Greenhouse gases and global warming have received increasing attention in recent years. The identification of the ozone hole in 1985 combined with unusual fluctuations in global temperatures have combined to capture the eye of the global media. Recent scientific study and analysis of the greenhouse gases has added to this interest. Greenhouse gases in the atmosphere have an important influence on the climate of our planet. Quite simply, greenhouse gases hinder the outward flow of infrared radiation rays more effectively than they impede the incoming solar radiation of the sun. Because of this imbalance, the earth’s atmosphere and its oceans are warmer that what they would be in the absence of these gases. 
Figure 1.1- A diagram showing a simplified illustration of the Greenhouse Effect. 
The major greenhouse gases are water vapor, carbon dioxide (CO2), methane (CH4), chlorofluorocarbons (CFC’s), ozone (O3), and Nitrous Oxide (N20).  Of these, water vapor and CO2 are naturally occurring. Without these gases, the earth would be about 33 degrees Celsius colder than what it is, making it unsuitable for human inhabitation.  Human activity has contributed to the increased atmospheric concentration of CO2, CH4, and CFC’s. The possible warming of the earth’s atmosphere and subsequent increase in average temperatures is what is termed as the Greenhouse Effect. The Greenhouse Effect is of a global nature. Release of greenhouse gases in any part of the earth disperses rapidly. Neither the activity resulting in the release nor the location of the release makes much difference.  The problem lies in the variety of human activities that result in these emissions. Since releases of greenhouse gases are connected to most economic activity, significant reductions in their emission can affect the economic strength of countries.  This holds special significance for the developing countries that rely on industrial economies for growth and development. Most of their industries rely heavily on the use of non-renewable sources of energy such as the burning of fossil fuels. The three main fossil fuels in use are coal, petroleum and natural gas. As a result, we are constantly monitoring atmospheric concentration of greenhouse gases. As of 2001, the atmospheric concentration of greenhouse gases is classified under Table 1.1.
GasPre 1750 ConcentrationCurrent Atmospheric Concentration Concentration in parts per million (ppm)
Carbon Dioxide (CO2)
Concentrations in parts per billion (ppb)
Nitrous oxide (N2O)
Tropospheric ozone (O3)
Table 1.1 – Showing the relative concentrations of the primary greenhouse gases as parts of the atmosphere. .
The concentration of C02 has increased by around 25 per cent primarily due to emissions from fossil fuel burning and deforestation. CH4 has more than doubled in concentration since 1750.  Sources of CH4 are less certain than those of C02 but include rice paddies, animal and domestic waste, coalmining and venting of natural gas. The atmospheric concentration of N20 has also been growing since the mid-18th century, and its sources include nylon production, three-way catalytic converters in cars, and, possibly, agriculture. CFCs, used in refrigerators, air conditioners, and foam insulation, are not only involved in greenhouse warming in the troposphere, but also in the depletion of the ozone layer in the stratosphere.  Global environmental change is a general umbrella term for a whole range of mutually dependent global environmental problems attributable to human activities. They include acidification, deforestation, land degradation and desertification, loss of biodiversity and depletion of fresh water supplies. Major global environmental changes that can be expected to have a significant health effect include climate...