Facing up to our ecological footprint (page 1 of 2)

Illustrated were four- and-a-half images of Planet Earth, and emblazoned across them was: "If everyone lived like you, we would need 4.5 planets."

Firm in the belief that she was an environmentally conscious member of the community, Nouha had attempted the quiz with confidence. After all, she rarely wasted materials. She recycled, threw litter only in bins, participated with enthusiasm in cleanup campaigns, switched off lights when not required, never bought ivory or other items made from the body parts of endangered species...

Admittedly, doubts had crept in as she was filling the questionnaire. The queries posed were not ones that came to mind while she followed her "ecologically sensitive" lifestyle. There were questions on animal-based foods consumed; processed, packaged and imported foods eaten; size of the house lived in; fuel efficiency of her car; frequency of travel using public transport, and so on. She had been truthful with her answers.

"Well," she consoled herself, "At least my footprint is smaller than the country's average." Nouha lived in the United Arab Emirates. If the world lived like each individual in the UAE, we would need 5.5 planets.

The Footprint
For every kind of energy or matter we consume to maintain our lifestyles, some natural resource, somewhere, gets used up and waste is produced. The Ecological Footprint (EF), a resource management tool, measures how much productive land and water an individual, a city, a country or humanity requires to produce all the resources it consumes and to absorb all the waste it generates. This land and water area could be anywhere in the world. The EF is measured in global hectares, which represents the equivalent area (space) of world average productivity. It can also be measured in number of planets, whereby one planet represents the biological capacity of the Earth in a given year.

People's use of renewable resources is considered. These, and the ecological services they provide, are at even greater risk than the non-renewable resources such as mineral ores and petroleum. The name renewable is misleading. Renewable resources can be depleted if drawn down more rapidly than nature can build them back up. If we catch more fish than are spawned, the fish stocks die. If we dump more carbon dioxide into the atmosphere than nature can reabsorb, the atmosphere heats up and the climate is thrown out of balance. If we pump more water out of an aquifer than the rate at which it is recharged, it gets depleted.

To live, we consume what nature offers and every action impacts the planet's ecosystems. This is of little concern as long as human use of resources does not exceed what the earth can renew.

Ecological Overshoot
But today there is cause for concern. The WWF's Living Planet Report 2004 confirms that humanity is now consuming over 20 % more natural resources than the Earth can regenerate. We are plundering the planet at a pace that outstrips its capacity to support life.

• Global EF: 2.2 global ha/person
• Area available (for humans alone, with nothing kept aside for other species): 1.8 global ha/person
• Ecological overshoot: 20 %

In other words, it now takes at least one year and two months for the earth to regenerate what we use in a single year. We maintain this overdraft by liquidating the planet's natural resources, running up an ecological debt (overshoot).

Ecological overshoot is real; a situation created when humanity consumes more resources than nature can regenerate; and creates more wastes than nature can recycle.