Future Changes in Extreme High Temperature over China at 1.5°C–5°C Global Warming Based on CMIP6 Simulations

Abstract

Extreme high temperature (EHT) events are among the most impact-related consequences related to climate change, especially for China, a nation with a large population that is vulnerable to the climate warming. Based on the latest Coupled Model Intercomparison Project Phase 6 (CMIP6), this study assesses future EHT changes across China at five specific global warming thresholds (1.5°C–5°C). The results indicate that global mean temperature will increase by 1.5°C/2°C before 2030/2050 relative to pre-industrial levels (1861–1900) under three future scenarios (SSP1-2.6, SSP2-4.5, and SSP5- 8.5), and warming will occur faster under SSP5-8.5 compared to SSP1-2.6 and SSP2-4.5. Under SSP5-8.5, global warming will eventually exceed 5°C by 2100, while under SSP1-2.6, it will stabilize around 2°C after 2050. In China, most of the areas where warming exceeds global average levels will be located in Tibet and northern China (Northwest China, North China and Northeast China), covering 50%–70% of the country. Furthermore, about 0.19–0.44 billion people (accounting for 16%–41% of the national population) will experience warming above the global average. Compared to present-day (1995–2014), the warmest day (TXx) will increase most notably in northern China, while the number of warm days (TX90p) and warm spell duration indicator (WSDI) will increase most profoundly in southern China. For example, relative to the present-day, TXx will increase by 1°C–5°C in northern China, and TX90p (WSDI) will increase by 25–150 (10–80) days in southern China at 1.5°C–5°C global warming. Compared to 2°C–5°C, limiting global warming to 1.5°C will help avoid about 36%–87% of the EHT increases in China.

摘要

极端高温是气候变化所产生的较为严重的后果之一,特别是对于中国这样一个极易受气候影响的人口大国来说。本研究基于最新的CMIP6模拟结果,预估了在全球增暖达到相较于工业革命之前(1861–1900)的1.5°C–5°C情景下,中国未来极端高温的变化。结果表明,在三种排放情景下(SSP1-2.6、SSP2-4.5和SSP5-8.5),全球平均气温将分别在2030年和2050年之前上升到工业革命前的1.5℃和2℃水平。其中,SSP5-8.5情景下的升温速度更快。在SSP5-8.5情景下,全球变暖在2100年将超过5℃;而在SSP1-2.6情景下,全球变暖在2050年后将稳定在2℃左右。对于中国来说,约有50%–70%地区的升温将超过全球平均水平,其中大部分位于西藏和北方地区(西北、华北和东北)。同时,约有1.9–4.4亿人(占全国人口的16%–41%)将面临高于全球平均水平的增暖。而与现代期(1995–2014年)相比,北方地区最暖日的增幅将更大,而南方地区的暖昼日数和持续暖期指数的增幅将更大。例如,相对于现代期,当全球变暖达到1.5℃–5℃时,北方地区的最暖日将上升1℃–5℃,而南方地区的暖昼日数和持续暖期指数每年将分别增加25–150天和10–80天。与2℃–5℃温升水平相比,控制全球增暖在1.5℃,将令中国极端高温事件的增幅减少36%–87%。