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Footprint FAQs

What does the Ecological Footprint measure?
What assumptions do you make in your Footprint calculations?
What data sources do you use to calculate the Footprint?
What is the unit of measurement for a Footprint?
How do you calculate the size of an Ecological Footprint?
How do you interpret the results of a Footprint calculation?

What does the Ecological Footprint measure?

The Ecological Footprint measures the amount of natural resources an individual, a community, or a country consumes in a given year.

We use official statistics tracking consumption and translate that into the amount of biologically productive land and water area required to produce the resources consumed and assimilate the wastes (predominately carbon emissions) generated.

Because people use resources from all over the world, and affect faraway places with their pollution, the Footprint is the sum of these areas wherever they are on the planet.

Ecological Footprint
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What assumptions do you make in your Footprint calculations?

Ecological Footprint calculations are based on five assumptions:

  • It is possible to keep track of most of the resources people consume and many of the wastes people generate. Much of that information can be found in existing official statistics.
  • Most of these resource consumption and waste flows can be converted into the biologically productive area that is required to maintain these flows.
  • These different areas can be expressed in the same unit (hectares or acres) once they are scaled proportionally to their biomass productivity. In other words, each acre can be translated into an equivalent area of world-average land productivity.
  • Since these areas stand for mutually exclusive uses, and each standardized acre represents the same amount of biomass productivity, they can be added up to a total—a total representing humanity's demand.
  • This area for total human demand can be compared to Earth's supply of natural resources, since it is also possible to assess the area on the planet that is biologically productive.

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What data sources do you use to calculate the Footprint?

The analysis is primarily based on data published by United Nations agencies and the Intergovernmental Panel on Climate Change.

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What is the unit of measurement for a Footprint?

The Ecological Footprint is expressed in global hectares (gha) or acres. 1 gha = 2.47 acres.

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How do you calculate the size of an Ecological Footprint?

Footprints are calculated using a methodology that includes these steps:

  • Identify and add up the amount of biocapacity in a country or the world; i.e., how many hectares (or acres) of land are dedicated to crop production, pasture land, forests, fishing, carbon storage areas, and built space.
  • Use equivalence factors to normalize all biocapacity categories into global hectares; i.e., making crop land, grasslands, and forest comparable using a common denominator such as net primary productivity or agricultural potential.
  • Subtract biocapacity for the needs of non-human life.
  • Determine the average yield factors for a hectare of biocapacity; e.g., how many tons of beans per hectare of crop land are produced.
  • Use the biocapacity and yield factors to measure the area of biocapacity a population’s consumption and waste output requires over the course of a year; e.g., one ton of beans might require 1/2 global hectare to grow, and thus the footprint of two tons of bean consumption is one global hectare.
  • For a country-level Footprint an additional step is taken to add in imports and subtract exports in the final tally. (This step is not needed for the global Footprint-biocapacity estimates.)

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How do you interpret the results of a Footprint calculation?

On a global level, the results are biocapacity (supply) estimates for crop land, pasture land, forest, fisheries, and carbon storage areas. We compare that to the footprint (demand) for food, forest, and other resource consumption categories, as well as carbon emissions.

The Footprint is the area of biocapacity needed to produce what the world’s population consumes, and to absorb (some of) the ensuing waste.

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