GCSE Combined Science (AQA)

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The Early Atmosphere: Carbon Dioxide

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Chemistry of the atmosphere The composition and evolution of the Earth's atmosphere

The Early Atmosphere: Carbon Dioxide

6:40 Changes in Earth's Atmosphere Over Time
Spec 4.9.1.4
Previous The Early Atmosphere: Oxygen Next Greenhouse Effect
  • Early atmosphere was mostly carbon dioxide.
  • Scientists believe more than three quarters of the early atmosphere was carbon dioxide, with the remainder being methane, nitrogen, and ammonia.
  • Over time, the amount of carbon dioxide decreased significantly.
  • Present atmosphere contains only about 0.04% carbon dioxide, with nitrogen and oxygen being more prominent.
  • Formation of sedimentary rocks removed carbon dioxide from the atmosphere.
  • Oceans and lakes formed from water vapor, dissolving carbon dioxide to form carbonate compounds like calcium carbonate.
  • Carbonates, being insoluble, settled as sediments or became part of sea creatures' skeletons and shells.
  • Over millions of years, some sediment turned into limestone, a sedimentary rock mostly consisting of calcium carbonate.
  • Algae and plants decreased carbon dioxide through photosynthesis, converting it to oxygen.
  • Fossil fuels formation removed carbon dioxide from the atmosphere.
  • Fossil fuels include coal, oil, and natural gas, which are major energy resources.
  • Coal is a sedimentary rock that can be burnt for energy.
  • Oil is refined into petrol or diesel for vehicles.
  • Natural gas is used for heating and cooking.
  • Coal formed from trees and plants in dense forests and wetlands, buried under sediment preventing oxidation.
  • Over millions of years, compression and heating turned plant matter into coal.
  • Crude oil and natural gas formed from oceanic plants and tiny animals buried under sediment.
  • Heat and pressure converted remains into crude oil and natural gas over millions of years.
  • Today, these resources are extracted by drilling into the ocean.

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