Different multi-year mean temperature in mid-summer of South China under different 1.5 °C warming scenarios

The Paris Agreement proposed a goal of “pursuing efforts to limit the temperature increase to 1.5 °C above pre-industrial levels”. The Community Earth System Model, version 1, with the Community Atmosphere Model, version 5 (CESM1-CAM5), designed a set of experiments that fulfilled the 1.5 °C warming goal. By analyzing the outputs, this study aims to present projections associated with warming in South China (SC). Interestingly, if the global mean temperature (GMT) overshoots to 1.7 °C above the pre-industrial levels in 2050 and back to 1.5 °C by 2100, additional warming in the SC mid-summer will occur when approaching 2100 compared to that in the scenario under which the GMT stabilizes at an increase of 1.5 °C after the mid-2040 s. In the final 1 to 3 decades of 21(st) century in most parts of SC, the multi-year mean warming differences, as well as the difference of extreme hot days, between the two scenarios are significant among the ensembles in mid-summer. Under the scenario in which the GMT overshoots an increase of 1.5 °C, the decrease of mid-level clouds leads to increased downwards solar radiation in the SC and warms the surface, resulting in increases in both outgoing longwave radiation and latent heat flux into the atmosphere and maintenance of the surface balance of the heat budget.