Global warming refers to the increase of average world temperatues due to greenhouse gas effect frrom emission. A major contribution is large scale deforestation. However , the more significant culprits are coal , oil and fossil fuels burned in power stations, cas and factories.
While carrbon dioxide contrributes about 50 per cent the greenhouse effect, other gases that also add to the greenhouse effect are methane, chlorofluorocarbons and nitrous oxide (N2O).
Reportedly, the amount of methane in the air has increased by 1 percent per year, much faster than the build up of carbon dioxide.