The Social Cost of Carbon – Revisited

The case for using global rather than simply U.S. impacts.

The estimated harm done by a single ton of carbon in the atmosphere – the “social cost of carbon” — is a key factor in setting climate policy. The Trump Administration is trying to get its estimate as close to zero as possible. A key part of this effort is to exclude from consideration the impacts of climate change outside the United States. It seems unlikely that courts will impose a mandatory duty on EPA to consider these global impacts. But EPA does have discretion to do so and will need to provide a cogent explanation for ignoring these important effects.

It’s true that in many settings the cost-benefit analysis includes only the domestic effects of regulation. But there is certainly a legal basis taking international impacts into account. Here are three relevant statutory provisions.

First, the National Environmental Policy Act (NEPA). Section 102(2)(F) of NEPA provides that each agency of the federal government shall “recognize the worldwide and long-range character of environmental problems and, where consistent with the foreign policy of the United States, lend appropriate support to initiatives, resolutions, and programs designed to maximize international cooperation in anticipating and preventing a decline in the quality of mankind’s world environment.” Note that this is in the same section of the statute that imposes the mandate for environmental impact statements, not in the policy provisions of the Act that the Supreme Court has found to be merely advisory.

Next, the Clean Air Act. Section 115 requires EPA to take action whenever it “has reason to believe that any air pollutant or pollutants emitted in the United States cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare in a foreign country.” The Clean Air Act is the statute that gives EPA power to regulate greenhouse gases. Although EPA is yet to take action under the specific authority of section 115, this section is nevertheless significant. It indicates that global impacts were well within the scope of congressional concern. Moreover, action under section 115 is contingent on other countries showing reciprocity with the United States, again showing that Congress was aware of the need for international cooperation to deal with air pollution issues.

Finally, section 335 of the Defense Authorization Act of 2018 (HR 2810). This statute states that it is the sense of Congress that “climate change is a direct threat to the national security of the United States and is impacting stability in areas of the world both where the United States Armed Forces are operating today, and where strategic implications for future conflict exist.” It also says that sea level rise “will threaten the operations of more than 128 United States military sites, and it is possible that many of these at-risk bases could be submerged in the coming years.” And moreover, it says, “As global temperatures rise, droughts and famines can lead to more failed states, which are breeding grounds of extremist and terrorist organizations.” Thus, Congress has clearly identified ways in which foreign impacts in turn impose domestic costs on the U.S., which a cost-benefit analysis should not ignore.

The language of these statutes stops well short of a clearcut mandate to consider global impacts. But they do provide a strong basis for concluding that EPA has the discretion to do so. In the context of administrative law, “discretion” is not a blank check. To the extent that costs and benefits are legally relevant to an agency decision, EPA or other agencies must provide a reasoned justification based on record evidence to support any decision to ignore global impacts.

The Obama Administration’s interagency working group on the social cost of carbon provided strong policy arguments for considering global costs, including the facts that most of the available models do so. Another reason for using a global figure is the need for other countries to take our interest into account when they implement their own climate policies. If the Trump Administration wants to do otherwise, it will need to come up with some very cogent counter-arguments.

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Reader Comments

7 Replies to “The Social Cost of Carbon – Revisited”

  1. Dan – Always appreciate your articles….very thoughtful and interesting. Today’s on global impacts was especially good Many thanks for ryour work. Amy Skewes-Cox, Environmental Planner

  2. Dan said;
    “…..The estimated harm done by a single ton of carbon in the atmosphere – the “social cost of carbon” — is a key factor in setting climate policy…..”

    Dear Dan,
    Given the fact that water vapor is a much more potent greenhouse gas than carbon dioxide, we may also wish to inquire about the estimated harm done by a single ton of water in the atmosphere. Ha Ha Ha

  3. BRQR, you keep on repeating yourself after this issue has already been discussed on Legal Planet in the past. Water vapor in the atmosphere and its overall radiative forcing effect is a response to, and an effect of, other GHG-related radiative forcing impacts in the atmosphere, and when the overall level of the latter is reduced, the overall radiative forcing effect of the former is also reduced. This is discussed extensively in Chapter 8 of the IPCC 2013 report.

    1. Dear Todd,
      I was not referring to radiative forcing effects which are minor and insignificant.

      To clarify, atmospheric water vapor absorbs and releases huge amounts of energy when water changes phases – solid, liquid, vapor. That energy is what drives weather and climate. Water vapor is the major greenhouse gas and has far more effect on climate than carbon dioxide – an innocuous trace gas.

      CO2 has the characteristics of an ideal gas, it does not change phases in the atmosphere, and it has minuscule impact for absorbing/releasing energy (heat capacity) when compared to water vapor in the atmosphere.

      The role and effects of carbon dioxide as both a greenhouse gas and “pollutant” have been greatly exaggerated and misrepresented.

      1. You are wrong. You do not know what you are talking about. Water vapour is feedback that amplifies. Take away the other GHGs and the planet freezes. From Page 667 of Chapter 8, IPCC AR5, 2013: “Currently, water vapour has the largest greenhouse effect in the Earth’s atmosphere. However, other greenhouse gases, primarily CO2, are necessary to sustain the presence of water vapour in the atmosphere. Indeed, if these other gases were removed from the atmosphere, its temperature would drop sufficiently to induce a decrease of water vapour, leading to a runaway drop of the greenhouse effect that would plunge the Earth into a frozen state. So greenhouse gases other than water vapour provide the temperature structure that sustains current levels of atmospheric water vapour. Therefore, although CO2 is the main anthropogenic control knob on climate, water vapour is a strong and fast feedback that amplifies any initial forcing by a typical factor between two and three. Water vapour is not a significant initial forcing, but is nevertheless a fundamental agent of climate change.”

        1. Dear Todd,
          My model is far superior to your model and much more accurate. My model proves that water vapour is the most dominant and significant forcing, and carbon dioxide is negligible and inconsequential.

          That’s why we canceled Obama’s CPP and turned things around and got America moving in the right direction. Tears of Joy.

          1. The degree with which the right has deluded itself is on full display in your comments. You reject evidence at every turn and then pat yourself on the back for your middle school level understanding of the issue.

            Fortunately for any undecided readers on this website, you show your stubborn unwillingness to respond to evidence so transparently that your arguments can usually be safely ignored while the adults in the room continue to converse.

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About Dan

Dan Farber

Dan Farber has written and taught on environmental and constitutional law as well as about contracts, jurisprudence and legislation. Currently at Berkeley Law, he has al…

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