Today’s landscapes bear the imprint of mankind and the marks of our economic growth: areas under cultivation, infrastructures, hydroelectric dams, urban sites, pollution. What is the impact of such damage, beyond the visual evidence?
Certain consequences are immediately apparent. Hydroelectric dams, for example, which impede the flow of over half the planetís major rivers, prevent migrations and permanently affect pre-existing living conditions for many species. Similarly, highways carve up natural habitats, imprisoning living creatures on one side or the other of an insuperable barrier. Other effects are less direct. With the spread of urban areas and infrastructures, the earth is blanketed in concrete, making it impermeable to rainfall. Surface water increases, feeding streams and rivers and giving rise to more frequent and more serious flooding.
Invisible chemical pollutants are even more insidious. They are carried far and wide by air and sea currents, turning up as far away as Greenland, for example, where they accumulate in the fat of marine animals. Studies carried out in the 1970s revealed the presence of a pesticide, DDT, in the bodies of seals and polar bears, and of mercury in white whales. These toxic substances are described as “persistent“ because they accumulate and contaminate the entire food chain from plankton to fish to seals, right up to the Inuit who hunt the seals. The breast milk of some Inuit women is so heavily contaminated that it could be classified as toxic.
Humanity puts great strain on the natural world. But what role does each of us play in this? We now have a tool that can measure it: we can calculate what is known as our ìecological footprintîóthe necessary surface area of the planet for the production of our food, the manufacture of the objects we rely upon, and the absorption of our waste products. The average ecological footprint, taking humanity as a whole, is 4.4 acres (1.8 hectares), but the average for a European is 11.8 acres (4.8 hectares). The overall resources used by human beings already exceed the planetís capacities for regeneration by 30%. If our consumption continues at the same rate, by 2030 we will need the equivalent of two planets to maintain our way of life.