Role of dust, climate, and marine biota in glacial-interglacial CO2 cycles

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Antarctic ice-core records document dramatic changes in atmospheric CO2 over the past 8 glacial cycles (740,000 years). The goal of this research program is to obtain a better understanding of the processes controlling carbon sequestration in the ocean throughout the last full glacial-interglacial cycle by investigating the linkages between dust input, physical oceanography, and marine biology. The specific research objectives are: (1) to measure changes in surface water stratification (due to ice melt), dust inputs, and carbon export to the seafloor as archived in marine sediments over the last 140,000 years, specifically in the North Pacific Ocean; (2) to develop a global database of paleoceanographic proxies that record biogenic fluxes and ocean characteristics over the past 140,000 years, in order to examine the phasing of physical, chemical, and biological changes as the earth enters a glaciation; and (3) to use a biogeochemistry model in concert with these newly-developed environmental databases to assess the dominant controlling processes (iron flux or stratification) on marine productivity. Sediment analyses and collaborative modeling work will elucidate the different hydrographic and geochemical processes that have affected atmospheric CO2 while the earth was entering into and coming out of the last major glacial period, and how they are expected to affect carbon sequestration and atmospheric CO2 in the face of future climate change.