Removal of carbon dioxide
- Carbon dioxide is a water soluble gas (it is the gas used in fizzy drinks) and dissolves readily
- There were high concentrations of carbon dioxide in the early atmosphere
- ,The levels of carbon dioxide have decreased because:
- When the water vapour in Earth’s early atmosphere condensed, large amounts of CO2 dissolved in the oceans
- Carbonates were precipitated during this process which later formed sediments on the seabed
- Green plants and algae began to evolve and absorbed considerable amounts of carbon dioxide during photosynthesis
- Animals fed on the plants which transferred carbon to their tissues including bones and shells and when these organisms died, their remains formed sedimentary rocks
- Dead organisms turn into fossil fuels, such as crude oil, natural gas and coal which 'locked up' the carbon
Examiner Tip
Giving reasons for why carbon dioxide levels decreased is a common exam question so make sure you learn the reasons!
