Acid rain occurs when emissions from coalburning factories and power plants are transformed into sulphuric and nitric acids and fall to earth. In Europe, more than 100,000 stained glass objects, some of them more than 1,000 years old, are threatened by acid rain. Documentary records show that the stained glass in Europe was in a relatively good condition up to the turn of the century and even the Second World War caused practically no damage since all European stained glass was sheltered during that time, but in the last 30 years the deterioration process has accelerated to the extent that a total loss is expected within a few decades. Glass dating from the 8th to the 17th centuries is particularly endangered. Sulphuric acid has an etching effect on the surface and the resulting salts form a chalky crust that accelerate the decomposition process, allowing the paint to peel off. The glass substance finally splits and disintegrates into minute particles. Sulphur compounds also seriously crack old organically treated leather and paper produced after 1750.
The Encyclopedia of World Problems and Human Potential is a collaboration between UIA and Mankind 2000, started in 1972. It is the result of an ambitious effort to collect and present information on the problems with which humanity is confronted, as well as the challenges such problems pose to concept formation, values and development strategies. Problems included are those identified in international periodicals but especially in the documents of some 60,000 international non-profit organizations, profiled in the Yearbook of International Organizations.
The Encyclopedia includes problems which such groups choose to perceive and act upon, whether or not their existence is denied by others claiming greater expertise. Indeed such claims and counter-claims figure in many of the problem descriptions in order to reflect the often paralyzing dynamics of international debate. In the light of the interdependence demonstrated among world problems in every sector, emphasis is placed on the need for approaches which are sufficiently complex to encompass the factions, conflicts and rival worldviews that undermine collective initiative towards a promising future.
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