Global warming is said to increase the average temperature of the Earth's surface, enough to cause climatic change. The increase in greenhouse gases such as carbon dioxide is seen as the important factor. The rise in their levels in the atmosphere is caused by human activities such as deforestation, carbon dioxide combustion, etc.
Global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the last century.
See also: greenhouse effect