The footprint of a city is defined as the amount of land required to sustain its metabolism; that is, to provide the raw materials on which it feeds, and process the waste products it excretaes.
The blue line indicates the limit of Tokyo as defined in this write-up
"Tokyo" as defined here is a conurban region that includes the 23 wards of Tokyo Metropolitan Government and the surrounding prefectures of Kanagawa, Chiba and Saitama (Yokohama city is therefore included within Kanagawa prefecture.)
With this definition, Tokyo population was 26.6 million for 1995. The total population of the country was 125.1 million (1995). The total land area of Japan is 377, 700 sq km. (37,770,000 ha) (habitable land is equal to 125,500 sq km or 12,550,000 ha, approximately 33% of the total land).[ OneWorld ]
1. According to the Earth Council report, "Ecological Footprints of Nations" a biologically productive area of 1.7 ha is available per capita for basic living. This means that for sustainable living, the people in Tokyo alone need an area of 45,220,000 ha - which is 1.2 times the land area of the whole of Japan. If mountains and other regions are discarded and only habitable land included, then this becomes 3.6 times the land area of Japan.
2. From the same report, taking the country as a whole, Japan has a demand for 6.25 ha per capita (for resources such as energy, arable land, pasture, forest, built-up area, etc.). But the supply has been 1.88 ha per capita. This leaves a 'ecological deficit' of 4.37 ha per person that has to be met from outside the country. For Tokyo alone, this is equal to 116,242,000 ha or 3.07 times the land area of Japan.
3. Lets take another viewpoint, based on the write-up, "London's Footprint" in OneWorld. 26,600,000 people live in Tokyo. Area required for food production is 0.2 ha per person. For Tokyo, this will be a total of 5,320,000 ha ... (1) Similarly the forest area required by Tokyo for wood products is 0.109 ha per person. Tokyo's value is 2,899,400 ha. ... (2) Land area that would be required for carbon sequestration (=fuel production) is 1.5 ha per person This is 74,214,000 ha for Tokyo ... (3) The total of 1, 2 and 3 is 108,528,000 ha - 2.14 times the land area of the whole of Japan!!
Each of the above methodologies give different multiples of Japan's land area needed to sustain the population of only Tokyo, the world's largest city. The key point to understand here is the sponge that an urban area is, in soaking up the earth's natural resources.
But environmental footprints are not an 'exact science'. As we saw above, different definitions can provide different footprints. It also depends on issues of scale in which it is measured - city, nation, region. Besides, excess footprints for small, developed nations are inevitable.
Footprints are useful, however from three points of view:
- to shock, to generate awareness - focussing on urban lifestyles and living, resource utlization etc.
- to build scenarios: if criteria used to define the footpirnts are changed, or resource utilization reduced, how does it affect the footprints?
- to evaluate and monitor policies and programmes. What footprints have particular policies and programmes generated? If their structure is changed/modified, or new policies put inplace, how are footprints affected?