I think it stinks if the professor was fired for being skeptical. I believe in man-made or at least man-influenced global warming, but even still...
It's a theory... it's pretty much a scientist's job to challenge a theory until it can be sufficiently proven or disproven. To simply accept the status-quo "just because" is quite hurtful to our knowledge of the universe.
I'm not saying a scientist should then support or teach creationism as a science which (as much as fundies deny) is not grounded in ANY science.
But to challenge or be skeptical of a theory that, let's face it, is going to be *really* hard to 100% prove one way or the other... I don't see that as terrible.
And certainly not a fireable offense.
In science, it's technically just as exciting to disprove something as it is to prove something... because either way we've LEARNED something about the universe.
"Space. It seems to go on and on forever. But then you get to the end and a gorilla starts throwing barrels at you." -Fry, Futurama