Methane (CH4) is the second most abundant greenhouse gas (GHG) after carbon dioxide (CO2), accounting for 14 percent of global emissions. Though CH4 is emitted into the atmosphere in smaller quantities than CO2, its global warming potential (i.e., the ability of the gas to trap heat in the atmosphere) is 25 times greater. As a result, methane emissions currently contribute more than one-third of today’s anthropogenic warming.

Here is a graph which illustrates the magnitude of CH4 emissions on a global basis:

Figure 01

At the global scale, the key greenhouse gases emitted by human activities are:

  • Carbon dioxide (CO2): Fossil fuel use is the primary source of CO2. The way in which people use land is also an important source of CO2, especially when it involves deforestation. Land can also remove CO2 from the atmosphere through reforestation, improvement of soils, and other activities;
  • Methane (CH4): Agricultural activities, waste management, and energy use all contribute to CH4 emissions;
  • Nitrous oxide (N2O): Agricultural activities, such as fertilizer use, are the primary source of N2O emissions; and
  • Fluorinated gases (F-gases): Industrial processes, refrigeration, and the use of a variety of consumer products contribute to emissions of F-gases, which include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6).

CH4 is a hydrocarbon and the primary component of natural gas. CH4 is also a potent and abundant GHG, which makes it a significant contributor to climate change, especially in the near term (i.e., 10–15 years). CH4 is emitted during the production and transport of coal, natural gas, and oil. Emissions also result from livestock and other agricultural practices and from the decay of organic waste in municipal solid waste landfills and certain wastewater treatment systems.

Here is a graph which illustrates the sources of CH4:

Figure 02

Global anthropogenic CH4 emissions for 2010 were estimated at 6,875 million metric tons of CO2 equivalent (MMTCO2E).  Approximately 50 percent of these emissions come from the five sources targeted by the Global Methane Initiative (GMI):

  • Agriculture;
  • Coal Mines;
  • Landfills;
  • Oil and Natural Gas Systems; and
  • Wastewater.

GMI emissions are projected to increase by 15 percent to 7,904 MMTCO2E by 2020.  From 2010 to 2020, the relative contributions of the agriculture, coal mining, and landfill sectors are projected to remain relatively constant, changing by less than 1 percent of global anthropogenic CH4 emissions or approximately 7 to 10 percent within each sector. CH4 emissions from wastewater treatment systems are expected to increase by nearly 12 percent. Oil and gas emissions, however, are expected to increase by nearly 35 percent from 2010 to 2020, and will account for 3 percent more of the projected global anthropogenic methane emissions annually.

CH4 is the second most prevalent GHG emitted in the United States from human activities. In 2013, CH4 accounted for about 10 percent of all US GHG emissions from human activities. CH4 is emitted by natural sources such as wetlands, as well as human activities such as leakage from natural gas systems and the raising of livestock. Natural processes in soil and chemical reactions in the atmosphere help remove CH4 from the atmosphere. Methane’s lifetime in the atmosphere is much shorter than CO2, but CH4 is more efficient at trapping radiation than CO2. Pound for pound, the comparative impact of CH4 on climate change is 25 times greater than CO2 over a 100-year period.

Here is a graph which illustrates the sources of US CH4 emissions:

Figure 03

CH4 is emitted from industry, agriculture, and waste management activities, described below:

  • IndustryNatural gas and petroleum systems are the largest source of CH4 emissions from industry in the United States. Methane is the primary component of natural gas. Some CH4 is emitted to the atmosphere during the production, processing, storage, transmission, and distribution of natural gas. Because gas is often found alongside petroleum, the production, refinement, transportation, and storage of crude oil is also a source of CH4 emissions;
  • AgricultureDomestic livestock such as cattle, buffalo, sheep, goats, and camels produce large amounts of CH4 as part of their normal digestive process. Also, when animals’ manure is stored or managed in lagoons or holding tanks, CH4 is produced. Because humans raise these animals for food, the emissions are considered human-related. Globally, the Agriculture sector is the primary source of CH4 emissions; and
  • Waste from Homes and Businesses: CH4 is generated in landfills as waste decomposes and in the treatment of wastewater. Landfills are the third largest source of CH4 emissions in the United States.

CH4 is also emitted from a number of natural sources. Wetlands are the largest source, emitting CH4 from bacteria that decompose organic materials in the absence of oxygen. Smaller sources include termites, oceans, sediments, volcanoes, and wildfires.

The Obama administration announced on 18 August 2015 an ambitious new goal to cut CH4 emissions from the oil and gas sector by 40-45 percent from 2012 levels by 2025. Achieving this goal would save up to 180 billion cubic feet of wasted natural gas in 2025 — enough to heat more than 2 million homes for an entire year.

The United States is now the largest oil and natural gas producer in the world, and developing these cleaner-burning fuel sources to light and heat American homes and businesses is crucial to the President’s energy strategy. But while these important energy sources produce less carbon pollution overall, CH4 leaks throughout the oil and gas system are fueling climate change — and wasting valuable fuel that should be captured and used.

The steps announced were also a sound economic and public health strategy because reducing CH4 emissions means capturing valuable fuel that is otherwise wasted and reducing other harmful pollutants – a win for public health and the economy.   Here are the highlights of the proposed steps:

  1. Standards for Methane and Ozone-Forming Emissions from New and Modified Sources:  In 2012, the Environmental Protection Agency (EPA) laid a foundation for further action when it issued standards for volatile organic compounds (VOC) from the oil and natural gas industry.  These standards, when fully implemented, are expected to reduce 190,000 to 290,000 tons of VOC and decrease methane emissions in an amount equivalent to 33 million tons of carbon pollution per year. The standards not only relied on technologies and practices already in widespread use in the oil and gas sector, but also incorporated innovative regulatory flexibility.  Along with a rule to streamline permitting of oil and gas production on certain tribal lands, this approach ensured that important public health and environmental protections could be achieved while oil and gas production continued to grow and expand;
  2. New Guidelines to Reduce Volatile Organic Compounds: EPA will develop new guidelines to assist states in reducing ozone-forming pollutants from existing oil and gas systems in areas that do not meet the ozone health standard and in states in the Ozone Transport Region. These guidelines will also reduce CH4 emissions in these areas. The guidelines will help states that are developing clean air ozone plans by providing a ready-to-adopt control measure that they can include in those plans;
  3. Consider Enhancing Leak Detection and Emissions Reporting: EPA will continue to promote transparency and accountability for existing sources by strengthening its GHG Reporting Program to require reporting in all segments of the industry. In addition to finalizing the updates to the program EPA has already proposed by the end of 2015, EPA will explore potential regulatory opportunities for applying remote sensing technologies and other innovations in measurement and monitoring technology to further improve the identification and quantification of emissions and improve the overall accuracy and transparency of reported data cost-effectively;
  4. Lead by Example on Public Lands:  The Department of Interior’s Bureau of Land Management (BLM) will update decades-old standards to reduce wasteful venting, flaring, and leaks of natural gas, which is primarily CH4, from oil and gas wells.  These standards, to be proposed this spring, will address both new and existing oil and gas wells on public lands. This action will enhance the energy security and economy by boosting America’s natural gas supplies, ensuring that taxpayers receive the royalties due to them from development of public resources, and reducing emissions. BLM will work closely with EPA to ensure an integrated approach;
  5. Reduce CH4 Emissions while Improving Pipeline Safety: The Department of Transportation’s Pipeline and Hazardous Materials Safety Administration (PHMSA) will propose natural gas pipeline safety standards in 2015.  While the standards will focus on safety, they are expected to lower methane emissions as well;
  6. Drive Technology to Reduce Natural Gas Losses and Improve Emissions Quantification:  The President’s FY16 Budget will propose $15 million in funding for the Department of Energy (DOE) to develop and demonstrate more cost-effective technologies to detect and reduce losses from natural gas transmission and distribution systems.  This will include efforts to repair leaks and develop next generation compressors. The President’s budget will also propose $10 million to launch a program at DOE to enhance the quantification of emissions from natural gas infrastructure for inclusion in the national GHG Inventory in coordination with EPA;
  7. Modernize Natural Gas Transmission and Distribution Infrastructure:  DOE will continue to take steps to encourage reduced emissions, particularly from natural gas transmission and distribution, including:
  • Issuing energy efficiency standards for natural gas and air compressors;
  • Advancing research and development to bring down the cost of detecting leaks;
  • Working with FERC to modernize natural gas infrastructure; and
  • Partnering with NARUC and local distribution companies to accelerate pipeline repair and replacement at the local level.

8.  Release a Quadrennial Energy Review (QER):  The Administration will soon release the first installment of the QER, which focuses specifically on policy actions that are needed to help modernize energy transmission, storage, and distribution infrastructure. This installment of the QER will include additional policy recommendations and analysis on the environmental, safety, and economic benefits of investments that reduce natural gas system leakage;

9. Industry Actions to Reduce CH4 Emissions:  Several voluntary industry efforts to address these sources are underway, including EPA’s plans to expand on the successful Natural Gas STAR Program by launching a new partnership in collaboration with key stakeholders later in 2015.   EPA will work with DOE, DOT, and leading companies, individually and through broader initiatives such as the One Future Initiative and the Downstream Initiative, to develop and verify robust commitments to reduce methane emissions.  This new effort will encourage innovation, provide accountability and transparency, and track progress toward specific methane emission reduction activities and goals to reduce methane leakage across the natural gas value chain.

Voluntary efforts to reduce emissions in a comprehensive and transparent manner hold the potential to realize significant reductions in a quick, flexible, cost-effective way. Achieving significant CH4 reductions from these voluntary industry programs and state actions could reduce the need for future regulations. The Administration stands ready to collaborate with these and other voluntary efforts, including in the development of a regime for monitoring, reporting and verification; and

10. Building on Progress:  Today’s announcement builds on the “Strategy to Reduce CH4 Emissions” released in March 2014. Since its release, the Administration has taken a number of actions to set us on a course to reduce methane emissions from the oil and gas sector and other sources:

  • DOE has launched a new initiative that will make up to $30 million available to develop low-cost highly sensitive technologies that can help detect and measure methane emissions from oil and gas systems. Just last month, DOE announced the 11 innovative projects selected;
  • DOE convened a series of roundtable discussions with leaders from industry, environmental organizations, state regulators, consumer groups, academia, labor unions, and other stakeholders.  The meetings culminated in July 2014, with the creation of an Initiative to Modernize Natural Gas Transmission and Distribution Infrastructure that laid out a series of executive actions, partnerships, and stakeholder commitments to help modernize the nation’s natural gas transmission and distribution systems, increase safety and energy efficiency and reduce methane emissions;
  • The USDA, EPA and DOE, in partnership with the dairy industry, released a Biogas Opportunities Roadmap in August 2014 highlighting voluntary actions to reduce CH4 emissions through the use of bio-digesters;
  • BLM released an Advanced Notice of Proposed Rulemaking (ANPRM) in April 2014 to gather public input on the development of a program for the capture and sale, or disposal, of waste methane from coal mines on public lands; and
  • EPA proposed updates to its 1996 New Source Performance Standards for new municipal solid waste landfills and sought public feedback on whether EPA should update guidelines for existing landfills in June 2014, which they anticipate finalizing this year.

The rules represent President Obama’s first big climate push on the oil and gas sector, after moving to cut emissions from power plants and, during his first term, cars and trucks.  Unfortunately, the clock is ticking. Any new EPA regulations would have to be finalized by the end of 2016 – and Republicans in Congress and industry lobby groups are already mobilizing to oppose the standards.

Figure 04

Unlike the power plant rules, which left industry a fair amount of latitude in cutting emissions, the CH4 standards are believed to be tightly focused on plugging leaks.  The new rules could directly target leaking valves and other equipment that allow methane to escape from wells, pipelines and other infrastructure.

Figure 05

The new rules could also be backed up with voluntary guidelines for other types of air pollutants that would also lower methane emissions.

“If you take steps to reduce volatile organic compounds, those steps would automatically have the secondary benefit of reducing CH4 emissions,” said Sandra Snyder, an environmental attorney at the Bracewell Giuliani law firm.

Oil and gas companies oppose the proposals, calling them unnecessary and costly, while environmental advocacy groups say they do not go far enough because they apply mainly to new wells and not most existing ones.

According to the New York Times, Janet McCabe, the Environmental Protection Agency’s acting assistant administrator for the Office of Air and Radiation, said the rules were designed to ensure that oil and gas companies reduced waste and sold more gas that would otherwise be lost, while protecting the climate and the health of the public.  Ms. McCabe estimated that the proposals — which would require drillers to stop leaks and capture lost gas even in wells intended to extract only oil — would cost the industry up to $420 million to carry out by 2025, but that there would be savings, including reduced waste, of as much as $550 million during that period, bringing a net benefit of as much as $150 million.


  1. Global Methane Initiatives: Global Methane Emissions and Mitigation Opportunities;
  2. EPA: Global Greenhouse Gas Emissions Data;
  3. EPA: Overview of Greenhouse Gases;
  4. The Whitehouse: New Actions to Reduce Methane Emissions;
  5. The Whitehouse: Fact Sheet – Administration Takes Steps Forward on Climate Action Plan;
  6. The Guardian: Brock Obama moves to cut US methane emissions; and
  7. The New York Times: EPA Announces New Rules to Cut Methane Emissions.