1. The Nature of the Problem 1 I The globa.l varriing problem has three distinct but strongly inter-relatel parts: global chemical pollution; the greenhouse effect of these pollutants; and the global climatic change resulting from the greenhouse effect. Significant scientific progress has been made in observing, understanding and documenting many of these effects. This progress has led to an international consensus among scientists on the significance and the seriousness of the potential global-scale warming and the accompanying rise in sea-level. The predicted warming rates for the next several decades are unprecedented in terms of climate changes of the last several thousand years Global Chemical Pollution "Visions of environmental catastrophe and the collapse of society [have been] awakened. These are alluring scenes, if only because the failure of large regions and complex SOcieties is evident in our history." Thomas E. Downing University of Birmingham, UK - Monitoring of the atmosphere has demonstrated that the concentrations of several trace gases, such as carbon dioxide (CO2), methane (CH4), chlomfluorocarbonsCFCs (CF2Cl2, CFC13 and others), tropospheric ozone (03) and nitrous oxide 20) have increased significantly during the last century and are continuing to increase. Until the 1960s, carbon dioxide had been seen as the most significant greenhouse gas, however the role of methane is now becoming increasingly important. The methane concentration in the atmosphere is currently growing by an estimated 1.1% per year, released primarily from rice paddies, and also from ruminants, marshes and natural gas exploration. While carbon dioxide is the most abundant greenhouse gas, methane, nitrous oxide and CFCs are far more efficient at "trapping heat" and thus contribute significantly to global warming although they are in relatively small concentrations. CFCs are primarily used in spray cans and refrigeration. Nitrous oxide is mainly produced through biotic processes, including use of nitrogen fertilizers. While most of the emitted carbon dioxide is naturally absorbed by the oceans, the increasing rate of emissions has resulted in increasing atmospheric concentrations. Trees and other vegetation also absorb carbon dioxide, but then release it when destroyed by burning or decomposition. However, they naturally act as net carbon sinks since the rate of organic matter production exceeds the rate of decomposition. Over the last thirty years or so, the combustion of fossil fuels has been the main source of carbon dioxide emissions. Between 1960 and 1987 fossil fuel contribution to atmospheric carbon rose 124% (from 2.5 billion tonnes annually to 5.6 billion tonnes annually). Another major source is deforestation and land clearance, accounting for over 20% of carbon dioxide emissions. Currently fossil fuel burning alone accounts for a release of about 6 billion tonnes of carbon per year, while deforestation and land clearing account for another I billion tonnes. The Greenhouse Effect of the Pollutants 1 The probability that the world's climate would change due to fluctuations in atmospheric carbon dioxide concentration was postulated by S. Arrhenius, the Swedish Nobel Prize chemist in 1896. However, studies on this subject have only assumed great significance within the last few years since the 1985 Villach meeting in Austria. The scientists attending the conference announced, "As a result of the increasing concentrations of 'greenhouse gases', it is now believed that in the first half of the next century, a rise in global mean temperature could occur which is greater than any in man's history." They predicted a rise in global temperature of 1.5-4.5°C. While there is consensus that global climate change will occur, the nature of climate ch an ge at th e re gion al level is not yet well unde rstood. Recent an alyses indicate th at th e earth as a whole has wa rm ed by abo ut 0.3-0.6°C over th e p as t century. It is ex pe cted th at th is rate wi ll inc re a se significantly, by 0.5-1.0°C per decade through the next few decades, if human activities which emit greenhouse gases continue unabated. The industrialized countries contribute over 0~,