[snikeris]

You didn't address the problem of Nigeria that the OP brought up. How will a carbon tax in the U.S. address the issue of the Nigerian people rightly desiring a better standard of living?

[adrianN]

If Nigeria wants to trade with US they'd have to pay carbon tariffs that encourage them to decarbonize their economy.

[jeremyjh]

What if OPEC collects the tax worldwide?