Environmental Science & Technology POLICY ANALYSIS Figure 2. Spatial distribution of Chinese cities included in analysis. Panel U1 (1990 1998) consists of 174 cities. Panel U2 (1997 2006) consists of 135 cities. Panel U3 (1990 2006) consists of 121 cities that appear in both U1 and U2 panel. and/or other remote sensing data and ground surveys. The MOHURD combines these two data source and produces the initial data. The Department of Urban Social and Economic Survey at the National Bureau of Statistics performs sample investigation in selected cities, to calibrate the initial data produced by the MOHURD. The resulting measure is considered as the best proxy of the real urban area in China.24,35,36According to He et al.,37 the relative error between the derived total urban land area and the statistical built-up area data at national scale was less than 2% in 1992, 1996, and 1998, and maximum relative error at province scale did not exceed 10% with most of the provinces less than 3%. Three panels of urban data and one panel of provincial-level data are used for the causality test. It is common in China that a city includes some counties which are largely rural. In order for the city data to reﬂect only urban component and exclude the counties within the city administrative boundaries, our data set exclude county level cities/towns. The GDP, year-end popula- tion, and built-up area excluding counties for the 174 Chinese cities (1990 1998) in panel U1 come from a single source, Cities China 1949 1998,38 and the data for the 135 Chinese cities (1997 2006) in panel U2 are from the China City Statistical Yearbook series.39 See Figure 2 for their spatial distribution map, and Supporting Information for the list of cities in each panel. We excluded those cities that do not have the full range of data for the period of interest, and those that have apparent data errors in the original database. Panel U3 consists of 121 cities that appear in both panels U1 and U2, and thus have time range of 1990 2006. All the GDP data are converted into compar- able prices, and GDP per capita is calculated from GDP divided by the year-end population. We also test whether built-up Figure 3. Rapid urban expansion of Shenzhen City from 2000 to 2007 based on remote sensing image interpretation. Red color for urban land, yellow for bare land, green for land with vegetation, blue for water body. ETM+ image on November 1st 2000, TM image on September 15th 2000, ETM+ SLC-oﬀ composite data on December 7th and November 30th 2007 are used for this comparison. area expansion contributes to regional economic growth, with a panel (P) of built-up area and GDP per capita data (1997 2006) for all 34 provincial regions except Hong Kong, Macau, and Taiwan, compiled from the China Statistical Yearbook series.40 134 dx.doi.org/10.1021/es202329f |Environ. Sci. Technol. 2012, 46, 132–139