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Wednesday, November 17, 2010

Green House Effect, Global Warming and Climate Change

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The warming effect produced inside a green house by its glass panels, is called as Green House Effect. A green house is a specialized house constructed at horticulture stations for keeping plants that survive better in warm surrounding.

Green House Effect: How does it occur?
The walls or panels of a green house are made of specialized glass that allows short wave solar radiations to go inside but does not allow long wave infrared heat energy of the glass house to pass out. In fact, some of the solar radiations that are absorbed inside the green house get transformed into heat energy in the form of long wave infrared radiations that can not go out of the glass panels of the green house. Thus, temperature inside the green house rises as compared to the temperature outside. The term- Green House Effect was coined by   J. Fourier in 1827.

Green House Gases (GHGs)
Gases that help in causing green house effect are called as Green House Gases (GHGs). These gases either occur naturally or are produced on earth due to human activities of burning fossil fuel and bio-mass.

One of the most abundant naturally occurring green house gases is the water vapour. Other green house gases are carbon dioxide, methane, Nitrous oxide, Trifluoromethyl sulphur pentafluoride and hydrochlorofluorocarbons. Trifluoromethyl sulphur pentafluoride is an industrially produced chemical compound. It is a serious heat trapping compound which could be discovered only after the year 2000. It is since 1700s, that a substantial increase in the concentration of green house gases has occurred in the atmosphere.

Importance of Green House Effect
Our Earth is subjected to green house effect which is very important for creating a climate favourable to the sustenance of most forms of life on it. In this context, the green house effect can be defined as –

The effect of warming and insulation of the earth caused due to some heat trapping gases accumulated in the atmosphere after their emission from the earth surface, is called as green house effect.

The natural green house effect is in fact, a process of Thermal Blanketing of the earth which maintains its temperature around 33 Celsius degrees which helps in the sustenance of life on it. Without the green house effect, the climate of the earth is reported to become too cold for most of the life to survive. Then, the temperature may fall much below the required level essential for the existence of life. Hence green house effect is an important natural process which is essential for the survival of life on this planet.

Global Warming
Human activities of pollution are modifying the natural process of green house effect. The advent of the Industrial Revolution in the 1700s boosted up the activities of burning of fossil fuels like coal, oil and natural gas which released lots of heat absorbing gases into the atmosphere. Clearing of land for agriculture or for urban settlements, wiped out the vegetation that acted as ecological sink for some of those gases like carbon dioxide.

 The heat absorbing gases accumulate in high concentrations in the upper atmosphere around the earth extending up to 100 km above its surface and act as glass panels of a green house. They allow much of the short wave solar radiation to reach to the earth surface but stop much of the long wave infrared rays against escaping out as heat. They absorb these infrared radiations and then re-radiate most of them back to the earth surface. Thus, the temperature of the atmosphere rises gradually causing an unnatural heating effect which is called as the Global Warming. Global warming is the enhanced green house effect due to greater accumulation of GHGs in the upper atmosphere.

The warming of the earth’s atmosphere attributed to a build up of green house gases in high concentration in the atmosphere is called as the Global Warming. It is a term which is used to refer to the observed increase in the average temperature of the earth’s atmosphere and oceans in recent decades. Scientific discoveries reveal that the world experienced warmest atmosphere during last 50 years out of the period of 100 years. The global mean temperature increased by about 0.5 to 1 degree Celsius, within a period of last 100 years.

Global Warming and Climate Change
The regular pattern of weather conditions of a particular place is called as climate of that place. This regular pattern of weather conditions is considerably disturbed by fluctuations in temperature. The disturbance in the pattern of weather conditions at a particular place may rightly be called as Climate Change.

The Global Warming itself is not the Climate Change as the effects of global warming may not be uniformly negative. But, it is the abnormal rise in global temperature that is causing changes in the global climate. Let us see, how abnormal changes in temperature may lead to climate change.

Temperature  has significant role in the regulation of water cycle in the environment. Hence, rise in global temperature can change the pattern of water cycle. On the other hand, increased temperature can cause most of the ice to melt down. The increased evaporation of water due to high temperature may alter the pattern of cloud formation and rains at different places. The physical features of the earth also play important roles in causing temperature variations that finally result into variations in air pressures. These variations cause disastrous conditions like storms, cyclones, tornadoes and hurricanes etc.

International agencies studying the climate change have projected the globally averaged temperature to increase by 1.4 to 5.8 degrees Celsius over the period 1990 to 2100. The Intergovernmental Panel on Climate Change (IPCC) does important climatic researches and surveys on periodic basis. It has hundreds of scientists from many different countries that study and analyse the meteorological changes and provide a collective pictures of global warming and other changes in the climate systems.

Impacts of Global Warming
The Global Warming has various types of impacts on the whole earth and its systems. Some of the major impacts of Global Warming are mentioned below.

. Global Warming may cause frequent natural disasters like cyclones, storms and hurricanes, floods and droughts. It may also cause cloud bursts, avalanches, landslides, mud- flows and earthquakes.

. Global Warming is causing melting of ice and glaciers which is leading to a rise in sea- level. As a result, the creeping up of oceans swallow low lying islands and coastal areas.    
                                         
The rising sea level is causing loss of land, loss of property and loss of lives. It may also cause large scale displacement of people which may further create a problem of rehabilitation.

. It is damaging forests, agriculture and water supplies.

. It is damaging various ecosystems like mangrove- swamps, coral reefs and coastal lagoons etc. due to various reasons like reduction in pH of oceanic water and increasing deposits of acids.

. Some populations of migratory birds have been declining because of unfavorable variations in climatic conditions. On the other hand the migration time of spring butterflies in Britain has become earlier than it was 30 years ago. It has been observed that the behaviors of some bird species have changed due to climatic variations in some  Indian states .Some birds like Black Headed Oriole and Open Billed Stork have changed their times of migration where as some birds like Bronze Winged Jacana and Indian Small Skylark have changed their nesting behaviors.



Image 1:  Black headed oriole



 Image 2: Open billed stork



Image 3: Bronze Winged Jacana
 courtesy all images - flickr

. The change in climate due to rise in global temperature is causing migration of species of wild animals towards poles and high altitudes. Since those areas are already inhabited by animals of different species, the migrated species receive the status of Refugee Species.


Key Words : Green House Effect, Global Warming, Climate Change

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