Oh, so that's what he was going for with that ice levels comic a while back.
My main problem with this comic as an infographic is that it seems kinda disconnected from itself. Most of the things listed (pottery, writing, Shakespeare), while important to human history, have approximately zero effect on the climate. I understand that it's not Randy's fault that human history is like that - Earth lives on a whole different scale from us - but it still gives us a lot of information that isn't really related to the point he's trying to make. I will say that it's neat to scroll manually through all that history, it's like that solar system distance thing.
I'll also say that, terrible Pokemon joke aside, this comic does a pretty good job of explaining the difference between 'typical' climate change and what people usually mean when they say the phrase "climate change". Speaking as someone that used to have this exact problem (thanks for NOTHING, Michael Crichton!), I think this comic might have converted me to its side.
I, the little guy, am not the person that needs to be convinced. I could work my whole life to destroy as much environment, and I wouldn't fuck things up as much as the big companies do in a day. I don't mean to get all preachy and stuff, but y'know that whole ozone layer thing? They told me in middle school it closed up, but it's still there! We all agree that chlorofluorocarbons caused the big ozone hole (or at least, that's what my astronomy textbook says) but the end goal for phasing them out is still set to 2030! I know that we can't shut everything down overnight, but we've known since the eighties! (According to my astronomy textbook!)
And those big corporation peeps aren't reading XKCD, they're snorting coke off of expensive strippers, since they're all rich and corrupt and rich. So while this comic has nothing but good intentions, it has not succeeded unless it inspires people to go out and do something. It's like that one Chumbawamba song says: "If our music makes you happy or content, it has failed. If our music entertains, but doesn't inspire, it has failed. The music's not a threat. Action the music inspires can be a threat." (that's from the excellent Revolution EP, if you were wondering)
My astronomy class actually explained this to me so I get the joke! And it is a joke, even if it's one that only smart college-educated people like me can understand.
For you DUMB HICKS, there are like, these spectrum thingies, and the black lines tell you which elements there are in the thing its a spectrum of, BUT THERE AREN'T SUNGLASSES IN THE REAL SUN. It actually lends itself pretty well to this joke, since it puts the sunglasses in the last place that the reader reads (in a traditional western left-to-right style).
This comic would be EXTRA not-bad if "those giant sunglasses" if it was phrased "silicon (for those giant sunglasses" because like, silicon makes glass (and plastic, maybe??) so it'd be scientifically accurate too. That's a nitpick, though, and if we put aside accessibility, I give this one a passing grade.