Il seminario è stato organizzato all’interno del Programma di Dottorato in Sciernza e Gestione dei Cambiamenti Climatici.

Le informazioni su questo evento sono disponibili solo in lingua inglese

Recent levels of atmospheric CO2 (about 390 ppmv) and the accompanying change in radiative forcing are unique with respect to carbon cycle changes in the past 2 million years and possibly beyond. Atmospheric CO2 concentrations in Antarctic ice cores show a recurrent pattern of low glacial (about 180 ppmv) and higher interglacial (about 280 ppmv) CO2 concentrations. However, for example interglacials differ in duration, CO2 level and evolution. Millennial CO2 changes are also observed during glacial times superimposed on the long-term glacial decrease. Moreover, the CO2 changes during deglaciations and inceptions suggest a complex interplay of the different components in the global carbon cycle during these time intervals.

Here, the main processes acting in the ocean, atmosphere and biosphere leading to the observed global carbon cycle changes will be discussed using in light of latest ice core results. These comprise high-resolution CO2 records over the last glacial cycle and the phase relationship between CO2 and climate as well as latest results on the stable carbon isotopic composition of CO2. The latter provides an independent strain of information to decipher and quantify the contribution of individual processes. The discussion on the isotopic changes in CO2 concentrates on communalities and differences between the last two glacial terminations and the consequences for the subsequent CO2 evolution during MIS5.5 and the Holocene, respectively. Moreover d13C evidence is discussed to explain the enigmatic lag of CO2 concentrations at the end of MIS5.5 relative to Southern Ocean temperatures as well as the potential influence of imbalances in the global carbon cycle on orbital time scales.

Speaker:
Hubertus Fischer is a Full Professor for Experimental Climate Physics, University of Bern, Switzerland. His research interests: Ice core studies on aerosols, greenhouse gases and stable water isotopes
, Quaternary changes in climate and the atmosphere
, Past changes in global biogeochemical cycles
, Development of new high-precision mass spectrometric techniques.