U.S. Department of Energy - Energy Efficiency and Renewable Energy
Federal Energy Management Program
Greenhouse Gas Basics
Federal agencies must understand key terms and management basics to successfully manage greenhouse gas (GHG) emissions.
Greenhouse gases correlate directly to global warming, which impacts arctic sea ice. This image shows current arctic sea ice formation. The red outline depicts arctic sea ice boundaries in 1979.
Greenhouse gases are trace gases in the lower atmosphere that trap heat through a natural process called the "greenhouse effect." This process keeps the planet habitable. International research has linked human activities to a rapid increase in GHG concentrations in the atmosphere, contributing to major shifts in the global climate.
The information below outlines greenhouse gas basics across the following categories:
Types of Greenhouse Gases
Greenhouse gases are defined in two categories; naturally occurring and manmade (also known as anthropogenic emissions). Ice core samples indicate that concentrations of naturally occurring GHGs have remained relatively steady for thousands of years (fluctuating within a range of 100 parts per million (ppm) of naturally occurring carbon dioxide over the last 400,000 years). Among others, these naturally occurring GHGs include:
- Carbon dioxide (CO2)
- Methane (CH4)
- Nitrous oxide (N2O).
Manmade greenhouse gases are a particular problem as they remain in the atmosphere for thousands of years and can be thousands of times more effective at trapping heat. Among others, these gases include:
- Perfluorocarbons (PFCs)
- Hydrofluorocarbons (HFCs)
- Sulfur hexafluoride (SF6).
The six gases listed above were identified in Executive Order (E.O.) 13514 as the major contributors to global climate change. Other greenhouse gases exist, including nitrogen trifluoride (NF3), which is receiving increasing attention across the globe due to its high global warming potential.
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Burning fossil fuels, increased agriculture, and deforestation all emit natural greenhouse gases and are concerning due to their contribution to increased concentrations of these greenhouse gases. Human activities also increase GHG emissions that are not naturally occurring in the atmosphere. These activities include semiconductor manufacturing, refrigerant leaks, and other industrial sources. The high level of greenhouse gases trap heat close to the surface of the earth, contributing to major shifts in the global climate.
Figure 1: Common sources of greenhouse gas emissions from Federal facilities typically fall into one of three scopes. Other greenhouse gases exist, but these six are called out by E.O. 13514.
* Additional significant Scope 3 sources exist beyond the examples provided.
Figure 1 shows common sources of natural and artificial greenhouse gases frequently employed by Federal agencies. These sources span three commonly used scopes:
Scope 1 includes greenhouse gas emissions from sources that are owned or controlled by a Federal agency.
Scope 2 includes greenhouse gas emissions resulting from the generation of electricity, heat, or steam purchased by a Federal agency.
Scope 3 includes greenhouse gas emissions from sources not owned or directly controlled by a Federal agency but related to agency activities, such as business travel and employee commuting.
Climate change is often used interchangeably with global warming, but climate change is growing in preference because it conveys greenhouse gas impacts beyond rising temperatures. By definition, climate change refers to any significant change in measures of climate (e.g., temperature, precipitation, wind) lasting an extended period (decades or longer). Global warming is an average increase in lower atmosphere temperature that can contribute to changes in global climate patterns.
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Greenhouse Gas Management
Effective management of greenhouse gas emissions is essential to reducing the Federal Government's contribution to global climate change. Managing greenhouse gas emissions involves several steps, including:
Creating an Inventory: GHG inventories establish a baseline of emissions produced by buildings, transportation, industrial processes, agriculture, and other energy consuming/producing activities. The baseline is typically expressed in tons of carbon dioxide equivalent or MTCO2e.
Setting Goals and Milestones: With a baseline established using inventory data, the next step is setting an end goal, whether it be a reduction of GHG emissions or complete climate neutrality. Milestones should be created to help track results to the end goal.
Creating a Strategic Greenhouse Gas Management Plan: GHG management, like all energy management activities, requires a thorough plan. Creating a comprehensive portfolio of emission reduction activities ensures targeting strategic reductions across all opportunities instead of a loose collection of one-off activities. Savings will be realized during the implementation phase.
Plan Implementation: Plans will not succeed if not implemented. During the implementation process, greenhouse gas management plans are often updated based on changes in mission and incremental findings and results.
Measurement and Verification: Projects must be measured and verified to ensure emission reduction measures meet planned milestones and goals. GHG inventories should also be verified to ensure accuracy and consistency across the Federal Government. Additional resources are available on FedCenter.gov, including an inventory management plan template.
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