> Past periods of high CO2 do not contradict the notion that CO2 leads to higher global temperatures. Indeed, it confirms that there is a strong relationship between the two.

The relationship, at least in the smaller graph, isn't in question. The causality is. I didn't say it contradicts the causality, I say it doesn't support the causality.

If you look at the larger graph, whatever relationship there is between CO2 and global temperature becomes indiscernible.

> There are other sources of temperature change so you can't use one indicator to prove there is no effect

You can't prove a negative in the first place. Of course there's bound to be some effect, but how large is it really?

> On the right of that graph, there is a vertical red line. That's not an axis or a border, that's the recent rise in CO2 levels, and it's unprecedented.

The rise may be unprecedented, the level isn't.

> The overwhelming majority of evidence shows that human activity, mainly greenhouse gases, is causing climate change.

That's a strong statement for what it is at best a discernible correlation.

I'm willing to take it on faith. Humans cause climate change? Now what? We absolutely have to drop everything and start cooling the planet? Until the next ice age, when presumably we'll have to warm it?