Have you ever seen a greenhouse in a garden? It is a small enclosure with a glass roof where plants are grown. The glass roof has a special purpose. It allows sunlight to enter the house and heat the ground. The enclosed air also gets heated up as the hot ground radiates heat. This hot air cannot escape through the glass roof and so the inside of the green house becomes hotter than the outside. This helps plants to grow inside a greenhouse even in cold weather and thus the name "greenhouse".
Our earth is also like a greenhouse. There is no glass roof, but there is a layer of air around our earth called the atmosphere. When sun rays fall on earth, the atmosphere allows the rays to pass through them. After traveling through the atmosphere, the rays heat up the earth. The hot surface of the earth then radiates heat. If there was no atmosphere, this heat would have been lost in space and the earth would have been very cold. However, our atmosphere comes to the rescue. As the earth radiates heat it passes through the atmosphere and special gases present in the atmosphere absorb the heat. Constant circulation of air then redistributes the heat around the globe and the end result is a warm globe where we and all other living beings survive. One of the special gases that is responsible for the earth's greenhouse effect is called carbon dioxide. It is the colorless, odourless gas that we breathe out everyday. An easy experiment where you can observe the gas is the following: in a small ceramic bowl pour some vinegar and add to it a pinch of baking soda - you will see small bubbles emerging and the bubbles are nothing but carbon dioxide released by the reaction of acetic acid (vinegar) and baking soda (sodium bicarbonate).
There is an optimum balance of different gases in the atmosphere, perfect for maintaining an optimum earth temperature, not too cold and not too hot. Unfortunately, human activity, especially consumption of energy, for the last fifty years has disrupted the optimum balance of different gases in the atmosphere. A large amount of energy comes from burning fossil fuels (wood, coal, petrol, gas) where the end product is carbon dioxide. As a result, carbon dioxide has over accumulated in the atmosphere resulting in a slow increase in the earth's temperature.
What happens if the earth's temperature rises? The answer to this question is not so easy. Our environment is the result of many forces balancing each other and a change in one factor leads to completely unpredictable disasters. However, some disaster scenarios can be predicted. It has been estimated that if the average temperature of earth increases by only a few degrees, part of the huge amount of snow in the Antarctic will melt. This will raise the height of oceans and low lying areas will be submerged. A large part of Bangladesh, for example, lies almost at sea level, and so it will completely disappear under the ocean. Isn't it scary?
How can this be stopped? Currently human civilization is heavily dependent on energy use, so it is not practical to suddenly give up using energy. But it is possible to use only as much as we need (for example, don't forget to switch off the fan when you leave a room -- it may seem like only a small, symbolic gesture, but all the energy adds up!). Also, people around the globe have been developing and using alternate sources of energy that do not use fossil fuels. These include solar power, tidal power, geothermal power, wind power and of course hydro-power. Have you noticed a solar powered car that was recently introduced between Salt Lake and Ultadanga? Maybe when you grow up to become like your parents, all cars will be solar powered! Interestingly, trees can also help. Trees use carbon dioxide and water to make their food. So growing more trees means reducing atmospheric carbon dioxide and avoiding a future green house disaster.
--- By Dr. Gautam Basu ("Gautam Uncle")
Front cover
Page 1
Cheese Balls Recipe by Tania Das
A visit to RCFC by Mini Chaterjee
Titans of the deep by Aparupa Biswas
Memories of being small by Miki Deb
Animal Corner: "Talk" to the animals ?? by Johara Shahabuddin
Craft Idea by Bidisha Das
Our Earth = A Garden Green House by Gautam Basu
Thank you
Back cover
