CO₂排出削減による濃度安定化効果の検討

CO₂濃度推定モデルの適用と問題点

抄録

Through a CRIEPI international research collaboration, climate changes under a set of CO₂ stabilization (WRE550) and BAU (IS92a) scenarios were projected by the NCAR coupled climate model (CSM). In these projections, the carbon-cycle model of Wigley (1993) was used to estimate atmospheric CO₂ concentrations. In this model, which has been used in many investigations, e. g., the IPCC second assessment report (1995), both the ocean and terrestrial biomass components of the CO₂ cycle are simulated. Verification of the model is demonstrated by comparison of observational data and calculations over the period of the 1990s. Future concentrations depend strongly on the value of D_n (1980s), which is the net CO₂ emission from land use change in 1980s. In the long term, however, the ocean uptake in this model tends to be over estimated. Moreover, the model results reveal that the Kyoto reduction will delay the occurrence of any given concentration by only a few decades. It is obvious that reductions by only advanced countries are not sufficient to stabilize the CO2 concentrations. In future research, improvements in the carbon cycle model should be made in order to better estimate future limits on CO₂ emissions.