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What Causes Global Warming?

Roy D'Silva
What are the causes of global warming? What is the greenhouse effect? Is global warming really as destructive as it is believed to be?
Global warming has surfaced as a major environmental issue, especially over the past few decades. There has been a lot of hue and cry about global warming, and its impact on the climate, ever since the idea was first put forth. Even though there is no dearth of books or articles on the Internet, the layman still seems unaware of the basic causes of global warming.

Causes of Global Warming

Global warming is basically a change in the climatic conditions of the Earth, brought about by a considerable rise in the near-surface temperature of the planet. A number of factors have been contributing to this rise in the average global temperature - either directly or indirectly, right from the time the planet came into existence.
It is the alarming rate at which the temperature has been rising over the last few decades that has the scientific fraternity on its toes, and the desperate measures to find out what is causing the global temperature to rise at this rate, hints at this very fact.
Global warming, and the resulting climate change, can be caused by natural as well as man-made factors (anthropogenic factors, to be precise). The natural factors causing this are sudden warming of the planet include the greenhouse effect, solar activity, volcanic emissions, orbital forcing (slow tilting of the Earth's axis), etc.
The anthropogenic causes, on the other hand, include various human activities - right from breathing (respiration), to the use of vehicles and various industrial processes, which add to the greenhouse effect and cause the Earth to become warm.
The greenhouse effect is said to be the most crucial factor contributing to global warming. It refers to the process wherein the radiations coming from the Sun are trapped by the greenhouse gases within the atmosphere of the Earth, which in turn causes the temperature near the Earth's surface to soar.
The greenhouse gases, include carbon dioxide, carbon monoxide, methane, chlorofluorocarbons (CFCs), water vapor, etc.
It is believed that the greenhouse effect has increased the Earth's temperature by somewhere around 24 percent, with carbon dioxide contributing to about 12 percent of the greenhouse effect, water vapor contributing around 36 percent, methane 5 to 10 percent, and Ozone making around 3 to 7 percent to the same.
The changes in the amount of radiant energy emitted by the Sun, i.e. solar variation, is said to be yet another reason of global warming. This solar variation has been correlated with the changes in the Earth's climate and temperature. The solar variation theory states that the amount of solar radiation has been increasing with time.
If the proponents of the solar variation theory are to be believed, the Sun has been gaining strength, and is at its strongest since the last sixty odd years. And thus, it is believed that the Sun may now be acting as a cause of global warming.
It isn't quite a coincidence that global warming and industrialization seem to go hand in hand, and that becomes obvious as you compare the industrialization and temperature rise trends over the last few decades.
Even scientists acknowledge that rapid industrialization, wherein we have opted for quite a few shortcuts, has contributed to the increase of global warming today.
Humans had started contributing to global warming some 8000 years ago with the start of agriculture, wherein deforestation to clear land for farming resulted in a significant rise in the amount of carbon dioxide in the atmosphere.
A prominent greenhouse gas, methane is released in the atmosphere as a part of the digestive process in cattle and other ruminating animals.
Scientists are of the opinion that bad practices in industries result in release of various greenhouse gases which eventually trap the Sun's radiations in the atmosphere, and contribute to global warming.
Though the use of household appliances which release chlorofluorocarbons (CFCs) in the atmosphere has come down now, it was at its peak in the 90s and caused irreversible damage to the atmosphere.
Other than cattle, methane also exists in plenty beneath the Earth's crust, and the release of methane during mining indirectly contributes to rising temperature on the planet. Other than deforestation, humankind has also contributed to global warming by using fossil fuels, which emit carbon dioxide and other such harmful gases.
While all the natural factors do come into play when it comes to global warming, one has to understand that they are necessary in maintaining the right balance on the Earth. Had it not been for all these natural occurrences, the entire planet would have had been a cold desert resembling the continent of Antarctica.
In fact, some scientists are of the opinion that human life would have been impossible on the planet in the absence of greenhouse effect (human activities excluded), because the average temperature of the planet would be around 27°C in that case.