book_cover_big.gifWe all know that in the industrialized part of the world we are taking advantage of a disproportional part of the world’s resources. And of course there are all kinds of angles that you can look at this problem. For instance you can look to the rate of consumption or use of certain resources (like minerals or energy) per capita or the amount of CO2 produced in each part of the world. Another way to look at the entire matters is the amount of land needed to sustain a given economy like the amount of arable land available. This amount is not a constant in time. Since about 1700 there has been an increase in arable land. For instance between 1860 and 1985 there has been added[i]  worldwide about 852 106 ha[ii] of arable land. This was done by deforestation, irrigation projects, land reclamation (of wetlands for example) and transformation of grazing lands[iii]. In this way it was possible for societies like cities to grow their populations while keeping up with food demand.

Food is an important requirement but an economy needs more than only arable land. Other requirements are energy, urban surface, minerals, water surface for fishing etc. When all these factors are accounted for one arrives at what is called an ecological footprint. Another term often used in this context is that of carrying capacity that basically tells you how many people in a given economical activity can be supported by a given amount of land without degrading that habitat. This is a very relevant issue because :

  • Human population increases
  • Average consumption per capita increases[iv]
  • Total area of productive land decreases
  • Stocks of natural capital decreases

An interesting article from W.E. Rees[v] at the University of Columbia, Canada discusses this view and I will show in the rest of this text a few eye opening examples from his work.

Example 1: The city of Vancouver (British Columbia, Canada)

1991 population = 472,000

City area = 11400 ha

Estimated needed footprint = 4.9 ha per capita[vi]

Thus total city footprint = 472,000 x 4.9 = 2,312,800 ha

Therefore the city has a footprint 2312800/11400 = 202 times as large as it city area.

Example 2: The Netherlands

The Netherlands has a surface area of 33,920 km2 and in 1995 15.5 million inhabitants. When doing a similar calculation as done for the city of Vancouver above, one comes to an ecological footprint of about a factor 15 larger that the country’s surface area!

Example 3: Global calculation

1996 global population: 5.8 109

Current North American ecological standard: 4.5 ha/capita

If everybody starts to live at current NA standards we would need an ecological footprint of: 5.8 109  x 4.5 = 26 109 ha

The total world surface area is: 13 109 ha of which only 8.8 109 ha is productive and thus world wide productive area is: 8.8 109 / 5.8 109 = 1.6 ha/capita.

The important conclusion we can draw then is that we need a planet at least twice as big as earth if every person on the globe wants to live at north American standards. All this becomes of course even worde when the world population continues to increase as well as the consumption per capita.

Copyright © 2007 John E.J. Schmitz


[i] Richard J.F., Sustainable Development of the Biosphere, eds. W.C. Clark and R.E. Munn, p 53-74, Cambridge Univ. Press (1986)[ii] one ha (hectare) is 10,000 m2, which as about 3 acre (1 acre = 0.4 ha)[iii] However, at the same time there are also mechanisms that convert arable land into non-arable lands through processes like erosion and also deforestation[iv] The energy take up per American has increased with a factor of 20 from 1800 to 1980 (see ref 1), in the 21st century energy demand has grown with 15% already (source L. Conn, BP 2006)[v] Reese W.E., Revisiting Carrying Capacity: Area-Based Indicators of Sustainability; Journal of Interdisciplinary Studies, Vol 17, no 3 (1996)[vi] Included in the footprint is land for: crop, grazing, wood, paper, urban, CO2 eating, fish.

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