I'd add to Megan's points that a carbon tax provides revenue that lets you cut taxes elsewhere.
Ideally, we should understand what the economic cost of carbon emissions is, and use a carbon tax to raise the price until it includes the cost of that negative externality. If, once we have raised the cost of carbon to the price of the utility + the negative utility, and people still continue consuming carbon-intensive goods, then that is telling us something important about the value of that added carbon-intensive economic activity.
By the way, the "negative externality" from carbon-based energy is not just climate change but also serious problems of ordinary air pollution and environmental damage from mining and drilling--plus the geopolitical disaster of buying oil from dictators and terrorism enablers.
UPDATE: Fixed spelling of McArdle.