Anthropogenic influence on the frequency of extreme temperatures in China

Anthropogenic influence on the frequencies of warm days, cold days, warm nights, and cold nights are detected in the observations of Chinese temperature data covering 1958-2002. We used an optimal fingerprinting method to compare these temperature indices computed from a newly homogenized observational data set with those from simulations conducted with multiple climate models that participated in the Coupled Model Intercomparison Project Phase 5. We found the clear anthropogenic signals in the observational records of frequency changes in warm and cold days and nights. We also found that the models appear to be doing a better job in simulating the observed frequencies of daytime extremes than nighttime extremes. The model-simulated variability appears to be consistent with that of the observations, providing confidence on the detection results. Additionally, the anthropogenic signal can be clearly detected at subnational scales, with detectable human influence found in Eastern and Western China separately.