Wind-driven evolution of the North Pacific subpolar gyre over the last deglaciation

• Published in: Geophysical Research Letters
• Main Authors: Gray, William Robert, Wills, Robert CJ, Rae, James William Buchanan, Burke, Andrea, Ivanovic, Ruza F, Roberts, William HG, Ferreira, David, Valdes, Paul J
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2020
• Subjects: North Pacific; Deglaciation; Gyre circulation; Westerlies; Oxygen isotopes; Climate models; Pacific; Ice Sheet
• Online Access: https://risweb.st-andrews.ac.uk/portal/en/researchoutput/winddriven-evolution-of-the-north-pacific-subpolar-gyre-over-the-last-deglaciation(59536cf2-40d3-4a79-9607-d58672d1c08e).html; https://doi.org/10.1029/2019GL086328; https://research-repository.st-andrews.ac.uk/bitstream/10023/21638/1/Gray_2020_GRL_Wind_drivenevolution_VoR.pdf

North Pacific atmospheric and oceanic circulations are key missing pieces in our understanding of the reorganisation of the global climate system since the Last Glacial Maximum (LGM). Here, using a basin‐wide compilation of planktic foraminiferal δ 18 O, we show that the North Pacific subpolar gyre extended ~3° further south during the LGM, consistent with sea surface temperature and productivity proxy data. Climate models indicate that the expansion of the subpolar gyre was associated with a substantial gyre strengthening, and that these gyre circulation changes were driven by a southward shift of the mid‐latitude westerlies and increased wind‐stress from the polar easterlies. Using single‐forcing model runs, we show that these atmospheric circulation changes are a non‐linear response to ice‐sheet topography/albedo, and CO 2 . Our reconstruction indicates that the gyre boundary (and thus westerly winds) began to migrate northward at ~16.5 ka, driving changes in ocean heat transport, biogeochemistry, and North American hydroclimate.