Any model of international trade that does not also model externalities is worse than useless. International trade accounts for 30 percent of CO2 emissions alone.
Maybe you should produce X and Z.
Maybe you should produce X and Z.
Not because it's difficult to identify emissions generated in order to produce those goods subsequently exported (it would be arduous to do so, but not infeasible), but because absent that particular manufacturing effort for those specific exports, what would that nation state instead be doing with those resources / what emissions would they be generating in the pursuit of domestic consumption needed to replace the income from those exports.
Are tariffs a veiled carbon tax?