Overturning the Endangerment Finding Threatens Americans’ Health, Wealth, and Security

On April 20, the rescission of the 2009 endangerment finding went into effect, eliminating the legal basis for the United States’ regulatory action on greenhouse gas (GHG) emissions and climate change. The scientific consensus that GHG emissions harm Americans’ health and welfare is well-established and growing, with air pollution from fossil fuels being responsible for an estimated 91,000 premature U.S. deaths and thousands of other chronic and acute conditions each year, generating major costs in terms of care and lost productivity. Despite the rhetoric surrounding the decision, the legal case does not challenge the scientific basis underlying the original rule. But while the case has been portrayed as a regulatory decision, debate has largely failed to recognize that this is fundamentally a public health issue—and policymakers are liable for trading short-term economic gain for generational damage to Americans’ health.

Q1: Why does the endangerment finding matter for public health?

A1: The endangerment finding had long served as the regulatory basis for U.S. domestic climate policy, with its ruling rooted in protecting Americans’ health from GHG emissions. In 2007, in Massachusetts v. Environmental Protection Agency (EPA), the Supreme Court ruled that GHGs are pollutants under the Clean Air Act and directed the EPA to determine whether the gases threaten human health. In the 2009 endangerment finding, the EPA found that GHG emissions “in the atmosphere threaten the public health and welfare of current and future generations,” due to their role in warming, rising sea levels, ocean acidification, and shifting precipitation. The EPA was therefore required to regulate the six GHGs included in the ruling: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. The finding spurred the development of EPA regulations on GHG emissions for vehicles and later power plants and factories.

Twenty-four states and health and environmental groups have sued the Trump administration for overturning the endangerment finding, marking the beginning of court battles that will play out for years. The revocation of the rule is already having regulatory and commercial reverberations that will likely increase the scale of GHG emissions, but the true economic and geostrategic impact of this policy decision remains to be seen as industry leaders and other countries weigh how to respond. In the meantime, the risks to Americans’ health from the direct and indirect consequences of climate change will continue to compound, even as the resulting toll may not be felt for decades.

Q2: How do greenhouse gas emissions impact Americans’ health?

A2: Greenhouse gas emissions are already harming Americans’ health. As GHG emissions are released into the atmosphere, the Earth’s surface is warmed and the climate changes. This intensifies the risk of population exposures to extreme heat, air pollution, allergens, vector-borne disease, and extreme weather, all of which generate a host of acute and long-term cardiovascular, respiratory, and infectious conditions. Extreme weather events such as heat waves, wildfires, droughts, and flooding have become more frequent, increasing the risks to human health, including from delayed care, injury, illness, and death. Extreme heat is the leading weather-related cause of death in the United States, with deaths doubling between 1999 and 2023. There is increasing evidence that climate change also impacts mental health, nutrition, immune health, antimicrobial resistance, kidney disease, and pregnancy-related outcomes.

The revocation of the endangerment finding stands to increase these mounting challenges to health associated directly and indirectly with climate change. However, the long-term impacts of the change will not be immediately apparent. Even if emissions ended today, the resulting impacts of those pollutants on the climate would unfold over the next two to three decades. Attributing and quantifying the impact of climate change on health is a complicated and long-term process, as it contributes to chronic conditions that manifest over the lifetime. Despite a growing body of scientific and public health evidence on how GHGs harm human health, it is difficult to assess or connect such events to real-time policy decisions.

Q3: Does the new ruling challenge that GHGs are detrimental to health?

A3: No.

While the regulatory framework for U.S. climate policy has been repealed, the repeal does not change nor challenge the scientific foundation on which the endangerment finding was based, only the requirement to act. The scientific consensus remains the same: GHG emissions pose a danger to public health. Since 2009, the evidence for the current and future impacts of GHG emissions has only increased. Any further increase in GHG emissions goes against scientific evidence alerting to the dangers of emissions. The Trump administration had convened a panel to try to dispute the scientific claims underlying the ruling, but its composition and findings came under significant dispute as being unsubstantiated, and it was not referenced in the final rescission.

The final ruling focuses on cutting emissions standards for motor vehicles, the highest-emitting sector in the U.S. economy, with transportation broadly accounting for nearly 30 percent of U.S. emissions. The EPA has claimed that removing these regulations will generate $1.3 trillion for the U.S. economy in savings from cheaper new cars. But it also has contradicted its own arguments, acknowledging that there could be equally great long-term costs in higher fuel prices passed on to consumers, and maintaining rules regulating methane pollution under the Clean Air Act.

Over the next three decades, this regulatory change could lead to billions of extra tons of GHG emissions in the atmosphere. The administration’s economic estimates fail to account for how these emissions could inflate the annual damages of extreme heat and other climate-induced impacts on public health, rising healthcare costs, declining labor productivity, lost agricultural yields, and infrastructure damage from increasingly frequent and costly natural disasters.

Q4: What will happen now that the ruling has been revoked?

A4: As the legal challenges unfold, domestic and multinational companies will have to make difficult decisions about how to proceed, with significant implications for the levels of GHGs emitted by the United States and the long-term health consequences for Americans. While regulating GHG emissions is no longer a legal requirement in the United States, companies will face questions from investors and exporters about their environmental impact and will still have to adhere to stricter standards in other countries where they do business. Industry may also be wary of changing its policies if companies have already made expensive investments to shift their supply chains to support greener technologies, and for fear that a future administration might reverse course. These considerations may ultimately have a mitigating effect on the impact of the ruling on industry behavior, the emissions that result, and their health consequences.

If the overturning of the endangerment finding withstands legal challenges, it would take years for a future administration to make and enforce a new determination and resume the regulation of GHGs. Congress could restore federal legal authority to regulate GHG emissions through new legislation, but such action seems unlikely given narrow majorities in both chambers and current political fragmentation, particularly in an election year. The acute health consequences for their constituents have thus far failed to resonate with a bipartisan coalition of lawmakers. Absent new legislation, more responsibility would fall on states to meet climate goals. This may increase volatility as states could go even further to introduce legal and regulatory challenges in the absence of overarching national rules, complicating the landscape for industry leaders as they face inconsistent laws across the country.

The endangerment finding has driven U.S. climate policy internationally by providing the scientific backing that supports international climate agreements and the domestic regulatory standards to meet those commitments. Under the George H.W. Bush administration in 1992, the United States signed the United Nations Framework Convention on Climate Change (UNFCCC), the treaty that sets a legal framework for international negotiations to address climate change, under which the 2015 Paris Agreement was negotiated during the Obama administration. Under the 2015 agreement, the United States and nearly every other nation agreed to reduce their GHG emissions to limit global warming. Yet the United States has missed recent emissions targets due to inconsistent support from both sides of the aisle, and President Trump’s presidencies have marked a new era, with his outright rejection of climate change as a “hoax” and withdrawal from the Paris Agreement and UNFCCC.

Q5: How might this U.S. action influence global policy on climate and health?

A5: Changes to U.S. domestic policy on GHG emissions standards mark a further retrenchment of U.S. climate policy and will have major implications for global health. Air pollution alone is associated with 6.7 million premature deaths annually around the world, with a disproportionate impact on children’s long-term health and development. Effective global climate policy requires the United States to meet international climate goals because it is the world’s second largest emitter of GHGs, behind only China, and has released the most GHG emissions since the Industrial Revolution—now those contributions are liable to increase. Shifting U.S. policy on climate and health signals an abdication of global responsibility and could erode international consensus around climate goals, influencing other countries to follow suit in decreasing their emissions standards and withdrawing from international commitments. The U.S. withdrawal from climate agreements such as the UNFCCC and the Paris Agreement also indicates to lower- and middle-income nations that the United States will not financially aid their efforts to lower emissions, making it much more difficult for these countries to turn away from fossil fuel production and exports.

A lack of U.S. leadership in this area is part of a worrisome trend against climate and health action that will leave the United States behind in terms of health, scientific leadership, and geopolitical competitiveness. It accompanies funding cuts and staffing disruptions at the EPA—including the most recent proposal to cut its budget in half—and similar actions to reduce environmental health research at the National Institutes of Health and the U.S. Centers for Disease Control and Prevention. To maintain competitiveness with the world’s industrialized nations in Europe and East Asia, the United States needs to invest in research and development now; lagging industrial policy will take years to catch up. The United States’ isolation from the international market could further cede the future of technology to Chinese companies investing heavily in electric vehicles and other green innovations, providing an opening for China to widen its lead as a renewable superpower and strike new diplomatic and economic deals. These technologies may have increased relevance as countries recognize the vulnerability of fossil fuel supply chains to geopolitical shocks and the potential benefits of diversifying energy sources and reducing their external dependencies. The Iran war has forced many countries to consider the benefits that transitioning to renewable energy may have to avoid fuel disruptions.

What is lost alongside the broader debate is that each of these diplomatic, industrial, and geostrategic decisions will shape health exposures for generations. U.S. policymakers should not be willing to accept the long-term damage to Americans’ health from GHG emissions in exchange for short-term economic gain. The health and well-being of the U.S. population is the basis on which all other goals follow—a sicker nation has reduced economic output and commercial competitiveness, and ultimately is a national security vulnerability. It is in the U.S. interest to limit domestic and international emissions and reinstate the research and development practices, agreements, and regulations that help achieve that goal.

Caitlin Noe is a program coordinator with the Global Health Policy Center at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Michaela Simoneau is a fellow with the CSIS Global Health Policy Center.