28. Desertification – the process whereby productive arid and semi-arid land is rendered economically unproductive – and large-scale deforestation are other examples of major threats to the integrity of regional ecosystems. Desertification involves complex interactions between humans, land, and climate. The pressures of subsistence food production, commercial crops, and meat production in arid and semi-arid areas all contribute to this process.
29. Each year another 6 million hectares are degraded to desert-like conditions. Over three decades, this would amount to an area roughly as large as Saudi Arabia. More than 11 million hectares of tropical forests are destroyed per year and this, over 30 years, would amount to an area about the size of India Apart from the direct and often dramatic impacts within the immediate area, nearby regions are affected by the spreading of sands or by changes in water regimes and increased risks of soil erosion and siltation.
30. The loss of forests and other wild lands extinguishes species of plants and animals and drastically reduces the genetic diversity of the world's ecosystems. This process robs present and future generations of genetic material with which to improve crop varieties, to make them less vulnerable to weather stress, pest attacks, and disease. The loss of species and subspecies, many as yet unstudied by science, deprives us of important potential sources of medicines and industrial chemicals. It removes forever creatures of beauty and parts of our cultural heritage; it diminishes the biosphere.
31. Many of the risks stemming from our productive activity and the technologies we use cross-national boundaries; many are global. Though the activities that give rise to these dangers tend to be concentrated in a few countries, the risks are shared by all, rich and poor, those who benefit from them and those who do not. Most who share in the risks have little influence on the decision processes that regulate these activities.
32. Little time is available for corrective action. In some cases we may already be close to transgressing critical thresholds. While scientists continue to research and debate causes and effects, in many cases we already know enough to warrant action. This is true locally and regionally in the cases of such threats as desertification, deforestation, toxic wastes, and acidification; it is true globally for such threats as climate change, ozone depletion, and species loss. The risks increase faster than do our abilities to manage them.
33. Perhaps the greatest threat to the Earth's environment, to sustainable human progress, and indeed to survival is the possibility of nuclear war, increased daily by the continuing arms race and its spread to outer space. The search for a more viable future can only be meaningful in the context of a more vigorous effort to renounce and eliminate the development of means of annihilation.
- UNEP, 'General Assessment of Progress in the Implementation of the Plan of Action to Combat Desertification 1978-1984', Nairobi, 1984; WCED Advisory Panel on Food Security, Agriculture, Forestry and Environment, Food Security (London: Zed Books, 1987).
- World Resources Institute/International Institute for Environment and Development, World Resources 1986 (New York: Basic Books, 1986).