The increasing frequency of heavy rainfalls and severe typhoons is said to be caused by the adverse effects of climate change. Among various climate change risks, physical damages by natural disasters in Japan are increasingly being acknowledged by the public and have been investigated in many studies. However, studies from overseas have pointed out that climate change impacts in various parts of the world can increase economic and sociopolitical risks through various routes. Climate change impacts, therefore, need to be recognized as a compound risk that includes diverse domestic and international impacts. To date, this approach has not yet been taken in Japan. The aim of this research project is to deepen our knowledge from the perspective of each of the six types of climate risks shown in Figure. Until now, these risks have merely been discussed in Japan, even though they are particularly important for national risk management. As shown in the figure, these risks are not only components of the compound risk for Japan, but each type of risk can also contribute to the others. The research for this project is ongoing, but the findings and results obtained at this stage are as follows.
(1) Corporate activities are affected by climate change through various routes. In general, companies have a greater awareness of the effects of short-term risks such as torrential rains and floods, but they are not necessarily aware of risks resulting from high temperatures or slow-onset events that appear gradually over time.
(2) We are developing an international trade model that represents the import and export of 5041 products. We can now reproduce past performance values, and we plan to use the model to show the relationship between past disasters and changes in the quantity of trade. It is expected that an increase in the number or severity of disasters in a region will affect trade between that region and Japan.
(3) Because of the effects of drought and high temperatures, it is expected that world food production will decline if no countermeasures are taken in the future. The world population is expected to continue increasing, so Japan, which imports a large amount of food, needs to consider the regions from which food (especially grain) is procured as well as its food supply methods.
(4) Targeting Asian countries that have strong ties with Japan, we independently developed a climate vulnerability index based on multiple indicators. This index can be used to show the vulnerability of countries to climate change impacts and their reliance on emergency humanitarian assistance from abroad, including from Japan.
(5) The concept of climate security is related to other types of security concepts. Although studies have clarified the strong links between food and energy security and climate security, climate mitigation actions are likely to have positive effects in other areas of security, such as maritime and human security.
(6) Island countries such as Japan are affected by sea-level rise, which could lead to Japan’s territory, territorial waters, and Exclusive Economic Zone shrinking in the long run. In addition, the number of refugees overseas is increasing as a result of climate change, and there is a growing demand for a response in the international community. It is important for Japanese stakeholders to start discussing these issues.