Fig. 2.
Annual (a) and cumulative (b) contributions of different environmental factors to changes in global warming potential (Pg CO2 eq/year) in the terrestrial ecosystems of North America. The secondary Y-axis in (a) is the annual actual global warming potential under combined scenario (contribution of individual factors + baseline); Combined combined scenario (include all the environmental factors), LC land conversion, Nfer N fertilizer use, O 3 O3 pollution, CO 2 atmospheric CO2, NDEP N deposition, CLM climate variability, Interaction interaction among multiple factors calculated as: Combined – LC – Nfer – O 3 – CO 2 – NDEP – CLM