Common Green House Gases (GHGs) and their Impact to our environment

Greenhouse gases (GHGs) are gases in the Earth’s atmosphere that trap heat and help keep the planet warm enough to support life.

Definition of GHGs:

Greenhouse gases are atmospheric gases that absorb and emit infrared radiation, causing the greenhouse effect — a natural process that warms the Earth’s surface.

How It Works:

1. The Sun’s energy reaches Earth as sunlight (shortwave radiation).

2. The Earth absorbs some of this energy and re-emits it as heat (longwave infrared radiation).

3. Greenhouse gases absorb and re-radiate some of this heat back toward the surface, preventing it from escaping into space.

4. This process keeps the Earth’s atmosphere about 33°C warmer than it would otherwise be.
   

Major Greenhouse Gases:

• Carbon dioxide (CO₂) – from burning fossil fuels, deforestation

• Methane (CH₄) – from livestock, landfills, natural gas

• Nitrous oxide (N₂O) – from fertilizers and agriculture

• Fluorinated gases (F-gases) – from industrial and refrigeration processes

• Water vapor (H₂O) – naturally occurring but influenced by climate feedbacks

⚠️ Why It Matters:

While natural greenhouse gases are essential for life, excess concentrations from human activities intensify the greenhouse effect, leading to global warming and climate change.

🌍 1. Carbon Dioxide (CO₂)

Main sources:

• Burning fossil fuels (coal, oil, natural gas) for electricity, heating, and transportation

• Deforestation — trees absorb CO₂, so cutting them down reduces carbon storage

• Industrial processes (cement production, steelmaking)

• Wildfires and land-use changes

  
  

Notes:CO₂ is the largest contributor to human-caused global warming. It can remain in the atmosphere for hundreds to thousands of years.

🔥 2. Methane (CH₄)

Main sources:

• Agriculture — especially cattle, sheep, and rice paddies

• Landfills and waste decomposition

• Fossil fuel production and transport — leaks from oil, gas, and coal operations

• Wetlands (natural source)

  
  

Notes:Methane is much more potent than CO₂ — about 28–36 times stronger at trapping heat over a 100-year period — but lasts only about 12 years in the atmosphere.

🏭 3. Nitrous Oxide (N₂O)

Main sources:

• Agricultural activities — use of nitrogen-based fertilizers is the biggest contributor

• Manure management

• Industrial processes (chemical manufacturing)

• Combustion of fossil fuels and biomass

  
  

Notes:N₂O is ≈265 times more powerful than CO₂ over 100 years and contributes to both global warming and ozone depletion.

⚙️ 4. Fluorinated Gases (F-gases)

Includes: Hydrofluorocarbons (HFCs), Perfluorocarbons (PFCs), Sulfur Hexafluoride (SF₆), Nitrogen Trifluoride (NF₃)

Main sources:

• Refrigeration and air conditioning systems

• Electronics manufacturing

• Aluminum and semiconductor industries

• Electrical transmission equipment (especially SF₆)

  
  

Notes:Though present in smaller quantities, these gases can have global warming potentials thousands of times higher than CO₂, and some persist in the atmosphere for thousands of years.

Summary Table

Greenhouse Gas	Main Human Sources	Relative Warming Power (vs. CO₂)	Approx. Atmospheric Lifetime
Carbon Dioxide (CO₂)	Fossil fuel use, deforestation	1	Hundreds–thousands of years
Methane (CH₄)	Agriculture, landfills, fossil fuels	28–36	~12 years
Nitrous Oxide (N₂O)	Fertilizers, livestock, industry	265	~120 years
Fluorinated Gases (F-gases)	Refrigerants, manufacturing	100–23,500	Decades–thousands of years

References & Additional Readings:

1. https://www.hko.gov.hk/en/wxinfo/climat/greenhs/e_grnhse.htm

2. https://science.nasa.gov/climate-change/faq/what-is-the-greenhouse-effect/

3. https://www.epa.gov/ghgemissions/overview-greenhouse-gases

4. https://www.epa.gov/ghgemissions/understanding-global-warming-potentials

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