Long-Term Variability in Pliocene North Pacific Ocean Export Production and Its Implications for Ocean Circulation in a Warmer World

• Published in: AGU Advances
• Main Authors: Abell, J.T., Winckler, G.
• Other Authors: Department of Geosciences, University of Arizona
• Format: Article in Journal/Newspaper
• Language: English
• Published: John Wiley and Sons Inc 2023
• Subjects: constant flux proxy; North Pacific Deep Water; Pliocene; subarctic North Pacific; North Atlantic; Subarctic
• Online Access: http://hdl.handle.net/10150/673271; https://doi.org/10.1029/2022AV000853

Unlike in the high-latitude North Atlantic, no deep water is formed in the modern subarctic North Pacific. It has previously been suggested that during climate states different from today, this dichotomy did not endure, and the formation of North Pacific Deepwater (NPDW) occurred in the subarctic North Pacific, which supported an active Pacific meridional overturning circulation (PMOC). Here we provide new records of productivity and sedimentary redox conditions from the central subarctic North Pacific spanning the late Miocene to early Pleistocene. These reconstructions indicate greater-than-modern and temporally varying North Pacific export production across the interval of ∼2.7–6 Ma. Our time series, combined with previously published data sets and model output for Pliocene North Pacific Ocean dynamics, support the presence of an active PMOC during the Pliocene, and suggest that the characteristics of NPDW formation varied during this warmer interval of Earth's history. This finding of elevated export production at a time of deep water formation presents a conundrum when considering Quaternary North Pacific Ocean dynamics, where subarctic North Pacific productivity declines during intervals when enhanced overturning is posited to occur. We evaluate our data considering the caveats of both (i.e., Pliocene and Quaternary North Pacific circulation) hypotheses, as well as additional mechanisms unrelated to ocean circulation. Because the Pliocene is a possible analogue for near-future climate, our results and analyses have important ramifications for our understanding of regional and global climate in the coming decades as the planet continues to warm. © 2023. The Authors. Open access journal This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [e-mail].