When you want information on any topic, don't trust bloggers, don't trust talkshow pundits, don't trust folk music forum pundits, and don't trust TIA. Trust the experts (thousands of them). For global warning, try starting here. Notice the word "start". This is not the be-all-end-all:

http://www.ucsusa.org/global_warming/science/global-warming-faq.html

For politicizing science, the above also holds true. Start (*start*) here:

http://www.ucsusa.org/scientific_integrity/interference/a-to-z-guide-to-political.html