Gulf of Alaska Deep and Intermediate Watermass Changes and Paleoventilation

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The North Pacific today is not a significant source of deep and intermediate water to the global oceans. Was it in the past? Changes in this system during past climate regimes are poorly constrained and controversial, but are an important part of the global system with profound implications for global heat transports and carbon budgets of the deep sea. This research, led by scientists from Oregon State University, tests hypotheses about the role of North Pacific subsurface circulation in modulating global climate (i.e., heat transport associated with thermohaline overturn in the Pacific) and the carbon cycle (i.e., storage of an "old" CO2-rich watermass in the deep North Pacific during glacial time). The study will focus on a depth transect of new sites from the Gulf of Alaska ranging from ~4200 m to ~700 m depth. The researchers will generate 40,000 year records of stable oxygen and carbon isotopes in benthic foraminifera to assess paleo watermass structures, radiocarbon in foraminifera to assess watermass ventilation ages, and Neodymium isotopes in sedimentary oxides to trace changes in the sources of subsurface watermasses. The broader impacts of this project include workforce development-- training undergraduate and graduate students-- along with education and outreach to national and international policymakers. The work will be carried out in close collaboration with an Australian scientist, and because of the focus on recently collected Integrated Ocean Drilling Program cores it will contribute to collaborations among researchers from 13 countries.