why is being energy efficient so important?

Question: why is being energy efficient so important?
- Keywords:
  energy efficient
Asked by katyandlibs on 30 Jan 2017.
- Petra Cameron answered on 30 Jan 2017:
  
  We need to be energy efficieny as most of the ways humans create energy involve releasing CO2 and other green house gases to the environment. We need to drastically reduce the amount of CO2 we produce to avoid the worst of global warming.

Question: why is being energy efficient so important?