global cooling?

I am currently working on a paper for my bio class and my topic is global warming. My teacher wants us to have 2 sides to our topic. My paper is answering the question: Is global warming caused my humans? and the two sides are:

1) yes global warming caused by humans

2) no global warming is not caused by humans

At the start of my research I believed that humans were the cause of global warming...but now after reading a bunch of opposing viewpoints on the topic I am starting to believe that humans did not cause global warming. Scientists say that global warming is nature working....just warming after an ice age, and the world has actually been warmer than it currently is. But people like Al Gore, non-scientists, say that our greenhouse gas emmisons- like CO2- cause GLOBAL WARMING.

HELPPP!

I do not know which side to follow?? any suggestions??

Bueller?

Bueller?

Bueller?

please...