CO2e: 3.3 kg per kg (2 days, 5 hours)
Reference 1: http://www.york.ac.uk/sei/projects/completed-projects/york-ecological-footprint/
A Material Flow Analysis and Ecological Footprint of York
3.31 tonnes Co2e per tonne of cardboard.
In addition cardboard needs land to grow. According to refererence 1, one tonne requires
1.124 hectares per tonne of forestry lane (which is 1.78 times average productivity).
But is cardboard sequestered carbon or does it rot to MethAne in landfill??