EPA’s Proposed Auto Rule: What We Said at the Agency’s Zoom Meeting Today

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Today and tomorrow, the Environmental Protection Agency (EPA) is hosting a public Zoom meeting on the agency’s proposed motor vehicle greenhouse gas emission standards for model year 2023-2026 passenger cars and light trucks. My colleagues Devin Watkins, Sam Kazman, Patrick Michaels, and I each got his three minutes of fame.

Devin faulted the EPA the refusing to correct any of the “unstated, untested, unverified, or mistaken assumptions” identified by the agency’s Clean Air Scientific Advisory Council—irregularities and errors that inflate the health benefits of the proposed rule’s collateral reductions in fine particulate matter (PM2.5) emissions.

Sam hit the EPA’s narrow request for public comment on three stringent alternative emission standards, as well as the agency’s depreciation of the safety risks arising from the vehicle weight and size reductions induced by increasing regulatory stringency.

Pat challenged the proposal’s alleged $91 billion in climate benefits by 2050, noting that even under favorable assumptions, the standards would avert between 0.001°C and 0.002°C of warming by mid-century—an effect far too small to detect or verify.

Rather than summarize my spiel, I present it here:

My name is Marlo Lewis. I am a senior fellow in energy and environmental policy at the Competitive Enterprise Institute.

My comments address the EPA’s use of the social cost of greenhouse gases to estimate the net benefits of the agency’s proposed rule.

The EPA estimates that, during calendar years 2023-2050, the proposal’s greenhouse gas emission reductions will deliver $91 billion in climate change mitigation benefits.

Those benefits are a mirage. Since 2010, the Interagency Working Group, or IWG, has cherrypicked assumptions and inputs to produce wildly inflated social cost estimates. The IWG averages the results of three integrated assessment models, two of which ignore the immense agricultural benefits of atmospheric carbon dioxide fertilization. The IWG relies on climate sensitivity estimates derived from other models that project about three times more warming in the tropical bulk atmosphere than has been observed over the past 40 years.

The most egregious methodological bias, however, is the IWG’s selection of baseline emission scenarios. Four of its baseline scenarios assume that coal scales up rapidly to become the world’s leading energy source after 2050, with consumption continuing to increase well into the 23rd century.

Those scenarios result in post 2100 cumulative carbon dioxide emissions far in excess of estimated fossil fuel reserves, as the Electric Power Research Institute pointed out in its 2014 technical review of the IWG’s work.

“To even approach” the massive cumulative emissions projected in the IWG baselines, University of Colorado Professor Roger Pielke, Jr. explains, “the world would have to make it a policy goal to burn as much coal as possible over the coming centuries. That seems unlikely.”

In effect, the IWG’s procedure is to take the high-end 21st century forcing trajectory called RCP8.5 and then extend it out to the year 2300. 

As is well known, RCP8.5 carbon dioxide emissions in 2050 are more than twice the level projected by the International Energy Agency’s baseline emission scenarios. RCP8.5 is no longer a plausible emission pathway for the 21st century. There is no evidence the world will “return to coal” over the next eight decades, much less over the next 280 years.

The IWG’s social cost estimates are a methodological house of cards. Using those values to estimate the net benefits of the proposed rule flouts basic standards of scientific integrity.