ABSTRACT
In July 1990, an intergovernmental group of experts, convened by the World Meteorological Organization and the United Nations Environment Programme, produced a document summarizing what was known at that time on the biophysical perspectives of global climatic change (GIESCC 1990; IPCC 1990a). One of their main conclusions was that it can be inferred with a high level of certainty that during the next century the average temperature of the earth will rise steadily at a rate of 0.3°C per decade if the emission of greenhouse gases continues at its present trend. According to this expert panel, the Intergovernmental Panel on Climate Change (IPCC), a sea-level rise of approximately 5 cm per decade will affect natural ecosystems in different ways and will significantly disrupt the water balance in many regions of the globe. The same panel recently revised its estimates to predict a temperature rise of 1.4–5.8°C and a sea-level rise of about 0.09–0.88 m by the year 2100 (IPCC 2001). Large-scale climatic variation is an important element, but by no means the only one, of a series of large-scale disruptions in the global environment that are threatening the sustainability of the biosphere as a whole. Apart from the systemic effect of the emission of gases at a biospheric level, other phenomena are contributing significantly to so-called “global change.” Among these, pollution of air and water resources, soil depletion and erosion, deforestation, overgrazing, and depletion of biological diversity are possibly the most important.
Global change is more, much more, than climate change or global warming. Most would agree that the global changes that will strike the hardest blows on people and other living things in the next 20 or 50 or 100 years will not be those of climate change. If the world is in environmental extremis today, it is more through the rapidly changing chemistry of the air and soils and water, and through the inexorable and wide-reaching pressures of urbanization and intensive agriculture and land use. (Eddy 1991: 3)
