Very interesting read, thanks. They wiggled around a lot at the end to move the figure from 106 to 250. Most of those bits I disagree with. CO2 is CO2 no matter if a rich person or a poor person produces it, so it makes no sense to charge variably. Wars have a proximate human cause (aggression) so I don't think it makes sense to "charge" that to CO2. Adding in Ocean acidification makes perfect sense (though I'd prefer a better estimate than their hand wave) and of course adjusting from 2005 to 2013 dollars is necessary. Sound more like $150 per ton. Great, we have a starting point. It's been a while so it'd be worth reexamining with the additional years of data, but that will ever be the case.
As for implementing it, yeah that could be a tough sell. Just to reduce the shock, you'd probably want to phase it in, say 20% a year or something (and you may want to swing to 120% for a while before coming back down to 100% to allow for cleanup of preexisting pollution). And you'd have to do it as a treaty otherwise one country fixes theirs and everyone else becomes a free rider since we all pretty well share a single atmosphere and hydrosphere.
"And remember: Evil will always prevail, because Good is dumb." -- Spaceballs