Checking Greenhouse Gases for a Cool Planet

For nearly three decades, greenhouse gases have been censured, in academic circles as well as mass media, as the agents responsible for the greenhouse effect and hence for a considerable degree of global warming. As their levels rise in the earth’s atmosphere, they absorb and emit infrared radiation that would otherwise escape the earth and dissipate away into space. This way, greenhouse gases keep increasing the average global temperature of our planet.

Both natural and anthropogenic processes are the sources of greenhouse gases that accumulate in the atmosphere, blanketing the earth all around. Before discussing the relative role of natural versus human factors in producing greenhouse gases, it is worthwhile to know what greenhouse gases are and their relative proportion in earth’s atmosphere.

There are more than 20 greenhouse gases recognized by the Intergovernmental Panel on Climate Change (IPCC). More important greenhouse gases include: water vapors, carbon dioxide, methane, nitrous oxide, ozone, and chlorofluorocarbons (CFCs). Of these, water vapors are the most abundant in our atmosphere while CFCs have the lowest level of abundance. Some of the greenhouse gases are stronger than others in their capacity to absorb heat and radiate it back; methane, for example, is far stronger than carbon dioxide (CO2). However, the actual heating effect of a gas depends on its abundance plus its strength. Thus, CO2 has a greater greenhouse effect than methane due to its higher concentrations in the atmosphere. In terms of their overall greenhouse effect on earth, the four leading greenhouse gases are: water vapors, carbon dioxide, methane, and ozone.

Nature is a big polluting agency of itself. Volcanic eruptions and many inorganic and organic processes on earth’s surface produce huge quantities of greenhouse gases, particularly carbon dioxide. Ice samples from ancient glaciers and other indicators of paleoclimate reveal that the concentrations of carbon dioxide in earth’s atmosphere, long before the appearance of higher life forms, have varied from as much as 10 times to almost 350 times of the present CO2 levels (384 ppm) and other greenhouse gases. But then nature is also self-remedial. The worldwide spread of land plants on the globe and aquatic plants in water provided a huge sink for drawing CO2 down from the atmosphere, bringing the average global temperature in an ambient range. Nature has, since then, calmed down, giving atmospheric control to humans.

The anthropogenic sources of greenhouse gases are varied and, unfortunately, humans have not developed any good sinking source for carbon dioxide and other greenhouse gases. This has set the problem of global warming once again on a rise. Many human activities – including domestic, agricultural, commercial, and other – are continuously emitting loads of greenhouse gases into the atmosphere. To aggravate the problem, humans have been involved in deforestation of the earth on a large scale, destroying the natural sink for CO2, which is the major anthropogenic greenhouse gas responsible for global warming. Having the problem realized (better late than never), we are supposed to learn from Mother Nature in balancing the harm with good. A number of preventive and remedial measures have been emphasized by environmental authorities. More important of these include:

•    Extensive forestation
•    Energy-efficient building and means of transportation
•    Use of renewable and non-polluting energy sources for lighting and heating
•    Developing environmental-friendly communities

Nature has long stopped heating the globe for us. Somehow, it knew the threat millions of years before we showed up on this planet. It is our turn now to check global warming by cutting out the excess production of greenhouse gases. To live better and survive on earth, we need to make it stay cool.

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