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The role of Northeast Pacific meltwater events in deglacial climate change

February 26, 2020

Columbia River megafloods occurred repeatedly during the last deglaciation, but the impacts of this fresh water on Pacific hydrography are largely unknown. To reconstruct changes in ocean circulation during this period, we used a numerical model to simulate the flow trajectory of Columbia River megafloods and compiled records of sea surface temperature, paleo-salinity, and deep-water radiocarbon from marine sediment cores in the Northeast Pacific. The North Pacific sea surface cooled and freshened during the early deglacial (19.0-16.5 ka) and Younger Dryas (12.9-11.7 ka) intervals, coincident with the appearance of subsurface water masses depleted in radiocarbon relative to the sea surface. We infer that Pacific meltwater fluxes contributed to net Northern Hemisphere cooling prior to North Atlantic Heinrich Events, and again during the Younger Dryas stadial. Abrupt warming in the Northeast Pacific similarly contributed to hemispheric warming during the Bølling and Holocene transitions. These findings underscore the importance of changes in North Pacific freshwater fluxes and circulation in deglacial climate events.

Publication Year 2020
Title The role of Northeast Pacific meltwater events in deglacial climate change
DOI 10.1126/sciadv.aay2915
Authors Summer K. Praetorius, Alan Condron, Alan Mix, Maureen Walczak, Jennifer McKay, Jianghui Du
Publication Type Article
Publication Subtype Journal Article
Series Title Science Advances
Index ID 70211287
Record Source USGS Publications Warehouse
USGS Organization Geology, Minerals, Energy, and Geophysics Science Center; Woods Hole Coastal and Marine Science Center