How to Calculate the Global Footprint

The global footprint, also called the ecological footprint, is a calculation of the entire human population's competing demands on the biosphere, according to WWF's "Living Planet Report 2010." This accounting framework is set up to compare total human demand against the planet's regenerative capacity. The global footprint tracks the area of biologically productive land and water required to provide the renewable resources people use and to absorb the waste they generate, the report states. By knowing how to calculate the global footprint, we not only can measure the health of the world's biodiversity, states WWF, but we can measure humanity's demands on the Earth's natural resources.

Instructions

• 1

  Add together the areas required to provide renewable resources people use, the areas occupied by infrastructure and the areas required for absorbing waste. For example, in the current National Footprint Accounts, the resources tracked include crops and fish, timber, grass and the waste product, carbon dioxide. The Global Footprint Network, which calculates the global footprint annually, expresses these areas in units called global hectares. One global hectare represents the productive capacity of one hectare of land at world-average productivity.

• 2

  Calculate each individual component of the global footprint. For example, the WWF report suggests to calculate the carbon uptake footprint as the amount of forest land required to absorb carbon dioxide emissions from burning fossil fuels, land-use change and chemical processes. Calculate the grazing-land footprint from the area used to raise livestock for meat, dairy, hide and wool. Calculate the forest footprint from the amount of lumber, pulp, timber and fuel-wood that a country consumes each year. Calculate the fishing-grounds footprint from the production required to support the seafood caught. Calculate the cropland footprint from the area used to produce oil crops, rubber and food for human and livestock consumption. Calculate the built-up land footprint from the area of land covered by human infrastructure including transportation, housing, industrial structures and hydropower reservoirs.

• 3

  Determine whether the planet can maintain human demand for renewable resources and carbon dioxide uptake by comparing the global footprint to the biocapacity of the planet, states WWF. Biocapacity is the total regenerative capacity available to serve the demand represented by the global footprint. Use yield factors to normalize countries' biological productivity to world averages. For example, compare tons of wheat per U.S. hectare versus per-world average hectare. Use equivalence factors to take into account differences in world-average productivity among land types --- for example, world-average forest versus world-average cropland.