Discuss the concept, causes and effects of green house effect.

Concept of Greenhouse Effect — Greenhouse effect means the progressive warming up of the Earth's surface due to the blanketing effect of man-made carbon dioxide in the atmosphere. It is a natural process in which certain gases like carbon dioxide and water vapour (called greenhouse gases) trap heat that radiates from the earth's surface. These gases act like the glass panels of a greenhouse, allowing short-wave solar radiation to enter but preventing long-wave infrared radiation from escaping. Without the greenhouse effect, the earth's temperature would be below the freezing point of water (–18°C).

Causes of Greenhouse Effect — The chief causes are:

1. Carbon Dioxide — Released by burning of fossil fuels in factories, power plants, automobiles, deforestation and burning of firewood.

2. Water Vapour — Increased water vapour and changes in atmospheric circulation create changes in cloud cover.

3. Chlorofluorocarbons (CFCs) — Used in refrigerators, air conditioners and sprays. They have 15,000 times the impact of carbon dioxide and account for 25% of greenhouse effect.

4. Nitrogen Oxides — Released by use of nitrogen fertilisers and vehicular traffic. They have 230 times the heat-absorbing capacity of carbon dioxide.

5. Methane — Generated by hydroelectric reservoirs and bacterial decomposition. Its capacity to absorb heat is 25 times more than CO₂.

6. Ozone — Has a global warming potential about 2000 times that of carbon dioxide.

Effects of Greenhouse Effect — While the greenhouse effect makes the earth habitable, an excess of greenhouse gases leads to:

1. Global warming and climate change.
2. Extinction of many animals and migratory birds.
3. Increase in storms damaging the breeding of sea birds and sea animals.
4. Rise in sea level destroying beach nesting shelters of sea turtles.
5. Growing water scarcity destroying wetland areas.
6. Heat waves leading to heat strokes, heart attacks and other ailments.
7. Glacier retreat around the world.
8. Slowing down of thermohaline circulation, affecting ocean currents.