Assessing the geographical diversity of climate change risks in Japan by overlaying climatic impacts with exposure and vulnerability indicators

Understanding multifaceted climate change risks and their interconnections is essential for effective adaptation strategies, which require comprehensive assessments of both climatic impact variations and social-environmental exposures/vulnerabilities. This study examines these interconnections and creates multitier delineations of future climate risks across Japan by overlaying homogeneous impact zones (HIZs) with exposure-vulnerability complexes (EVCs). We delineated eight EVC regions, each exhibiting similar patterns of exposure and vulnerability, via multivariate clustering and similarity search on the basis of future population and land cover/use data. Under the Shared Socioeconomic Pathway 5 scenario, 8.07 % of Japan's area was identified as urban, 66.18 % as forest, and 16.66 % as agricultural land, depending on vulnerability and exposure characteristics. We then spatially intersected these EVCs with six HIZs, which represent common patterns of multisectoral climatic impact variations. This intersection revealed low geographical correspondence between climatic impact variations and exposure-vulnerability factors, indicating high spatial variability in climate risk across Japan. The use of EVCs helps identify areas with anticipated climate change risks. The spatial nexus between HIZs and EVCs underscores the geographical complexity and diversity of climate risks, revealing regions with high-impact variations alongside significant exposures and vulnerabilities. For example, urban EVCs highlight critical issues such as heat-related mortality and flood damage. By mapping these impact variations while focusing on exposure and vulnerability disparities, insights from HIZs and EVCs can inform future climate risk management and effective adaptation strategies at the national and regional levels.