Thanks for clarifying. I don’t see why the Paris Agreement is a useful analog for a carbon tax. A carbon tax doesn’t depend on the good faith of partner countries, but the border adjustment itself incentivizes other countries to reduce their emissions (they want to trade with us). The more wealthy countries who implement a carbon tax with border adjustment, the stronger this incentive mechanism becomes. There is a political problem in getting a larger block of wealthy countries on board, but it’s not unrealistic to think of Europe and North America forming that initial block, and surely there’s enough wealth in those markets that it would incentivize other countries to get on board.

In whatever case, I can’t imagine an environmental solution that won’t have the same (or worse) political problems. As far as I can tell, border adjuster carbon tax most neatly and efficiently aligns incentives.