Contribution of anthropogenic land cover change emissions to pre-industrial atmospheric CO₂

Based on a recent reconstruction of anthropogenic land cover change (ALCC), we derive the associated CO₂ emissions since 800ADby two independent methods: a bookkeeping approach and a process model. The results are comparedwith the pre-industrial development of atmospheric CO₂ known from antarctic ice cores. Our results show that pre-industrial CO₂ emissions from ALCC have been relevant for the pre-industrial carbon cycle, although before 1750 AD their trace in atmospheric CO₂ is obscured by other processes of similar magnitude. After 1750 AD, the situation is different: the steep increase in atmospheric CO₂ until 1850 AD—this is before fossil fuel emissions rose to significant values—is to a substantial part explained by growing emissions from ALCC.