The Greenhouse Effect
CO2 and Methane trap heat in the atmosphere
What this lesson covers
Why it matters
Burning coal glows red, releasing invisible carbon dioxide that traps heat like a blanket. This simple combustion reaction is the primary driver of global warming.
Predict first
Which pair of gases traps infrared heat in the atmosphere?
Carbon dioxide and methane absorb infrared radiation and re-radiate it back down. Nitrogen, oxygen and the noble gases let it pass straight through — abundance isn't what matters, molecular structure is.
- CO₂ and CH₄ — correct
- N₂ and O₂
- Argon and helium
What you do
Put the steps of the greenhouse effect in order — follow one ray of sunlight from space to a warmer planet.
Check yourself
Where does most of the CO₂ driving the greenhouse effect come from?
Combustion of carbon-based fuels releases CO₂; photosynthesis removes it. The industrial-era rise comes overwhelmingly from fossil-fuel burning.
Why is CO₂ considered a greenhouse gas in this context?
CO₂ is a greenhouse gas because it absorbs and traps infrared (heat) radiation. Being a product of fossil-fuel combustion is its source, not the reason it traps heat.
Methane (CH₄) is also a greenhouse gas. Which everyday source releases it?
Methane comes largely from agriculture — livestock digestion and waterlogged rice paddies — and from natural-gas leaks.
- Burning fossil fuels like coal and petrol (C + O₂ → CO₂) — correct
- Volcanoes alone
- Plants during photosynthesis
- It absorbs and traps infrared (heat) radiation from the Earth — correct
- It is heavier than air
- It is toxic to breathe
- Cattle digestion and paddy fields — correct
- Car exhaust only
- The ozone layer