CMIP6 evaluation and projection of climate change in Tibetan Plateau

With the release of general circulation model (GCM) outputs from CMIP6 (coupled model intercomparison project phase 6), it is of great importance to explore future variation characteristics of precipitation and air temperature over the Tibetan Plateau (TP), which is the potential trigger and amplifier in global climate change．In this study based on the performance evaluation of CMIP6 multi-GCM over the TP, the DM (Direct Method) statistical downscaling model was developed to project climate change scenarios by taking 1979-2014, 2031-2050, and 2061-2080 as the baseline, near-term, and long-term periods respectively．Future variation patterns in precipitation, mean air temperature, minimum air temperature and maximum air temperature under four shared socioeconomic pathways and representative concentration pathways (SSP) scenarios (SSP126, SSP245, SSP370, and SSP585) were investigated．Projected future precipitation over the TP derived from different GCM under different SSP scenarios showed an overall increasing trend．Compared with the baseline period, projected near-term precipitation varied from −3% to 16%, projected long-term precipitation varied from −1% to 21%．Projected future mean, minimum and maximum air temperatures all showed a consistently rising tendency with similar increasing amplitude．Compared with the base period, projected short-term three air temperatures all increased from 0.9 to 2.3 ℃, projected long-term air temperatures all increased more significantly from 1.01 to 4.6 ℃．Further, with the increase in greenhouse gas emission concentration, warming trends indicated by three air temperatures were consistently more pronounced: SSP585 > SSP370 > SSP245 > SSP126．In addition, the temperature rising in higher altitude areas located in the northern part of TP was greater than in lower altitude areas distributed in the southeastern part, implying a significant elevation dependency of air temperature rising over the TP．These data have important implications for the impact of climate change on water cycles in alpine regions．