April 20, 2009Client Alert

U.S. EPA Announces Its Proposed “Endangerment Finding” on Greenhouse Gas Emissions

In what has been called a “momentous change in government policy” by the Washington Post, on Friday, April 17, 2009, the United States Environmental Protection Agency (“EPA”) issued its proposed finding that greenhouses gases (“GHGs”) threaten public health and welfare and that emission of certain GHGs from motor vehicles contribute to climate change. These findings provide the foundation for ultimate GHG emission regulation pursuant to the federal Clean Air Act (“CAA”).

EPA’s Findings

EPA made the following two distinct proposed findings:

  • Endangerment Finding: The current and projected concentration of six GHGs – carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride – in the atmosphere are harmful to public health and welfare.
  • Cause or Contribute Finding: Emissions of four GHGs – carbon dioxide, methane, nitrous oxide, and hydrofluorocarbons – from new motor vehicles and motor vehicle engines contribute to the concentration of these GHGs in the atmosphere and thus, contribute to climate change.


In 2007, the United States Supreme Court held that GHGs are air pollutants covered by the CAA. Massachusetts v. EPA, 549 U.S. 497 (2007). Accordingly, the Court found that the EPA must determine whether GHG emissions from new motor vehicles cause or contribute to air pollution, resulting in harm to public health or welfare, under Section 202(a) of the CAA.

Scientific Analysis

As a result of the Court’s holding in Massachusetts, EPA examined scientific studies regarding the causes and impacts of climate change and the relationship to GHGs. Based on the scientific studies, EPA concluded that GHGs adversely impact public health and welfare by causing climate change. The effects of climate change include increased drought, more frequent and intense heat waves, increased frequency of wild fires, and more intense storms, particularly on the Gulf and Atlantic coasts. These and other negative effects of climate change directly impact public health and welfare in a number of ways.

  • Effects on Human Health:

EPA concluded that climate change has a multitude of negative effects on human health. First, higher temperatures increase the occurrence of heat-related mortality and sickness. Second, increased ozone pollution increases the risk of respiratory infection, asthma attacks and premature death. Additionally, climate change is likely to cause more severe storms, resulting in increased risk of flooding, runoff and erosion. Such events decrease water quality and increase the occurrence of certain diseases and injuries. Finally, higher temperatures have the potential of increasing the occurrence of climate-sensitive diseases, such as tick-borne diseases.

These problems disproportionately impact the very young, elderly, poor, disabled, and indigenous populations that rely on only a few resources.

  • Effects on Human Welfare:

EPA further concluded that climate change has negative effects on human welfare. First, rising sea levels around the world increase storm-surge flooding and shoreline erosion. Second, rising temperatures will further constrain the availability of water in some areas of the United States. Increases in ozone will negatively impact crop yields. Additionally, increased temperatures will likely result in a greater number of forest fires and insect outbreaks. Further, temperature changes will likely cause animal species to move north and to higher elevations, resulting in fundamental changes to the United States’ ecosystems. Finally, it is predicted that climate change may even have national security implications. Specifically, a decrease in the availability of certain resources, such as water, is likely to result in increased violence in destabilized regions.

What Happens Next?

EPA’s findings will be published in the Federal Register. A 60-day public comment period will begin upon publication, after which EPA will issue its final ruling. EPA will hold public hearings on May 18, 2009, and May 21, 2009, in Arlington, Virginia and Seattle, Washington, respectively. Those unable to attend the public hearings can listen to the hearings via web-streamed audio.

It is possible that Congress may pass legislation to address these issues in the meantime. There are a number of bills that are likely to be taken up by Congress as early as this summer.

Want More Information?

EPA’s pre-publication package of what is expected to be published in the Federal Register, which contains the proposal and discusses the underlying scientific findings, can be found at 

Materials in the docket related to the rulemaking will be available at by searching for docket identification number EPA-HQ-OAR-2009-0171.

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