ecological footprint measures human demand on nature, i.e., the quantity of nature it takes to support people or an economy. It tracks this demand through an ecological accounting system. The accounts contrast the biologically productive area people use for their consumption to the biologically productive area available within a region or the world (biocapacity, the productive area that can regenerate what people demand from nature). In short, it is a measure of human impact on Earth's ecosystem and reveals the dependence of the human economy on natural capital.
The ecological footprint is defined as the biologically productive area needed to provide for everything people use: fruits and vegetables, fish, wood, fibers, absorption of carbon dioxide from fossil fuel use, and space for buildings and roads.
Footprint and biocapacity can be compared at the individual, regional, national or global scale. Both footprint and biocapacity change every year with number of people, per person consumption, efficiency of production, and productivity of ecosystems. At a global scale, footprint assessments show how big humanity's demand is compared to what planet Earth can renew. Since 2003, Global Footprint Network has calculated the ecological footprint from UN data sources for the world as a whole and for over 200 nations (known as the National Footprint Accounts). Every year the calculations are updated with the newest data. The time series are recalculated with every update since UN statistics also change historical data sets. As shown in Lin et al (2018)[2] the time trends for countries and the world have stayed consistent despite data updates. Also, a recent study by the Swiss Ministry of Environment independently recalculated the Swiss trends and reproduced them within 1-4% for the time period that they studied (1996-2015)[3]. Global Footprint Network estimates that, as of 2014, humanity has been using natural capital 1.7 times as fast as Earth can renew it.[4][2][5] This means humanity's ecological footprint corresponds to 1.7 planet Earths.
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