Sometimes, when people deny the effects of climate change, it reminds me of the Black Knight in "Monty Python and the Holy Grail" who, as his limbs are lopped off by King Arthur, says, "Just a scratch," "Just a flesh wound" ...
How bad does it have to get before some people will accept the evidence that we're in a little trouble here?
Catastrophic global warming wouldn't be that hard to prevent (or at this point, mitigate), either: Energy
(I was prompted to make this comparison on the Huffington Post when some doubters of climate change posted skeptical comments: "Hundreds Of Icebergs Breaking Off Of Antarctica, Headed For New Zealand.")
I just read another comment that reminded me of this, a concise little evaluation of the risk of doing nothing to combat global warming: