The Ecological Footprint adds up all the ecological services people demand that compete for space. It includes the biologically productive area (or biocapacity) needed for crops, grazing land, built-up areas, fishing grounds and forest products. It also includes the area of forest needed to absorb carbon dioxide emissions that cannot be absorbed by the ocean. Carbon from burning fossil fuels has been the dominant component of humanity’s Ecological Footprint for more than half a century and its share continues to grow.
Both biocapacity and Ecological Footprint are expressed in a common unit called a global hectare (gha). In 2012, the Earth’s total biocapacity was 12.2 billion gha, or 1.7 gha per person, while humanity’s Ecological Footprint was 20.1 billion gha, or 2.8 gha per person. The Ecological Footprint is unequally distributed, with residents of high-income countries placing a disproportionate pressure on nature as they use more than their fair share of the Earth’s resources. At the other end of the scale, people in some of the world’s lowest-income countries struggle to meet basic needs.
For more information : Global Footprint Network