Honjo Keita, Gomi Kei, Kanamori Yuko, Takahashi Kiyoshi, Matsuhashi Keisuke
Global Warming Countermeasures Group, Center for Environmental Science in Saitama (CESS), 914 Kamitanadare, Kazo, Saitama, 347-0115, Japan.
Center for Social and Environmental Systems Research, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506, Japan.
Heliyon. 2021 Mar 8;7(3):e06412. doi: 10.1016/j.heliyon.2021.e06412. eCollection 2021 Mar.
Assessing climate change impacts on local communities is an urgent task for national and subnational governments. The impact assessment requires socioeconomic scenarios, including a long-term outlook for demographic and economic indices. In Japan, the National Institute for Environmental Studies developed the Japan Shared Socioeconomic Pathways (JPNSSPs) and presented regional population scenarios corresponding to five different storylines. However, there exists no quantitative information about changes in local economies under the population scenarios. This study examines the economic activities in Japan's 47 prefectures using statistical models and calculates changes in the major economic indices (e.g., production, capital stock, and labor population) until 2100. The economic projection is based on ten socioeconomic scenarios generated from the JPNSSP population scenarios and original productivity scenarios. The economic projection results clearly show that Japan's population aging and decline have catastrophic impacts on national and subnational economies. Even in the most optimistic scenario, assuming a massive influx of immigrants and fast productivity growth, the GDP growth rate becomes negative in the 2090s. In the most pessimistic scenario, the GDP growth rate becomes negative in 2028 and continues to decline. As a result, Japan's GDP decreases to the level of the 1970s by 2100. The improvement of productivity cannot offset the GDP shrink caused by demographic changes. Furthermore, the population aging and decline accelerate the wealth concentration in urban areas. The Theil index, calculated using the economic projection results, shows increasing trends in all the scenarios. Tokyo's presence in Japan's economy will continue to increase throughout this century. Meanwhile, Kanagawa and Saitama, which belong to the top five prefectures in terms of economic production, may lose their positions. The Tohoku region, already suffering from population decline, will face severe economic stagnation. Our findings suggest that the depressing future is inevitable unless Japan overcomes the population aging and decline.
评估气候变化对当地社区的影响是国家和地方政府的一项紧迫任务。影响评估需要社会经济情景，包括人口和经济指标的长期展望。在日本，国立环境研究所制定了日本共享社会经济路径（JPNSSPs），并提出了与五种不同故事情节相对应的区域人口情景。然而，在这些人口情景下，缺乏关于地方经济变化的定量信息。本研究使用统计模型考察了日本47个都道府县的经济活动，并计算了到2100年主要经济指标（如生产、资本存量和劳动力人口）的变化。经济预测基于从JPNSSP人口情景和原始生产力情景生成的十种社会经济情景。经济预测结果清楚地表明，日本的人口老龄化和减少对国家和地方经济具有灾难性影响。即使在最乐观的情景下，假设大量移民涌入且生产力快速增长，国内生产总值（GDP）增长率在2090年代也会变为负数。在最悲观的情景下，GDP增长率在2028年变为负数并持续下降。结果，到2100年日本的GDP降至20世纪70年代的水平。生产力的提高无法抵消人口变化导致的GDP萎缩。此外，人口老龄化和减少加速了财富向城市地区的集中。使用经济预测结果计算的泰尔指数在所有情景中均呈上升趋势。东京在日本经济中的地位在整个本世纪将持续上升。与此同时，在经济生产方面属于前五大都道府县的神奈川县和埼玉县可能会失去其地位。已经遭受人口减少之苦的东北地区将面临严重的经济停滞。我们的研究结果表明，除非日本克服人口老龄化和减少问题，否则黯淡的未来将不可避免。
