What are Greenhouse Gas Emissions?

Emissions are substances released into the air. When we're talking about greenhouse gas emissions, or GHGs, the main emissions are water vapor (H20), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulfur hexafluoride (SF6).

These gases get their name because they trap solar energy (heat) and prevent the sun's energy from bouncing back into space. This creates a “greenhouse effect”, similar to what a blanket does when you're sleeping at night. It traps your body heat to keep you warm. Human activities have largely led to the high concentrations of greenhouse gases and climate change we see now.

Each gas has a different lifespan. According to the EPA, CO2 can last in our atmosphere for thousands of years, though some is quickly captured by our oceans. Methane, which has a global warming potential 28 times more than carbon dioxide, will stay in our atmosphere for about 10 years before it is converted into CO2. Nitrous oxide has a warming potential 265 times more than CO2, lasting 121 years in our atmosphere. 

Sources of Greenhouse Gas Emissions


Energy use and production, followed by agriculture, are the largest sources of emissions worldwide. In the United States, transportation is responsible for 29 percent of emissions, while energy is responsible for 28 percent. Agriculture produces 9 percent of America's GHGs. Carbon dioxide from burning fossil fuels accounts for about three-fourths of current total greenhouse gas emissions.

What do Greenhouse Gas Emission do?

  • create conditions that cause further warming, such as higher evaporation rates and a wetter atmosphere
  • create conditions for increased ozone, smog and heat waves that worsen respiratory disease, asthma and other health issues
  • change the ocean’s chemistry through ocean acidification, making it harder for marine animals to survive and sustain crucial global food webs

Our Future with Greenhouse Gas Emissions

We cannot reverse some changes resulting from releasing greenhouse emissions into our atmosphere. Thousands of years from now, about 20 percent of recent human-caused carbon dioxide emissions will still be in the atmosphere.

Clean technologies and energy conservation strategies have proven to be effective solutions for households, businesses and municipalities. For example, from 1990 to 2014 in the United States, increased energy efficiency and structural changes in the economy contributed to a 40 percent decline in greenhouse gas emissions per dollar of GDP. Such initiatives require political, financial and personal efforts from the public to put them into place globally.


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