Historical assessment and future projection of extreme precipitation in CMIP6 models: Global and continental

Abstract

AbstractIn this study, the new gridded daily precipitation dataset REGEN (Rainfall Estimates on a Gridded Network) was used to verify the performance of 23 global climate models participating in the 6th phase of the Coupled Model Intercomparison Project (CMIP6) in terms of extreme precipitation over global and continents during 1950–2014. Projected changes were also evaluated using CMIP6 multi‐model ensemble (MME) under different Shared Socioeconomic Pathway (SSP) by the end of the 21st century. Although positive biases exist in the climatology of most extreme precipitation indices simulated by the CMIP6 MME compared with observations, most of the CMIP6 models can reproduce the spatial distribution characteristics and temporal evolution trends of global extreme precipitation. The simulation is improved by using the CMIP6 MME, relative to the results from individual models. The projected results showed that in most regions of the world, extreme precipitation will significantly increase in the future, with more significant increase under higher SSPs. By the end of the 21st century, total precipitation of wet days (PRCPTOT), simple daily intensity (SDII), the number of very heavy rain days (R20mm), maximum 1‐day precipitation (Rx1day) and maximum consecutive 5‐day precipitation (Rx5day) over the global will increase by up to 50%, 20%, 70%, 50% and 50%, respectively, under the SSP5‐8.5 scenario. Nevertheless, marked uncertainties exist in the projection of extreme precipitation in South America and in the global for consecutive dry days (CDD) index. Noteworthy, average PRCPTOT, Rx1day and Rx5day over Asia, Europe and North America, as well as of the whole world, have significantly increased where the CDD index is also higher, shown by projected results. In summary, global extreme precipitation will increase in the future, and precipitation will become more uneven in space and time. Moreover, as the SSP scenario becomes higher, the uneven distribution of precipitation will become more pronounced.