Authors such as Meadows et al.[i] and Catton[ii] described global carrying capacity overshoot in the 1970s and 1980s in theoretical terms without the ability to adequately measure it. The problem they faced included the sheer size of the exercise on a global scale together with the complication of incalculable amounts of imports and exports of resources and environmental impacts flowing between regions. To combat this challenge, Mathis Wackernagel, and his thesis supervisor William Rees, developed an approach in the early 1990s known as Ecological Footprint analysis[iii] which converted human activity into land requirements with the aim of establishing its ecological impact.[iv]
Ecological Footprint is an inversion of the carrying capacity approach. While carrying capacity assessment begins with a specific landscape and derives a population per area outcome, Ecological Footprint takes a population and estimates a land requirement per person result.[v] Accordingly, it first determines the demands of the population, either at a global or local scale and then calculates the amount of land that this set of lifestyle parameters would require. The land requirement however, could be drawn from anywhere on the planet,[vi] is consequently usually measured in global hectares, and illustrates the condition of ecological overshoot when exceeding the actual land available. Given the globalised nature of modern trade, proponents of this approach argue that Ecological Footprint analysis is thus an accurate representation of existing circumstances.[vii]
Global Footprint Network’s online Footprint Calculator. The user takes on an avatar who inhabits a suburban scene which is progressively illustrated while lifestyle choices are made. Then, at the end of the process, the user is informed of their global footprint and the proportion of land-uses required such as land for food, shelter, mobility, goods and services.
Wackernagel[xi] explored three potential approaches to the calculation of this feature, firstly, by estimating the amount of land required to replace existing fossil fuel production with ethanol grown from cropland. While acknowledging that this approach would require substantial infrastructural changes to accommodate a new fuel source, Wackernagel points out that this approach would, theoretically at least, illustrate a viable alternative to the existing use of fossil fuels. His second alternative was to estimate the amount of land required in sequestering the carbon dioxide emitted by the burning of fossil fuels. This approach converts the existing environmental impacts of fossil fuel usage into an equivalent land area value, but only addresses the aspect of carbon emissions and, in the absence of a strategy to transition to renewable sources, seems to ignore the finite nature of the fossil fuel source. Lastly, Wackernagel[xii] described his third approach as, “assessing the land area required to rebuild a natural capital stock at a rate that is equivalent to the consumed fossil fuel.” Essentially, this strategy involves the growing of trees for firewood at a rate and amount (in energy value) equivalent to current fossil fuel usage.[xiii] It takes a similar approach to the ethanol option in assuming that vegetative matter could substitute fossil fuel production but also suggests that the only form of land required in addressing the problem is timbered land, potentially excluding the necessity to encroach on arable land. Interestingly, each approach generated a similar land requirement and Wackernagel eventually settled on the sequestering approach in which he estimated that each hectare of land could potentially absorb 100Gj of energy.[xiv] It could be argued, however, that only the ethanol alternative offers a truly sustainable option because it caters to a phasing out of finite fossil fuel supplies.
The proponents of Ecological Footprint analysis have developed and refined their methodology since its inception over 20 years ago and recent improvements include more comprehensive accounting procedures[xv] and previously omitted resources such as fisheries.[xvi] Over this period, a growing number of government agencies, organizations and communities have adopting the Ecological Footprint as an indicator of sustainable resource usage and the Global Footprint Network has emerged as an international co-ordinating agency to raise awareness and set international standards.[xvii]
In contrast to a carrying capacity approach, Ecological Footprint analysis generates nominal rather than geographically-specific land requirements. For example, an analysis of Australia[xviii] may find that each Australian requires seven global hectares for their resource demands. As the description suggests, these seven global hectares are not necessarily tied to any specific geographic location, but rather, form a generic landmass. Consequently, its originators also referred to the process as “appropriated carrying capacity.”[xix] This approach is useful in comparing the demands of affluent lifestyles with those less privileged. For instance, at 0.7 global hectares, Bangladesh’s Footprint[xx] is a tenth of Australia’s. Ecological Footprint analysis is also an excellent measure of humanity’s ever-increasing demands on the natural environment as a whole.[xxi] However, as a land-use planning tool, its effectiveness can be limited by a focus on the global rather than local landscape. Lenzen and Murray[xxii] also suggest that Ecological Footprint analysis, particularly in its earliest examples, did not adequately reveal the location, nature or severity of ecological impacts. A further criticism levelled against this approach is that it is orientated towards an assessment of existing circumstances[xxiii] rather than an exploration of potential alternatives. As its name suggests, Footprint connotes an assessment of what has happened in the past or present, thus a society leaves a footprint. Wackernagel’s[xxiv] definition of the Ecological Footprint approach seems to reinforce this criticism when he describes it as, “the land that would be required now on this planet to support the current lifestyle forever.” Alternatively carrying capacity assessment more easily accommodates an anticipatory design process at scales smaller than the global level because it involves the assessment of real pieces of land, with actual rather than appropriated attributes, against which future options in human behaviour can be measured.
While Wackernagel’s original Ecological Footprint analyses were represented merely as a collection of mathematical output, the most recent mapping and online tools are both engaging and educational. For instance, the Global Footprint Network offer maps highlighting the extend of global ecological overshoot[xxv] as well as an interactive tool[xxvi] which takes users through a series of questions associated with their diet, energy use, transport, housing and recycling choices. The technique employed to illustrate these processes is the illustration of an online avatar representing the user, who walks around a suburban house while various consumer-driven choices are made and then visually added to the scene. The process culminates in a summary of the user’s Ecological Footprint either as a summary or with more detail including their global hectare requirements in land-type form (in a bar graph) or consumer-consumption form (in a pie chart) and finally in an visual representation of how many earths it would take if the global population adopted the same lifestyle. Users then have the opportunity to revise their lifestyle choices to investigate which ones made the largest impact. McManus and Haughton,[xxvii] suggest that interactive tools such as Global Footprint Network’s Footprint Calculator possesses, “major visual and commonsense appeal, making it a useful tool for raising awareness of issues.”
Above: Global Footprint Network’s map of global ecological overshoot. The nations where ecological footprint is greater than the biocapacity of the landscape are in red and nations under with so-called “spare” capacity are in green.
Above: Global Footprint Network’s online Footprint Calculator. Various choices such as dietary choices are offered as slider bars.
[i] MEADOWS, D. H., MEADOWS, D. L., RANDERS, J. & BEHRENS, W. (1972) The Limits of Growth. A Report for The Club of Rome's Project on the Predicament of Mankind, London, Pan.
[ii] CATTON, W. R. (1982) Overshoot: The Ecological Basis of Revolutionary Change, Chicago, University of Illinois Press.
[iii] Subsequent exponents of this approach include Cole and Sinclair COLE, V. & SINCLAIR, J. (2002) Measuring the Ecological Footprint of a Himalayan Center. Mountain Research and Development, 22, 132-141., Bicknell et al.BICKNELL, K., BALL, R., CULLEN, R. & BIGSBY, H. (1998) New Methodology for the Ecological Footprint with an Application to the New Zealand Economy. Ecological Economics, 27, 149 - 160., and Parker and Selman PARKER, J. & SELMAN, P. (1997) Working Towards Sustainable Communities in Canada. The London Journal of Canadian Studies, 13, 61-76..
[iv] Wackernagel WACKERNAGEL, M. (1994) Ecological footprint and appropriated carrying capacity: a tool for planning toward sustainability. School of Community and Regional Planning. Vancouver, University of British Columbia. states, “[t]o establish an account of these competing and mutually exclusive uses of nature, [Ecological Footprint analysis] converts individual uses into a land area equivalent. Having various kinds of different human uses and activities converted into land areas makes the ecological impacts of these uses comparable and permits us to add them up.”
[v] Ibid.
[vi] RITCHIE, J. (2012) Bill Rees' Last Lecture. Vancouver, The Tyee.
[vii] LENZEN, M. & MURRAY, S. A. (2003) The Ecological Footprint - Issues and Trends. Sydney, University of Sydney.
[viii] WACKERNAGEL, M. (1994) Ecological footprint and appropriated carrying capacity: a tool for planning toward sustainability. School of Community and Regional Planning. Vancouver, University of British Columbia.
[ix] Ibid.. In the most recent publication of Ecological Footprint methodology BORUCKE, M., MOORE, D., CRANSTON, G., GRACEY, K., IHA, K., LARSON, J., LAZARUS, E., MORALES, J. C., WACKERNAGEL, M. & GALLI, A. (2011) Accounting for demand and supply of the Biosphere’s regenerative capacity: the National Footprint Accounts’ underlying methodology and framework. Oakland, CA, Global Footprint Network., the land-use categories have been reduced to just five: cropland, grazing land, fishing grounds, forest land, carbon footprint (formerly known as fossil energy equivalent) and built-up land.
[x] BORUCKE, M., MOORE, D., CRANSTON, G., GRACEY, K., IHA, K., LARSON, J., LAZARUS, E., MORALES, J. C., WACKERNAGEL, M. & GALLI, A. (2011) Accounting for demand and supply of the Biosphere’s regenerative capacity: the National Footprint Accounts’ underlying methodology and framework. Oakland, CA, Global Footprint Network.
[xi] WACKERNAGEL, M. (1994) Ecological footprint and appropriated carrying capacity: a tool for planning toward sustainability. School of Community and Regional Planning. Vancouver, University of British Columbia.
[xii] Ibid.
[xiii] Ibid.
[xiv] This was the initial approach adopted by Wackernagel and may have since changed.
[xv] WACKERNAGEL, M., MONFREDA, C., MORAN, D., WERMER, P., GOLDFINGER, S., DEUMLING, D. & MURRAY, M. (2005) National Footprint and Biocapacity Account 2005: The underlying calculation method. Oakland, Calif, Global Footprint Network.
[xvi] Ibid.
[xvii] GLOBAL FOOTPRINT NETWORK (2012) Application Standards. Oakland, CA, Global Footprint Network.
[xviii] GLOBAL FOOTPRINT NETWORK (2011a) Country Trends - Australia. Oakland, CA, Global Footprint Network.
[xix] REES, W. (1992) Ecological Footprints and appropriated carrying capacity: what urban economics leaves out. Environment and Urbanization, 4, 121-130. and WACKERNAGEL, M. (1994) Ecological footprint and appropriated carrying capacity: a tool for planning toward sustainability. School of Community and Regional Planning. Vancouver, University of British Columbia.
[xx] GLOBAL FOOTPRINT NETWORK (2011a) Country Trends - Australia. Oakland, CA, Global Footprint Network.
[xxi] WACKERNAGEL, M. (1994) Ecological footprint and appropriated carrying capacity: a tool for planning toward sustainability. School of Community and Regional Planning. Vancouver, University of British Columbia.
[xxii] LENZEN, M. & MURRAY, S. A. (2003) The Ecological Footprint - Issues and Trends. Sydney, University of Sydney.
[xxiii] Gutteridge GUTTERIDGE, M. (2006) How Big is the Pond? South East Queensland's Ecological Footprint & Carrying Capacity. Brisbane., for examples criticises Ecological Footprint analysis as concentrating too much on a business as usual approach to energy supplies and agricultural yields.
[xxiv] WACKERNAGEL, M. (1994) Ecological footprint and appropriated carrying capacity: a tool for planning toward sustainability. School of Community and Regional Planning. Vancouver, University of British Columbia.
[xxv] BORUCKE, M., CRANSTON, G., GALLI, A., GRACEY, K., IHA, K., LARSON, J., MATTOON, S., MOORE, D., MORALES, J. C., POBLETE, P. & WACKERNAGEL, M. (2012) The National Footprint Accounts: 2011 edition, Working paper. Oakland, CA, Global Footprint Network.
[xxvi] GLOBAL FOOTPRINT NETWORK (2011b) Footprint Calculator. Oakland, CA, Global Footprint Network.
[xxvii] MCMANUS, P. & HAUGHTON, G. (2006) Planning with Ecological Footprints: a sympathetic critique of theory and practice. Environment and Urbanization, 18, 113-127.
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