Past and future carbon balance of European ecosystems from pollen data and climatic models simulations

As climate changes, there is considerable uncertainty whether northern hemisphere ecosystems will act as atmospheric CO2 sinks or sources. Here, we used statistical models calibrated on field measurements, past terrestrial biomes and climates inferred from pollen and future climatic change scenarios simulated by General Circulation Models (GCMs), to investigate the processes controlling past, present and future CO2 fluxes in the European ecosystems. Our results suggest that climatic change can significantly affect spatial and temporal variations of net primary production and soil respiration, and alter the net ecosystem exchange of CO2. Most of the potential terrestrial biomes in Europe will likely change from a net CO2 sink, which provided a negative feedback for atmospheric CO2 during the last 13 000 yr BP, to a net CO2 source, providing a positive feedback following global warming. The results further illustrate that there is no analogue in the recent past (Late Quaternary) for the probable future ecosystem dynamics.