Ecological footprint

Valentina Locher and Maricel Massera

The ecological footprint is an indicator that measures the biologically productive area—both terrestrial and marine—that a population needs, given current technologies and economic processes, to generate the resources it consumes and absorb the waste it produces, thereby making it possible to identify potential surpluses relative to the sustainability threshold. In this way, it makes it possible to compare the ecological demands of individuals, nations, or humanity, regardless of differences in productivity among ecosystems. When a population’s ecological footprint exceeds the area that ecosystems can effectively regenerate—known as biocapacity—this is referred to as an ecological deficit or overshoot (see Limits).

This concept was developed by ecologist William Rees (1992), initially under the name “appropriated carrying capacity,” through which he proposed quantifying the ecologically productive area that cities require to function. He later coined the term “ecological footprint,” and its calculation method was systematized by Mathis Wackernagel in his doctoral dissertation (1994). The publication of the book Our Ecological Footprint: Reducing Human Impact on the Earth (Wackernagel & Rees, 1996) established the indicator as an accessible tool for governments, organizations, and the public, making it the foundational reference for popularizing the field.

The calculation of the ecological footprint is based on estimating how much biologically productive land area is needed to meet a population’s consumption needs and absorb its waste. This area is typically broken down into six categories: cropland, grazing land, forests, fisheries, urban areas, and the space needed to sequester carbon emissions from fossil fuels—which, in most countries, accounts for the largest relative share of the indicator. The weight of each category varies according to the consumption profile of each country or region, making the indicator sensitive to very different contexts and allowing us to identify which aspects of consumption are most decisive in each case.

The result is expressed in global hectares per capita and compared with available biocapacity, both at the national and global levels. When an area’s ecological footprint exceeds its biocapacity, the resulting deficit can be temporarily offset by importing resources from other regions, degrading its own ecological assets—for example, through overfishing or deforestation—or by generating CO₂ emissions that exceed the absorption capacity of ecosystems. Wackernagel et al. (2002) estimated that humanity began to exceed the planet’s biocapacity in the 1970s, a trend that has intensified in subsequent decades (Lin et al., 2018). This finding helped establish the concept of ecological overshoot as a central theme in contemporary debates on sustainability.

Beginning in the 2000s, the indicator was gradually institutionalized and began to establish itself as a useful tool for governments, cities, and businesses to communicate, assess, and discuss issues related to sustainability. In 2003, Mathis Wackernagel founded the Global Footprint Network, an organization dedicated to standardizing and updating ecological footprint and biocapacity calculations for more than 200 countries, as well as promoting their incorporation into the design and evaluation of public policies. As part of its work, the organization annually calculates the date on which demand for ecological resources and services exceeds the planet’s capacity to regenerate them during that year—known as Earth Overshoot Day. In 2025, this date was July 24. Over time, the ecological footprint was adopted by various international organizations, including the United Nations Environment Programme (UNEP) and the International Union for Conservation of Nature (IUCN), which contributed to its recognition as an indicator of sustainability on an international scale.

Despite its widespread use and international recognition, the indicator has been the subject of numerous observations and criticisms, which focus on conceptual and methodological aspects, as well as the political consequences of its use.

One of the main criticisms levelled at the ecological footprint calculation concerns the fact that a single indicator can capture the complexity and multidimensional nature inherent in environmental sustainability. This argument suggests that an aggregate indicator is incapable of capturing the nonlinear relationships, ecological thresholds, and hierarchies of scales that define the sustainability of a socio-ecological system, and that its uncritical use could lead to inappropriate policies (Giampietro and Saltelli, 2014) (see Ecosystems and Ecological Collapse).

From a conceptual and methodological standpoint, the selection of areas considered for estimating biocapacity has been questioned. In particular, because the traditional ecological footprint approach has a utilitarian perspective and an anthropocentric viewpoint typical of environmentalism, since it considers exclusively those parts of nature or portions of the Earth that provide services directly to humans, without taking into account the needs of other species (see ecosystem services). Furthermore, these estimates do not account for toxic pollutants and waste that cannot be absorbed by productive ecosystems, nor for the consumption of non-renewable resources (minerals, metals), ecosystem degradation, biodiversity loss, and groundwater contamination (Blomqvist et al., 2013; Venetoulis & Talberth, 2010). According to critics, the exclusion of all these aspects from the calculation results in a systematic underestimation of human impact on nature.

Along these lines, various critiques have pointed out that the Ecological Footprint methodology tends to equate the biological productivity of ecosystems with their biocapacity, reducing the latter to the capacity to produce biomass and absorb certain wastes (Galli et al., 2016). From this perspective, the indicator makes an error by assuming that certain changes introduced into ecosystems with the aim of increasing their productivity—for example, the expansion of the agricultural frontier into certain natural ecosystems—would result in an increase in biocapacity, even when they entail environmental degradation. Consequently, the concept of biocapacity used in the ecological footprint does not necessarily equate to greater sustainability. In other words, for the indicator to be consistent with its purpose of measuring sustainability, the measure of biocapacity used should explicitly account for which portion of production comes from renewable and sustainable processes, and which depends on the exploitation of non-renewable resources or environmental degradation (see Renewable Energy).

From a methodological standpoint as well, the assumptions regarding carbon sequestration capacity that underpin the calculation have been questioned; these assumptions result from simplifications and are based on weak data, leading to inaccurate estimates of ecological damage (Blomqvist et al., 2013).

Along these lines, criticism has also been directed at the technique used to aggregate different land types (cropland, grasslands, forests, fishing grounds, built-up land) under the assumption that they are equivalent in terms of their contribution to sustainability. According to Ayres (2000), this equivalence makes no biophysical sense, especially since the equivalence factors used are based on arbitrary assumptions and are extremely sensitive to small changes, resulting in estimates that lack robustness.

Problems of double-counting among the components of the ecological footprint have also been identified in these calculations. In particular, the same forested land is simultaneously counted as a source of biomass (wood, biomass, and bioenergy) and as a carbon sink for absorbing CO₂ emissions, assigning the same area to two distinct functions and adding them together (Lenzen & Murray, 2001).

Finally, a group of critics has pointed to the political implications of a synthetic indicator—based on averages—that obscures various inequalities that are key to designing policies that contribute to ecological justice (see Ecosocial Justice). A crucial aspect in this regard is the role of international trade in sustainability. In particular, Van den Bergh and Verbruggen (1999) argue that the ecological footprint confuses sustainability with territorial self-sufficiency: a country can maintain an environmentally sustainable consumption pattern even when it depends on resource imports, provided that such transfers are compatible with the sustainability of the global system. According to these authors, the ecological footprint confuses territorial self-sufficiency with sustainability by interpreting national deficits as signs of unsustainability. However, from the perspectives of political ecology, ecological economics, and particularly the literature on ecologically unequal exchange—which analyzes how international trade transfers environmental costs from consumer countries to producer countries—a more significant problem regarding inequality emerges. From this perspective, the problem is not that countries import biocapacity, but rather that the indicator fails to identify the power relations, trade asymmetries, and unequal transfers of resources and environmental burdens implicit in these exchanges. In other words, the ecological footprint does not reveal who bears the environmental costs of the production and consumption system (Martínez-Alier, 2003; Srinivasan et al., 2008)

Other authors go further and point out that the calculation by country obscures intranational inequalities, which, according to some estimates, are as significant as—or even more significant than—international inequalities (Hubacek et al., 2017). Since low-income countries are often also the most unequal, internal disparities in the ecological footprint among social groups tend to be more pronounced there, which exacerbates the negative impact of these costs on the most vulnerable populations (see ecological vulnerability).

Finally, feminist economics and feminist political ecology question the use of aggregated biophysical indicators, such as the ecological footprint, since they fail to identify gender inequalities in access to, control over, and distribution of nature, nor do they account for the differential allocation of environmental costs. Nor do they take into account care work and social reproduction, and they tend to represent society as a homogeneous unit, rendering invisible the power relations that underlie sustainability (see Ethics of Care). In this regard, some research shows that ecological losses weaken women’s position in terms of access to and control over basic natural resources (McKinney and Fulkerson, 2015). Furthermore, it has been documented that consumption patterns with the largest ecological footprints—such as food and transportation—are strongly linked to gender identities and roles, suggesting that climate policies may have gender-differentiated effects (Berland & Leroutier, 2025) (see Ecofeminism).

In summary, the ecological footprint is a widely used indicator that has succeeded in placing the issue of planetary boundaries on political and institutional agendas at the global level, linking ideas from economics, sociology, and anthropology with the biological and earth sciences. As such, it has become a valuable tool for highlighting and bringing into the public discourse the relationship between human demand for resources and the available biologically productive land area. However, its conceptual and methodological limitations—outlined above—require that it be supplemented with other indicators capable of capturing the complexity of the sustainability crisis, and its use should not oversimplify the relationship between consumption and inequality: the largest ecological footprints have historically been concentrated in the countries of the Global North and among sectors with the highest purchasing power, while the most vulnerable populations—including women living in poverty in the Global South—bear the disproportionate consequences of ecological overshoot, despite having contributed to a lesser extent to its creation.

Bibliography:

Ayres, R.U. (2000). Commentary on the utility of the ecological footprint concept. Ecological Economics, 32(3), 347–349.

Berland, O & Leroutier, M. (2025). The gender gap in carbon footprints: determinants and implications. 25/53. Institute for Fiscal Studies. Disponible en: https://ifs.org.uk/publications/gender-gap-carbon-footprints-determinants-and-implications

Blomqvist, L., Brook, B.W., Ellis, E.C., Kareiva, P.M., Nordhaus, T. & Shellenberger, M. (2013). Does the shoe fit? Real versus imagined ecological footprints. Plos Biology, 11(11).

Chancel, L. (2022). Global carbon inequality over 1990–2019. Nature Sustainability, 5, 931–938. https://doi.org/10.1038/s41893-022-00955-z

Galli, A., Giampietro, M., Goldfinger, S., Lazarus, E., Lin, D., Saltelli, A., Wackernagel, M., & Müller, F. (2016). Questioning the Ecological Footprint. Ecological Indicators,69, 224–232. https://doi.org/10.1016/j.ecolind.2016.04.014

Giampietro, M. & Saltelli, A. (2014). Footprints to Nowhere. Ecological Indicators, 46, 610–621. https://doi.org/10.1016/j.ecolind.2014.01.030

Hubacek, K., Baiocchi, G., Feng, K., Muñoz Castillo, R., Sun, L., & Xue, J. (2017). Global carbon inequality. Energy, Ecology and Environment, 2(6), 361–369. https://doi.org/10.1007/s40974-017-0072-9

Lenzen, M. & Murray, S.A. (2001). A modified ecological footprint method and its application to Australia. Ecological Economics, 37(2), 229–255

Lin, D., Hanscom, L., Murthy, A., Galli, A., Evans, M., Neill, E., Mancini, M. S., Martindill, J., Medouar, F.-Z., Huang, S., & Wackernagel, M. (2018). Ecological Footprint Accounting for Countries: Updates and Results of the National Footprint Accounts, 2012–2018. Resources, 7 (3), 58. https://doi.org/10.3390/resources7030058

Martínez-Alier, J. (2003). Scale, environmental justice, and unsustainable cities. Capitalism, Nature, Socialism, 14 (4), 43–63. https://doi.org/10.1080/10455750308565545

McKinney, L. A., & Fulkerson, G. M. (2015). Gender equality and climate justice: A cross-national analysis. Social Justice Research, 28 (3), 293–317. https://doi.org/10.1007/s11211-015-0241-y

Rees, W. E. (1992). Ecological footprints and appropriated carrying capacity: What urban economics leaves out. Environment and Urbanization, 4(2), 121–130. https://doi.org/10.1177/095624789200400212

Srinivasan, U. T., Carey, S. P., Hallstein, E., Higgins, P. A. T., Kerr, A. C., Koteen, L. E., Smith, A. B., Watson, R., Harte, J., & Norgaard, R. B. (2008). The debt of nations and the distribution of ecological impacts from human activities. Proceedings of the National Academy of Sciences of the United States of America, 105(5), 1768–1773. https://doi.org/10.1073/pnas.0709562104

Van den Bergh, J.C.J.M. & Verbruggen, H. (1999). Spatial sustainability, trade and indicators. Ecological Economics, 29 (1), 61–72.

Venetoulis, J., & Talberth, J. (2010). Refining the ecological footprint. En O. Ukaga, C. Maser, & M. Reichenbach (Eds.), Sustainable development: Principles, frameworks, and case studies (pp. 83–120). CRC Press.

Wackernagel, M. (1994). Ecological footprint and appropriated carrying capacity: A tool for planning toward sustainability [Tesis doctoral, University of British Columbia]. Recuperado de: https://open.library.ubc.ca/collections/ubctheses/831/items/1.0088048

Wackernagel, M. & Rees, W. (1996). Our Ecological Footprint: Reducing Human Impact on the Earth. New Society Publishers.

Wackernagel, M., Schulz, N. B., Deumling, D., Callejas Linares, A., Jenkins, M., Kapos, V., Monfreda, C., Loh, J., Myers, N., Norgaard, R., & Randers, J. (2002). Tracking the ecological overshoot of the human economy. Proceedings of the National Academy of Sciences, 99 (14), 9266–9271. https://doi.org/10.1073/pnas.142033699