Cascading effects of climate change on planetary health in the absence of robust federal regulation in the USA #image_title

Stronger evidence, weaker protections: planetary health consequences of rescinding the U.S. Environmental Protection Agency endangerment finding

Originally published: The Lancet on Volume 10, Issue 5101473, May 2026 by Kristen N Cowana, Joshua D Millera, Ellie M Madsona, Shelby S Yamamotoa, Mark M Jankoa, Kim Diana Connollya and Kelly K Baker (more by The Lancet) (Posted Jul 09, 2026)
EnvironmentAmericas, United StatesNewswireU.S. Environmental Protection Agency (EPA)

The U.S. has arrived at a crucial juncture for public health and climate governance. On Feb 12, 2026, the U.S. Environmental Protection Agency (EPA) rescinded its endangerment finding, which established that six greenhouse gases (GHGs) threaten public health and welfare, thereby dismantling a central pillar for regulating GHG emissions. In doing so, the EPA cited regulatory cost concerns—grounds that are legally irrelevant under the Clean Air Act’s public health mandate—and invoked a scientifically discredited federal report to support a de minimis claim: that U.S. GHG emissions produce harm too small to warrant federal regulation.1,2 This decision is not only scientifically unfounded but also represents a direct dismantling of a foundational public health protection framework.3 This Comment describes what is lost and the scientific basis for reinstatement and outlines the consequences for health and society both domestically and globally (figure).

Cascading effects of climate change on planetary health in the absence of robust federal regulation in the USA

Figure Cascading effects of climate change on planetary health in the absence of robust federal regulation in the USA

The endangerment finding emerged from the Clean Air Act of 1970, which directed the EPA to regulate air pollutants that “may reasonably be anticipated to endanger public health or welfare”. Over five decades, this framework led to the National Ambient Air Quality Standards and evidence-based thresholds for harmful pollutants, such as ozone and sulphur dioxide. These standards resulted in landmark public health achievements, including the phase-out of leaded gasoline, sustained reductions in fine particulate matter concentrations, and notable reductions in the levels of pollutants linked to cardiopulmonary disease and premature mortality.4 In 2007, the Supreme Court held in Massachusetts v EPA that GHGs also fell within the Act’s definition of air pollutants and mandated EPA review; in 2009, this review resulted in a finding that six GHGs—carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulphur hexafluoride—met the endangerment threshold.5 These gases, released primarily through fossil fuel combustion, industrial processes, and agricultural activities, trap heat in the atmosphere and are the principal drivers of global climate change. This endangerment finding has withstood repeated legal challenges in courts, reinforcing its scientific and legal foundation.6

The scientific rationale for the finding has only strengthened since its issuance. In 2009, the EPA drew on scientific syntheses indicating that continued GHG emissions would likely increase heat-related morbidity and mortality, degrade air quality, intensify extreme weather events, expand the geographical range of vector-borne diseases, and exacerbate respiratory and cardiovascular illness.7 Subsequent Intergovernmental Panel on Climate Change (IPCC) assessments and U.S. National Climate Assessments have reinforced and expanded this evidence, with advances in attribution science enabling higher confidence in linkages between anthropogenic emissions and harms. The Sixth IPCC Assessment Report, drafted by hundreds of scientists worldwide and citing tens of thousands of scientific studies, concluded with unequivocal certainty that human influence has contributed to climate change and that such change is already producing widespread adverse health impacts.
Rescinding the endangerment finding will have profound consequences (figure). Unmitigated emissions will degrade the natural systems American communities depend on through the exacerbation of extreme weather; biodiversity loss; air, soil, and water pollution; and crop failures. In turn, public health will suffer owing to an increased incidence of cardiopulmonary disease, infections, malnutrition, and climate-related mental health disorders.
Economic instability is already deepening as insurance markets contract and infrastructure damage costs escalate, while heat stress reduces labour productivity. These burdens fall disproportionately on populations already facing structural inequities (including low-income communities, communities of colour, and Indigenous populations), who contribute the least to GHG emissions and who already contend with compounding burdens of degraded air and water quality, inadequate housing and health-care access, and legacies of structural racism. Rescission also eliminates the legal foundation for emerging domestic accountability mechanisms, including state-enacted Climate Superfund laws, and exposes U.S. firms to growing stranded asset risk and litigation as global markets increasingly reward decarbonisation.
As the world’s second largest current GHG emitter and a historical leader in environmental regulation, policy decisions in the USA reverberate far beyond its borders. The same harms that Americans face—extreme weather, crop failures, disease burden, and economic disruption—will also impact countries globally, including those with far less capacity to absorb them. Nations with constrained financial resources, weaker health-care infrastructure, and greater dependence on climate-sensitive sectors, such as subsistence agriculture, face compounding risks with few buffers. Climate-driven displacement and intensifying competition over water, food, and arable land threaten to deepen conflict and instability across already fragile regions. At the geopolitical level, rescission accelerates the erosion of U.S. clean energy leadership, weakens multilateral mitigation efforts, and further undermines American credibility in global climate governance at a moment when collective action is urgently needed. The assertion that U.S. emissions are too small to be regulated contradicts both climate science and the collective-action framework that underpins global mitigation efforts. Accountability for U.S. emissions is not only moral, but also urgently needed.
Although multiple legal challenges are under way, resolution might take years.8 In the interim, the opportunities for harm mitigation that remain should be actively pursued. U.S. states and local municipalities retain meaningful authority and should build upon it, drawing on existing mechanisms, including California’s independent vehicle emissions standards, the Regional Greenhouse Gas Initiative, and local climate action plans.9,10 As federal monitoring programmes face mounting pressure, researchers should expand on and protect rigorous scientific work, translating health evidence into economic and cost-effectiveness frameworks and designing studies capable of supporting expert testimony in climate-related litigation. Health practitioners, educators, and local elected and religious leaders, trusted for their direct relationships with communities, are uniquely positioned to connect climate science to individual and community welfare. Consumer pressure on industry is also imperative; in the absence of federal mandates, sustained public demand for reducing emissions remains a powerful tool.
The path forward requires sustained engagement from researchers; health practitioners; advocates; state, local, and tribal governments; courts; labour and workforce organisations; financial and insurance actors; community-based organisations; media and communications leaders; and the private sector to ensure that those facing the greatest risk from climate change do not also shoulder the cost of its denial. The scientific evidence on the harms of GHG emissions has never been stronger and neither has the responsibility to act to prevent avoidable human suffering been more urgent.

Competing Interests

KNC held a research position at the Environmental Protection Agency through Oak Ridge Associated Universities (ORAU) before the commencement of this work. KNC holds a position on the International Society for Environmental Epidemiology (ISEE) policy committee with no financial interests. MMJ and KKB both serve on scientific committees for the American Society for Tropical Medicine and Hygiene with no financial interests. All other authors declare no competing interests. During the preparation of this work, the authors used Claude AI to refine the text for clarity and concision. After using this tool/service, the authors reviewed and edited the content as needed and take full responsibility for the content of the published article.

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