Session – 14
Unit – VI
CLIMATIC CHANGE AND GLOBAL WARMING
Dr. H.S. Ramesh
Professor of Environmental Engineering
S.J. College of Engineering, Mysore – 570 006

Carbon di-oxide is a natural constituent of atmosphere, but now, its concentration is increasing at an alarming rate. According to an estimate, CO2 level is expected to be doubled by 2030 A.D.

The term ‘Green House Effect’ is also called as ‘Atmospheric Effect’, ‘Global
Warming’ or ‘CO2 Problem’.
Human activities are changing the composition as well as behaviour at an unprecedented rate.

The pollutants form a wide range of human activities are increasing

the global atmospheric concentration of certain heat trapping gases, which act like a blanket, trapping close to the surface that would otherwise escape through the atmosphere to the outer space. This process is known as ‘Green House Effect’. Green House is that body which allows the short wave length incoming solar radiation to come in, but does not allow the long wave outgoing terrestrial infra red radiation to escape.

The

progressive warming up of the earth’s surface due to blanketing effect of manmade CO 2 in the atmosphere is called ‘Green House Effect’. (Figure 1).

The four major green house gases, which cause adverse effects are CO2, CH4,
N2O and CFC’s.

Among these CO2 is the most common and important green house gas.

In addition, ozone and SO2 are also act as serious pollutants in causing global warming.

Green House Effect
Under normal concentrations of CO2, the temperature of the earth’s surface is maintained by the energy balance of the sun’s rays that strike the planet and the heat is radiated back into the outer space.

However, when concentration of CO2 in the

atmosphere increases, the thick envelope of this gas prevents the heat from being reradiated out. The heated earth can radiate this absorbed energy as the radiation of longer
wave