Puget Sound Clean Air Agency

What is Climate Change?

Climate change refers to the various impacts of an ever-warmer planet, brought on by increased levels of greenhouse gases in our atmosphere. In the Puget Sound region, scientists no longer debate whether climate change is occurring, but wonder how greatly we will be impacted. They predict that unless we change our patterns today, the damage we are doing to our ecosystem will be irreversible.

What is the greenhouse effect?

The ‘greenhouse effect’ is a natural process in the earth’s atmosphere that helps retain solar heat, keeping the Earth’s temperature warm enough to support life. Energy from the sun is absorbed by the Earth’s surface. Some of this energy is then radiated back into the atmosphere, heating up the air. Some of the greenhouse gases interact with that energy and ‘trap’ the radiated heat, helping to further raise the temperature of the atmosphere and the Earth’s surface. Increases in these greenhouse gases increase the amount of heat trapped by the atmosphere and cause overall warming of the planet. This warming is referred to as global warming. The various impacts from global warming are referred to as climate change.

Photo/chart: The greenhouse effect, courtesy EPA

Additional climate change resources :

What are greenhouse gases and where do they come from?
The major greenhouse gases include ozone, carbon dioxide, methane, nitrous oxide, and hydrofluorocarbons. They come from both natural processes as well as human activities, though increases in the human-made greenhouse gases are most responsible for disrupting the balance of the atmosphere.

Greenhouse gas

Natural origins

Man-made origins

Ozone (O3)

Occurs naturally in upper layers of the atmosphere

Transportation, industry.
Formed when exhaust from automobiles or industrial activities reacts with sunlight (smog).

Carbon dioxide (CO2)

Occurs naturally in the atmosphere, and through respiration (breathing) of plants and animals.


Combustion of fossil fuels:

  • Exhaust from motor vehicles
  • Burning
  • Industrial activities (power plants)

Methane (CH4)

  • Decomposition of organic matter
  • Marshes

Agricultural activities (livestock, rice paddies)

Nitrous oxide (N2O)

Naturally emitted from soils and oceans

  • Agricultural activities (soil cultivation, use of nitrogen fertilizers)
  • Exhaust from motor vehicles


Sources of greenhouse gases in region

CO2 Equivalents, Inventory for year 2002


Chart: Sources of greenhouse gases in region: CO2 Equivalents, Inventory for year 2002


What are the greatest sources of greenhouse gas emissions in the Puget Sound region?
Cars, trucks, ships, planes, trains and other motor vehicles contribute the vast majority of greenhouse gas emissions in our region, followed by electricity generation.

  • Industry (Process) — including cement and lime manufacture

  • Industry (Energy)— natural gas turbines, etc.

  • Agriculture, Forestry and Solid Waste— methane from landfills, dairy farm waste and decomposing waste

  • Commercial— heating and air conditioning, gas appliances, hot water heating

  • Residential— same as above

  • Electricity generation— non-hydroelectric generated power (primarily natural gas and nuclear power)

  • Transportation— combustion of fossil fuels from cars, trucks, buses, aircraft, construction equipment, recreational vehicles, boats and ferries, as well as off-road sources such as construction equipment