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Global Environmental Changes

Introduction

     The atmosphere resource of our world is unique and available to our planet only. No other planet is found to have similar atmosphere. Earth's atmosphere is a legacy from history of this planet. It was formed billions of years back. In the formative years, as the earth started cooling, it did not have free oxygen (theory of chemical evolution by Oparin and Haldane). The atmosphere, lithosphere and hydrosphere were not clearly distinguishable. As micromolecules and macromolecules of C, H, N and O compounds like, glycerol, fat, pyrimidines, polysaccharide, lipid, proteins, nucleic acids were formed, the life forms originated.

Types of Environmental Changes

     Environment of earth includes the whole of atmosphere, hydrosphere as related to biosphere. Therefore, environment includes nature, composition of air, characters of hydrological parameters, sunshine, air pressure, temperature, water resources - their storage and flow and all other physical parameters of earth and its atmosphere.

Green House Effect

     Before green house effect is studied one needs to know what kind of radiation / sunshine we receive on earth.

Mechanism of Green House Effect

     The solar spectrum of electromagnetic waves include energy packed heat generating waves called radiation waves. As they lie beyond red colour waves of visible spectrum, they are also called 'infra-red rays'. These infrared rays lie in the wave length range of 700-900 mm. Two types of infrared rays can be identified - a shorter wavelength radiation rays (700 - 800 mm) and larger wave length radiation rays (800 - 900 mm).

Reasons for Green House Effect

     Out of total air pollutants to be 1 x 1012 tons, man made pollutants are 5 x 108 tons.

Impact of Green House Effect

     Change in the composition of air due to several human activities has brought about green house effect. Green house effect has brought about following phenomenal changes. The severity of these changes will aggravate further in the next 10-20 years. By 2040, CO2 level in air is expected to reach a level of 450 ppm (0.04%).

Green House Gases

     The concept of green house - though identified by man late - is certainly as old as global environment itself. That is, a part of radiation received by earth's surface is reflected back to environment and trapped due to certain gases. These gases are called green house gases.

Natural Green House Effect

     Before interference by any human activities green house effect by a coverage of gaseous blanket was in close equilibrium with earth's surface in the form of equilibria of carbon, oxygen and hydrogen cycles.

Man Made Green House Effect

     Realising the changes in global climate and human interferences resulting in such changes, many global conferences are held in order to reach consensus among countries to plan and implement the measures to mitigate the harmful effects of climate change.

The Ozone Layer

     Contrary to common misconception, Ozone is not in the form of thick layer surrounding atmosphere. Equally untrue is another misconception that a hole is made in this ozone layer. To understand low ozone spread in atmosphere, one needs to know the structure and composition of atmosphere.

Impact of Ozone Depletion

     Systematic study of impact of ozone depletion on the health of human beings/animals as well as crop/forest resources is yet to be made and published. In a country like India it is difficult due to poor documentation of health of animals and even health of human beings.

Control of Ozone Depletion

     Policy decisions are already taken in India to undertake technology developments for alternatives to CFCs. Two CSIR laboratories - National chemical laboratory and Indian Institute of Chemical technology are working on this. Along with this, parameters for design modifications such as compressors, heat exchanges, motors are also under investigation at several CSIR laboratories.

Summary

     The basis of life on earth is atmospheric cover on earth and natural cycles like carbon, oxygen, nitrogen and hydrological cycles.



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