It is now 15 years since the scale of the problem of desertification in drylands was brought to world attention. The problem has continued to intensify and, according to regional and local sources, the extent of the land areas and numbers of people affected are still increas- ing. It is difficult to confirm this point from United Nations sources for the results of the surveys of 1977, 1984 and 1991 are not strictly comparable.

The latest UN world map of dry- lands and global desertification is claimed to have + / - 10 per cent accuracy and any change since 1977 falls within this degree of error. However, observers in such areas as dryland Africa south of the Sahara and in parts of Asia and South America assert that rangelands have continued to deteriorate since 1977.

Areas adjacent to semi-arid, rainfed, farming regions appear to be the worst affected: within the rainfed croplands themselves, degradation is increasing most rapidly in the tropical areas of Africa, South Asia and South America. So far as irrigated lands are concerned, while desertification remains a significant localised problem, gains from reclamation and land improvement seem to be keeping the overall situation in balance.