Research into landfill methane suggests daily emissions as large as 250 tonnes/sq km of landfill. Collection systems can help recover much of this, but efficiency of recovery can vary from 30% for surface gas collection systems (least efficient) to 55% for pipe collection systems installed during landfill operation (least costly).
Total anthropogenic sources of methane are estimated at about 275 Mt per year. However, as with natural sources, these estimates have large uncertainties.
In 1996, UK methane emissions were 3.7 million tonnes, 16 per cent lower than in 1990. The main sources of methane emissions in 1996 were landfill (46 per cent) and farm animals (28 per cent).
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.
Non-profit, apolitical, independent, and non-governmental in nature, the UIA has been a pioneer in the research, monitoring and provision of information on international organizations, international associations and their global challenges since 1907.