GCSE Chemistry · Edexcel 1CH0 · Topic 8B
Earth and atmospheric science
Key points
- The early atmosphere came from volcanoes: mostly carbon dioxide and water vapour, with little or no oxygen.
- Water vapour condensed to form oceans, which dissolved carbon dioxide; later, photosynthesis by plants and algae added oxygen.
- Test for oxygen: it relights a glowing splint.
- Greenhouse gases (carbon dioxide, methane, water vapour) absorb heat radiated from the Earth, keeping it warm.
- Human activities (burning fossil fuels, farming, deforestation) have increased greenhouse gases. There is a correlation between rising CO₂ and global temperature, giving climate change.
- Effects: sea level rise, extreme weather, habitat change. Reduce it with renewable energy, efficiency and carbon capture.
- Historical climate data is less accurate than modern measurements.
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Earth's atmosphere has not always been the mixture of nitrogen and oxygen we breathe. These notes tell the story of how it changed over billions of years, and how human activity is now changing it again by adding greenhouse gases.
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