Cap-and-Trade Protects the Economy
The second part of cap-and-trade -- trading -- provides covered entities with the freedom and flexibility to identify the most efficient, least cost means of reducing emissions. A well-designed emissions trading program will reduce costs for both consumers and businesses alike, and achieve the greatest emissions reductions for a given input of societal resources.
The United States invented emissions trading as a means to reduce acid rain while keeping electricity prices down. Under the 1990 Clean Air Act Amendments, the US required major reductions of the emissions which cause acid rain, SO2 and NOx, but allowed companies to trade in order to make it easier to reduce emissions. Most studies estimate the savings to be between $700 and $800 million per year -- for a savings of over 40%. Some studies estimate the savings were twice as high -- $1.6 billion per year.
When Congress was considering ratifying the Kyoto Protocol, the Congressional Research Service compiled 17 different estimates, by eight different organizations including the US government, of the costs of complying with the Protocol with and without trading. All 17 analyses estimated dramatically lower costs when trading was allowed. Cost estimates with no trading allowed ranged from $193 to $348 per ton. Trading within developed countries reduced these estimates to between $61 and $175 per ton, while global trading reduced the estimated prices to between $14 and $50 per ton of carbon. The US Energy Information Administration estimated that partial trading would reduce US costs by 68%, and full trading by 88%. More recent analyses, such as the Stern Review on the Economics of Climate Change, draw similar conclusions.

Part of my job as a software support engineer is to generate the reports sent to the EPA containing CO2 levels generated. I know how these numbers are generated; I had to write the program that generates them. Currently, the numbers are a bunch of baloney. They would not stand close scientific scrutiny.
Why?
Well, the topic is carbon. One of our customers has a CO (carbon monoxide) monitor. Yet the carbon that is shown to be produced by CO is not taken in to consideration when calculating (yes, calculating, not measuring directly) CO2. Furthermore there are within federal law tests that can be run to determine the accuracy of these numbers...these tests are neither run nor required to be run by the federal government . Oh, I generate numbers, but there is no solid backing behind these numbers aside the fact that the formula that we use (as prescribed by the federal government) says that that is the amount that we must be producing.
Remember that most places do not monitor CO2, including refineries and power plants. Why? Well, to put in a CO2 monitor one must be able to troubleshoot it, a procedure which usually involves putting in a gas with a known amount of CO2. But CO2 is a pollutant! There is an alternative: Oxygen. Now that is nice and harmless; certainly not a pollutant. And for the refinery/power plant manager, measuring Oxygen gives him/her a better idea of how the process (refining oil or generating electricity) is working. You dont get that kind of data from CO2.