RESPIC - Paleoclimatic changes in the global carbon cycle

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

Influence of large-scale teleconnection patterns on methane sulfonate ice core records in Dronning Maud Land

Records of methane sulfonate (MS) in ice cores from the high plateau of DronningMaud Land (DML), Antarctica, drilled in the framework of the European Project for IceCoring in Antarctica, are investigated for their potential as an environmental andclimate archive for the Atlantic sector of the Southern Ocean. Despite postdepositionalchanges, years of extraordinary MS concentrations can be clearly detected in the icecore records. We use composite anomaly maps of atmospheric parameters from theNational Centers for Environmental Prediction/National Center for Atmospheric Researchreanalysis fields for years of extreme MS concentration to detect atmospheric patternscausing MS variability. Changing atmospheric transport is shown to be an important,but not exclusive, parameter being conserved in the MS record in DML. The oftenhypothesized direct link between high MS concentrations and El Nino events is notsupported for the observed region whereas the Antarctic Dipole (ADP), which ismodulated by El Nino Southern Oscillation conditions, exerts significant influence. Aclear 13.9-year cycle can be found throughout a 2000-year MS record that can be relatedto variations in the ADP. Over the last 300 years a 4.6-year cycle is revealed in theMS (and sea-salt record), which vanishes in the deeper part of the ice core as aconsequence of diffusion processes. From the long-term perspective, periods of high MSconcentrations are connected to, on average, higher sea-salt aerosol as well, reflecting aseasonally independent influence of transport on both species. A distinctive period ofefficient atmospheric transport, probably due to a pronounced ADP, could be foundfrom 1200 to 1600 A.D