Global warming and climate change

As a result of increasing human population and impact of its activities on natural resources, Earth's environment has been undergoing significant changes, especially during 20th century. One of the most significant changes brought about by human activities is an increase in the concentration of carbon dioxide and other greenhouse gases in the atmosphere.

Greenhouse effect

Greenhouse or glass house is an enclosure of glasses in which tropical plants are grown during winters in areas of colder climate. Heat trapped by the glass keeps the temperature inside the greenhouse much higher than the surrounding atmosphere. A similar heating phenomenon occurs in the atmosphere also under normal conditions with normal concentration of carbon dioxide and other greenhouse gases, and hence the name greenhouse effect given. The temperature at the earth surface is maintained by the energy balance of the sun rays that strike the earth and heat that is radiated back into space and this is known as heat balance.

How greenhouse effect occurs in nature?

Air is a mixture of several gases like carbon dioxide oxygen water vapour and other gases. A blanket of air around the earth is called as atmosphere. Earth receives heat from the sun during day While some of the heat is reflected into the space during night.

The water vapour, carbon dioxide and methane form a blanket of gases that does not allow the solar radiation to escape back into the space. This blanket functions like the glass panels of a Greenhouse or Windows of a motor car which allows the sunlight to pass through but prevents the heat from being Re-radiated in outer space. This results in to warming of the Earth surface. This is  so-called greenhouse effect. This natural greenhouse effect is essential to maintain the temperature of earth at a normal habitable level.

      Besides carbon dioxide, Methane and water vapours, nitrous oxide and chlorofluorocarbons also aborbs solar radiation. These five  gases are called major Greenhouse gas is because they act like a blanket spread over the Earth surface helping it to keep warm. The major greenhouse gases includes

* carbon dioxide

* methane

* water vapour

* nitrous oxide

* chlorofluorocarbons

These gases occur in minute quantities in the atmosphere but play a critical role in maintaining even temperature on earth. Carbon dioxide contributes about 50% of total warming whereas Methane, chlorofluorocarbon and nitrous oxide 20% and 40% and 6% respectively. Besides these major greenhouse gases, hydrochlorofluorocarbons, chlorofluorocarbons, halogen, carbon tetrachloride and Ozone also called as greenhouse effect. The relative contribution of different sources to greenhouse gases is as follows:

Burning of fossil fuels --- 49%

Agriculture ---- 13%

Deforestation ----- 14%

Industrial process ------ 24%

Human activity has been making the blanket of greenhouse gases thicker,  resulting in enhanced greenhouse effect. The thicker blanket due to increasing concentration of greenhouse gases had disturbed the Global climate system. There is global warming due to enhancement of greenhouse effect all over the world.

           By 1995, it became evident that the main culprit was carbon dioxide emissions produced by the burning of fossil fuels - coal, gas and oil, in factories, power stations and cars. When we burn coal, firewood and natural gas, huge amount of carbon dioxide escape to the atmosphere. Basic activities like cattle raising and paddy planting also emit Methane, nitrous oxide and other greenhouse gases. If emissions continue to grow at current rates it is almost certain that atmospheric level of carbon dioxide will double from pre-industrial levels during the current century and it is quite possible that levels will triple by the year 2100.

Consequences of global warming and climate change

As a result of this continuous increase in levels of greenhouse gases, earth has been suffering from fever, and we have to act sincerely to cure it. Climate change has become one of the prime issue threatening the sustainability of World Environment. Besides environment, climate change has also impact on livability health and economy of the globe.

* Rise in global temperature causes sea levels to rise as polar ice caps and glaciers begin to melt, along with thermal expansion of water.

* More droughts and floods

* More terrible storms

* Many more hot days

* More diseases like malaria and dengue.

* Impacts on ecosystem would change the crop production potential of a region, especially in Asia, Africa and South and Central America.

* There will be a drastic change in  weather patterns bringing more floods or droughts in some areas.

* Forests may disappear.

* Biological diversity may reduce some species could become extinct

* Billions of people will be affected by problems of drinking water supply, sanitation and draught.