The long term increase in the average temperature on earth is known as global warming. It occurs due to the presence of carbon dioxide (CO₂) and other green house gases in the earth's atmosphere. CO₂ molecules have tendency to trap radiations from sun. This is the reason why the earth's atmosphere remains warm even after sun set. Because of this, the average temperature of earth is rising which is mainly responsible for melting of glaciers and has many other adverse effects on animals, natural resources, plants etc.
