How the presence of life on Earth has brought about environmental change
Atmospheric carbon dioxide
- Carbon dioxide is naturally released into the atmosphere by volcanoes.
- It is an essential greenhouse gas, helping to retain heat in the atmosphere.
- Without it, the Earth would be too cold to support life.
- However, excessive carbon dioxide levels would cause temperatures to rise too high for lifw to survive.
- The light output of the Sun inceases by about 10% every billion years, so it is about 30% brighter now than when life first developed.
- If the carbon dioxide content had remained constant, then the Earth would have heated up and life would have died out, but living organisms have helped to maintain suitable atmospheric temperatures by removing carbon dioxide from the atmosphere and storing the carbon in fossil fuels and carbonate rocks such as limestone and chalk.
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