Abstract China has a vast territory with diverse climates, including the arid Northwest China (NWC), semi-arid and semi-humid mixed North China (NC), humid Yangtze River Valley (YRV) and South China (SC). Previous studies on extreme heat event attribution mainly focus on individual events in specific regions, with less attention paid to comparisons of different historical events. Here, we use three indicators with daily maximum temperature exceeding 35°C, to investigate human influence on the strongest extreme heat events in early and recent periods. Based on the newest observations, we find clear increase of all the heat indicators across China, with a rapid rise in recent decade and the hottest event occurred in 2022. The Coupled Model Intercomparison Project Phase 6 (CMIP6) models generally capture the evolution of these indicators, but some biases exist. We utilize an annual cycle-based method to correct the model biases in climate state and then use the adjusted model results to conduct the event attribution in different historical periods. We find that human influence has greatly increased the probability of recent events across all regions, while having no impact on the early historical events. For the hottest 2022 event, the risk ratios for duration of extreme heat in a few regions could not be estimated due to zero probability in the natural world, indicating that such events could not happen without human influence. In different climate zones, the risk ratios for all indicators in NWC exceed those in other regions when using consistent observational thresholds, indicating a greater response of extreme heat to anthropogenic forcing in this arid region. For the same event, attribution results of different indicators yield varying risk ratios, highlighting the importance of considering multiple indicators in event attribution. Additionally, model performance notably affects attribution results; without bias correction, human influence may be incorrectly estimated.
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