xkcd : Earth Temperature Timeline

The point of the graph isn't to show the warming amount its to show how much faster the rate of warming is now compared to previous warming events.

What conclusion would change if the graph started at an earlier, warmer period?

As far as I know, three crucial things would still hold true:

• Earth has not been as warm as today since humans existed, in the past 200'000 years. We don't know if we can thrive in these conditions. Chances are, we can't. We're optimized for another climate. We have no precedent wether future Earth is habitable for us.
• Earth has never warmed this rapidly, never. Speed matters a lot, as lack of time makes the difference between adaption and extinction.
• Whatever the cause, and however normal it may be, the current development, and rate thereof, causes substantial issues on many fronts.

I don't see how this is biased. Showing that the Earth did warm up over time before major human climate change started would be, very weakly, supporting that climate change isn't real. If they wanted to be biased they would start at a warm point, and when the Earth is cooling down they'd be like "see! Earth cools naturally, so it must get warm because of climate change!"

To make my stance crystal clear, I believe in and am deeply concerned by climate change

"My bank funds history chart starts at the lowest point my funds have been since opening the account. Definitely not biased."

Tell me you're a blithering idiot without telling me.

20000 BCE was the coldest point in the last 66 million years?

Not only have you misunderstood the graph, your counterpoint is also stupid.