There may be no surprise that an Exchange like ours would support a Cap and Trade system, over say, taxation, but we support it because we believe it to be the most effective and economic way to reduce Green House Gas (GHG) emissions at the lowest cost to the American consumer.
The Government and the Market do what they do best in a Cap and Trade system. The Government, assisted by the best scientific advice, sets and enforces the annual cap required to achieve the atmospheric goal. The market, establishes the most efficient price, given the economic circumstances of the time.
With a tax, there are no guarantees that GHGs will be reduced but there is also no way of knowing what the right price / cost / tax level would be to change behaviour.