Sustainability

Sustainable use of resources

When can the use of a natural resource be defined sustainable? In general we may say that a natural resource is used by human beings in a sustainable way when, in the light of its reproducing ability (think about fish as a natural resource) or its ability of maintaining certain qualities (for example the purity of the air we breath), its exploitation does not exceed a certain limit. When the use of that resource exceeds the given limit, it means that its progressive and dangerous depletion has started, either in quantitative (the global fish population sinks to a limit under which the species is bound to disappear) or qualitative terms (the air is so polluted that it cannot be breathed any longer and causes grave illnesses in living organisms). If this “depletion” of the natural resource is definitive (the extinction of the species), the damage caused is said to be “irreversible”, i.e. reversing the development and bringing the species back to life is impossible.
A depletion is said to be “reversible” if the development can be reversed and the natural resource can be restored (the polluted air can be purified if polluting emissions stop).
Actually, the concept of sustainability can only be applied to renewable natural resources reproducing within human times. In the case of non-renewable resources, such as fossil fuels, reference should be made to optimum exploitation. In other words, we can endeavour to use them efficiently (making them last for the longest possible time) and in the meantime develop technologies allowing the exploitation of alternative resources, possibly marked by the characteristic of being renewable (for example a future replacement of the energy produced through fossil fuels with solar energy, a renewable source).