Robust elevation dependency warming over the Tibetan Plateau under global warming of 1.5 °C and 2 °C

Abstract

The Tibetan Plateau (TP) is called the “third pole” and the “Asian water tower”, and climate change over the TP is evident in recent decades. However, the elevation dependency warming (EDW, larger temperature increases with higher elevation) over the TP under global warming of 1.5 °C and 2 °C is not well understood. In this study, future changes in the monthly mean, maximum, and minimum temperature over the TP derived from 21 global climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) are investigated using a midrange/high emission scenario (RCP4.5/8.5) in which the global surface temperature has risen by 1.5 °C and 2 °C relative to the pre-industrial period. The multi-model ensemble mean of 21 CMIP5 models indicates that the TP has rapidly warmed to a larger degree than the global mean and the whole China. Overall, the mean temperature over the TP under RCP4.5/8.5 scenarios under global warming of 1.5 °C and 2 °C will increase by 2.11/2.10 °C and 2.89/2.77 °C, respectively, particularly in the western TP. The midrange emission scenario RCP4.5 shows larger temperature changes under global warming of 1.5 °C and 2 °C than the high emission scenario RCP8.5. Furthermore, a robust EDW over the TP is found to intensify under global warming of 1.5 °C and 2 °C, which is probably contributed by the snow/ice-albedo feedback in the elevation range between 3.5 and 4 km over the TP. The EDW over the TP raises more robust under global warming of 2 °C than 1.5 °C. This study suggests that the TP is being influenced by global warming approximately 10 years earlier than the global scale under global warming of 1.5 °C and 2 °C, and the EDW under global warming of 1.5 °C and 2 °C will have potentially serious consequences for the third pole environment.