The greenhouse effect is the process by which gases like carbon dioxide and methane in the atmosphere trap heat from the sun, warming the planet's surface. Solar energy warms the Earth's surface, which then emits infrared radiation back towards space. Greenhouse gases like carbon dioxide, methane, nitrous oxide, CFCs, and ozone absorb this infrared radiation and re-emit it in all directions, trapping heat and causing the Earth's average surface temperature to be about 25°C warmer than it would be otherwise. Carbon dioxide levels have increased 27% since the industrial revolution due to human activities like burning fossil fuels, and methane levels have risen 145% over the last 200 years.

1. Greenhouse Effect

2. Greenhouse Effect The greenhouse effect is the process in which the emission of infrared radiation by an atmosphere warms a planet's surface. The Earth's average surface temperature is about 25°C warmer than it would be without the greenhouse effect

3. Greenhouse Effect The Earth receives energy from the Sun in the form of radiation. The Earth reflects about 30% of the incident solar flux. The remaining 70% is absorbed, warming the land, atmosphere and oceans.

4. Greenhouse Effect Solar Energy (sunlight) is short-wavelength radiation which easily penetrates the Earth's atmosphere and warms the Earth. Only about one quarter of incoming sunlight is reflected by the atmosphere. The warmed Earth emits long-wavelength radiation (infrared waves or heat energy) back into space. These longer waves are mostly reflected back to Earth by the atmosphere.

5. Greenhouse Gases

6. Carbon dioxide In the last 200 years, because of human activities the proportion of CO 2 has risen from 280 ppm to 360 ppm. The proportion of CO 2 has risen by 27% since the beginning of the industrial revolution, when we started to burn coal rather than wood to fuel civilization. At present, it is increasing by about 3 ppm a year.

7. Methane Methane has a much greater warming effect, about 21 times that of carbon dioxide by volume. Methane has increased 145% over the last 200 years. Despite its greater potential for green house effect, scientists seem less bothered about the rise in methane than that of carbon dioxide. The reason is that carbon dioxide survives longer in the atmosphere than methane (between 50 and 200 years) Methane is destroyed by chemical processes within 12 – 17 years.

8. Nitrous Oxide Nitrous oxide is over 200 times more powerful greenhouse gas than CO 2 on a per molecule basis. Its greenhouse role is minor compared with other greenhouse gases, but has a relatively long atmospheric life of 120 years. The volume is steadily growing at about 0.25% a year. The gas is produced in the ground following the application of ammonia based fertilizers. Various industrial processes also gives off nitrous oxide.

9. Chlorofluro carbons CFCs were invented by Thomas Midgley in 1930 and has been extensively used in refrigerators and air conditioners all over the world. It has also been used to blow foams and aerosol sprays. A CFC molecule added to the atmosphere has a greenhouse effect 5000 times greater than that of an added molecule of CO 2 . This means that despite their tiny concentration, compared with CO 2 , they have a significant impact. They have a long life span of 100 years.

10. Ozone Ozone acts as a shield in the stratosphere, protecting us from the harmful effects of UV rays. But in the troposphere it function as a green house gas. Emission of oxides of nitrogen and hydrocarbons from power stations and vehicles is increasing the concentration of Ozone in the lower atmosphere. It has been calculated that a doubling in its concentrations throughout the entire troposphere would lead to a one degree increase in surface air temperature.