Ecological Footprint

ecological footprint (EF), measure of the demands made by a person or group of people on global natural resources. It has become one of the most widely used measures of humanity’s effect upon the environment and has been used to highlight both the apparent unsustainability of current practices and the inequalities in resource consumption between and within countries.

The ecological footprint (EF) estimates the biologically productive land and sea area needed to provide the renewable resources that a population consumes and to absorb the wastes it generates—using prevailing technology and resource-management practices—rather than trying to determine how many people a given land area or the entire planet can support. It measures the requirements for productive areas (croplands, grazing lands for animal products, forested areas to produce wood products, marine areas for fisheries, built-up land for housing and infrastructure, and forested land needed to absorb carbon dioxide emissions from energy consumption). One can estimate the EF, measured in “global hectares” (gha), at various scales—for individuals, regions, countries, and humanity as a whole. (One hectare equals 2.47 acres.) The resulting figures can also be compared with how much productive area—or biocapacity—is available.

Canadian ecologist William Rees created the EF concept, which Swiss urban planner Mathis Wackernagel further developed in his dissertation under Rees’s supervision. Together, Wackernagel and Rees wrote Our Ecological Footprint (1996), which describes the concept.

EF calculations have questioned the sustainability and equity of current consumption and production practices. The Global Footprint Network (GFN)—a nonprofit organization that partnered with hundreds of cities, businesses, and other entities to advance the EF as a metric of sustainability—calculates the per capita global footprint. In 2014 the per capita global footprint was 2.8 gha. Since global biocapacity that year was 1.7 gha per person, the EF of humanity overshot Earth’s biocapacity by 1.1 gha. In other words, 1.7 “Earths” would be needed to sustain current resource demands or, alternatively, it takes Earth more than one year and eight months to regenerate what is used in one year. The implication of such “ecological overshoot,” which began in the mid-1970s, is that life-supporting biological resources, such as fisheries, forest resources, rangeland, and agricultural land, are being depleted.