> That's such a disingenuous argument. Their emissions add up. That's like saying at individual level gravity doesn't work because you don't feel a gravity from 1 atom.

I probably could have phrased it differently to make it more clear, but my argument is _not_ that individual contributions don't add up. Rather, they do add up, and after a certain "critical" threshold they add up to produce superlinear negative externalities and that attempting to price all carbon equally to add up to the sum of those externalities is potentially gameable and still allows for sufficiently profitable activities to effectively ignore them and push global climate change beyond acceptable levels.

> If you add oil tax the global consumption falls, it's only a matter of choosing a number big enough to make the total consumption fall below the threshold.

That's roughly true enough. It's subject to a form of "externality arbitrage" though. Let's say we're outputting enough carbon that externalities grow quickly as a function of carbon output rate. Legislators set a price on carbon based on how bad it currently is. Many activities are still profitable with respect to that tax and are still performed while others are axed. Assume that an agent scales up some profitable carbon-emitting activity, and to make the math simple they personally double global carbon output. By virtue of the fact that we're in a superlinear externality regime they now have to pay $N in taxes while causing damage much greater than $N.

> we don't only have 1 try, we can introduce tax, look at effects, make corrections.

Yes, eventually regulators step in and pick a bigger number, and presumably there are limits to any such profitable carbon-producing activity, so you're right that eventually we could level off total carbon output, but the large slope on that graph of externalities with respect to carbon production rate and the timescales involved in updating the tax code leave plenty of room for exploitation -- it's not an especially stable system that has a natural solution at our desired global output.

> I don't understand why you're trying to make it so complicated

It's...not thaat complicated? If your goal is to limit carbon production to a rate that leads to acceptable levels of climate change (which doesn't have to be your goal, but it's a central assumption in everything I've written, along with the notion that we can address carbon independently from other problems) then the most straightforward way to do that is to set a cap at the level you don't want to exceed and divvy out the credits as you see fit. You could tax those too if you'd like, or sell them, or whatever you want to do, but the critical piece is that to avoid exceeding your desired limit you just set the limit and ban exceeding it. Allowing a theoretically unbounded amount of carbon to be released and trying to manage a quickly-changing economic reality by imposing a flat tax to disincentivize the undesirable behavior is moderately more complicated and has likely, predictable failure modes. Flat externality taxes are not necessarily a bad idea in the abstract, but for the concrete case of carbon and global warming they don't seem like a good fit, at least not by themselves.