Illusory Climate Benefits: CEI Comments on EPA’s Motor Vehicle Greenhouse Gas Emission Standards

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CEI submitted comments yesterday on the Environmental Protection Agency’s (EPA) proposed greenhouse gas (GHG) emission standards for motor vehicles during model years 2023 through 2026. The EPA claims that the proposed standards will deliver $91 billion in cumulative climate change mitigation benefits by 2050. Our comments show those benefits are illusory.

The EPA bases its climate benefit calculation on the Biden administration Interagency Working Group’s (IWG) social cost of carbon (SCC) estimates. For those unfamiliar with the concept, the SCC is an estimate in dollars of the cumulative long-term damage caused by an incremental ton of carbon dioxide (CO2) emitted in a specific year. That number also represents an estimate of the benefit of avoiding or reducing one ton of CO2 emissions in that year. In the IWG’s central estimate, the SCC rises from $51 per ton in 2020 to $85 per ton in 2050.

Our comments chiefly do two things:

  1. Explain why SCC estimation is too speculative, assumption-driven, and vulnerable to political manipulation to inform public policy decisions; and
  2. Document the IWG’s many dubious methodological decisions that bias SCC analysis in favor of climate alarm and regulatory activism.

The IWG’s tricks include the use of:

  • Below-market discount rates to inflate the present value of future GHG emissions and reductions;
  • Damage estimates calculated out to 2300—far beyond the limits of informed speculation about future emissions, economic vulnerabilities, and technological development;
  • Outdated climate sensitivity assumptions derived from climate models that continually overshoot observed warming, especially in the tropical atmosphere;
  • Models that ignore the immense agricultural and ecological benefits of CO2 atmospheric enrichment;
  • A model that unreasonably assumes human ingenuity is powerless to mitigate the costs of even modest levels of warming and sea-level rise;
  • Implausible baseline emission scenarios in which coal increasingly dominates global energy supply over the next 280 years; and
  • Apples-to-oranges net-benefit calculations comparing the domestic costs of GHG regulations to the putative global benefits rather than to the smaller domestic benefits.

Absent the IWG’s methodological biases, the SCC during 2020-2050 could well be zero dollars. In fact, there are strong probabilities of negative SCC values, meaning that, on a per-ton basis, CO2-fertilization benefits may exceed CO2-warming damages.

Even apart from the foregoing methodological issues, the EPA’s $91 billion climate benefit estimate defies common sense. The proposed motor vehicle GHG standards are projected to avoid 0.001°C-0.002°C of global warming by 2050. That hypothetical change would be far too small for scientists to detect. It would make no discernible difference in weather patterns, crop yields, polar bear populations, or any other environmental condition people care about. Benefits no one can experience are “benefits” in name only.

Benefits no one can detect or verify are not real enough to be netted against the tens of billions of dollars in annual costs that the EPA’s proposal would indisputably impose on automakers and consumers.

CEI’s comments were co-authored by CEI climate scientist Patrick Michaels, Heritage Foundation Principal Data Scientist, Statistician, and Research Fellow Kevin Dayaratna, and yours truly. Dr. Dayaratna, whose peer-reviewed studies feature prominently in our analysis, contributed in his capacity as an independent scholar and not on behalf of any organization.

Ten other non-profit groups signed on to our comments: American Energy Alliance, the Heartland Institute, 60 Plus Association, CFACT, the Cornwall Alliance for the Stewardship of Creation, Energy and Environmental Legal Institute, FreedomWorks, Caesar Rodney Institute, Roughrider Policy Center, and Life Powered (a Project of the Texas Public Policy Foundation). American Enterprise Institute (AEI) economist Benjamin Zycher signed on in his capacity as an independent scholar and not on behalf of AEI.