Adaptation has been gaining attention as an important option for combating climate change, as it appears mitigation alone likely cannot solve the problem. Intergovernmental Panel on Climate Change (IPCC) started to discuss and analyze adaptation in its Assessment Reports in 2001. Stern Review, which was published in 2006, also highlighted the importance of adaptation as part of the response to climate change. In 2015, the Conference of the Parties 21st Session to the UN Convention on Climate Change (COP21) recognized an increasing role for adaptation and emphasized the cost reductions associated with adaptation efforts. Research has also been conducted on this topic. de Bruin et al. (2009) and de Bruin (2011) added adaptation decisions to her DICE model, which is an Integrated Assessment Model suggested by Nordhaus (1992), and examined how adaptation interacts with mitigation decisions in balancing climate change costs and economic costs. Barrage (2015) focused on the fiscal revenue effects of mitigation and adaptation options and discussed implications in the context of optimal taxation.