How living things changed Earth

• How have living things change Earth?

  • Photosynthesis
  • Evapotranspiration
  • Carbon sequestration
  • Biogeochemical cycles
• Photosynthesis:

  • Cyanobacteria and archaea
  • produces O2 used for aerobic respiration
  • produces O3 building up an Ozone layer, decreasing DNA damage from UV so land can be colonised
• Evapotranspiration:

  • Water evaporates from the ocean to form clouds
  • Clouds move from an area of high pressure and evaporation to an area of low pressure - over the land
  • They precipitate over land, adding water to the soil
  • This makes this coastal area have enough water to be in plants range of tolerance so plants begin to grow there
  • Evapotranspiration from plants forms clouds, which move to a low pressure area further in land where they precipitate, extending the area plants can grow.
  • This is a positive feedback loop
• Carbon sequestration:

  • photosynthesis sequesters carbon dioxide from the atmosphere, decreasing temperatures and stabilising temperature.
  • Stable temperatures allow life to form, biodiversity is higher in rainforests (which have experienced stable temperatures for a very long time) than in polar regions (unstable temperature)
• Biogeochemical cycles:

  • carbon, nitrogen, phosphates
  • organisms use and move lots of chemicals
  • recycling nutrients