1. Release of carbon dioxide into the atmosphere by power plants by burning fossil fuels( petrol, ets,.)& burning coal to generate power.
2. Release of carbon dioxide into the atmosphere by burning gasoline by automobiles.
3. Deforestation especially tropical forests for wood,pulp and farm land.
4. Increase in use of chemical fertilizers on croplands.
Current Global warming is called AGW-Anthropogenic Global warming; ( anthropogenuc mans caused by humans).