[Excerpt] This study addresses the economics of climate change in selected countries in the East Asian region, focusing on the People’s Republic of China, Japan, the Republic of Korea, and Mongolia. It is one in a series that ADB has been conducting for the Asia and the Pacific region, starting with the “Economics of Climate Change in Southeast Asia: A Regional Review,” and the “Economics of Climate Change in the Pacific.” Further studies in preparation include similar topics in South Asia and Central West Asia. The importance of the East Asian region in terms of addressing the impact of climate change has significant consequences that cross regional boundaries and affect the world. East Asia is a uniquely important region for climate change. As an export-oriented industrial powerhouse, the region accounts for roughly 30% of the world’s total energy-related emissions. This suggests that initiatives to mitigate climate change must include the region. From a country perspective, the region is vulnerable to the impact of climate change. For instance, three urban areas or megacities in the region—Guangzhou and Shanghai in the People’s Republic of China (PRC), and Osaka/Kobe in Japan—are among the top 10 urban areas in the world severely exposed to sea-level rise. Further, climate change, if not addressed, may reduce yields of key crops in the PRC, thus increasing reliance upon food imports, and could exacerbate land degradation and desertification in Mongolia. This study is an advance over previous global and regional studies on climate change economics in several important ways. It explores the economics of climate change adaptation at a subnational scale (i.e., provinces or regions), incorporates more climate scenarios, and examines climate uncertainty in more depth than previous work. Moreover, this study explicitly combines the costs of adaptation and mitigation into a single framework, while exploring linkages with the global economy.