why won’t the carbon dioxide levels decrease if there are more people in the earth and starting to be less plants that

Question: why won't the carbon dioxide levels decrease if there are more people in the earth and starting to be less plants that can give out oxygen? Will there eventually be no oxygen?
- Keywords:
  carbon,
  Co2,
  earth,
  oxygen
Asked by embmay to Amy, Drew, Julia, Kimberley, Sara on 22 Jun 2011.
- Amy MacQueen answered on 21 Jun 2011:
  
  I’m not sure I understand quite what you mean – the more people there are the more carbon dioxide there would be (as we breathe it out). Plants take it in so the less plants there are the less carbon dioxide gets re-absorbed (why cutting the rainforest down is a bad idea – its a carbon sink!).
  
  Is this what you meant?
- Julia Griffen answered on 21 Jun 2011:
  
  So plants take in carbon dioxide and give out oxygen. So I see where you’re coming from less plants so less CO2 will be taken in so less oxygen given off??
  
  We wont run out of oxygen because there is so much of it it our atmosphere.
  
  The problem with CO2 is that its causes climate change and global warming.
  
  Humans breathe in oxygen and give out carbon dioxide, so if anything carbon dioixde levels will increase not decrease, as populations of countries are rapidly increases across the world!
  
  Hope that kinda answers your Q!
- Sara Imari Walker answered on 22 Jun 2011:
  
  Hi embmay! As Amy and Julia have said, plants thrive on CO2 and release oxygen. So yes less plants means less oxygen for us. But more CO2 from us means happier plants! (to a point).
  
  Also, interesting fact – most of the oxygen on Earth actually doesn’t come from plants but instead from little photosynthesizing bacteria called cyanobacteria. They live everywhere, but a lot of them are in the oceans – this is one reason healthy oceans are important for us to have a healthy planet. In fact, the only reason we have any oxygen at all, enabling us to appear as oxygen breathing animals, is because of little microbes like modern cyanobacteria. The Earth had little oxygen until about 2.5 billion years ago when these guys invented photosynthesis! (Or I should say till photosynthesis evolved). That enabled more complex life to come a long like us.
  
  The atmosphere of the Earth is really dependent on the life it harbors, its a delicate balance. So we don’t want to throw it too far off! (Although Earth will recover, we may not!).
  
  Great question!