1. The International Energy Outlook 2016 (IEO2016).http://www.eia.gov/outlooks/ieo/ (2016) .
2. World Energy Outlook;International Energy Agency, 2015.
3. A planet with two billion cars
4. Measured on April 10th 2016, at the Mauna Loa Observatory, Hawaii. Published by the Earth Systems Research Laboratory, Global Monitoring Division, National Oceanic and Atmospheric Administration. For more information, see:http://www.esrl.noaa.gov/gmd/ccgg/trends/graph.html (2016) .