Chip Knappenberger, a climatologist in Virginia's state climatology office has written an interesting blog piece in which he uses a basic climate model to estimate the climate effects of the currently-proposed Waxman-Markey "cap-and-trade" bill. While the model is certainly flawed, as are all such models, it's not unreasonable to use it as a tool for comparing climate expectations both in the presence and in the absence of the cap-and-trade bill.
See "Climate Impacts of Waxman-Markey (the IPCC-based arithmetic of no gain)
", Chip Knappenberger, 5/6/09
Knappenberger's conclusion is that you never hear "cap and trade" supporters touting the climate benefits of their bill because there are none worth mentioning: "The bottom line is that a reduction of U.S. greenhouse gas emissions of greater than 80%, as envisioned in the Waxman-Markey climate bill will only produce a global temperature “savings” during the next 50 years of about 0.05ºC."
While reading the article, remember that as bill's supporters throw around a $700 billion price tag (effectively higher costs/taxes on Americans who buy anything, drive a car, heat a home, etc), Budget Director Peter Orszag has repeatedly that "cap and trade" will substantially increase energy costs
(including, of course, electricity)...
and that the deputy director of the National Economic Council has said that the $646 billion estimate is far too low -- the real number will be double or triple that amount: