Today, I filed comments on EPA Administrator Lee Zeldin’s proposal to roll back the Obama-era Endangerment Finding (EF) and Greenhouse Gas (GHG) standards for light-, medium-, and heavy-duty vehicles. After fifteen years of regulation that has been damaging to the economy while delivering negligible, if any, environmental benefit, the action is long overdue. EPA did an excellent job of justifying the proposed rule from a legal and evidentiary standpoint.
Besides legal errors of the original EF, the reasoning behind it bordered on the absurd. It was bold in its desire to address the global problem of climate change, but paradoxically, based on the belief that the bigger the problem, the less significance was necessary. EPA admitted that the emissions reductions were less significant than would usually be required for a local or regional air problem, but that, ‘‘…contributors must do their part even if their contributions to the global climate change problem, measured in terms of percentage, are smaller than typically encountered..” In other words, the more expansive and global the problem, the less the need to show the emissions reductions contribute in a significant way. Likewise, the vehicle tailpipe emissions standards aggregated six “well-mixed” GHG emissions, two of which are not even emitted by motor vehicles. Absurd.
Besides the 2009 EF failing to show that U.S. GHG emissions from new vehicles significantly contribute to global temperatures and therefore, endanger public health, EPA violated the requirements of the Clean Air Act (CAA), both by deviating from CAA precedent before 2009 and now failing legal precedents since, particularly the major questions doctrine and the overturning of Chevron deference. To be valid, the EF needed to show that the emissions reductions would lead to meaningful public health outcomes. Yet running EPA’s MAGICC* model finds that eliminating all U.S. CO2 emissions from fossil fuels by 2030 would reduce the increase in mean worldwide temperatures by 0.052o Celsius. As that falls within the +0.1o C measurement error for global temperatures, it’s not measurable nor meaningful, and therefore, would have an insignificant impact on climate change and public health.
Of course, it’s completely unrealistic to eliminate all U.S. fossil fuel use, as there is no alternative that does everything that oil, natural gas, and coal do, especially when considering affordability. If eliminating all U.S. fossil fuel use has an insignificant impact on climate and hence, the public health of its citizens, then new vehicle emissions have even less significance. Since 2009, all U.S. vehicle emissions have dropped from 4.3% of global GHGs to 2.5%. Further, overall U.S. GHGs have dropped from 23.5% in 2005 to 11% of global emissions, caused both by significant reductions in the United States—largely thanks to natural gas—and huge increases in China, India, and other developing countries.***
Three Supreme Court rulings since the EF—Utility Air Regulatory Group v. EPA (UARG), West Virginia v. EPA, and Loper Bright Enterprises v. Raimondo—render the justification EPA used in 2009 invalid. SCOTUS has ruled decisively that when a federal agency regulates on “major questions” that have broad economic and political consequence, it must be able to show definitive statutory authority. Since Congress never clearly directed EPA to regulate GHGs in the Clean Air Act nor compel a wholesale market transformation to electric vehicles, as the Biden GHG vehicle standards do, then the rules are unlawful. EPA should finalize the proposed rule to overturn the Endangerment Finding.
My full comments are here.
* Model for the Assessment of Greenhouse Gas Induced Climate Change (MAGICC)
** The Materiality of U.S. CO2 Emissions on Global Climate Change, Brent Bennet, Texas Public Policy Foundation, June 2025.
*** All numbers from EPA data quoted in the proposed rule.
