This graph demonstrate a spatial representation of carbon sequestration of Beijing in the years 1990, 1995, 2000, 2005 and 2008 using Geographic Information Systems. In this case, the use of color differentiate between the denser sequestration areas within Beijing based on a proposed rating grade of I, II and III (lower grades represent higher sequestration). As illustrated, Beijing's high sequestrated areas were found in the outskirts of the city.