Administrative divisions of China By its political level, when a "city" is referred to, it can be a: By its actual area and population, it can be: When used in the statistical data, the word "city" may have three different meanings: It is important to specify the definition of "city" when referring to statistical data of Chinese cities, otherwise, confusion may arise. For example, Shanghai is the largest city in China by population in the urban area but is smaller than Chongqing by the population within the administration area. Before the establishment of the Qin Dynasty, China was ruled by a network of kings,
Environmental issues in China cumulative largest. China has ratified the Kyoto Protocol, but as a non-Annex I country is not required to limit greenhouse gas emissions under terms of the agreement. Various forms of pollution have increased as China have industrialized which has caused widespread environmental and health problems. China has responded with increasing environmental regulations and a build-up of pollutant treatment infrastructure which have caused improvements on some variables. As of 2013 Beijing, which lies in a topographic bowl, has significant industry, and heats with coal, is subject to air inversions resulting in extremely high levels of pollution in winter months. In response