If you think going back more than 20k years would in any way change the entire point of the cartoon[1], then by all means do the research, draw the graph and show where it's wrong.
[1] hint: rate of change is important.
Anyway, it's not anti-science. It's well-known that the earth was hotter during the time of the dinosaurs. Sure, rate of change is important, but as I said in the end, the biggest problem for humans is rising sea levels, because of where humans live. Worse storms are also a big problem, though here again where humans live is a big problem since they tend to live on coasts and storms usually hit there.
It's classic climate denial to continue to harp that the earth was hotter in the past so somethingsomethingsomething look over there and ignore the fact that the rate of change this century, not looking back a million years, is the point of the comic.
Of course, going back to the climate the Earth had in the Cambrian era, for instance, probably would not be comfortable to humans at all, but still, humans have survived for a much longer time than is illustrated here. Human civilization, OTOH, occupies about half the time period shown here.
The thing that's most important about climate change is: how will it affect human settlements where they're located now? You can't just pick up whole cities with billions of people and move them, and many (most?) of the cities are close to water.