[ESAC Seminar] Celeste Pallone

“Precession Forcing of the Eastern Equatorial Pacific Ocean-Atmosphere System in the Late Pleistocene”

Ocean-atmosphere interactions in the tropical Pacific produce the El Niño-Southern Oscillation, driving global-scale changes in temperature and hydrology on sub-decadal timescales today. However, the role of the tropical Pacific in past climate variability and its response to future forcing remain poorly understood. Here, I present multi-proxy paleoceanographic records from eastern equatorial Pacific (EEP) marine sediments over the past 160,000 years, which provide insights into the behavior of the tropical Pacific in different climate states and orbital configurations. I evaluate the hypothesis that precession-driven changes in the seasonal distribution of tropical insolation altered the mean state and variability of the tropical Pacific. Using microfossil planktic foraminifera oxygen isotope records, I demonstrate that changes in local insolation in boreal late summer/early fall were the primary control on EEP thermocline depth in the late Pleistocene. I also show that sea-surface variability co-varied with thermocline depth during the last interglacial, with extreme warm events becoming more frequent when the tropical Pacific was in a more El Niño-like mean state. Finally, I use U, Th, and Pa isotopes of deep-sea sediments to reconstruct marine productivity dynamics and ocean carbon storage, which demonstrate that the EEP was also influenced by processes in the high latitudes. These results suggest that the coupled dynamics that set tropical Pacific variability today also applied in the past and that the region was subject to both tropical and extra-tropical forcings.

ESAC Early-Career Seminar Series —

A forum for students and postdocs to share recent research, hone presentation skills, and build community among peers, sponsored by the EAPS Student Advisory Committee. Open to current EAPS graduate and undergraduate students and postdocs. Typically hosted on Thursdays during the semester, including pizza lunch.

Contact: esac.officers@gmail.com