| The combined heatwave events of temperature and humidity have a far greater impact on human health than a single factor.This article selects the middle and lower reaches of the Yangtze River with frequent the compound temperature-humidity heatwaves.The intensity exceeding 28°C/33°C/35°C,the duration≥3 days,and the affected area≥2000km~2,were defined as common/harmful/fatal compound temperature-humidity heatwave events.Based on the daily observation data of 2467 weather stations in China and the demographic data of the past year,to analyze the changes of common/harmful/lethal compound temperature-humidity heatwave events and their population exposure in the middle and lower reaches of the Yangtze River from 1961 to 2020.Comparison of data from five climate models of from the Coupled Model Intercomparison Project Phase 6,demographic change in combination with the Shared Socioeconomic Pathways(SSP1-5).Under seven scenarios:SSP1-1.9,SSP1-2.6,SSP4-3.4,SSP2-4.5,SSP4-6.0,SSP3-7.0,and SSP5-8.5,estimation of common/harmful/fatal compound temperature-humidity heatwave events and population exposure changes in the near term(2021-2040),medium term(2051-2070),and long-term(2081-2100)in the 21st century.Results show that:(1)From 1961 to 2020,the frequency of common/harmful/fatal compound temperature-humidity heatwave events was 877,381 and 2,the average intensity of each event was about29.5°C,33.4°C and 35.45°C,the duration was about 7 days,4 days and 3 days,the impact area was about 50.5×10~4km~2,6.7×10~4km~2 and 0.5×10~4km~2 and the exposed population was about1.68×10~8 people and 0.26×10~8 and 461.2×10~4,respectively.The common compound temperature-humidity heatwave events have the highest number of events,the longest duration,and the largest impact area,but the weakest event intensity.The frequency,duration and area are second of harmful compound temperature-humidity heatwave events.The frequency,duration and impact area of fatal compound temperature-humidity heatwave events are the least,but the intensity of the events is the strongest,endangering human life and safety.(2)From 2020 to 2100,the intensity,duration and impact area of common/harmful/fatal compound temperature-humidity heatwave events will show upward trend.However,the frequency of common compound temperature-humidity heatwave events will show a downward trend,the frequency of harmful/fatal compound temperature-humidity heatwave events will show increasing trend.Under the long term high emission scenarioes,the frequency of fatal compound temperature-humidity heatwave events will be about 77.2 times that of the base period.In the future,common compound temperature-humidity heatwave events will exceed 32°C,last more than 3 months and affect 97%of the study area.fatal compound temperature-humidity heatwave events will exceed 36°C,last more than two weeks and affect33%of the study area might occur.The high-value areas of fatal compound temperature-humidity heatwave events will be mainly located in the eastern part of the Dongting Lake Basin,most of the Poyang Lake Basin,the southeast of the Han River Basin,the eastern part of the middle main stream area,the northern and eastern part of the downstream mainstream area,and most of the Taihu Lake Basin.(3)From 2020 to 2100,the number of people exposed to common/harmful/fatal compound temperature-humidity heatwave events in the middle and lower reaches of the Yangtze River will show an upward trend.The maximum exposed population will occur in the long term,the number of exposed population will about 2.3×10~8-3.0×10~8,0.7×10~8-1.8×10~8 and 2362.3×10~4-9570.1×10~4,respectively,about 1.2-1.5 times,1.4-3.6 times and 2.1-8.5 times of the base period.Population exposure to fatal compound temperature-humidity heatwave events will increase the fastest compared with the base period.Among them,the central and eastern parts of the Dongting Lake Basin,the northwestern part of the Poyang Lake Basin,the eastern part of the Han River Basin,the northern part of the middle main stream area,the northern and eastern part of the downstream main stream area,and most of the Taihu Lake Basin will have more exposed people than other areas. |
