Wind‐Driven Evolution of the North Pacific Subpolar Gyre Over the Last Deglaciation

• Published in: Geophysical Research Letters
• Main Authors: Gray, William R., Wills, Robert C. J., Rae, James W. B., Burke, Andrea, Ivanovic, Ruza F., Roberts, William, Ferreira, David, Valdes, Paul J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2020
• Subjects: F600 Geology; F800 Physical and Terrestrial Geographical and Environmental Sciences; Pacific; Ice Sheet
• Online Access: https://nrl.northumbria.ac.uk/id/eprint/42705/; https://doi.org/10.1029/2019gl086328; https://nrl.northumbria.ac.uk/id/eprint/42705/1/2019GL086328.pdf

North Pacific atmospheric and oceanic circulations are key missing pieces in our understanding of the reorganization of the global climate system since the Last Glacial Maximum. Here, using a basin‐wide compilation of planktic foraminiferal δ18O, we show that the North Pacific subpolar gyre extended ~3° further south during the Last Glacial Maximum, 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 midlatitude westerlies and increased wind stress from the polar easterlies. Using single‐forcing model runs, we show that these atmospheric circulation changes are a nonlinear response to ice sheet topography/albedo and CO2. 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.