Evidence for a significant urbanization effect on climate in China

Abstract

China has experienced rapid urbanization and dramatic economic growth since its reform process started in late 1978. In this article, we present evidence for a significant urbanization effect on climate based on analysis of impacts of land-use changes on surface temperature in southeast China, where rapid urbanization has occurred. Our estimated warming of mean surface temperature of 0.05 degrees C per decade attributable to urbanization is much larger than previous estimates for other periods and locations. The spatial pattern and magnitude of our estimate are consistent with those of urbanization characterized by changes in the percentage of urban population and in satellite-measured greenness.

Fig. 1.

Monthly temperature anomalies in the observational and R-2 data for Shenzhen, a city with the fastest population growth in China, from January 1979 to December 1998: maximum (a), minimum (b), and DTR (c). A 3-month smoothing is applied. The correlation coefficient between the two data sets (without smoothing) is shown.

Fig. 2.

Observed winter temperature trends (in °C per decade) over southeast China from 1979 to 1998: maximum (a), minimum (b), and DTR (c).

Fig. 3.

Observed minus R-2 winter temperature trends (in °C per decade) in southeast China from 1979 to 1998: maximum (a), minimum (b), and DTR (c).

Fig. 4.

Relationship for the DTR trends (in °C per decade; Fig. 3c) versus the increases in percentage urban (a) and the minimum temperature trends (in °C per decade; Fig. 3b) versus summer greenness trends (per decade; Fig. 5) at provincial level (b). The correlation coefficients and their significance level are shown. The dashed line represents a least-squares fit.

Fig. 5.

Summer NDVI trends per decade from 1982 to 1998.