If global warming is in fact a problem, and if it can be controlled by reducing carbon emissions, then Georgists point out that “cap & trade” is a lousy way to accomplish this. Yoram Bauman says that a cap becomes effectively a floor, and that British Columbia actually has a revenue-neutral carbon tax.
Even if there’s no need to reduce carbon emissions, I don’t see how a carbon tax could be worse than taxes on retail sales and earned income.