Hey bran92. I did this case study and can i just say that instead of writing 'global warming' you shud change this to 'climate change' as it's more scientific - some land is having the opposite effect of global warming.
Secondly, you have to gather a few evidences about climate change issues. This should be after your scientific theory. Lookin at ur evidences, you should come up with a conclusion. Remember: you do not have to choose one or the other.
Look for the one which you know that you have the strongest opinions on and the ones were you can use alot of scientific explanations and make sure that you can find arguements for and against your case as this forms a large part of the case study.