The world is using resources faster than nature can replace them. According to the World Wildlife Fund (WWF), humans currently consume 20 percent more natural resources than the Earth can produce. The WWF found this out by measuring populations of wild species around the world (the Living Planet Index, or LPI) and the “Ecological Footprint” of 148 countries in its 2004 Living Planet Report.

The LPI shows the world’s biological diversity (biodiversity), which means the amount of species in terrestrial (land), freshwater and marine (oceans) ecosystems. (An ecosystem is a set of species that interact in the same place.) The LPI fell by 40 percent between 1970 and 2000. The terrestrial index fell by 30 percent, the freshwater index fell by 50 percent, and the marine index fell by 30 percent during the same time period. This means that there were 40 percent less species in the world as a whole in 2000 than in 1970, including 30 percent less species living on land, 50 percent less species in rivers, lakes and streams, and 30 percent less species in the oceans.

The Ecological Footprint is a measure of how much biologically productive land and water area a person, a city, a country, a region, or all of humanity requires to produce the resources it consumes and to get rid of the waste it makes, using the technology and resource management plans available now. In 2001 humanity’s Ecological Footprint was 2.5 times, or 160 percent, larger than in 1961. World population doubled over the same period.

The Ecological Footprint is measured in global hectares. (One hectare equals 2.47 acres.) A global hectare is 1 hectare of biologically productive space with world average productivity. This means that the global hectare can produce resources equal to the average produced in the whole world.

In 2001 the Earth had 11.3 billion hectares of biologically productive area equal to about one quarter of its surface. This included 2.3 billion hectares of water and 9.0 billion hectares of land. The land area includes 1.5 billion hectares of cropland, 3.5 billion hectares of grazing land, 3.9 billion hectares of forest land, and 0.2 billion hectares of built-up land.

The global Ecological Footprint is the area of productive biosphere (the part of the planet where life exists) required to maintain the material output of the human economy, under current management and production practices. As well as being measuring in global hectares, the Ecological Footprint can be measured in number of planets, in which one planet represents the biological capacity of the Earth in a year. The global Ecological Footprint increases with higher population size, higher average consumption per person or lower resource efficiency.

Two terms used in the WWF report are biocapacity and bioproductivity. Biocapacity (biological capacity) is the total usable biological production capacity in a given year of a biologically productive area, for example within a country. Bioproductivity (biological productivity) is equal to the biological production per hectare per year.

Biocapacity available per person is measured by dividing global biologically productive area (11.3 billion hectares) by the number of people alive (6.15 billion in 2001), which yields the average amount of 1.8 global hectares of biocapacity per person on the planet. In 2001 the global Ecological Footprint was 2.2 global hectares per person, so it was more than global biocapacity by 0.4 global hectares per person, or 20 percent. Therefore, the world is using its resources faster than they can be replaced, which may permanently damage its ecological capacity and environmental sustainability.

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