::The Crying Earth::

5.2.3 How climate changes happen?

The climate has and will always vary for natural reasons. Natural causes of this include fractional changes in solar radiation, volcanic eruptions that can shroud the Earth in dust which reflects the heat from the sun back into space, natural fluctuations in the climate system itself.

However, natural causes can explain only a small part of this warming. The overwhelming majority of scientists agree that it is due to rising concentrations of heat-trapping greenhouse gases in the atmosphere caused by human activities.

Energy from the sun warms the earth's surface and, as the temperature increases, heats are radiated back into the atmosphere as infra-red energy. Some of the energy is absorbed within the atmosphere by 'greenhouse gases'.

However, human activities are adding greenhouse gases, particularly carbon dioxide, methane and nitrous oxide, to the atmosphere, which are enhancing the natural greenhouse effect and making the world warmer. This man-made extra warming is called the "enhanced" greenhouse effect.