Cap on Carbon

Obama's efforts to combat global warming is about to begin, and Republican Lawmakers aren't too happy about it. Here's the skinny: Obama is proposing reducing carbon emissions by creating a cap-and-trade system whereby companies will have to pay to pollute. However, the incentive is that the less you pollute, the more money you save, and as an added benefit, reduce the amount of carbon in the air that is leading to global warming. Republicans complain that it imposes a tax where there currently is not one. I know I've grossly over simplified the issue, but what I'm concerned about is those who pollute more could purchase “carbon credits” from businesses that pollute less. Although it seems like the equation would balance itself out - some pollute less so that others can pollute more - doesn't necessarily give any incentive to larger companies to reduce their output of carbon, and reducing carbon emissions is the goal, isn't it? It seems that if there is going to be any "real" change towards combatting global warming, there should simply be a tax on polluting and no trading for "carbon credits."