GCSE-ready- Home
- Lessons
- GCSE & IGCSE Geography A
- Climate change: causes and evidence
Climate change: causes and evidence
🎬 The doodle video for this lesson is coming soon. Subscribe on YouTube to see it first.
The climate has always changed naturally, but people are now changing it faster. You need to know both kinds of cause and the evidence.
Natural causes
Orbital changes: slow changes in the Earth's orbit and tilt over tens of thousands of years.
Volcanic eruptions: ash and gases can block sunlight and cool the planet for a short time.
Solar output: small changes in the energy the Sun gives out.
Volcanic eruptions: ash and gases can block sunlight and cool the planet for a short time.
Solar output: small changes in the energy the Sun gives out.
Human causes
The enhanced greenhouse effect: extra greenhouse gases trap more heat.
Carbon dioxide from burning fossil fuels and deforestation.
Methane from cattle farming, rice paddies and landfill.
Carbon dioxide from burning fossil fuels and deforestation.
Methane from cattle farming, rice paddies and landfill.
Evidence
Ice cores: air bubbles trapped in ice show past carbon dioxide levels and temperatures.
Tree rings: wider rings show warmer, wetter years.
Historical records: diaries, paintings and harvest dates.
Sea level and retreating glaciers show recent warming.
Tree rings: wider rings show warmer, wetter years.
Historical records: diaries, paintings and harvest dates.
Sea level and retreating glaciers show recent warming.
How do ice cores give evidence of past climate?
- Snow falls each year and builds into layers of ice.
- Tiny air bubbles are trapped in each layer.
- Scientists measure the gases in the bubbles to work out past atmosphere and temperature.
Answer: Trapped air bubbles show past gas levels and temperatures.
Natural causes: orbit, volcanoes, solar output. Human causes: carbon dioxide from fossil fuels and deforestation, methane from farming and landfill. Evidence: ice cores, tree rings, records, glaciers and sea level.
Check you have got it
Answer 6 quick questions with instant marking. If you get one wrong, GCSE-ready shows you why and gives you another go. It is free, and you do not need an account.