The Enhancement of the Terrestrial Carbon Sink by CO2 Fertilization
Earth System Models are widely used to examine long-term changes in ecosystem function, but validation and attribution of observed changes can be difficult. This is particularly true for the effect of rising CO2, which is expected to increase leaf area, ecosystem productivity and the terrestrial carbon sink, due to the low signal to noise ratio and limited duration of most observations. Combining ecosystem experiments with models provides a potential opportunity to overcome these limitations.
The results suggest large past and potential future increases in the terrestrial carbon sink due to the effect of elevated CO2, emphasizing the importance of observation networks in the coming decades. The results also demonstrate the potential of combining models with results from ecological experiments.
We combine models and observations from elevated CO2 experiments to identify a strong effect of eCO2 on the global terrestrial carbon sink. We identify an emergent data-constrained eCO2 sensitivity of 0.64 ± 0.28 PgC yr−1 per hundred ppm of eCO2. Extrapolating worldwide, this northern temperate sensitivity projects the global terrestrial carbon sink to increase by 3.5 ± 1.9 PgC yr−1 for an increase in CO2 of 100 ppm.