State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China; Jiangsu Center for Collaborative Innovation in Geographic Information Resource Development and Application, Nanjing 210023, China.
Sci Total Environ. 2023 Aug 25;888:164142. doi: 10.1016/j.scitotenv.2023.164142. Epub 2023 May 12.
Global warming leads to more frequent and intense heatwaves, putting urban populations at greater risk. Previous related studies considered only surface air temperature or one or two Shared Socioeconomic Pathways (SSPs) and were limited to specific regions. Moreover, no research focused on heatwave exposure in highly-populated global megacities facing severe threats. This study is the first to project future population exposure to heatwaves in 83 global megacities by 2100 using fine-resolution data, suitable indices reflecting human comfort in heatwaves by incorporating temperature and humidity, and a future population exposure projection and analysis framework. The results show that (1) the global frequency of extreme heatwave events and average change rate in each megacity sequentially increase from SSP1-2.6 to SSP5-8.5, and the change rate is generally larger in megacities in the Southern Hemisphere; (2) the increases in heatwave exposure are greatest under SSP370, and the change rates are generally larger for megacities in Southern Asia; (3) there is a high degree of inequality (Gini of 0.6 to 0.63) in future heatwave exposure globally, with the highest inequality under SSP5-8.5 and the lowest under SSP3-7.0; (4) the average exposure, increase rate, and change are highest in low-income megacities and lowest in high-income megacities. The distribution of exposure is the most balanced in middle-income megacities and the least balanced in high-income megacities; and (5) population growth contributes more to the change in exposure than total warming in high-income megacities under SSP1-2.6, and total urban warming contributes much more than population growth in all other cases. Every effort should be made to avoid the SSP3-7.0 scenario and pursue sustainable and rational urban economic development. Mumbai, Manila, Kolkata, and Jakarta warrant particular attention due to their rapid exposure growth. Additionally, policymakers and urban planners must focus on improving sustainable development planning for megacities in southern Asia and low-income megacities.
全球变暖导致热浪更加频繁和剧烈，使城市人口面临更大的风险。之前的相关研究仅考虑了地面空气温度或一个或两个共同社会经济途径 (SSP)，并且仅限于特定地区。此外，没有研究关注面临严重威胁的人口众多的全球特大城市的热浪暴露情况。本研究首次使用细分辨率数据，通过结合温度和湿度来反映热浪中人体舒适度的合适指标，以及未来人口暴露预测和分析框架，预测到 2100 年 83 个人口众多的全球特大城市的未来人口暴露于热浪之中。结果表明：(1) 极端热浪事件的全球频率和每个特大城市的平均变化率从 SSP1-2.6 到 SSP5-8.5 依次增加，南半球特大城市的变化率通常更大；(2) 在 SSP370 下，热浪暴露的增加最大，南亚特大城市的变化率通常更大；(3) 全球未来热浪暴露的不平等程度很高 (0.6 到 0.63 的基尼系数)，SSP5-8.5 下的不平等程度最高，SSP3-7.0 下的不平等程度最低；(4) 低收入特大城市的平均暴露量、增长率和变化率最高，高收入特大城市的最低；中收入特大城市的暴露分布最均衡，高收入特大城市的暴露分布最不均衡；(5) 在 SSP1-2.6 下，高收入特大城市的人口增长对暴露变化的贡献大于总变暖，而在所有其他情况下，总城市变暖对暴露变化的贡献大于人口增长。应尽一切努力避免 SSP3-7.0 情景，并追求可持续和合理的城市经济发展。由于暴露增长率迅速，孟买、马尼拉、加尔各答和雅加达值得特别关注。此外，政策制定者和城市规划者必须专注于改善南亚和低收入特大城市的可持续发展规划。
