Urban climate change: A comprehensive ecological analysis of the thermo-effects of major Chinese cities

Using 89 major Chinese cities which comprise the case study area, this article computed the urban thermo-effect of summer in the 1990s and 2000s compared to that in the 1950s, using the database of highest monthly temperatures recorded by national weather stations from 1951 to 2007. We conducted a temporal-spatial analysis of the calculated urban thermo-effect, after which we carried out grey correlation degree analysis, system core and coritivity computation of the 22 selected indicators that could affect the urban thermo-effect. These were performed in order to determine the main factors for comprehensive analysis of urban thermo-effect. Finally, we conducted multiple regression analysis between the computed urban thermo-effect and the main factors to create the comprehensive ecological model of the urban thermo-effect. The results indicate that the urban thermo-effect in the 2000s compared to that in the 1950s is stronger than that in the 1990s. Meanwhile, the respective maximum urban thermo-effects in the 2000s and in the 1990s compared to that in the 1950s are 1.97 K and 1.50 K, respectively. The strong positive urban thermo-effect occurred mainly in the northeastern Chinese cities during the 1990s, while it occurred in the northwestern cities and southeastern coastal cities during the 2000s. The six main factors of the urban thermo-effect are the total size, the Gross Domestic Product (GDP), the green area, and the population of the built-up area, as well as the gross of freight and annual electricity consumption. The multiple comprehensive ecological model of the urban thermo-effect is reliable because the residual error of the created model is smaller than 0.5 K. The study discovers that the mitigation of urban temperature increase is possible with the adjustment of these controllable factors. Moreover, the findings in this article could provide references to decisions made while carrying out urban planning and while implementing policies in the national and local scale. Our findings can also provide references to the urban planning and construction of other developing countries with high levels of urbanization and economic development. (C) 2009 Elsevier B.V. All rights reserved.