Timeline of EPA Actions on Greenhouse Gases

The document details the EPA's trajectory in regulating greenhouse gases (GHGs) following the 2007 Supreme Court ruling in Massachusetts v. EPA. It outlines key milestones including the 2009 Endangerment Finding, the development of fuel economy standards for light- and heavy-duty vehicles, and the introduction of the Clean Power Plan to reduce carbon pollution from power plants. The timeline also tracks critical judicial decisions that have both affirmed and limited the EPA's authority under the Clean Air Act.

• The 2007 Supreme Court ruling in Massachusetts v. EPA established that greenhouse gases are air pollutants under the Clean Air Act, allowing the EPA to regulate them if they are found to be a danger to human health.
• In December 2009, the EPA issued an "Endangerment Finding" stating that current and projected levels of six greenhouse gases threaten the health and welfare of current and future generations.
• The EPA and NHTSA implemented fuel efficiency and tailpipe emission standards for light-duty vehicles for model years 2012-2016, targeting 35.1 miles per gallon by 2016 and emissions under 250 grams of CO2 per mile. These standards were later extended through model year 2025, with a target of 54.5 miles per gallon.
• The EPA established the first federal GHG emission standards for medium- and heavy-duty vehicles for model years 2014-2018, which is estimated to reduce CO2 pollution by 270 million metric tons over the vehicles' lifetimes.
• The Clean Power Plan, proposed in June 2014, aims for a 30 percent reduction in the carbon emission rate from the U.S. power sector by 2030 compared to 2005 levels, utilizing four 'building blocks': improving heat efficiency, substituting lower emissions generation, installing zero emissions generation, and increasing end-use energy efficiency.
• Judicial rulings have had mixed impacts on EPA authority: the Supreme Court struck down the Tailoring Rule in Utility Air Regulatory Group v. EPA, ruling the EPA cannot regulate a power plant solely due to GHG emissions, but affirmed the EPA's authority to regulate GHGs from new power plants if the source is regulated for other pollutants.

APA

Collins, J. (2014). Timeline of EPA Actions on Greenhouse Gases. Environmental and Energy Study Institute. https://www.eesi.org/files/FactSheet_EPA_timeline_092214.pdf

Chicago

Collins, Jenifer. Timeline of EPA Actions on Greenhouse Gases. Environmental and Energy Study Institute, 2014. https://www.eesi.org/files/FactSheet_EPA_timeline_092214.pdf.

Wikipedia

{{cite report |last1=Collins |first1=Jenifer |title=Timeline of EPA Actions on Greenhouse Gases |publisher=Environmental and Energy Study Institute |date=September 2014 |url=https://www.eesi.org/files/FactSheet_EPA_timeline_092214.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{collins2014timeline, author = {Collins, Jenifer}, title = {{Timeline of EPA Actions on Greenhouse Gases}}, institution = {Environmental and Energy Study Institute}, year = {2014}, month = sep, url = {https://www.eesi.org/files/FactSheet_EPA_timeline_092214.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }