ABSTRACT
The IPCC Working Group I (WGI) concentration profiles (S350-S750; Fig. 1) were constructed under the following constraints: (1) prescribed initial (1990) concentration and rate of change of concentration; (2) a range of prescribed stabilization levels and attainment dates; and (3) the requirement that the implied emissions should not change too abruptly. Inverse calculations
achieve stabilization via the specified pathways. These show that stabilization requires an eventual and sustained reduction of emissions to substantially below current levels. Furthermore, some have interpreted the results for the IPCC pathways to imply that an immediate reduction in emissions (relative to the central IPCC “existing policies” or “business as usual” emissions scenario, IS92a3) is required to achieve any of the stabilization targets.
