Greenhouse gases (GHGs) are gases in the Earth’s atmosphere that trap heat, preventing it from escaping into space, and thereby contributing to the greenhouse effect. They are essential for keeping the Earth warm, but excessive concentrations lead to global warming and climate change.
Major Greenhouse Gases
- Carbon Dioxide (CO₂):
- Sources: Burning fossil fuels (coal, oil, gas), deforestation, cement production.
- Most abundant anthropogenic greenhouse gas.
- Methane (CH₄):
- Sources: Livestock digestion, rice paddies, landfills, natural gas leaks.
- About 25 times more effective than CO₂ at trapping heat over 100 years.
- Nitrous Oxide (N₂O):
- Sources: Fertilizers, industrial processes, combustion of fossil fuels.
- Has a long atmospheric lifetime and strong warming potential.
- Ozone (O₃):
- Found in the upper atmosphere (stratosphere) as “good” ozone and in the lower atmosphere (troposphere) as a pollutant.
- Tropospheric ozone acts as a greenhouse gas.
- Fluorinated Gases:
- Sources: Refrigerants, air conditioning, industrial applications.
- Very potent greenhouse gases with long lifetimes but lower concentrations.
Role in the Greenhouse Effect
- These gases absorb infrared radiation emitted from Earth’s surface.
- Re-radiate heat back toward the surface, warming the atmosphere.
- Natural levels are crucial for life, but human activities have increased their concentrations, leading to global warming.