Not to give much credence to the guys in the (red) tinfoil hats, but that graph was produced by guys with blue tinfoil hats. There are two dishonest things about it.
1. This is another version of the fake "hockey stick graph." Only the points after "0" are measurements. Everything else is calculated from some proxy of unknown quality. Those points have much larger error bars. It is dishonest to plot it as a continuous line. It would b
e honest if they plotted the measured values and the modeled values as two different lines. And
showed the relative uncertainties for the different sources of data.
2. Everything before the final near-vertical line is an ice age. The presumptive whine behind this image is that only ice ages are politically correct.
Personally, I'd rather hang out in a speedo than four layers of fur anoraks.
The really interesting thing about the graph is that it shows other near-vertical excursions in the "recent" past. Although those were in the pleistocene, they point towards times that we might want to examine for evidence of what happens to the world when that occurs.
Of course, there are much bigger jogs in atmospheric composition in the distant past, correlated with big extinction events, but those signals are both larger and fuzzier - due to their great age.Oh dear. I seem to be getting larger and fuzzier...