The effect of greenhouse gases concentration and urbanization on future temperature over Guangdong-Hong Kong-Macao Greater Bay Area in China

Relative contributions of greenhouse gases (GHGs) concentration and land use/cover (LULC) change induced by urbanization on future temperature over the Guangdong-Hong Kong-Macao Greater Bay Area in China under different climate scenarios are investigated in this study. The Weather Research and Forecasting model is used to downscale the future mean and extreme temperature using the Representative Concentration Pathways (RCP) 4.5&8.5 simulations from the Community Earth System Model. Results show that GHGs concentration is the key dominate factor for future mean and extreme temperature over the Greater Bay Area in the next 10–30 years, LULC change (urbanization) has relative slight effect on the future regional temperature. On the urban local scale, the LULC change in urban area has an obvious warming effect on urban local temperature under future different GHGs concentration scenarios. The regional-averaged annual mean surface air temperature (SAT) of urban area will increase 0.51 °C (0.73 °C), 0.83 °C (1.17 °C) and 1.26 °C (1.74 °C) resulting from the combined contributions of urbanization and GHGs forcing for the year of 2030, 2040, and 2050 under RCP4.5(RCP8.5) scenario, respectively. The contributions of the GHGs forcing are 0.33 °C (0.53 °C), 0.66 °C (1.00 °C) and 1.12 °C (1.58 °C), the urbanization forcing are 0.18 °C (0.20 °C), 0.17 °C (0.17 °C) and 0.14 °C (0.16 °C). Same as regional-averaged annual mean SAT, for the extreme high- and low-temperature, the contribution of GHGs forcing is more important than that of the urbanization forcing. The extreme temperatures are more sensitively to GHGs concentration under RCP8.5 scenario than that under RCP4.5, especially for the extreme low-temperature. GHGs are the most important factor for dominating the future mean and extreme temperature of the Greater Bay Area.