Greenhouse gases (GHGs) are gases which trap heat within the earth's atmosphere. According to the National Oceanic and Atmospheric Administration (NOAA), the earth's natural greenhouse effect keeps it about 60 degrees warmer than it would be otherwise.
Yet GHGs from human activity such as the burning of fossil fuel, mining, deforestation, landfills, and certain agricultural operations are known to be increasing the content of these gases (including carbon dioxide, methane, nitrous oxide and fluorinated gases) in the atmosphere. The effect is a warming global climate which is having complex impacts on many natural systems and life forms.
Many individuals, governments, businesses, and other organizations are measuring their greenhouse gas emissions, or carbon footprint, in order to determine a path toward emission reductions.
Many activities which contribute to greenhouse gas emissions include:
- burning fossil fuels - oil, gasoline, natural gas and coal
- industrial processes and mining
- landfills, septic and sewer systems
- agricultural practices, including fertilizer and manure management
- land use practices, including deforestation.
The Washington State Department of Ecology Climate Change website answers frequently asked questions and provides links to other important resources related to climate change.
City of Bellevue's Environmental Stewardship Initiative calculates the community-wide carbon footprint and that of city-specific operations (facilities, fleet, water pumps, employee commuting, etc). A link to this report, updated in 2012, is available online.