The Earth is finite: its resources are limited, they’re not infinite. Imagine the Earth as a giant spaceship: on its journey around the Sun, it must have on board everything necessary to keep all its passengers comfortable, fed and entertained. We can’t stop at a service station to fill up on energy and other resources and to unload waste, as a bus would do during a school trip. We have to get by with what we have, and we have to manage waste and pollution. A definition of sustainability “Meeting the needs of the present without compromising the ability of future generations to meet their own needs” is the definition of sustainability given by the United Nations World Commission on Environment and Development in 1987. The experts discussed two fundamental concepts: ecological footprint and carrying capacity. With heavy feet: the ecological footprint The ecological footprint is a calculation that analyses whether a single individual or a group of people (a city, a region, a country) is in balance with the limits of the Earth. It was developed around 1990 by two scientists, Mathis Wackernagel and William Rees, with the aim of estimating the consumption of resources necessary both to produce individual goods or services and to support the needs of an entire community. While the ecological footprint is “the amount of land required to produce the resources necessary for life and to absorb the waste produced by the population of a given species”, the carrying capacity is “the maximum burden, exerted by the population of a certain species, that a given amount of land can bear without compromising its productivity.” Nature is sufficient for everyone: carrying capacity Carrying capacity is closely linked to the issue of food chains, where humans are at the top and all the resources of the land (animals, plants, minerals) are used for their well-being. Keeping an eye on the carrying capacity means not overdoing it, being in balance with one's habitat through a sustainable lifestyle. Don’t overexploit a field, or the soil will become depleted and will no longer produce fruit and vegetables. Don’t pollute the air in the cities, because everyone will get sick, the plants won’t grow, etc., and the city will become unliveable. The ecological deficit Since the 1970s, humanity has always been in ecological deficit, with an annual demand for resources that exceeds the Earth’s biological and geological capacity to provide all the resources needed. Today humanity uses the equivalent of 1.7 Earths to provide the resources we use, and to absorb our waste. But if we consume an average of 1.7 planets every year while living on just one planet... how is it that there are still resources left? It’s because we don't all consume resources in the same way. The ecological footprint of a citizen in the United States is 8.1 hectares/person; 3.4 of those are resources that they have “at home” (resources found in their country), and 4.7 are resources that they must obtain from somewhere else. If we look at Europe, in Germany, for example, the ecological footprint of a citizen is 4.7 hectares/person, which is 3.2 hectares (GHA, or global hectares) more than the ‘biocapacity’ they actually have. In Gabon, on the other hand, the ecological footprint is 2 (the quality of life is very low there) but that territory has incredible resources, as many as 19.1 per inhabitant, so there is a surplus of 17.1. This surplus, like the resources of a large part of Africa, Latin America and some parts of Asia, goes to satisfy the requirements of Western citizens’ super-well-being (well-being that’s extravagant and often very wasteful). This is clearly not a balanced and sustainable situation.
