Positive Feedback

• There are limits to this negative feedback.

  • Water also acts as a greenhouse gas. Too much water in the atmosphere can cause the temperature to rise further.
  • If it gets hot enough, water stops condensing. No rain.
  • Without rain, there is no erosion to help remove CO2 from the atmosphere.
  • CO2 from volcanoes starts to build up, increasing temperatures further.
  • More water evaporates, increasing temperatures further.
  • Eventually the oceans evaporate entirely.
  • Water in the atmosphere is broken into hydrogen and oxygen.
  • The hydrogen escapes, oxygen combines with minerals, no water remains.

• This is what happened to Venus. Runaway greenhouse

Notes: