Chicago city lights 
© National Geographic stock/Jim Richardson/WWF

Ecological Footprint

For more than 40 years, humanity’s demand on nature has exceeded what our planet can replenish. We would need the regenerative capacity of 1.5 Earths to provide the ecological services we currently use. “Overshoot” is possible because we cut trees faster than they mature, harvest more fish than oceans replenish, or emit more carbon into the atmosphere than forests and oceans can absorb.
The consequences are diminished resource stocks and waste accumulating faster than it can be absorbed or recycled, such as with the growing carbon concentrations in the atmosphere.

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. Both biocapacity and Ecological Footprint are expressed in a common unit called a global hectare (gha).

Carbon from burning fossil fuels has been the dominant component of humanity’s Ecological Footprint for more than half a century, and remains on an upward trend. In 1961, carbon was 36 per cent of our total footprint; by 2010, it comprised 53 per cent.

Technological advances, agricultural inputs and irrigation have boosted the average yields per hectare of productive area, especially for cropland, raising the planet’s total biocapacity from 9.9 to 12 billion global hectares between 1961 and 2010.

However, during the same period, the global human population increased from 3.1 billion to nearly 7 billion, reducing the available biocapacity per capita from 3.2 to 1.7 gha. Meanwhile, Ecological Footprints increased from 2.5 to 2.7 gha per capita. So, while biocapacity has increased globally, there is actually less of it to go around.

With world population projected to reach 9.6 billion by 2050 and almost 11 billion by 2100, the amount of biocapacity available for each of us will shrink further – and it will be increasingly challenging to maintain biocapacity increases in the face of soil degradation, freshwater scarcity and increased energy costs.
© WWF International
© WWF International