One feature of economic incentive-based environmental policy is that it is possible to achieve (1) a given amount of emissions reductions at lower cost and/or (2) additional emissions reductions at the same cost relative to environmental standards (i.e., command and control regulation):
Gov. Jerry Brown issued an executive order Wednesday dramatically ramping up this state’s already ambitious program aimed at curbing greenhouse gas emissions, saying it was critical to address what he called “an ever-growing threat” posed by global warming to the state’s economy and well-being.
Under Mr. Brown’s order, emissions would have to be reduced by 40 percent over 1990 levels by 2030. Under existing state law, emissions are supposed to be cut back by 80 percent over 1990 levels by 2050, and Mr. Brown said this tough new interim target was essential to helping the state make investment and regulatory decisions that will assure that goal is reached.
Mr. Brown’s order marks an aggressive turn in what had already been among the toughest programs in the nation aimed at reducing greenhouse gas emissions. Under the law put into place by Mr. Brown’s predecessor, Arnold Schwarzenegger, the state was required to reduce greenhouse gas emissions to 1990 levels by 2020 on the way to reach the 2050 target; California is already well on its way to meeting the 2020 goal, and may exceed it, officials said Wednesday.
Unless I'm told otherwise, I'm attributing California's ability achieve additional emissions reductions to cap-and-trade.