and obliquity forcing in early Pleistocene benthic δ18O records using a new method termed Empirical Nonlinear Orbital Fitting (ENOF). Analysis of a high-resolution record from the North Atlantic indicates a significantly larger precession contribution than previously recognized, which is found to gradually intensify throughout the Pleistocene. Significant early-Pleistocene precession is also found in six other benthic δ18O records on both tuned and orbitally-independent age models. I will also discuss recent work to evaluate the relationship between orbital forcing and 100-ky glacial variability in the early Pleistocene, and model the sensitivity of glacial-cycle amplitude to a gradual decrease in atmospheric CO2 concentration. Our results to date suggest that early Pleistocene glacial variability is qualitatively consistent with that of the late Pleistocene, but with the response to orbital forcing gradually amplifying over the past 3 Ma.