Assessments of GHG emission reduction scenarios of different levels and different short-term pledges through macro- and sectoral decomposition analyses

Macro- and sectoral-decomposition analyses were conducted using emission reduction scenarios from a global energy-system model. Emission reduction scenarios with targets of 550 ppm CO2eq and 450 ppm CO2eq, which consider variations in short-term emission fixes, up until 2030, based on extensions of the Copenhagen pledges, were selected from the AMPERE scenarios. All of the assessed emission reduction scenarios are technologically feasible through radical transformations in energy systems. Within the power sector, improvement of CO2 intensity requires wide deployment of carbon-dioxide capture and storage, nuclear power, and renewable energies. In end-use sectors, not only energy intensity improvements but also CO2 intensity improvements must be achieved by switching from fossil fuels to decarbonized energy by means of CO2 intensity improvements on the energy supply side. The feasibility of improvements in CO2 and energy intensities differs between sectors according to the types of mitigation options employed. The required carbon prices are $183/tCO2 for the 550 ppm CO2eq target and $645/tCO2 for the 450 ppm CO2eq target. When the short-term emission reduction is fixed at the level set by extensions of the Copenhagen pledges, long-term emission reductions by 2050 are more difficult to achieve because rapid and radical transformation of energy systems is required between 2030 and 2050.