I saw this article linked from a comment on Bryan Alexander's blog. This part jumped out at me:
e360: I understand that the Dome C record shows very clearly that we've got more CO2 in our atmosphere now than at any time in 800,000 years.
Mosley-Thompson: Oh yeah. Very clearly. If you look back over the eight glacial/interglacial cycles, you essentially see that CO2 never rises above 300 parts per million and we're at about 389 now. Methane never rises above about 800 parts per billion, and I think we're at about 1,700 parts per billion. So we're clearly outside the range of natural variability. I personally think that graph simply showing the natural fluctuations in those two important greenhouse gases, over almost a million years of Earth history — and then you see the two dots [today] that are so much higher than anything that we see in that near-million history — tells us very clearly that we have a serious problem.
Um. Yeah. But please feel free to continue denying climate change as scientific fraud or something. Significantly higher CO2 levels than at any point in the last 800 THOUSAND years. (update: oops. I'd typed MILLION. it was clearly not 800 MYA. I must have been thinking "almost a million" and the fingers just followed...)
More info and graphs from NASA, including this gem:
The recent increase in CO2 levels is so sudden, it's a simple vertical line. That's not a natural increase.