A greenhouse gas is a gas that absorbs and emits thermal infrared radiation in the atmosphere. The greenhouse effect is caused by this process. Water vapor, CO2, methane, nitrous oxide, and ozone are the major Earth-bound greenhouse gases.

Greenhouse gases and the greenhouse effect

How does the greenhouse effect work?

The greenhouse effect is an essential natural process that heats the Earth’s surface. When light energy reaches the planet’s atmosphere, some of it is reflected back into space and some of it is absorbed and re-emitted as infrared radiation.

Other greenhouse gases and CO2 absorb this infrared radiation, keeping the heat in the atmosphere and causing temperatures to rise.

The greenhouse effect is essential for human life on Earth. Without it, the planet would be too cold to sustain life. However, human activities are causing the greenhouse effect to intensify, resulting in more extreme weather and climate change.

What are greenhouse gases?

Greenhouse gases are basically chemical molecules in the atmosphere that absorb and retain infrared radiation from the Sun.

Carbon dioxide, water vapor, methane, and nitrous oxide, are some of the greenhouse gases.

An increase in human activities is adding to the total number of greenhouse gases, effectively strengthening the greenhouse effect.

The major source of greenhouse gases produced by humans is the combustion of fossil fuels like natural gas, coal, and oil.

Unfortunately, we humans are also contributing to greenhouse gas emissions including deforestation, agriculture, and the production and use of certain chemicals and materials.

What are the specific greenhouse gases?

Believe it or not, water vapor is the most common of the greenhouse gases in our atmosphere, but the good thing is, that it doesn’t stay in the atmosphere long.

Water vapor molecules eventually condense to form clouds, which eventually reenter our atmosphere as rain (precipitation).

While water vapor plays an important role in the greenhouse effect, it is not considered a pollutant because it is a natural component of the atmosphere.

The most significant man-made greenhouse gas is carbon dioxide (CO2). It’s released when fossil fuels are burned, and it remains in the atmosphere for a long time.

Methane (CH4) is another important greenhouse gas. It is released into the atmosphere through natural processes like decomposition and livestock farming, as well as human activities like coal mining and the production and use of natural gas.

Nitrous oxide (N2O) is a greenhouse gas that is released into the atmosphere when nitrogen-containing fertilizers are used in agriculture and when combustion engines burn fossil fuels.

Chlorofluorocarbons (CFCs) are man-made chemicals that were once widely used in refrigerators, air conditioners, and aerosol cans.

CFCs rise into the stratosphere, where they break down ozone molecules and release chlorine atoms.

Ozone (O3) is a naturally occurring gas in the Earth’s atmosphere. The ozone molecules are absorbed by the ultraviolet light emitted from the sun, which eventually protects the earth.

While ozone in the upper atmosphere is beneficial, ground-level ozone pollution is a health hazard.

Ground-level ozone is formed when emissions from cars and industrial facilities react with sunlight.

Sources Of Greenhouse Gases

  • Agriculture.
  • Commercial/Residential.
  • Electricity.
  • Industry.
  • Land Use/Forestry.
  • Transportation.


The majority of our power is generated from the combustion of fossil fuels, especially coal and natural gas.

The second greatest source of greenhouse gases is electricity generation (25% of 2020 carbon dioxide emissions).


Transportation is a major source of greenhouse gas emissions, accounting for about 30% of total United States emissions in 2020.

The majority of these emissions come from light-duty vehicles such as cars and SUVs.


The third sector (24% of 2020 greenhouse gas emissions) – The industry’s main sources of greenhouse gases include burning fossil fuels for energy and releasing greenhouse gases as a result of certain chemical reactions required to manufacture items from raw materials.


Commercial/Residential buildings are responsible for approximately 12% of greenhouse gas emissions.

The combustion of fossil fuels for space heating and water heating is the largest contributor to these emissions.


Agriculture is a significant source of greenhouse gases, accounting for about 11% of total U.S. emissions in 2020.

Methane and nitrous oxide emissions come from agricultural activities such as livestock farming and the application of nitrogen-containing fertilizers.

Land Use/Forestry

The use of wood in the land, agricultural, and forestry applications (23% of 2020 greenhouse gas emissions) – Clearing and burning forests releases carbon dioxide and other heat-trapping gases into the atmosphere.

Trees also play an important role in absorbing atmospheric carbon dioxide, so deforestation can exacerbate climate change.


What are the sources of fluorinated gases?

Fluorinated gases are gases that nearly all contain fluorine. The majority of greenhouse gases that contain fluorine are man-made, and they are used in a variety of applications such as refrigeration, air conditioning, and insulation.

Will methane stay in the atmosphere for a long time?

Methane is a highly powerful greenhouse gas, but it does not last as long in the atmosphere as carbon dioxide. In the atmosphere, methane decomposes into water vapor and CO2, with an atmospheric lifetime of roughly 12 years.

Will water vapor cause climate change?

Water vapor is the most common greenhouse gas in the atmosphere, but it does not create climate change on its own. Water vapor has a brief atmospheric existence of only 10 days, so it cannot build up in the air like carbon dioxide can.

What are CFCs?

Chlorofluorocarbons (CFCs) are man-made chemicals that were once widely used in refrigerators, air conditioners, and spray cans. CFCs rise into the stratosphere, where they break down ozone molecules and release chlorine atoms.

What is the Montreal Protocol?

The Montreal Protocol is an international agreement that was created to reduce the use of CFCs and other ozone-depleting chemicals. The convention has been successful in lowering CFC output, and it is credited with playing a role in repairing the ozone layer.

What are HFCs?

Hydrofluorocarbons (HFCs) are man-made chemicals that are used as substitutes for CFCs in refrigeration and air conditioning. HFCs don’t damage the ozone layer, but they are powerful greenhouse gases.

What is the LULUCF sector?

The LULUCF sector (Land Use, Land-Use Change, and Forestry) refers to activities that involve the management of forests, cropland, and grassland. These activities can either remove carbon dioxide from the atmosphere (such as through deforestation) or release it into the atmosphere (such as through wildfires).

Will the ozone layer protect us from greenhouse gases?

The Earth’s ozone layer protects us from the sun’s harmful ultraviolet radiation. Because the ozone layer does not absorb greenhouse gases, it is ineffective in preventing climate change.

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