Greenhouse gases

We are working to reduce greenhouse gas emissions to protect Washington's economy and environment from the effects of climate change. We track emission sources and require large facilities and state agencies to report their emissions. We publish an inventory of greenhouse gas emissions in Washington every two years.

What are greenhouse gases?

The term "greenhouse gases," or GHGs, covers a wide variety of gases that, once they are released into the atmosphere, trap the sun’s heat. When the sun’s energy reaches the Earth's atmosphere, some of it is reflected back to space and the rest is absorbed and trapped in the lower atmosphere, heating the Earth. This is called the "greenhouse effect." Up to a point, the greenhouse effect helps keep the Earth at a temperature suitable for life. As more greenhouse gases are pumped into the atmosphere, however, the temperature increases and there's a risk of creating feedback effects that could make the Earth warmer still.

Many greenhouse gases occur naturally in the atmosphere, such as:

  • Water vapor (H2O)
  • Ozone (O3)
  • Carbon dioxide (CO2)
  • Methane (CH4)
  • Nitrous oxide (N2O)

Many other greenhouse are man-made, such as:

  • Chlorofluorocarbons (CFCs)
  •  Hydrofluorocarbons (HFCs)
  • Perfluorocarbons (PFCs)
  • Sulfur hexafluoride (SF6)

Atmospheric concentrations of both the natural and human-made gases have been rising over the last few centuries due to the Industrial Revolution, population growth, and our dependence on fossil fuels. 

Slowing climate change

Washington's Legislature recognizes the need to reduce greenhouse gas emissions in order to slow climate change and protect the state's economy and environment. In 2008, the Legislature set emission reduction targets. Washington's current targets are to:

  • Reduce total greenhouse gas emissions to 1990 levels by 2020. ​
  • ​Reduce total greenhouse gas emissions 25 percent below 1990 levels by 2035.
  • Reduce total greenhouse gas emissions 50 percent below 1990 levels by 2050.
View the text version of this image.

Sources of greenhouse gases in 2015

Sector Percent Million metric tons Description
Transportation 42.5 percent 41.4 Transportation was the largest category of greenhouse gas emissions in Washington during 2015. This category includes emissions from on-road gasoline and diesel vehicles, marine vessels, jet fuel and aviation gasoline, railroads, and natural gas used in transportation. Emissions from on-road gasoline - personal cars and trucks - contributes over half of total emissions in this category.
Residential, commercial, industrial 21.3 percent 20.7 Emissions in this sector come from burning fuels to heat our homes and workplaces, and the heat needed for industrial processes. This category includes power generated from coal, natural gas, oil, and wood. 
Electricity 19.5 percent 19.0 Worldwide, electricity generation is the largest source of carbon emissions, but the category comes in third in Washington. This category includes emissions from power generated from coal, natural gas, petroleum, and biomass and waste.
Agriculture 6.8 percent 6.6 Agricultural activities such as manure management, fertilizer use, and livestock digestion (enteric fermentation) result in methane and nitrous oxide emissions, which are measured in this category. 
Industrial processes 5 percent 5.3 This sector includes greenhouse gas emissions from industry-specific processes such as aluminum or cement manufacturing, or fugitive emissions such as sulfur hexafluoride (SF6) released from electric power transmission and distribution systems. 
Waste management 2.8 percent 3.5 This sector includes greenhouse gas emissions from landfills and wastewater treatment facilities. 
Fossil fuel industry 1 percent 0.8 This sector includes fugitive greenhouse gas emissions that are released during the production, processing, and distribution of fossil fuels. These emissions are typically fugitive methane due to leakage and venting from natural gas pipelines, and petroleum systems. 

We require facilities and state agencies to report their emissions and publish an inventory of Washington's greenhouse gases to help us design policies to reduce greenhouse gas emissions and track progress.