EPA is calling it the “largest deregulatory action in U.S. history.” The New York Times called it “President Trump’s most consequential step yet to derail federal climate efforts,” which “appears to represent a shift toward outright denial of the scientific consensus.” Others say that the proposal “rejects mainstream science and misunderstands the law” and “relies on misinterpretations of the law and recent cases, fringe science, and tortured cost analysis.” And that EPA is choosing “polluters over people.”
Whatever side of the science and policy issues you find yourself on, this proposal is big news. And rightfully so. The Endangerment Finding, which EPA Administrator Lisa Jackson issued in 2009 under Section 202(a) of the Clean Air Act, is the legal underpinning for the rules EPA has issued in the past 15 years that limit emissions of greenhouse gases from motor vehicles and has provided vital support for rules limiting greenhouse gas emissions from power plants, oil and gas operations, and landfills. Motor vehicles and power plants make up about half of US emissions; oil and gas operations are the largest single industrial source; and landfills are significant emitters of methane, a greenhouse gas more potent than CO2. If the proposal is finalized and withstands legal challenge, it could well preclude EPA from regulating greenhouse gases in the future (indeed, this is the objective of the rulemaking), meaning that the only way greenhouse gases could be controlled at the federal level in the United States would be if Congress passed a law either doing so itself or giving EPA specific new authority to do so.
In its Endangerment Finding One Pager, EPA states that “The 2009 Endangerment Finding was the first step in the Obama-Biden Administration’s (and later the Biden-Harris Administration’s) overreaching climate agenda. That agenda has imposed trillions of dollars of costs on Americans. For a generation, defenders of this agenda have avoided scrutiny of how it all began.” As someone who worked in EPA’s Office of Air and Radiation when the Endangerment Finding was issued and throughout the rest of the Obama Administration and then again during the Biden Administration, it is difficult to read statements like these without providing a response.
First Claim: Has EPA’s “climate agenda” been overreaching? Climate scientists around the world are increasingly in agreement that 1) anthropogenic greenhouse gas emissions are the major cause of increased GHGs in the atmosphere; 2) that those increased GHGs are causing the earth’s surface to warm; 3) that the warming is affecting not just the “climate” (i.e., long term, geographically broad conditions of temperature, precipitation, wind speed, etc.) but also the “weather” (e.g., do I need an umbrella today? Are we having a hurricane or windstorm or heat wave today?). The Clean Air Act charged EPA with addressing “any air pollutant” that the Administrator determines “may reasonably be anticipated to endanger public health or welfare,” and to set standards regulating the emission of that air pollutant from mobile sources. CAA Section 202(a)(1). The US Supreme Court decided in 2007 in Massachusetts v. EPA that greenhouse gases do fit within the term “air pollutant,” and EPA should therefore respond—in whatever way it determined was correct—to a petition asking the agency to regulate GHGs from motor vehicles under Section 202(a)(1). Subsequent court decisions, even ones that invalidated specific EPA climate rules (such as the 2015 Clean Power Plan), have not reversed or undermined the ruling in Mass v. EPA.
Second Claim: Has EPA’s regulation of GHGs imposed trillions of dollars of costs on Americans? EPA does not provide support for this statement, and I am hard-pressed to understand how it could be true. The Regulatory Impact Assessment for the GHG rules for powerplants finalized in 2024 calculated around $20B in costs for the power plant rule. For the 2024 motor vehicle rules, the cost was projected to be $40B. Cost-benefit analysis is both art and science, and the many choices agencies make about what costs to count and how to count them can dramatically change the outcome. What is clear in this rulemaking action, however, and in the “trillions of dollars of costs” statement, is that the EPA is choosing not to consider any of the benefits that have already been experienced by the American people or that will be in the future from less pollution and mitigation of climate change impacts. A CBS review of the Draft Regulatory Impact Assessment found that the Administration’s own analysis shows that if the current GHG standards were repealed as proposed, gasoline prices would increase, and nearly a half million jobs would be lost by 2035. The regulatory impact analysis shows, under its two most likely and realistic scenarios, that repealing the vehicle GHG standards would result in a cost of $260 billion dollars between 2027 and 2055 in one case and $350 billion dollars in net costs in the other.
Third Claim: Have “defenders of this agenda…avoided scrutiny of how it all began”? Not hardly. Every one of EPA’s greenhouse gas regulations has been challenged in court, with exhaustive discussion of EPA’s legal underpinnings, technical analysis, cost-benefit analysis, and the scientific basis of the Finding. EPA has kept pace with science over the years; the more recent rules have updated the facts on the ground and the predictions of future climate impacts. Indeed, the scientific record has grown ever more robust, with each year of record temperatures, runaway wildfires that affect air quality across massive areas of the US, and storms that take lives and destroy property. The Endangerment Finding has been examined in a sea of lawsuits and withstood each challenge. (See Inside Trump’s Renewed Effort to Undo a Major Climate Rule, Zraick and Friedman, NYT January 18, 2025).
We’ll see what happens this time. The proposal relies on several legal arguments for overturning the 2009 Finding, the passage of time, court decisions such as West Virginia v. EPA (major questions), and a draft report from the Department of Energy to support its conclusions that EPA does not have the authority to regulate greenhouse gases under the Clean Air Act, did it wrong in 2009, and alternatively, that circumstances have changed such that a finding (and the subsequent regulation of emissions from mobile sources) is no longer warranted. There are lots of summaries available from different perspectives, and fact-checking posts such as EPA attacks climate science. Here are the facts. – E&E News by POLITICO, and I encourage you to read them. You may also want to read the report issued by the National Academies of Science on September 17, which focuses on climate science since 2009 and finds that “the evidence for current and future harm to human health and welfare created by human-caused greenhouse gases is beyond scientific dispute.”
Every day that goes by with more greenhouse gases emitted and the delay of available opportunities to shift to cleaner sources of energy makes it that much harder for society to manage what the future will look like.
