Tibetan Plateau amplification of climate extremes under global warming of 1.5 °C, 2 °C and 3 °C

Global warming may increase the frequency of climate extremes, but systematic examinations at different temperature thresholds are unknown over the Tibetan Plateau (TP). Changes in surface temperature and precipitation extreme indices derived from a mull-model ensemble mean (MMEM) of the Coupled Model Inter-comparison Project Phase 5 (CMIP5) models are examined under global warming of 1.5 degrees C (RCP2.6), 2 degrees C (RCP4.5) and 3 degrees C (RCP8.5) above pre-industrial levels. The TP amplification of future temperature and precipitation changes is evident for all three scenarios, with greater trend magnitudes in extreme indices than those for the whole China, regions between 25 degrees N and 40 degrees N, Northern Hemisphere (land only), Northern Hemisphere and the global mean. The TP amplification is also projected to intensify in each scenario, resulting in faster changes in intensity, duration and frequency of climate extremes. There appears to be greater difference for precipitation-based indices between 2 degrees C and 3 degrees C than for temperature, and the differences between 1.5 degrees C and 2 degrees C are less dramatic. Overall changes in climate extremes at 2 degrees C are greater than at 1.5 degrees C, but differences are less discernible between 3 degrees C and 2 degrees C. The Kolmogorov-Smirnov test between simulated and scaled temperature distributions shows that accelerated warming over the TP from 1.5 degrees C to 2 degrees C follows a broadly linear response, but the nonlinearity occurs between 2 degrees C and 3 degrees C. This suggests that the rate of warming might make a large difference to the future TP amplification at different thresholds.