The EPA’s Elusive Climate Change Endangerment Report

NOTE: The following is one of a series of case studies produced by the Union of Concerned Scientists' Scientific Integrity Program between 2004 and 2010 to document the abuses highlighted in our 2004 report, Scientific Integrity in Policy Making.


In December of 2009 the Environmental Protection Agency published the final version of its finding that global warming emissions endanger public health and welfare in the United States. The finding, mandated by the United States Supreme Court’s decision in Massachusetts vs. EPA, was the first step towards regulation of global warming emissions under the Clean Air Act.

The EPA’s ability to base the finding on the best available science has been challenged throughout the process, first by a series of actions from the Bush White House and later during the public comment period by submissions from corporations and trade associations misrepresenting scientific work. 

Massachusetts vs. EPA

In 1999 a group of actors, including the state of Massachusetts, petitioned the EPA to regulate the emissions of several global warming gases from new motor vehicles under the Clean Air Act1. The Clean Air Act requires the EPA to regulate emissions of any pollutant that “may reasonably be anticipated to endanger public health or welfare in the United States,” and the petitioners argued that global warming emissions fall into that category because they contribute to climate change.

In 2003 the EPA rejected the petition, arguing that the Clean Air Act did not authorize it to regulate global warming emissions, as they fall outside the original intent of the law, and furthermore the agency would decline to regulate even if it did possess the authority, due to various practical considerations.

The petitioners appealed to the Court of Appeals for the D.C. Circuit, and in 2005 the Court decided for the EPA in a 2-1 decision, with each judge writing a separate opinion. One judge ruled that the petitioners lacked standing, since there was no injury suffered from the EPA’s actions, and the other judge ruled that the EPA was permitted to exercise its own discretion in deciding whether to regulate.  The petitioners appealed the decision to the United States Supreme Court, which issued a 5-4 decision for the petitioners in 2007, with the majority opinion written by Justice John Paul Stevens2

The court reasoned as follows:

  • First, the plaintiffs, Massachusetts et al, did pass the three prong standing test – injury, causation, and remedy – since climate change, principally via sea level rise, will injure Massachusetts, the EPA has not disputed that global warming emissions cause climate change, and the regulation of greenhouse emissions from new vehicles will help to remedy the problem.
  • Second, the EPA does have the authority to regulate global warming emissions under the Clean Air Act. The definition of “air pollutants” in the Act was intended by congress to be construed broadly, keeping the Act relevant over time, and as such it applies to carbon.
  • Third, and finally, practical considerations do not give the EPA discretion to avoid exercising its regulatory authority. If a threat to public health or welfare exists from pollutants, then the Clean Air Act requires the EPA to regulate.

As a result of the decision, the EPA was required to prepare a finding on whether global warming emissions endanger public health or welfare in the United States, and if so, regulate those emissions.

White House refused to read EPA report

In response to the Supreme Court’s decision, the EPA spent much of 2007 and 2008 internally reviewing the likely impacts of climate change to determine if global warming would endanger public health or welfare. Jason Burnett, a high-level EPA advisor who coordinated agency climate change actions and was a lead author of the endangerment report, alleged that the EPA's report faced intense resistance and interference from the White House. Burnett resigned in June 2008 over his objections.3

According to Burnett, EPA scientists realized early on that the only scientifically defensible conclusion would be that global warming emissions did endanger public health, a finding which would trigger nationwide regulation of carbon emissions.

To shore up support for this course of action, the EPA held multiple meetings during the fall of 2007 with various government organizations and White House staff.4 Burnett also double-checked with OMB, including reading portions of the report out loud to them, to make sure they agreed with the wording and were prepared to receive the report.5

By November 2007, there was support within the administration for proceeding and EPA Administrator Stephen Johnson was given the go-ahead from the White House to submit the endangerment finding.6

On December 5, 2007 Burnett emailed the EPA’s finalized endangerment report to the White House Office of Management and Budget. Minutes later Johnson received a phone call from the White House instructing EPA to retract the email and say it had been sent in error.7 Johnson refused, saying that the email had not been sent in error and was in fact consistent with previous instructions from the White House.

The White House then requested that EPA send an email asking the White House not to review the document because provisions in the Energy Bill, then under consideration in Congress, might make the finding moot; Johnson again refused.8 The White House then decided it would not open the EPA's email, because doing so would require them to move ahead with the formal regulatory process and make the documents public. 9

EPA's response

After the White House refused to read the original endangerment report, the EPA reworked it into a May 2008 draft Advanced Notice of Proposed Rulemaking (ANPR), which is a preliminary step towards enacting regulation. Neither this draft nor the original December 2007 report were ever made public, although congressional staff from the Senator Barbara Boxer's Environment and Public Works (EPW) committee and Representative Edward Markey's House Select Committee on Global Warming were allowed to view copies of the documents and take "reasonable notes."10 The May 2008 draft ANPR was also leaked to various news outlets.11

Investigations by Senator Boxer12 and Representative Markey13 show that pressure from the White House resulted in progressively weaker documents from the EPA. For example:

  • The December 2007 report found that "elevated levels of [greenhouse gas] concentrations may reasonably be anticipated to endanger public welfare" and proposed regulation of carbon emissions from cars and light trucks. The endangerment finding and the proposed regulation were stripped out of the ANPR, which only seeks public comment asking "whether" global warming emissions pose a danger.
  • The December 2007 report admitted the existence of some positive benefits of climate change but concluded that they were outweighed by more numerous and serious negative effects. This language was changed in the draft and final ANPR to ask for public comment on this balance.
  • The December 2007 report and the May 2008 draft ANPR included analysis estimating the economic benefits to greenhouse gas regulation, including up to $2 trillion in consumer benefits by the year 2040. All such analysis was removed from the final ANPR.

The EPA released a final ANPR on July 11, 2008.14 The same day the EPA released the ANPR, the White House released a 14-page policy memo indicating that “EPA staff draft does not represent administration policy."15

The CDC testimony

The finding document itself was not the only target of political interference. In October 2007, CDC Director Julie Gerberding testified before Congress on the public health effects of climate change. According to Burnett, the White House Council on Environmental Quality (CEQ) asked him to "convince CDC to delete particular sections of their testimony" in order to "keep options open" for EPA's endangerment finding, which was then in mid-process. 

In other words, the CEQ did not want official government testimony stating that climate change would affect public health, as that would require the EPA to include such findings in their endangerment report. Burnett refused to participate in deleting any of Gerberding's testimony, but said that both the CEQ and the Office of the Vice President took part in removing 7 pages of official written testimony.

Read more about the CDC's testimony being edited here

California's greenhouse gas waiver

During sworn testimony before the EPW committee, Burnett also drew connections between the national endangerment finding and EPA Administrator Stephen Johnson's 2007 decision to deny California's request to regulate its own global warming emissions. Under the Clean Air Act, the state of California has the right to enact more stringent regulations than what the Federal government requires, provided the EPA issues a waiver allowing them to do so. On December 19, 2007, Johnson denied California's request for a waiver, the first time that such a request had ever been turned down.

Burnett revealed that the denial was due to direct political interference from the White House. Burnett testified that, contrary to Johnson's own statements on the matter, Johnson and his advisors had agreed that California should be granted a waiver and notified the White House of their decision. But after a last minute trip to the White House Johnson reversed course and denied California's request.16

On June 30, 2009, EPA granted a waiver of Clean Air Act preemption to California for its greenhouse gas emission standards for motor vehicles beginning in the 2009 fiscal year.17

To read more about political interference at the EPA, see the UCS report here.

Finding release and public comment period

The EPA published its proposed Endangerment Finding in the Federal Register on April 24, 2009, followed by a public comment period of 60 days. During the public comment period interested citizens, organizations, corporations, and other stakeholders had the opportunity to weigh in on all aspects of the finding and possible regulatory responses, and the EPA received over 380,000 comments in total18.

Among the submissions were comments from trade associations and corporations that used misrepresentations of scientific work on climate change to call for the Endangerment Finding to be withdrawn. For example, a comment from FMC Corporation asserted that “The current state of scientific knowledge on the contribution of human-caused climate change is so profoundly uncertain that it is not clear, even when using the data and sources that the United Nations’ Intergovernmental Panel on Climate Change (IPCC) and EPA rely on, whether there will be global warming or global cooling over the course of the twenty-first century.”19 To read more about the comments of corporations and trade associations see the UCS report A Climate of Corporate Control.

After the comment period closed, the EPA issued a response to the comments which incorporated some suggestions, replied to criticisms, and left the basic claims of the original Endangerment Finding substantially unchanged20.  The final version of the Endangerment Finding was signed by Administrator Jackson on December 7, 2009. 


1. The Oyez Project at IIT Chicago-Kent College of Law. "MASSACHUSETTS v. ENVIRONMENTAL PROTECTION AGENCY.” Online at http://www.oyez.org/cases/2000-2009/2006/2006_05_1120/
2. U.S. Supreme Court, Massachusetts v EPA, Decided April 2, 2007, Docket #05-1120.
3. Boxer, B. 2008. Letter to Jason K. Burnett.  July 1; Burnett, J.K. 2008. Letter to Senator Barbara Boxer. July 6. Barbara Boxer (D-CA) is the Chairman of the Senate Environment and Public Works (EPW) Committee
4. Burnett, J.K. 2008. Testimony before the Senate Environment and Public Works Committee. July 22.
5. Ibid.
6. Select Committee on Energy Independence and Global Warming Majority Staff. 2008. Investigation of the Bush Administration’s Response to Massachusetts v. EPA. July 18, p. 8.
7. Eilperin, J. 2008a. White House tried to silence EPA proposal on car emissions. Washington Post, June 26.
8. Burnett, J.K. 2008b. Interview with staff of the House Select Committee on Energy Independence and Global Warming. July 15.
9. Barringer, F. 2008. White House refused to open pollutants e-mail. New York Times, June 25.
10. Eilperin, J. 2008b. EPA e-mail concluded global warming endangers public health, senator says. Washington Post, July 25.
11. U.S. Environmental Protection Agency. 2008. Regulating Greenhouse Gas Emissions under the Clean Air Act.  Draft dated 5-30-08. Part 1 and Part 2 online at the Wonk Room blog. Cited in Johnson, B. 2008. Bush Hiding Truth: Global Warming Regulations Worth $2 Trillion Benefit. Wonk Room blog post, June 30.
12. Eilperin 2008b.
13. Select Committee on Energy Independence and Global Warming 2008, p. 32.
14. U.S. Environmental Protection Agency. 2008. Advance Notice of Proposed Rulemaking: Regulating Greenhouse Gas Emissions under the Clean Air Act. July 11.
15. White House Policy Memorandum. 2008. Environmental Protection Agency Advance Notice of Proposed Rulemaking Regarding Greenhouse Gas Emissions and the Clean Air Act. July 11.
16. Burnett testimony, July 22, 2008; Eilperin, J. 2008c. Ex-EPA official says White House pulled rank. Washington Post, July 23.
17. California Greenhouse Gas Waiver Request.  http://www.epa.gov/oms/climate/ca-waiver.htm.
18. Environmental Protection Agency. 2012. Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act. Online at http://epa.gov/climatechange/endangerment/
19. FMC Corporation. 2009. Comments in Endangerment and cause or contribute findings for greenhouse gases under Section 202(a) of the Clean Air Act submitted by the Energy Companies Coalition on behalf of its members (U.S. EPA document EPA-HQ-OAR-2009-0171), Commenter 3722. Washington, DC: EPA.
20. Environmental Protection Agency. 2012. Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act. Online at http://epa.gov/climatechange/endangerment/

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