The Greenhouse Effect
The greenhouse effect is the rise in temperature that the Earth experiences because certain gases in the atmosphere (water vapour, carbon dioxide, nitrous oxide, and methane, for example) trap energy from the sun. Without these gases, the earth would be a frozen planet, with an average temperature of about -18 degrees C.
Greenhouses work by trapping heat from the sun. The glass windows of the greenhouse let in light but prevent heat from escaping. This causes the greenhouse to heat up, much like the inside of a car parked in sunlight, and keeps the plants warm enough to live in the winter.
Greenhouse gases in the atmosphere behave much like the glass panels in a greenhouse. Sunlight enters the Earth's atmosphere and passes through the layer of greenhouse gases. As the sunlight reaches the Earth's surface, land, water, and biosphere absorb it. Once absorbed, this energy is sent back into the atmosphere. Some of the energy passes back into space, but much of it remains trapped in the atmosphere by the greenhouse gases, causing our world to heat up.
Although the greenhouse effect is very important, the amount of Carbon dioxide in the atmosphere has increased by about 28% in the last 100 years. Scientists believe that this increase is due to: the burning of fossil fuels (oil, gas and coal), the chopping of trees in the tropical forests and the increase of levels of methane and chlorofluorocarbons in the air. If the greenhouse effect becomes stronger, it could make the Earth warmer than usual causing Global Warming. Even a little extra warming may cause problems for humans, plants, and animals.
In 1995, leading scientists predicted the rise in temperatures of 2 degrees C by the year 2005. Warming of this scale will change the climates throughout the world and cause the sea levels to rise significantly.
International efforts have been undertaken to reduce greenhouse gas emissions. In 1997 the Kyoto Protocol was set up.
This pack obliges 38 countries to reduce emissions of any 6 greenhouse gases.