Man has been the mentor of earth's civilization since time immemorial. He has
brought about tremendous change from his "Nomadic life style" in the very beginning to
that of the present "Modem life style", due to inventions and discoveries at an
unprecedently fast rate. Application o f advanced technologies together with the
burgeoning of human and animal population in recent years has put immense load on the
environment. This load mainly being industrial, domestic and chemical pollutants
released in the enviromnent as a consequence o f our daily activities. Singh and Bose
(2002).
Human activity since the industrial revolution has increased the amount of
greenhouse gases in the atmosphere, leading to increased radioactive forcing from carbon
dioxide, methane, tropospheric ozone, chlorofluorocarbons and nitrous oxide. The
concentrations of carbon dioxide and methane have increased by 36% and 148%
respectively since 1750. These levels are much higher than at any time during the last
650, 000 years, the period for which the reliable data has been extracted from ice cores.
Fossil fuel burning has produced about three-quarters of the increase in carbon dioxide
from human activity over the past 20 years. Fossil fuels burned to run cars and trucks,
heat homes and businesses, and power factories are responsible for about 98% o f carbon
dioxide emissions, 24% of methane emissions, and 18% o f nitrous oxide emissions. Most
o f the rest is due to land-use change, increased agriculture, deforestation, landfills,
industrial production and mining.