What is the greenhouse effect and how does it cause climate change?
Short answer
The greenhouse effect is the natural process by which gases in the atmosphere, such as carbon dioxide, methane and water vapour, trap some of the heat radiated by the Earth, keeping the planet warm enough for life. Human activities, mainly burning fossil fuels and deforestation, add more of these gases, which traps more heat and causes global warming.
Step by step
- Short-wave radiation from the Sun passes through the atmosphere and warms the Earth's surface.
- The Earth gives off long-wave (infrared) radiation.
- Greenhouse gases absorb some of this radiation and re-emit it, warming the lower atmosphere.
- More greenhouse gases mean more heat is trapped: the enhanced greenhouse effect.
- Consequences include rising sea levels, more extreme weather and changing rainfall patterns.
Worked example
Main human sources of greenhouse gases
- Carbon dioxide: burning coal, oil and gas; deforestation
- Methane: livestock, rice paddies, landfill
- Nitrous oxide: fertilisers
Common mistakes
- Saying the greenhouse effect is bad in itself. Without it, the Earth would be about 33 °C colder.
- Confusing climate change with the hole in the ozone layer.
- Listing effects without linking them to causes.
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