Variability of bio-climatology indicators in the Southwest China under climate warming during 1961-2015

Southwest China (SWC), characterized by complex climate, undulating topography, intertwined mountains and basins, and diverse ecosystem, is a global hotspot in biodiversity. SWC also is sensitive to climate change, the effects of which can be expressed through alterations in bio-climatology indicators. In this study, we investigated the trends of the key bio-climatology indicators, including mean temperature of the warmest month (TWM), mean temperature of the coldest month (TCM), accumulated temperature above 5 °C (AT₅) and 10 °C (AT₁₀), number of days with daily mean temperature above 5 °C (DT₅) and 10 °C (DT₁₀), annual precipitation (P), precipitation days (DP), and moisture index (MI). The 105 meteorological stations data from 1961 to 2015 were selected to examine the trend of these indexes in SWC. The results suggested that TWM and TCM both experienced a significant upward trend, with the more pronounced increase in TCM than that in TWM. TWM increased by 0.011 °C year^-1 and TCM increased by 0.025 °C year^-1. AT₅, AT₁₀, DT₅, and DT₁₀ also exhibited increasing trend, with AT₁₀ > AT₅ and DT₁₀ > DT₅, and the trend in DT was found to be less significant than that in AT. The increment of AT₅, AT₁₀, DT₅, and DT₁₀ were 6.452 °C year^-1, 7.158 °C year^-1, 0.164 days year^-1, and 0.263 days year^-1, respectively. P, DP, and MI showed a downward trend, among which DP experienced a significant decrease with - 1.018 days year^-1. In general, SWC tends to be drier and warmer, which may alter the structure and function of the local ecosystem, further then affect the role as a global diversity hotspot.