Nuruddin Azam-Australia

The climate system is a very complex mechanism of nature having the following components:  atmosphere (air), cryosphere (ice), biosphere (living things), geosphere (land), and hydrosphere (water). Solar radiation, deviations in the earth's orbit, mountains and oceans, and greenhouse gas emissions all play important roles in the shaping of climate of the earth.

The motion of tectonic plates reconfigures land and ocean areas over a period of time that may spread millions of years, affecting both global and local patterns of climate and atmosphere-ocean circulation.

Both long and short-term variations in solar intensity affect global climate.

The orbital variations of the earth may lead to changes in the seasonal distribution of sunlight across the globe.

Volcanic eruptions and other volcanic processes release gases and particulates into the atmosphere. Large eruptions blocking transmission of solar radiation occur several times every century.

Alterations to ocean processes such as Thermohaline circulation redistributes heat by carrying out a very slow and extremely deep movement of water.

Anthropogenic factors (human activities) affecting the climate include increase in CO2 levels due to emissions from the use of fossil fuel, aerosols and industrial pollutants, animal farming and deforestation. If there are more gases in the atmosphere, more of the sun's energy is trapped on earth giving rise to a warmer climate, popularly known as greenhouse gas effect.

But we need to remember that greenhouse gas effect is a natural warming system that keeps the earth habitable.