Our advanced civilization is much more vulnerable to climate change. We can't just migrate like primitive man.
The scientific data is undeniable. 99+% of scientists around the world believe global warming is real and mostly caused by us.
http://en.wikipedia.org/wiki/Scientific_opinion_on_climate_change
And any number of very distinguished people, too.
"I wasn’t convinced by a person or any interest group—it was the data that got me. I was utterly convinced of this connection between the burning of fossil fuels and climate change. And I was convinced that if we didn’t do something about this, we would be in deep trouble.”
Vice Admiral Richard H. Truly, USN (Ret.)
Former NASA Administrator, Shuttle Astronaut and the first Commander of the Naval Space Command
Here are two summaries of the mountain of peer reviewed data that convinced Admiral Truly, short and long.
http://www.globalwarmingart.com/wiki/Image:Climate_Change_Attribution.png
http://www.ipcc.ch/SPM2feb07.pdf
"There's a better scientific consensus on this [climate change] than on any issue I know - except maybe Newton's second law of dynamics. Global warming is almost a no-brainer at this point,You really can't find intelligent, quantitative arguments to make it go away."
Jerry Mahlman, NOAA
Good websites for more info:
http://profend.com/global-warming/
http://www.realclimate.org
"climate science from climate scientists"