Back-casting analysis for 70% emission reduction in Japan by 2050

This article envisions a future in which advances in technology and urban development have transformed Japanese society by 2050, resulting in significant greenhouse gas reductions. Pathways leading Japan towards a low-carbon society are calculated using a scenario approach based on 'back-casting' techniques. It is possible to reach a 70% reduction in CO 2 emissions through a combination of demand-side and supply-side actions. On the demand side, reductions of 40-45% are possible through efficiency improvements, decreased population and the more rational use of energy despite increased energy demands arising in certain sectors. On the supply side, CO 2 emissions can be reduced through a combination of the appropriate choice of low-carbon energy sources (including carbon capture and storage) and improving energy efficiency. The estimated direct annual cost of technology to achieve this by 2050 is 6.7-9.8 trillion yen, approximately 1% of the estimated 2050 GDP. However, this excludes costs involved in infrastructure investments with aims other than climate policy (e.g. strengthening international competitiveness, improving security, enhancing urban development, and reinforcing energy). To avoid investing in its current high-carbon-emitting infrastructure, Japan must develop long-term strategies to create the necessary technological and societal innovations and to channel the appropriate financial resources for intensive economy-wide change, such as development of land, urban areas, and buildings, improvements in industrial structures, and new technologies.