You Can't Have It Both Ways
I cannot believe I actually have to write this, but apparently there are a number of folks in Washington and the media for which this will be a surprise. Specifically: A carbon tax or a cap-and-trade bill must either greatly increase prices of fossil fuels and the products of their combustion, or else they will have no impact on CO2 emissions. Placing a high cost on emissions, and then giving everyone with a modicum of lobbying power an exemption is not going to move the meter either. All the absurd talk of stimulation from new green jobs not-withstanding, either a climate bill imposes huge new costs or it has no real impact on emissions. One simply cannot get to an end point of obsoleting the entire US electrical generation and transportation infrastructures for free.
As someone who thinks the threat from Co2 is greatly exaggerated, this is why I have never worried overly much about American legislative efforts. Congress will mandate something or other that will not have much effect and will impose a lot of cost, but politicians will stop way short of the draconian legislation that would be necessary to achieve their stated carbon goals (e.g. 80% reduction). European politicians are way more committed than ours are to Co2 reductino, and Europe hasn't really done much at all either. A legislative body that continues passing costs to our kids in the Social Security ponzi scheme and an administration that plans already to add 10 trillion to the national debt doesn't really care about future generations. If they are unwilling to bear current pain for future benefits in fiscal policy, they certainly aren't going to do it in the much more uncertain arena of climate policy.
Postscript: Note that the costs can show up in other ways. For example, if one puts carbon caps in place as well as price controls, the cost would appear in the form of massive shortages, lines, and blackouts. If one tried to address the problem via command and control solutions, the cost appears in massive capital spending requirements that cannibalize from economic growth (which are likely to be made all the worse given that the commanders will probably not mandate the best solutions -- in fact, given variations from individual to individual, they simply cannot mandate the best solution for everyone).