Undermining Science, Undermining Climate: Trump’s EPA Deregulates the Endangerment Finding
- Sandro Boujaoude
- 3 minutes ago
- 5 min read
By Sandro Boujaoude, EnviroHealthExplorer | February 2026
Introduction: A Historic Rollback with Global Consequences
On February 12, 2026, the U.S. Environmental Protection Agency (EPA), under the Trump administration, formally repealed the 2009 “Endangerment Finding” — a landmark scientific determination that greenhouse gases (GHGs) like carbon dioxide and methane endanger public health and welfare.
This repeal, spearheaded by EPA Administrator Lee Zeldin, is being hailed by the administration as “the largest deregulatory action in American history.” Yet scientists, environmental advocates, and public health experts warn it could dismantle the foundation of federal climate policy, making it nearly impossible for the United States to curb emissions that drive climate change.
In this post, we’ll explore:
The history behind the Endangerment Finding and its role under the Clean Air Act
The science and purpose it upheld
What the Trump administration’s EPA has done, and why it matters
The environmental, economic, and health implications of this repeal
How the Sierra Club and its partners are fighting back
And finally, what each of us can do to act now
Background: From Supreme Court to Sierra Club
The story of the Endangerment Finding begins in 2007, when the Massachusetts v. EPA decision determined that greenhouse gases are “air pollutants” under the Clean Air Act. This ruling compelled the EPA to decide whether these gases endanger public health or welfare.
In 2009, after an extensive review of peer-reviewed science, the EPA under President Obama issued the Endangerment Finding, identifying six major greenhouse gases — including carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and several hydrofluorocarbons — as threats to public health and the environment.
This finding legally obligated the EPA to regulate these gases under the Clean Air Act, paving the way for vehicle emissions standards, power-plant limits, and other climate regulations that shaped U.S. climate policy for more than a decade.
Over the years, Sierra Club and its legal teams have been deeply involved in defending these protections, from submitting amicus briefs to mobilizing public awareness and legislative advocacy. These victories represent not only policy milestones but also decades of grassroots activism grounded in science and justice.
As a member of the Sierra Club Youth Action Committee, I’ve seen how this history inspires young advocates today. Our generation has grown up in the shadow of both scientific consensus and political resistance, and we understand what’s at stake when truth and policy diverge.
What the Endangerment Finding Did, and Why It Mattered
The 2009 Endangerment Finding did two key things:
1. It Defined Which Gases Threaten Health and the Climate
EPA scientists concluded that certain gases — CO₂, CH₄, N₂O, HFCs, perfluorocarbons, and sulfur hexafluoride — contribute to climate change and harm human welfare through rising temperatures, worsening air pollution, heat-related illnesses, and ecosystem damage.
2. It Triggered Federal Action Under the Clean Air Act
Once the EPA determined these gases were dangerous, it became legally required to regulate them. This enabled vehicle emission standards, industrial pollution limits, and climate programs that collectively reduced greenhouse-gas output and improved air quality nationwide.
In short, the Endangerment Finding was the legal and scientific cornerstone of U.S. climate action.
The Great Deregulator: What the Trump EPA Has Done
In one of the most sweeping environmental rollbacks in U.S. history, the Trump administration and EPA Administrator Lee Zeldin — dubbed by many as “the Great Deregulator” — formally rescinded the Endangerment Finding.
Their stated rationale: that the Obama-era finding “exceeded EPA’s statutory authority” and imposed “undue economic burdens” on industry. The repeal asserts that Congress, not the EPA, should determine whether greenhouse gases warrant regulation.
Critics, however, point out that this reasoning directly contradicts the Massachusetts v. EPA precedent and dismisses decades of climate research. Environmental groups call it an attack on science itself, effectively erasing the federal government’s acknowledgment that greenhouse gases endanger human health.
As of February 2026, this move eliminates the legal foundation for:
Vehicle and power-plant emissions standards
Industrial greenhouse-gas reporting and regulation
Federal carbon-reduction programs
Without the finding, these regulations cannot stand, unless reinstated by future administrations or through new congressional action.
The Impacts and Implications: From Automobiles to the Atmosphere
Climate and Health Consequences
Without the Endangerment Finding, the U.S. loses its federal mandate to curb greenhouse gases. Scientists warn this could significantly increase emissions, leading to more intense heat waves, air-quality degradation, and respiratory illnesses, particularly in vulnerable communities.
It also undermines U.S. credibility in global climate agreements, making it harder to meet international reduction targets.
Automotive Industry Uncertainty
The auto industry now faces regulatory chaos. Federal fuel-efficiency standards are in flux, and automakers may no longer be required to meet emissions goals that promote electrification. Some companies may voluntarily continue transitioning toward cleaner technologies — but without federal backing, progress could stall.
Meanwhile, states like California and New York are preparing to set their own stricter standards, likely triggering legal battles over states’ rights versus federal authority.
A Blow to Science and Policy Stability
Beyond environmental impact, this repeal sends a message that scientific consensus can be discarded for political convenience. That precedent threatens not only climate science but also future environmental policymaking across the board.
Next Steps: Sierra Club’s Response and Legal Action
The Sierra Club, along with state governments and allied organizations, is preparing to challenge the repeal in court. The case will likely argue that the EPA violated the Clean Air Act, ignored overwhelming scientific evidence, and failed to justify overturning a well-established finding.
Legal strategies will focus on restoring the EPA’s duty to protect public health from climate-driven harm and ensuring that environmental regulations remain grounded in science, not politics.
Sierra Club’s campaign teams are also mobilizing at the grassroots level — launching national awareness efforts, community education, and congressional outreach to pressure lawmakers to uphold science-based climate protections.
Call to Action: Science, Justice, and the Future We Choose
This is not merely a policy debate, but a turning point. If the foundation of federal climate action can be dismantled, every environmental safeguard built upon it is at risk.
Here’s what you can do:
Stay informed — Share credible reporting from trusted sources.
Support organizations taking legal action, like Sierra Club and Earthjustice.
Contact your representatives — Urge them to defend the Clean Air Act and restore the Endangerment Finding.
Engage your community — Host discussions, join youth initiatives, and participate in climate rallies.
Our climate won’t wait for politics to catch up. The time for science-driven action is now.
Do you believe federal climate policy should continue to be based on scientific evidence about the harms of greenhouse gases?
0%Yes — policy must remain science-based
0%No — climate decisions should not depend on thse findings
0%Unsure — I need to learn more before deciding
Credits & Sources
Based on reporting and analysis from:
Reuters — EPA revokes basis for U.S. climate regulation
Associated Press — EPA rollback sparks legal challenges nationwide
The Washington Post — Trump EPA dismantles key climate rule
The Guardian — EPA repeals Endangerment Finding despite scientific consensus
PBS NewsHour — Trump administration rolls back greenhouse-gas protections
CalMatters — California readies lawsuit over Endangerment repeal
U.S. Environmental Protection Agency official archives — Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a)
Sierra Club — Press statements and legal response materials