Bipolar Climate Machinery (BIPOMAC)

A study of the interplay of northern and southern polar processes in driving and amplifying global climate variability

Paleoclimatic research has outlined the extraordinary significance of processes in polar regions in driving and amplifying global climate variability at centennial to millenial time scales. This includes biological and physical processes in the polar oceans, the distribution of sea ice, and the volume and stability of continental ice. Polar and subpolar oceans represent major High-Nutrient-Low-Chlorophyll (HNLC) areas during warm climate modes having strong potential to represent major CO2 sink during glacial conditions, when increased input of the micronutrient iron results in biological productivity regimes that enhances the biological pump. Changes in the extent and the seasonal variability of sea ice exert strong influence on the Earth´s albedo, generation of water masses, the ocean-atmosphere exchange of heat and gas, as well as biological productivity. Ocean density disturbances via melt water pulses have been identified to induce distinct and rapid climate change. The effect of such regional events in the Arctic Ocean, the North Atlantic and the Southern Ocean is believed to be propagated globally via ocean circulation through the operation of the so-called "bipolar seesaw". New data point to a less stable Antarctic ice volume than generally presumed even during cold climate periods and sheds new light on the vulnerability of the Antarctic ice sheets and their effect on global sea level development. The emerging view of a complex "bipolar climate machinery" urgently calls for a major international research effort to decipher and quantify the interplay of bipolar ice-ocean-atmosphere processes in climate evolution and sea level change during warm and cold climate conditions. BIPOMAC will combine (i) "process studies" based on an iron fertilization experiment to test the effect of iron addition as a mean for CO2 sequestration and to better understand and quantify the significance of resulting sedimentary proxies, (ii) "ground truthing" based on well synchronized northern and southern polar high resolution (102-103y) paleoceanographic, paleolimnological, paleoatmospheric and continental ice volume/extent records (time window: mid-late Pleistocene climate cycles, Holocene), and (iii) "numerical modeling" of ice-atmosphere-ocean processes to decipher the complex pathway and timing of climate development, its internal amplification and propagation mechanisms (ice/ocean/atmosphere) and the effect of external forcing (insolation/solar activity). These initiatives will be the base for the generation of models for realistic estimates of future climate and sea level development under different anthropogenic impact scenarios. The latter is of major socio-economic relevance in a world of growing human population and increasing coastal area settlement.