Signals In Temperature Extremes Emerge in China During The Last Millennium Based On CMIP5 and CMIP6 Simulations

Though the magnitude of any change is important, regions which have a larger signal of change relative to the background variations will potentially face greater risks than other regions, as they will see unusual or novel climate conditions more quickly (Frame et al. 2017). Providing more information about signal and noise on regional scales, and the associated attribution to particular causes, is therefore important for adaptation planning (Chen et al. 2021). However, whether a detectable signal in temperature extremes emerges in China at the local or regional level during 850−2005 has not been discussed. Based on six selected and bias-corrected global models under the Coupled Model Intercomparison Project phase 5, relative to pre-industrial levels (ca 1850), we show that the temporal information of signal-to-noise ratio (S/N) in annual temperature extremes are consistent with annual mean temperature variations in China during 850−2005. Before 1850, absolute values of regional mean S/N in temperature extremes under cold climatic conditions are generally larger than that under warm climatic conditions. At the level of S/N > 1, local increasing signals of cold extremes emerge in the second half of 13th century and in the early 19th century after intensively volcanic eruptions in 1257 and 1815 in most part of China, especially in southern China and Tibet Plateau. Over the past 150 years under global warming, absolute values of regional mean S/N in temperature extremes have increasing trends. The regional mean increasing signals of warm extremes over China begin to exceed natural variability in 1969 at the level of S/N > 1, and local warm signals first occur in 1929 in Tibet Plateau. These warming signals are related to greenhouse gas forcing.