Emissions of gaseous air pollutants have increased in the last years in spite of increased controls and concern for air quality. Predictions of future development also indicate that a further increase in emissions must be expected. From an extensive analysis of fuel use in conventional power plants in industry and for domestic heating, Brocke and Schade (1971) and Schade (1975) predict that sulfur dioxide (S02) emissions in the Federal Republic of Germany will increase from '3. 5 million t in 1969, over 4. 2 million t in 1973, to 4. 6 million t in 1980. Rasch (1971) predicts that emission of hydrogen chloride (HCI) from burning of wastes will increase from a present 8000 t/year to about 100000 t in 1980. Emission of gaseous fluoride compounds, in North Rhine Westphalia alone, are expected to increase from 7500 t in 1969 to 8800 t in 1985 (MAGS, 1972). Similar predic tions have also been made in the USA (Heggestadt and Heck, 1971). A doubling of S02 emissions from oil and particularly coal-fired power plants is expected between 1960 and 1980 (Wood, 1968; Lewis et aI. , 1974). When it is considered that total control of air pollutants is technically and especially economically impossible, it is important that, in the future, emissions are controlled within a technical and economic framework to such an extent that ambient pollutant concentrations near the ground present no hazard to man or his environment (BImSchG, 1974).

Desertification is land degradation due to climatic and anthropogenic causes where land includes soil, water and the biological productive capacity. This has become a major environmental, economic and political issue in Mediterranean countries. In order to address the problem in the European countries of the Mediterranean, the European Commission established a number of major research projects under its DGXII Environment and Climate Programme MEDALUS (Mediterranean Desertification and Land Use). This book describes the results from the first phase of the project, dealing with local physical, socio-economic and political controls on desertification. In particular the book concentrates on the models developed, calibrated and validated, the field investigations into biological, hydrological and erosional processes at the seven main sites, and provides an introduction to the problems associated with global warming in the Mediterranean context. GIS and remote sensing are an integral part of the investigation and the results are described and discussed in detail.