Which biogeochemical feedback mechanisms control the natural limits of atmospheric concentrations of greenhouse gases and aerosols?

Ice-core records indicate that natural variations in atmospheric concentration of e.g. CO₂ occur within certain limits during the last glacial-interglacial cycles. By combing the latest data with newly developed comprehensive Earth-system models INTERDYNAMIC aims at understanding the origin of this range and the underlying coupling between climate variations and biogeochemical cycles.