Ecological footprint defined
Ecological footprint includes all the cropland, grazing land, forest, and fishing grounds required to produce the food, fibre, and timber people consume. It also includes the land required to absorb emissions from the energy people use, and to provide space for its infrastructure including roads and built areas.
People consume resources and ecological services from all over the world, so their footprint is the sum of these areas, wherever they may be on the planet. That is what global hectare (gha) means.
You can work out the ecological footprint of a person, a household, a city, a country or the world. It is also possible to work out the footprint of a product or service.
Separating the ecological footprint into its individual components demonstrates how each one contributes to humanity’s overall demand on the planet. Globally, the carbon footprint was the fastest growing component, increasing more than ninefold from 1961 to 2003.
The grazing land footprint measures the area of grassland used in addition to crop feeds to support livestock. Grazing land comprises all grasslands used to provide feed for animals, including cultivated pastures as well as wild grasslands and prairies.
The cropland footprint consists of the area of land required to grow all crop products, including livestock feed, fish meal, oil crops and rubber. It is the most bio-productive of the land-use types. In other words, the number of global hectares of cropland is large compared to the number of physical hectares of cropland in the world.
The footprint of each crop type is calculated as the area of cropland that would be required to produce the harvested quantity at world-average yields.
The fishing grounds footprint is calculated based on the annual primary production required to sustain all harvested aquatic species. This primary production requirement is the mass ratio of harvested fish to annual primary production needed to sustain that species, based on its average trophic level. Calculations for fishing catches also includes by-catch whether it is wasted or not.
The forest land footprint measures the annual harvest of fuelwood and timber to supply forest products. Worldwide in 2008 there were 4.04 billion hectares of forest land area in the world.
The Footprint Accounts calculate the footprint of forest land according to the production quantities of primary timber products and wood fuel products.
The carbon land footprint is the uptake land to mitigate carbon dioxide and other greenhouse gas emissions. Also, it is the only land use type for which biocapacity is not explicitly defined.
Many different ecosystem types have the capacity for long-term storage of CO2, including cropland and grassland. However, since most terrestrial carbon uptake in the biosphere occurs in forests, and to avoid overestimations, carbon uptake land is assumed to be forest land by the ecological footprint methodology. For this reason, it is considered to be a subcategory of forest land.
The built-up land footprint is calculated based on the area of land covered by human infrastructure including roads, carparks, houses and buildings, industrial structures and reservoirs for hydroelectric power generation. In 2008, the built-up land area of the world was approximately 170 million hectares. Global Footprint Network assumes that built-up land occupies what would previously have been cropland. This assumption is based on the observation that human settlements are generally situated in fertile areas with the potential for supporting high-yielding cropland.