Definition and methodology
Widely used by scientists, businesses, governments, agencies, civil society organisations and individuals working to monitor ecological resource use and advance sustainability, the ecological footprint (EF) represents the amount of land and water area needed to produce the resources an individual, population or activity consumes and to absorb and render harmless the corresponding waste, given prevailing technology and resource management practices. This area can then be compared with the amount of productive area that is available to generate these resources and to absorb the waste (particularly the carbon dioxide).
The calculation method of the EF involves an accounting of combined demand for ecological resources, expressed as the global average area needed to support human activity. An important component of this, particularly for rich countries, is inclusion of the amount of land with new vegetation that would hypothetically take up carbon dioxide emissions, in contrast to land actually used for food or timber. (In reality, however, a large part of human produced carbon dioxide emissions are not taken up through photosynthesis on land but are taken up by oceans, with about half accumulating in the atmosphere causing the increased greenhouse effect.) In EF calculations, land is scaled according to its biological productivity. This scaling makes it possible to compare ecosystems with differing bio-productivity and in different areas of the world in the same unit, a global hectare (gha). Six main land use types are considered in EF accounts: cropland, grazing land, fishing ground, forests for timber and fuelwood, forests for carbon dioxide uptake and built-up land. For all land use types, there is a demand on the area, as well as a supply of such an area. Usually, the EF of a population is calculated from a consumption perspective, i.e. it measures the land demanded by the final consumption of the residents of the country. This includes household consumption as well as their collective consumption of items, such as schools, roads, etc.
Application and use
Metrics such as the EF are a useful tool in the sustainability debate, since they allow us to give an attractive representation (in terms of hectares), easy to grasp, of the present use of natural resources. For example, using an EF analysis, Wackernagel and his associates (1996 ; 2002) estimate how many planet Earths it would take to support humanity if everybody lived a given lifestyle. According to the Ecological Footprint Atlas of 2009 of the Global Footprint Network (Ewing et al., 2009), in 2006, humanity’s total EF was 17.1 billion global hectares (gha); with world population at 6.6 billion people, the average person’s footprint was 2.6 global hectares. The area of biologically productive land and water on Earth was estimated at approximately 11.9 billion hectares, or 1.8 gha per person. This overshoot of approximately 40 percent means that, in 2006, humanity would have used the equivalent of 1.4 Earths to support its consumption (and dispose of carbon dioxide). Global comparisons also clearly show the inequalities of resource use worldwide. Per capita EF is a means of comparing consumption and lifestyles. While an average inhabitant of Bangladesh or Nepal consumes 0.5 gha per year (in 2006), an average Chinese takes 1.8 gha and an average American 9.0 gha.
EF can inform policy by examining to what extent a nation, a region or a city uses more (or less) than is available within its territory, or to what extent the nation’s lifestyle would be replicable worldwide. It can also be a useful tool to educate people about carrying capacity and over-consumption, with the aim of influencing individual behaviour. EF may also be used to highlight the (un)sustainability of individual lifestyles, goods and services, organisations, industry sectors, neighbourhoods, cities, regions and nations. However, while EF is an intuitively appealing indicator (easy to communicate and understand), as a single indicator, it is unable to illustrate the complexity of these impacts and their interrelations, in particular, regarding burden shifting between different types of impacts. Moreover, two important issues are not properly addressed in EF calculations. First, how much land should be devoted to the maintenance of ‘wild’ species? Second, why to express the issue of excessive carbon dioxide emissions in terms of hypothetical land required to absorb it? Therefore, sustainability assessment should not rely on the use of a single tool or indicator, but use a set of indicators covering different perspectives and dimensions of sustainability. See for instance the WWF’s biennial Living Planet Report. EF may be a powerful and useful tool in this context.
Ewing B., S. Goldfinger, A. Oursler, A. Reed, D. Moore, and M. Wackernagel (2009) The Ecological Footprint Atlas 2009. Oakland: Global Footprint Network.
Wackernagel, M. and W. Rees (1996) Our Ecological Footprint: Reducing Human Impact on the Earth. New Society Publishers.
Wackernagel, M., N., Schulz, D. Deumling,, A. Callejas Linares, M. Jenkins, V. Kapos, C. Monfreda, J. Loh, N. Myers, R. Norgaard, and J. Randers (2002) Tracking the ecological overshoot of the human economy. Proceedings of the National Academy of Sciences, 99 (14) 9266-9271.
For further reading:
Best, A., S. Giljum, C. Simmons, D. Blobel, K. Lewis, M. Hammer, S. Cavalieri, S. Lutter and C. Maguire (2008) Potential of the Ecological Footprint for monitoring environmental impacts from natural resource use: Analysis of the potential of the Ecological Footprint and related assessment tools for use in the EU‘s Thematic Strategy on the Sustainable Use of Natural Resources. Report to the European Commission, DG Environment.
van den Bergh, J. and H. Verbruggen (1999) Spatial sustainability, trade and indicators: an evaluation of the ‘ecological footprint‘, Ecological Economics, Vol. 29 (1) 63-74.
This glossary entry is based on a contribution by Paula Antunes
EJOLT glossary editors: Hali Healy, Sylvia Lorek and Beatriz Rodríguez-Labajos