The goal of RESPIC is the quantification of changes in the global carbon cycle (GCC) in the past. To this end relevant boundary conditions for the GCC have been reconstructed from the new EPICA ice cores and changes in carbon fluxes have been quantified using the new GCC-model BICYCLE. Ice core aerosol records show substantial changes in mineral dust, thus iron input, to the Southern Ocean (SO) parallel to changes in sea level. In contrast, changes in marine biogenic sulfur do not point to a substantial increase in marine sulfur productivity in parallel to a potential iron fertilisation. Sea ice coverage as revealed in sea salt aerosol doubles for glacial conditions connected to higher SO stratification and reduced gas exchange. In line, BICYCLE reveals a strong effect of SO mixing and carbonate sedimentation/dissolution on atmospheric CO2 while the influence of iron fertilisation is limited to about 20 ppmv. New quantitative information on carbon fluxes can be derived from novell high-precision d13CO2 measurements developed within RESPIC which show 0.5 o/oo higher levels during warm marine isotope stage (MIS) 5.5 compared to the penultimate glacial.