Continuous decline of climate fluctuations in the Kunlun–Pamir Plateau from the perspective of the bioclimatic variables

Understanding the changes in bioclimatic indicators is a prerequisite and foundation for biodiversity simulation and prediction of climate sensitive organisms. However, in high-altitude areas that are extremely sensitive to climate change, the long-term evolution patterns of bioclimatic indicators are still limited in understanding. For this purpose, we selected the Kunlun-Pamir Plateau, an irreplaceable biodiversity hotspot, as the research area, and to analyze the spatiotemporal evolution characteristics of bioclimatic indicators. We employed trend analysis, Empirical Orthogonal Function (EOF), and continuous wavelet analysis to conduct spatiotemporal analysis on 19 bioclimate indicators. We found that (1) Temporally, Mean Diurnal Range, Isothermality, Temperature Seasonality, Temperature Annual Range, Precipitation Seasonality are all trending downward in the time series; Spatially, the trend of change shows spatial variability. Central Kunlun is experiencing the biggest increases in energy factors. A western part of the Kunlun Pamir Plateau exhibits the pronounced rises in water factors. (2) The first two EOFs of 15 bioclimatic variables explained over 50% of the total variance, showing significant variations and spatial heterogeneity. (3) Regarding the periodicity: bioclimatic variables showed no significant periodicity, with the majority of events occurring at irregular intervals of 1-4 years and in different years. These insights enhance our understanding of climate characteristics in the Kunlun-Pamir Plateau, providing valuable input for devising effective biodiversity conservation strategies.