Variability and timing of Glacial-Interglacial productivitiy in the polar South and North Pacific - Implications for global climate development (PROPAC)

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The polar South and North Pacific represent prominent “high nutrient-low chlorophyll” (HNLC) areas of the World Ocean where phytoplankton productivity is rather low in spite of high macro-nutrient concentrations. This pattern has been related to the scarcity of micronutrients (e.g. iron) in these areas. Thus, the Pacific HNLC areas represent potential regions for increased productivity and related carbon sequestration resulting in a reduction of atmospheric CO2 concentration during climate periods when micro-nutrient deposition is enhanced via eolian or oceanic input. Although this mechanism may play a crucial role in the climate development, little is known about past productivity changes in the polar Pacific. In consideration of this gap in knowledge, we propose to a) reconstruct the timing and magnitude of glacial/interglacial variability of biological productivity in the polar South and North Pacific and reveal E-W gradients in relation to dust sources, sea ice extent and ocean ventilation over the past two terminations; and b) synchronize and compare the records with Greenland and Antarctic ice core CO2 and dust records to estimate response/role of polar Pacific HNLC areas to/in glacial climate development. The reconstruction will rely on a combined paleobiological (diatoms/ dinoflagellates/radiolarians) and geochemical (15Ndiat) approach. Core material will be recovered during RV Sonne cruise SO-202 (INOPEX) to the polar North Pacific (7.7.-28.8.09) and RV Polarstern cruise ANT-XXVI/2 (2.12.09-3.2.10) to the polar South Pacific. PROPAC will provide new data and paleoenvironmental scenarios, which can be used to better understand mechanisms amplifying climate variability related to CO2 sequestration and model their impact on global scale. With this PROPAC will tackle a topic that has been highlighted by IPCC 2007 as a major challenge in climate research.