I might be if you have lots of exceptions and exemptions to the tax, but you should set it up as a tax of $$/ton of CO2 emitted (with credits for sequestration). You can change the tax rate but you don't have all of these piece meal subsidies and tax credits (wind, solar, electric cars, plug in hybrids, etc.) that can extract donations from various industries to get their specific business subsidized. Pay a small campaign donation for a huge payoff, ie. corruption.