Urbanization exacerbated the rapid growth of summer cooling demands in China from 1980 to 2023

Abstract

Annual land cover data and daily air temperature data in China from 1980 to 2023 were obtained to attribute the urbanization effect on cooling degree days (CDDs). Significant growth in both extreme daily CDDs and total summer CDDs was observed throughout China, excluding the Tibet Plateau. Urban stations exhibited a substantial increase, with extreme daily CDDs and total summer CDDs rising at rates of 0.46 °C·10 yr⁻¹ and 54.32 °C·10 yr⁻¹, respectively, which were ∼1.5 times higher than those observed at rural stations. The mean trends of extreme daily ΔCDDs and total summer ΔCDDs across 218 urban-rural station pairs were 0.19 °C·10 yr⁻¹, and 21.37 °C·10 yr⁻¹. Urban-rural urbanization ratio differences (ΔURs) exhibited significant correlations with both extreme daily ΔCDDs (r=0.85) and total summer ΔCDDs (r=0.89), attributing 72 %∼79 % of the increases to urbanization. For 66 % and 43 % of the urban-rural station pairs, growing speeds of extreme daily ΔCDDs and total summer ΔCDDs surpassed 0.2 °C·10 yr⁻¹ and 20 °C·10 yr⁻¹, respectively. After surpassing the 44 % threshold in ΔURs, the growth of both extreme daily ΔCDDs and total summer ΔCDDs accelerated with increasing ΔURs. The study emphasizes an increasing summer cooling demand in Chinese cities, necessitating prompt attention from urban planners amidst global warming and urbanization challenges.