Late Pliocene Cordilleran Ice Sheet development with warm Northeast Pacific sea surface temperatures

Sánchez-Montes, M.L.; McClymont, E.L.; Lloyd, J.M.; Müller, J.; Cowan, E.A.; Zorzi, C.; de Vernal, A.

Abstract

The initiation and evolution of the Cordilleran Ice Sheet are relatively poorly constrained. International Ocean Discovery Program (IODP) Expedition 341 recovered marine sediments at Site U1417 in the Gulf of Alaska (GOA). Here we present alkenone-derived sea surface temperature (SST) analyses alongside ice-rafted debris (IRD), terrigenous, and marine organic matter inputs to the GOA through the late Pliocene and early Pleistocene. The first IRD contribution from tidewater glaciers in southwest Alaska is recorded at 2.9 Ma, indicating that the Cordilleran Ice Sheet extent increased in the late Pliocene. A higher occurrence of IRD and higher sedimentation rates in the GOA during the early Pleistocene, at 2.5 Ma, occur in synchrony with SSTs warming on the order of 1 ∘C relative to the Pliocene. All records show a high degree of variability in the early Pleistocene, indicating highly efficient ocean–climate–ice interactions through warm SST–ocean evaporation–orographic precipitation–ice growth mechanisms. A climatic shift towards ocean circulation in the subarctic Pacific similar to the pattern observed during negative Pacific Decadal Oscillation (PDO) conditions today occurs with the development of more extensive Cordilleran glaciation and may have played a role through increased moisture supply to the subarctic Pacific. The drop in atmospheric CO2 concentrations since 2.8 Ma is suggested as one of the main forcing mechanisms driving the Cordilleran glaciation.

Citation

Sánchez-Montes, M., McClymont, E., Lloyd, J., Müller, J., Cowan, E., Zorzi, C., & de Vernal, A. (2020). Late Pliocene Cordilleran Ice Sheet development with warm Northeast Pacific sea surface temperatures. Climate of the Past, 16(1), 299-313. https://doi.org/10.5194/cp-16-299-2020

• Journal Article Type: Article
• Acceptance Date: Nov 21, 2019
• Online Publication Date: Feb 14, 2020
• Publication Date: Feb 14, 2020
• Deposit Date: Dec 10, 2018
• Publicly Available Date: Feb 14, 2020
• Journal: Climate of the Past
• Print ISSN: 1814-9324
• Electronic ISSN: 1814-9332
• Publisher: European Geosciences Union
• Peer Reviewed: Peer Reviewed
• Volume: 16
• Issue: 1
• Pages: 299-313
• DOI: https://doi.org/10.5194/cp-16-299-2020
• Public URL: https://durham-repository.worktribe.com/output/1307157