What is Global Warming? 

Global Warming is the increase of Earth's average surface temperature due to effect of greenhouse gases, such as carbon dioxide emissions from burning fossil fuels or from deforestation, which trap heat that would otherwise escape from Earth. This is a type of greenhouse effect.

The Earth is wrapped in a blanket of air called the 'atmosphere', which is made up of several layers of gases. The sun is much hotter than the Earth and it gives off rays of heat (radiation) that travel through the atmosphere and reach the Earth. The rays of the sun warm the Earth, and heat from the Earth then travels back into the atmosphere. The gases in the atmosphere stop some of the heat from escaping into space. These gases are called greenhouse gases and the natural process between the sun, the atmosphere and the Earth is called the 'Greenhouse Effect', because it works the same way as a greenhouse. The windows of a greenhouse play the same role as the gases in the atmosphere, keeping some of the heat inside the greenhouse.

The natural greenhouse effect

The atmosphere has a number of gases, often in tiny amounts, which trap the heat given out by the Earth.

To make sure that the Earth's temperature remains constant, the balance of these gases in the atmosphere must not be upset.

The greenhouse gases are very important and are mainly:

  water vapour: occurs naturally in the atmosphere.

  carbon dioxide: produced naturally when people and animals breathe. Plants and trees absorb carbon dioxide to live. Volcanoes also produce this gas. Carbon dioxide is not the same as carbon monoxide 

  methane: comes from cattle as they digest their food. The gas also comes from fields where rice is grown in paddy fields.

  nitrous oxide: when plants die and rot, nitrous oxide is produced. 

  ozone:occurs naturally in the atmosphere.