1.compare the natural greenhouse effect with the human-induced process.

2.what are the greenhouse gases? which one is the biggest concern?

3.what are scientists doing to collect data?

4.what role does the carbon cycle play in this problem?

5.what are the political and economic factors that complicate this problem?

6.why is the study of global warming so scientifically complicated?

7.are there skeptics of global warming? what are their arguments?

1. The greenhouse effect is useful. Without it we would all freeze to death on an earth with no atmosphere. Research has shown that the level of greenhouse gases in the air drop and rise as a natural cycle. However, human induced activities has made the amount of gg in the atmosphere rise to an natural amount. This is due to: cars, the industrial revolution in 19th century etc. 

2. Water vapour, carbon dioxide, methane, nitrous oxide and ozone which occurs naturally. CO2 is the one which is currently the biggest concern as it is increasing the most. 
3. Scientist melt ice containing bubbles of air from millions of years ago and compare it with today to see this is natural. 

4. We cut down trees which photosynthesise and is the only process to remove CO2 from the air. 

5. It is not always economically viable for the government to issue a clean air act which could help reduce problems. They are unwilling to spend money. 

6. Global warming happens naturally as well as global cooling so scientists are not sure if it is us or not. 

7. Yes there are. They say that our activities can't possibly be contributing to global warming that much, though it has been suggested that something like this caused extinction of dinosaurs years ago.