Steve Seidel, vice president for policy analysis, co-wrote this post.
With the failure of the Senate to act on climate change legislation, the focus of attention now shifts to possible regulatory actions by EPA. The Supreme Court in 2007  made it clear that greenhouse gases (GHGs) are pollutants under the existing Clean Air Act (CAA), and the overwhelming scientific evidence (spelled out in great detail in the endangerment finding ) demonstrates that such pollutants represent possible harm to public health and welfare.
Opposition to EPA action rests in part on concerns that any regulations will be excessively costly and burdensome to households and U.S. manufacturers. While it is certainly true that regulating GHGs will result in costs, it is also important to look at whether the economic benefits from those regulations will be greater than the costs they impose. In other words, will societal costs of allowing global GHG emissions to continue unabated (costs that will come in the form of impacts from rising sea levels, increased extreme weather including heat waves and droughts, among others) be greater than the costs of regulating those emissions responsibly?
This basic regulatory framework – that regulatory costs should be less than the resulting benefits – is codified in OMB review  of all major federal regulations by both Republican and Democratic Administrations, has historically been applied to all EPA regulations, and would certainly be applied to any future regulations of GHGs.
So what have been the costs and benefits of past EPA regulations under the CAA historically? Congress required EPA to undertake a retrospective  assessment of the costs and benefits of regulations under this statute. The conclusion of this retrospective review is that the CAA resulted in total benefits that are around $37 trillion, while total costs were $0.874 trillion (in 2010 dollars) – an astounding 40 to 1 benefit to cost ratio!
EPA has also produced a prospective  assessment of the costs and benefits of the CAA – this time for the time period of 1990 through 2010. In this review, EPA estimated that the most likely benefit to cost ratio of the CAA for this period is 4 to 1. While a very strong and positive value, the ratio is substantially lower than the estimated benefits for the first 20 years of the CAA.
This is not unexpected – early gains are usually greater, and more cost effective, because simple or cheap remedies are the first to be applied in response to regulatory requirements. As those requirements become more stringent, creating additional benefits becomes more costly (from an economics perspective this is described as moving up the marginal cost curve).
How credible is EPA’s assessment of its regulations? Alan Krupnick, formerly of the President’s Council of Economic Advisors, has testified  before Congress about the credibility of EPA’s analyses: “Under the auspices of the agency’s Science Advisory Board, both studies were scrutinized throughout the decade-long preparation by at least three expert committees of outside economists, air quality modelers, epidemiologists, and other health experts.”
In addition to these EPA assessments, there have been a handful of quality external analyses of the costs and benefits of the CAA. The Office of Management and Budget (OMB) found  that the “major rules” from EPA’s Office of Air resulted in total benefits between $145 and $218 billion annually, for the years between 1992 and 2002. This is compared to costs of between $22 and $25 billion over that same period. A study  by researchers at MIT found total annual benefits rising from $50 billion in 1975 to $400 billion in 2000. This report accounts for the monetary benefits of avoided premature death differently than the EPA studies, and as a result reports lower values for the total benefits. A sum of the total discounted benefits yields a total benefit of $6.85 trillion from 1975 through 2000 – a figure still substantially greater than the EPA estimate for the costs of the regulations.
So how might this play out in terms of future regulations of GHGs? EPA’s first GHG regulations were standards set for light duty vehicles (which it coordinated with the efficiency standards set by NHTSA ). These standards are expected to lead to net benefits of between $0.5 and 1.2 billion dollars (discounted back to present values using 7 percent and 3 percent discount rates, respectively) without even including a social cost of carbon. If a value is assigned to the avoided GHG emissions associated with this regulation, the net present benefits are even greater!
If there is a lesson that can be drawn from these previous regulatory efforts it is that while regulations do impose real costs, EPA’s actions under the CAA have consistently led to positive environmental and economic outcomes. By not regulating, we would have foregone these positive net benefits and incurred the social costs imposed by unabated pollution.
So the next time someone tells you that the costs of reducing air pollution are too high, ask them what would be the costs to society of not reducing those emissions.
Russell Meyer is the Senior Fellow for Economics and Policy. Steve Seidel is Vice President for Policy Analysis.