Global surface air temperatures in CMIP6: historical performance and future changes

Surface air temperature outputs from 16 global climate models participating in the sixth phase of the coupled model intercomparison project (CMIP6) were used to evaluate agreement with observations over the global land surface for the period 1901-2014. Projections of multi-model mean under four different shared socioeconomic pathways were also examined. The results reveal that the majority of models reasonably capture the dominant features of the spatial variations in observed temperature with a pattern correlation typically greater than 0.98, but with large variability across models and regions. In addition, the CMIP6 mean can capture the trends of global surface temperatures shown by the observational data during 1901-1940 (warming), 1941-1970 (cooling) and 1971-2014 (rapid warming). By the end of the 21st century, the global temperature under different scenarios is projected to increase by 1.18 degrees C/100 yr (SSP1-2.6), 3.22 degrees C/100 yr (SSP2-4.5), 5.50 degrees C/100 yr (SSP3-7.0) and 7.20 degrees C/100 yr (SSP5-8.5), with greater warming projected over the high latitudes of the northern hemisphere and weaker warming over the tropics and the southern hemisphere. Results of probability density distributions further indicate that large increases in the frequency and magnitude of warm extremes over the global land may occur in the future.