School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan.
Department of Global Health Policy, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
Environ Health Perspect. 2023 Nov;131(11):117012. doi: 10.1289/EHP11246. Epub 2023 Nov 23.
The impact of climate change on mental health largely remains to be evaluated. Although growing evidence has reported a short-term association between suicide and temperature, future projections of temperature-attributable suicide have not been thoroughly examined.
We aimed to project the excess temperature-related suicide mortality in Japan under three climate change scenarios until the 2090s.
Daily time series of mean temperature and the number of suicide deaths in 1973-2015 were collected for 47 prefectures in Japan. A two-stage time-stratified case-crossover analysis was used to estimate the temperature-suicide association. We obtained the modeled daily temperature series using five general circulation models under three climate change scenarios from the latest Coupled Model Intercomparison Project Phase 6 (CMIP6) Shared Socioeconomic Pathways scenarios (SSPs): SSP1-2.6, SSP2-4.5, and SSP5-8.5. We projected the excess temperature-related suicide mortality until 2099 for each scenario and evaluated the net relative changes compared with the 2010s.
During 1973-2015, there was a total of 1,049,592 suicides in Japan. Net increases in temperature-related excess suicide mortality were estimated under all scenarios. The net change in 2090-2099 compared with 2010-2019 was 1.3% [95% empirical confidence interval (eCI): 0.6, 2.4] for the intermediate-emission scenario (SSP2-4.5), 0.6% (95% eCI: 0.1, 1.6) for a low-emission scenario (SSP1-2.6), and 2.4% (95% eCI: 0.7, 3.9) for the extreme scenario (SSP5-8.5). The increases were greater the more extreme the scenarios were, with the highest increase under the most extreme scenario (SSP5-8.5).
This study indicates that Japan may experience a net increase in excess temperature-related suicide mortality, especially under the intermediate and extreme scenarios. The findings underscore the importance of mitigation policies. Further investigations of the future impacts of climate change on mental health including suicide are warranted. https://doi.org/10.1289/EHP11246.
气候变化对心理健康的影响在很大程度上仍有待评估。尽管越来越多的证据表明自杀与温度之间存在短期关联，但尚未彻底研究未来因温度导致的自杀预测。
我们旨在根据三种气候变化情景预测 21 世纪 90 年代之前日本因气温相关的超额自杀死亡率。
我们收集了日本 47 个都道府县 1973 年至 2015 年期间的日平均气温和自杀死亡人数的时间序列数据。采用两阶段时间分层病例交叉分析来估计温度与自杀的关联。我们使用最新耦合模型比较计划第六阶段（CMIP6）共享社会经济途径情景（SSP）下的五个通用环流模型获得模型化的日平均气温序列：SSP1-2.6、SSP2-4.5 和 SSP5-8.5。我们预测了每个情景下直至 2099 年的因气温相关的超额自杀死亡率，并评估了与 2010 年代相比的净相对变化。
1973 年至 2015 年期间，日本共有 1049592 人自杀。所有情景下均估计到与气温相关的超额自杀死亡率的净增加。与 2010 年至 2019 年相比，2090 年至 2099 年的净变化在中等排放情景（SSP2-4.5）下为 1.3%（95%经验置信区间（eCI）：0.6，2.4），在低排放情景（SSP1-2.6）下为 0.6%（95% eCI：0.1，1.6），在极端情景（SSP5-8.5）下为 2.4%（95% eCI：0.7，3.9）。情景越极端，增加幅度越大，在最极端的情景（SSP5-8.5）下增幅最大。
本研究表明，日本可能会经历与气温相关的超额自杀死亡率的净增加，尤其是在中等和极端情景下。研究结果强调了减排政策的重要性。进一步研究气候变化对心理健康（包括自杀）的未来影响是必要的。https://doi.org/10.1289/EHP11246.
