Coastal adaptation to climate change in Japan: a review

In parallel with many other countries, the government of Japan has started to tackle coastal adaptations to climate change. In 2020, the national Basic Policy for Coastal Protection was revised to add the statement that coastal management should account for future changes in coastal hydrodynamic conditions due to climate change. Following this policy, the management body of each coast is requested to revise the Basic Plan for Coastal Protection by 2025. This paper first reviews the current legal frameworks and measures of coastal protection and conservation, such as disaster prevention and mitigation against stormy waves, storm surges and tsunamis, beach conservation, and maintenance of coastal protection facilities. Second, the paper outlines the recent actions taken for coastal adaptation to climate change. With example cases in Osaka and Tokyo bays, it is described how design conditions such as design waves and water levels should account for the influence of climate change. It is also described how adaptive beach management should be implemented accounting for projections of future beach changes. Finally, the paper discusses future challenges in coastal adaptation strategies to climate change in Japan, such as introduction of integrated coastal zone management and other potential options that have not been implemented in Japan.