Temperature and Precipitation Change over South China in CMIP5 and CMIP6 Models: Historical Simulation and Future Projection

Revealing regional climate changes is vital for policymaking activities related to climate change adaptation and mitigation. South China is a well-developed region with a dense population, but the level of uncertainty in climate projections remains to be evaluated in detail. In this study, we comprehensively assessed the historical simulations and future projections of climate change in South China based on CMIP5/CMIP6 models. We show evidence that CMIP5/CMIP6 models can skillfully reproduce the observed distributions of annual/seasonal mean temperature but show much lower skill for precipitation. CMIP6 outperforms CMIP5 in the historical simulations, as evidenced by more models with lower bias magnitude and higher skill scores. During 2021–2100, the annual mean temperature over South China is projected to increase significantly at a rate of 0.53 (0.42–0.63) and 0.59 (0.52–0.66)°C (10 yr)⁻¹, while precipitation is projected to increase slightly at a rate of 0.78 (0.15–1.56) and 1.52 (0.91–2.30) % (10 yr)⁻¹, under the RCP8.5 and SSP5-8.5 scenarios, respectively. CMIP6 models project larger annual/seasonal mean temperature and precipitation trends than CMIP5 models under equivalent scenarios. The temperature in South China is projected to increase robustly by more than 1.5°C during 2041–2060 under RCP4.5 and SSP2-4.5, but by 4.5°C during 2081–2100, under RCP8.5 and SSP5-8.5 with respect to 1850–1900. The uncertainty in temperature projections is mainly dominated by model uncertainty and scenario uncertainty, while internal uncertainty contributes some of the uncertainty during the near-term. The uncertainty in precipitation projection stems mainly from internal uncertainty and model uncertainty. For both the temperature and precipitation projection uncertainty, the relative sizes of contributions from the main contributors vary with time and show obvious seasonal differences.