Wednesday, January 9, 2008



Climate change is neither new nor unusual. The earth’s average surface temperature and climate have been changing through out the world’s 4.7 billion history. Sometimes it has changed gradually (over hundreds to millions of years) and at other times fairly quickly (over a few decades).
The last two million years has seen more climate changes than any other time in the earth’s history. This period is known as the Quaternary period. More than nine separate cold and warm spells occurred in the Quaternary period.
Recent Warming:
Scientists have found that the earth’s temperature increased by up to 0.6º C. (1º F) during the 20th Century. They believe that one of the main cause of this global warming is the increase in green house gases in the atmosphere. They estimate that if the amount of green house gases continues to increase, the earth’s temperature will continue to rise too, perhaps up to 3.5º c. (6.3º F) over coming decades. Major cause of the green house gases are the burning fossil fuels and deforestation.
During the day, green plants absorb carbon dioxide in the air to make food. According to reports plants remove about 60 billion tones of carbon from the atmosphere each year.
Reports say ‘to minimize’ carbon from the atmosphere grow more tree. Surprisingly recent findings reveal that plant produce methane gas which is also the important green house gas responsible for global warming. Much more carbon dioxide is spread into the atmosphere every year, but one kilogram of methane warms the earth 23 times more than a kilogram of carbon dioxide does.
Most people know methane as natural gas. Found in oil fields and coal beds as well as in natural gas fields, it has become an important source of energy. Approximately 600 million metric tons of it- both anthropogenic and natural- rise into the atmosphere every year. Most of these emissions have been thought to come from the decay of non fossil organic material as result of activity by anaerobic bacteria. Wetlands such as swamps, marshes and rice paddies provide the greatest share. It was discovered that aging plants provide most of the chloromethane found in the atmosphere. Chloromethane is a chlorinated gas that destroys ozone.
It was also found that the rates of methane production increased dramatically, jumping to 10 to 100 times those of leaves detached from plants. In 2005 the scientists satellite measurements revealed “clouds” of methane over tropical forests.
During the last glacial maximum-around 21,000 years ago- the plant growth of the Amazon forests was only half as extensive as today, and tropical vegetation might thus have released much less than methane. Since that time, global surface temperature and carbon dioxide concentrations have risen, leading to enhanced plant growth and, we would expect, to more and more methane released from vegetation.

How might increased carbon dioxide levels affect photosynthesis?

Some studies suggest that more carbon dioxide in the atmosphere could increase the rate of photosynthesis in areas with adequate amounts of water and other soil nutrients. This would remove more carbon dioxide from the atmosphere and help slow atmospheric warming.
However, recent studies cast doubt on such a generalization for these reasons. First, this effect would slow as the plant reach maturity and take up less carbon dioxide. Second, it is a temporary effect. When the plants die and are decomposed or burned, the carbon they stored is returned to the atmosphere.
Seeing the above studies it can be said that plants are not going to help much in fighting global warming. The way we are producing carbons in the atmosphere I don’t think the growing trees can absorb so much of carbons, on the other hand they may take part in increasing global warming.
· G. Tyler Miller, Jr. 2004. Environmental Science working with the earth. Thomson Asia Pte. Ltd. Singapore.
· F. Keppler, T., Rockmann, Feb.2007. Methane, Plants and Climate Change. Scientific American, India Jour.

Dr. Nitish Priyadarshi
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