The problem is akin to computing value of human life. If you burning gasoline will kill 3 humans and make life a misery for 20, what's the proper price?

Many would argue it's infinity. It's not safe to continue burning fossils in any way, shape or form, not burning fresh biomass either. Reclaiming biogas is probably the only sane way of burning anything now... (Prevents methane releases.)

Unfortunately most people don't or can't run moral calculations like this.

If you don't or won't run calculations, that's fine.

Using the word "externalities" though means you will and did and you accept the use of numbers which are not "infinity" and can be compared to other numbers.

When you give away that you don't care at all about the meaning of the words you use to try to get leverage, it might as well be the buzzing of gnats.

You can't take language wholly as a means to manipulate people and be transparent about it and expect it to continue to work.

Anyone who actually believes that the damage done by burning one gallon of gas is "infinity" would be willing to sacrifice humanity to avoid it. But I'm not interested in debating whether that's a correct ethical perspective! You're entitled to feel whatever you feel.

My irritation is with people who appropriate economic jargon without the least intent to communicate the ideas a word denotes. To me, destroying the communication value of a word, is like some sort of semantic atrocity.

(note, "you" is the generic you, I'm not blaming you for the original poster)

I think it's about $1.40 given the price of sucking CO2 from the atmosphere estimated by Carbon Engineering.