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The Environmental Protection Agency (EPA) was created in 1970 by President Richard Nixon to address growing public concerns about deteriorating city air, natural areas littered with debris, and urban water supplies contaminated with dangerous impurities. Under his plan, many environmental responsibilities of the federal government were consolidated under the EPA.  

In 2009, the EPA published an that stated carbon dioxide and other greenhouse gases endangered public health, allowing the agency under the Clean Air Act to impose new rules to govern the emission of greenhouse gases. The finding is the basis for regulations around climate pollutants from power plants, automobiles, and methane emissions from the oil and gas industries.

The Trump administration now wants to reverse the endangerment finding, arguing that the Obama administration to pursue its climate agenda.

To understand how this proposed reversal will likely affect the environment, public health, the food we eat, and the standing of the United States in global conversations on climate change, we asked several Harvard Kennedy School faculty members on the front line of climate and environmental work for their thoughts. Their analysis has been lightly edited for length.

• Joseph Aldy: Ignoring vehicle emissions in the United States has significant adverse consequences
• John Holdren: Eliminating the endangerment finding undermines concrete scientific studies on climate
• Sheila Jasanoff: Aligning the power of the Federal government with the expertise of climate science
• Wolfram Schlenker: Understanding how warming trends may affect the economy
• Robert Stavins: Rolling back regulations reverses the many gains made in the fight against climate change

Ignoring vehicle emissions in the United States has significant adverse consequences

Joseph Aldy

The Environmental Protection Agency’s on greenhouse gas (GHG) emissions claims that “a complete elimination of all GHG emissions from new motor vehicles and engines would not address the risks attributed to elevated global concentrations of GHGs” (). Given that the endangerment finding focuses on whether motor vehicles “contribute to air pollution which may endanger public health and welfare,” this is a critical claim. It is also wrong.  

The EPA proposal employs a de minimis argument, much like its recent . The proposal claims that the U.S. transportation sector’s “relatively low share” of global emissions—estimated at more than 4% in the 2009 finding—are too small to meaningfully matter for atmospheric greenhouse gas concentrations.  

This framing is deeply flawed. Annual exceed those of except China, India, and Russia. If all nations adopted EPA’s proposed threshold—denying significance on the grounds of being a small share of global emissions—global action on climate change would stall. Moreover, focusing narrowly on percentage contributions to emissions ignores the meaningful benefits that arise from reducing these emissions.  

The focuses on the outcomes—public health and welfare—that would be adversely affected by air pollutant emissions. Since the original 2009 finding, numerous studies in the academic literature have estimated the impact of an incremental ton of carbon dioxide emissions on , , , and . The , which draws upon a and guidance from the , quantifies and . The domestic-only climate change harms from U.S. motor vehicles amount to more than $20 billion annually. The global harms would be an order of magnitude larger.  

When addressing the risk of climate change, every ton counts. Reducing “just a few billion” tons through motor vehicle regulations over the coming years would deliver billions of dollars benefits each year through improved public health and welfare. Even if motor vehicle emissions are only a few percent of global emissions, a few percent of a trillion-dollar problem represents a significant reduction in the risks to public health and welfare.  

Joseph Aldy is the Teresa and John Heinz Professor of the Practice of Environmental Policy.

Eliminating the endangerment finding undermines concrete scientific studies on climate

John Holdren 

The threat to the endangerment finding must be seen in the context of the Trump administration’s three-pronged approach to dismantling federal efforts to address climate change.  

First, they have been comprehensively undermining the nation’s scientific work to understand climate change and its consequences by:

• Ending climate-related research and monitoring within NOAA, EPA, NASA, NIH, USDA, USGS, DOE, USDA, and even the DoD;  
• Cancelling such research funded by these agencies at universities and other research organizations around the country; and
• Proposing, in the administration’s budget for FY2026, to cancel NOAA-supported monitoring of greenhouse gases by facilities at Mauna Loa, Utqiagvik, and the South Pole, as well as the network run by the Global Monitoring Laboratory with headquarters in Boulder.   

The second prong consists of depriving analysts, policymakers, and the public of information about climate change needed to support both mitigation (to slow climate change) and adaptation (to reduce the harm to people and property from the changes in climate that occur). In this prong of the strategy, the administration has:

• Taken down many government websites addressing climate change and its remedies, censored others, and taken down many of the climate-related databases essential for understanding what climate change is doing and crafting sensible mitigation and adaptation measures;  
• Dismantled the Congressionally mandated, multi-agency U.S. Global Change Research Program, terminating, in midstream, work on the sixth National Assessment of Climate Change Impacts on the United States (a series that has proven indispensable for preparing responses to the impacts of climate change on different regions and sectors of the economy) and;
• Removed the five previous National Climate Assessments from federal websites. 

The third prong of Trump’s approach is to shut down the federal government’s engagement in and support for actual action on both mitigation and adaptation. Steps in this vein include:  

• Withdrawing once again from the 2015 Paris Agreement (having done so in his first term), this time taking even more comprehensive and drastic actions than before to halt government measures aimed at fulfilling U.S. commitments made under the agreement;
• Rescinding all of the Biden executive orders supporting mitigation and adaptation efforts in federal agencies;  
• Eliminating, via the “Big Beautiful Bill,” nearly all of the incentives supporting the further development and deployment of solar, wind, and geothermal energy—as well as incentives for batteries and electric vehicles—while extending further tax breaks on fossil-fuel producers and;
• Cutting $15 billion in clean-energy funding in DOE’s FY2026 budget proposal.

Clearly, overturning the endangerment finding, which enables EPA’s regulation of greenhouse-gas emissions from vehicles and power plants, is the Trump administration’s next target under this third prong.  

I’ll simply say that it would be yet another Trump assault on rationality, the public interest, and U.S. standing in the world.  

John Holdren is the Teresa and John Heinz Research Professor of Environmental Policy. 

Aligning the power of the Federal government with the expertise of climate science  

Sheila Jasanoff 

On July 23, 2025, the International Court of Justice (ICJ) issued an stating that parties to the United Nations Framework Convention on Climate Change, including the United States, have an obligation to limit greenhouse gas emissions and cooperate with each other in protecting the climate system. On July 29, the Environmental Protection Agency (EPA) announced a proposal to withdraw its 2009 , a declaration that “six greenhouse gases…endanger both the public health and the public welfare of current and future generations.” If EPA follows through, it will gut the legal basis for reducing motor vehicle and power plant emissions under the 1970 Clean Air Act. It would also fly in the face of the ICJ’s endorsement of climate science and international cooperation.

EPA’s decision should not come as a surprise. The fossil fuel lobby has agitated for years against the endangerment declaration, and the Supreme Court turbocharged industry’s long-running fight against administrative discretion with its decisions in (undoing the principle of deference to agency expertise) and (greenlighting for now the mass firing of government employees).

It is easy to frame EPA’s proposed action as scientifically unsound and ill-advised. As John Holdren demonstrates, this is one prong in a barrage of actions that will demote the United States from global preeminence in climate research, green technology and environmental policy. Countries like China will continue to innovate while America stagnates, mired in business as usual. 

There is, however, another reason for dismay, and it goes to the heart of democracy in a technological age. As I argued in , agencies like EPA are part of the essential machinery of democracy in modern societies. Their job is to enable us to act smartly in the face of uncertainty. How should our government know what to make of complex scientific findings? How should it formulate policy balancing competing interests? Exasperatingly slow though they often are, independent agencies like EPA are tasked to do this work. They are our safeguard against power exercised without the discipline of knowledge.

The Trump administration argues that EPA overreached in curbing greenhouse gas emissions under the Clean Air Act. But it is precisely the job of independent agencies to align the power of the federal government with the best available facts and expert judgment. Congress has neither the technical bandwidth nor the political will to take up that challenge and has delegated this authority to specialized agencies. EPA, moreover, is required by law to conduct extensive public deliberation on every action it undertakes.  

American leadership on climate change depends on resisting misguided attempts to turn the clock back on decades of administrative expertise. We, the people, deserve better from our government than an assault on a declaration that expresses our democracy’s collective intelligence.

Sheila Jasanoff is the Pforzheimer Professor of Science and Technology Studies. 

Understanding how warming trends may affect the economy 

Wolfram Schlenker

There have been noticeable trends in the U.S. climate. The Chicago Mercantile Exchange offers futures contracts whose prices are functions of realized temperatures. Market participants use these contracts to hedge against uncertain weather events—for example, the need for heating (or cooling) depends on how cold (or warm) a winter (or summer) turns out to be. Notably, the of contracts measuring required cooling has been steadily trending upward, while the price for contracts measuring required heating has been trending downward. These price trends are consistent with climate projections; in other words, financial markets—where real money is at stake—are betting on a warming climate very much in line with the academic consensus.  

These warming trends will have a direct impact on various sectors. Several studies have shown that extreme heat is detrimental to human and . For example, a statistical analysis linking corn, soybean, and cotton yields from 1950 to 2005 predicted that an increase in extreme heat would significantly lower agricultural yields. In 2012, which turned out to be a particularly warm year, yields dropped by roughly 25%——leading to . The years with the largest amount of extreme heat ever experienced by U.S. corn growers were 1936 and 1934, which contributed to the Dust Bowl and had severe ramifications for farmers and food prices. suggest that U.S. corn farmers will commonly experience extreme heat levels comparable to those of 2012 by mid-century, and levels observed during the Dust Bowl by the end of the century.

While irrigation could reduce some of the predicted damage and also help cool extreme temperatures, these adaptation measures are costly and difficult to sustain as aquifers like the Ogallala are depleted. Similarly, CO2 fertilization has some beneficial effects on crop productivity, but the net effect of warming remains negative. Given that the United States has a large market share in commodity crops, the result will be higher prices for consumers.

Wolfram Schlenker is the Ray A. Goldberg Professor of the Global Food System. 

Rolling back regulations reverses the many gains made in the fight against climate change 

Robert N. Stavins 

The endangerment finding, issued by Barack Obama’s EPA in response to a U.S. Supreme Court decision handed down during the George W. Bush administration, recognizes that the major greenhouse gases (GHGs)—including carbon dioxide (CO₂) and methane—“endanger public health and welfare.” This has since become the legal grounding (within the Clean Air Act) for numerous other federal laws and regulations seeking to reduce GHG emissions in multiple sectors of the economy.

Repealing the endangerment finding will thereby strip the EPA of its fundamental authority under the Clean Air Act to regulate GHGs. Current regulations targeting motor-vehicle fuel efficiency and emissions, power plants, and methane leaks, to name just a few, could lose their legal basis. 

This can reduce or even roll back pollution reductions, increasing emissions and worsening both climate change and, importantly, local air quality (emissions of pollutants such as PM2.5 and mercury are correlated with emissions of CO2 from burning fossil fuels, particularly coal). Hence, public health will be damaged, and human welfare much more broadly will be hurt due to sea-level rise, worse and more frequent heat waves, forest fires, and storms, among other consequences. We are likely to see greater economic uncertainty about the efficacy of clean-energy investment, and hence dampened incentives for such investment.

Environmental advocacy organizations, plus state and local governments, will most likely challenge the repeal in the courts, drawing on the scientific basis of the endangerment finding as well as the Supreme Court decision that initiated this in the first place. If the repeal is inconsistent with any statutes, congressional action may be required for the repeal to have its full effects. Also, of course, state-level climate policies—such as California’s vehicle standards and cap-and-trade program—will continue to bring about emissions reductions even if all federal climate action stops (although California’s climate programs are under separate attack by the Trump administration and the Congress). All in all, it’s not a pretty picture.

Robert Stavins is the A.J. Meyer Professor of Energy and Economic Development.

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Banner photo by Kena Betancur/VIEWpress/Corbis/Getty Images

Faculty portraits by Martha Stewart