ECOLOGICAL FOOTPRINT

The ecological footprint, a different way of expressing carrying capacity, was developed by Mathis Wackernagel and William Rees in the early 1990s. Instead of working out how many people a particular area can take, the idea is to work out how much land and water is nec­essary to support a particular human population - a nation, a city, a company, a product, or even an individual - given their current levels of technology and consumption.

The Ecological Footprint is a tool for measuring and analyzing human natural resource consumption and waste output within the context of nature's renewable and regenerative capacity (or bioca­pacity). It represents a quantitative assessment of the biologically productive area (the amount of nature) required to produce the resources (food, energy, and materials) and to absorb the wastes of an individual, city, region, or country. (Venetoulis et al. 2004: 7)

Such analyses highlight the way that human populations, particularly cities, are dependent on environments well beyond their political bound­aries. It also shows that the area of land and water outside their bound­aries necessary to support them - the appropriated carrying capacity - is getting larger and larger. To be sustainable the ecological footprint must remain within the Earth's limits. If those limits are exceeded - a situation called 'overshoot' - then resources are used faster than they can be renewed, the environment becomes degraded and the ability of Earth to sustain life and economic activity is further reduced (Rees 1996; Venetoulis et al. 2004: 7).

In 2000 a joint analysis of national ecological footprints by WWF International and Redefining Progress found that although the footprint per person had been falling over the previous 20 years because of increased efficiencies in resource use, the total footprint had been increasing (Venetoulis et al.

Box 1.1 Glossary of ecological footprint terms

Appropriated Carrying Capacity: The biophysical resource flows and waste assimilation capacity appropriated per unit time from global totals by a defined economy or population.

Ecological Footprint: The corresponding area of productive land and aquatic ecosystems required to produce the resources used, and to assimilate the wastes produced, by a defined population at a speci­fied material standard of living, wherever on Earth that land may be located.

Fair Earthshare: the amount of ecologically productive land ‘available' per capita on Earth, currently about 2.2 hectares (2000). A fair seashare (ecologically productive ocean - coastal shelves, upwellings and estuaries - divided by total population) is just over.5 ha.

Ecological Deficit: The level of resource consumption and waste dis­charge by a defined economy or population in excess of locally/regionally sustainable natural production and assimilative capacity (also, in spatial terms, the difference between that economy/population's ecological footprint and the geographic area it actually occupies).

Sustainability Gap: A measure of the decrease in consumption (or the increase in material and economic efficiency) required to elimi­nate the ecological deficit. (Can be applied on a regional or global scale.)

Source (Rees 1996)

Partial measure

Footprint analysis is generally a conservative estimate, that is, it tends to understimate the amount of land and water required to support human populations. It does not take account of toxic pollutants; in fact, the only pollutant it generally considers is carbon dioxide.

Ecological footprint analysis is merely a rough measure of how much land is required for particular populations, based on current manage­ment and production practices and levels of consumption, to:

• grow crops for food, animal feed, fibre, oil, and rubber;

• graze animals for meat, hides, wool and milk;

• harvest timber for wood, fibre and fuel;

• fish for food;

• accommodate infrastructure for housing, transportation, industrial production and hydro-electric power;

• absorb carbon dioxide from burning fossil fuels (Wackernagel et al. 2002: 9267).

Analysis at the national level 'uses UN data on agricultural production, forest production, area of built land and trade' and trade data to take account of what is imported and exported (ECOTEC - UK 2001: 17-8). Analysts Mathis Wackernagel and his colleagues (2002: 9266) admit:

We recognize that reducing the complexity of humanity's impact on nature to appropriated biomass offers only a partial assessment of global sustainability. It is a necessary, but not sufficient, requirement that human demand does not exceed the globe's biological capacity as measured by our accounts.

Advocates also recognise that the measure 'provides a utilitarian view of nature - nature as a big bucket filled with resources - and measures who gets what' (Chambers et al. 2000: 31-2). In addition, ecological footprint analysis is based on current actual use of technology rather than poten­tial use of technology. Its advocates state:

While some technologies exist to reduce human impact, most tech­nology has been used to gain access to limited resources at a faster rate and with more ease. In other words, while we have the techno­logical capacity for a sustainable world, we seem to choose technolo­gies that increase our overall footprint and increase human overshoot. (Chambers et al. 2000: 115)

The estimates of footprints for particular nations, done by different experts, vary quite considerably, although not by whole orders of mag­nitude. Nevertheless the simplicity of the concept enables people to easily understand it, and analysts are generally open about their assumptions and omissions. It is based on publicly available govern­ment information. As such it provides an alternative measure of human progress to economic measures such as GDP, and emphasises the prin­ciple of ecological sustainability (ECOTEC-UK 2001: 30; Wackernagel et al. 2002: 9267).

The concept of ecological footprint has been criticised for reducing the value of land, and therefore ecosystems, down to productive capacity alone, and ignoring other environmental values such as diversity and beauty. It has also been criticised for implying that environmental protec­tion is an individual responsibility; that each person is to blame for their own footprint and can reduce it by consuming less:

This obscures the institutional and economic factors that constrain our choices, and that make it difficult to cut our own footprint down to size, even if we wish to. The problem is perpetuated in footprint analyses of nations, provinces and cities because the products of such analyses are usually interpreted in terms of the aggregated consump­tion behaviour of individuals.

Rees (2002: 276) notes in response to criticisms that it would be unreal­istic to expect any single measure to 'represent the total human impact on the ecosphere'. Nevertheless, ecological footprint analysis 'is compre­hensive enough to show, unambiguously, that the human eco-footprint on Earth is steadily increasing'.

Fair share

Ecological footprint analysis enables the resource use of different populations to be compared and for those that are clearly unsustain­able to be identified, that is, those that use more land than they own or more than their fair share of land. By considering the footprint of each nation, the disparities between nations become evident. The USA has the largest footprint per person of all nations (9.57 hectares) and various European nations and Australia are in the top ten (see table 1.2). These figures compare with the footprints of the poorest countries at 0.5 to 1 hectare per person, an average of around 2.2 hectares per person, and a sustainable footprint of 1.7 hectares per person, a figure most nations exceed (Venetoulis et al. 2004: 12; Wackernagel et al. 1997).

Table 1.2 Ecological footprint of ten heaviest nations

Source (Venetoulis et al.

Although the United Kingdom does not make the top ten, London's eco­logical footprint, at 5.8 global hectares per person, is amongst the highest, and means that an area twice the size of Great Britain is required to support the city (Edie News 2005). This is the case for all large cities: 'However brilliant its economic star, every city is an entropic black hole drawing on the concentrated material resources and low-entropy pro­duction of a vast and scattered hinterland many times the size of the city itself' (Wackernagel quoted in ISEE 1994).

Through such analysis of national ecological footprints, it becomes obvious that some countries are using more than their fair share of resources. Rees (1996) concludes that since affluent nations would need to use even more of their fair share of ecological space to achieve eco­nomic growth, to do so 'is both ecologically dangerous and morally questionable. To the extent we can create room for growth, it should be allocated to the third world'.

Other measures of human impact on the environment have been developed. One index, for example, measures the proportion of the planet's net primary production devoted to human use, where net primary production is:

[the] net amount of solar energy converted to plant organic matter through photosynthesis... Human appropriation of net primary pro­duction, apart from leaving less for other species to use, alters the composition of the atmosphere, levels of biodiversity, energy flows within food webs and the provision of important ecosystem services. (Imhoff et al. 2004: 870)

This and other indexes also show that humans, particularly those in affluent countries, are overshooting the carrying capacity of the planet.

Consequences of overshoot

The consequences of overshoot, that is, the way humans are exceeding the capacity of the environment to sustain their impact, are evident in the UN's Millennium Ecosystem Assessment (Reid et al. 2005), written by some 1360 scientists from 95 countries. The Assessment found that not only are humans already consuming ecosystems at an unsustainable rate and therefore degrading them, but that consumption is likely to increase by 3 to 6 times by 2050:

First, approximately 60% (15 out of 24) of the ecosystem services examined during the Millennium Ecosystem Assessment are being degraded or used unsustainably, including fresh water, capture fish­eries, air and water purification, and the regulation of regional and local climate, natural hazards, and pests...

Second, there is established but incomplete evidence that changes being made in ecosystems are increasing the likelihood of nonlinear changes in ecosystems (including accelerating, abrupt, and poten­tially irreversible changes) that have important consequences for human well-being.