Future Risks of Unprecedented Compound Heat Waves Over Three Vast Urban Agglomerations in China

Abstract

 Unprecedented compound heat waves will occur on a regular basis in three urban agglomerations in China since mid-21st century under RCP8.5  The likelihood of unprecedented compound heat waves in a 1.5 ℃ warmer world will halve compared to 2 ℃ warming scenario  Population exposures to future unprecedented compound heat waves will increase by nearly 70, 90, and 60 million by the end of this century

Compound events and associated impacts in China

“…Projections of compound hot extremes reveal an increase in the future, with a higher risk in urban areas ( Liao et al., 2021a ; Su and Dong, 2019 ; Wang et al., 2020b ; Xie et al., 2022 ). Under the representative concentration pathway (RCP) 8.5 (a high greenhouse gas emissions pathway), almost 50% of land areas in three urban agglomerations of China, including the Beijing-Tianjin-Hebei region (midlatitudes), the Yangtze River Delta (subtropical regions), and the Pearl River Delta (tropical regions), will experience historically unprecedented compound hot extremes regularly by 2050, 2050, and 2030, respectively, with a faster growth rate of the magnitude in Pearl River Delta ( Wang et al., 2020b ). The high population density in urban areas in China and the continuous increase in the population can further amplify the risk of compound hot extremes.…”

More Persistent Summer Compound Hot Extremes Caused by Global Urbanization

“…In this study, a Daytime/Nighttime hot extreme (DayHot/NightHot) is then identified as a period comprising at least three consecutive days with hot days/nights. A Compound hot extreme (CoHot) is identified as a period comprising at least three consecutive hot days and hot nights simultaneously (J. Wang, Feng, et al., 2020). The hot extremes were quantified based on three characteristics, that is, the count of hot events (CoHotN, DayHotN, and NightHotN), total duration of hot events (CoHotD, DayHotD, and NightHotD), and average intensity of hot events (CoHotI, DayHotI, and NightHotI) within a year.…”

Mutual effects of CO2 emission reduction and air pollution control policies in beijing-tianjin-hebei region

“…In contrast, under the 1.5D scenario, it could not offset the climate mitigation costs in all three regions with health benefits, particularly in Beijing, with the economic loss (12.0 BUSD) far more than the health benefits (1.57 BUSD). This phenomenon indicates that the climate mitigation policy before 2030 is difficult to show the health benefits, and the health risk would decrease in the long term under the strict climate change mitigation policy (Li et al, 2018;Wang et al, 2020), such as carbon neutrality and 1.5 °C climate target.…”