The debate at large doesn't consist of whether or not a global temperature shift is occurring but whether or not it is largely at the hands of human beings. Now, we know for a fact the rising CO2 levels can be attributed to us, but not all of it. Also, the data we have access to is only recent, something a little under or over a century, which is a blink of an eye in Earth time. We do have data on the large trends over Earth's "recent" history, but not anything on the level of saying that these kinds of changes can or can't happen this fast.

Basically what I'm saying is that scientists as a whole can't definitively say anything one way or another. Usually it has to happen for us to know, which in this case, could lead to millions dying.

Anyways, I think that the issue that this should highlight for people is that the Earth is an ever-changing landscape on which we must constantly evolve to survive, and eventually we should look towards the stars for our continued survival as a race. Because even if we do curb our current attitudes towards the environment and our natural resources, a few of the many ticking time bombs (natural disasters) will eventually happen, and in Earth's near future (thousands to hundreds of thousands of years) so it's best to spread as far as we can.

PS - Correlation is not causation. Big mistake laymen make in their scientific "proof". Best thing for any scientific theory is lots and lots of peer review until everyone is blue in the face...and even then you should question your findings.