The blue line indicates the limit of Tokyo as defined in this write-up
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.
"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 the Kanagawa prefecture where it is located). This mega region is called the "Capital Region" - Shuto-ken, or simply the Greater Tokyo Area.
With this definition, Tokyo population was 38.6 million for 2016. The total population of the country was 126.5 million (2018). 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).
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 65.62 million 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!!
Tokyo requires a land area equal to almost three times the land area of Japan as a whole to support its residents.
Each of the above three 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.
This situation is borne out by the food self-sufficiency rate of Japan. The "food self-sufficiency rate" shows how much a country can satisfy its food needs from its own domestic production in calorific terms. This stood at 37% for 2018. This means that more than 63% of the food consumed in Japan is imported from overseas, substantially increasing its global footprint, including Tokyo [MAFF, 2018].
The case is similar to waste generated in Tokyo [BoE 2012]. Due to its very high density and high cost of land, more than 80 percent of the waste generated by Tokyo was "exported" to landfill sites in other regions in the country for inceneration and disposal. This extended the footprint far beyond the boundaries of the area that falls under the definition of Greater Tokyo
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?
Footnote on footprints
When a city's footprint is counted, the amount of area 'artificialy' produced is usually overlooked. Having a large field with two country houses occupying the whole surface is not the same as having two houses in the same field in a compact two-storey building freeing the remaining space for agricultural and other purposes.
Tokyo is a city where the land is used several times at several levels, more than any other citiy in the world. Due to the extreme density, they use roof toops, overbulid four levels of transport aboveground, dig large cities underground (In some areas of Tokyo, this extends seven stories underground!), and use spaces 24 hours a day.
If all these variables were used to compute the ecological footprint, the difference between very high density cities and extended cities - like those in the US - would be three or four times greater.
A second point is that understanding ecological footprints will also have to take into account this 'efficiency' of land use and compactness of Tokyo. Compact cities such as Tokyo have a large population living in a very small and dense area of land, freeing land area for other purposes. It also reduces the amount of infrastructure needed to service them, and resources needed for everyday living, rather than having them spread out over a vast area.
- Hari Srinivas, with inputs from IvŠn Villarrubia Lorenzo
BoE (2012) "Current status of industrial waste." Tokyo: Bureau of the Environment, Tokyo Metropolitan Government. http://www.kankyo.metro.tokyo.jp/resource/industrial_waste/about_industrial_waste/about_03/index.html
Earth Council "Ecological Footprints of Nations" San Josť, Costa Rica: Earth Council http://www.ecouncil.ac.cr./rio/focus/report/english/footprint/
MAFF (2018), "The 92nd Statistical Yearbook of the Ministry of Agriculture, Forestry and Fisheries" Tokyo: Ministry of Agriculture, Forestry and Fisheries. https://www.maff.go.jp/e/data/stat/92nd/index.html
WWF (2009), "Japan Ecological Footprint Report"
Worldwide Fund for Nature. https://d2ouvy59p0dg6k.cloudfront.net/downloads/wwf_efj_2009e.pdf