Answers

2015-09-07T20:29:18+05:30
1 pollution
2 green house effect
3 cfc gas 
4 smog produced by the factoried
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2015-09-08T06:26:52+05:30
The main cause of global warming is the drastic increase in CO2( carbon dioxide) which is caused by the burning of fossil fuels. Hope you are fine with the answer.
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