Share 'Carbon footprint'

According to http://www.natlforests.org my carbon footprints came out to be 0.65 metric tons of CO2/year. My results in http://www.nature.org were slightly different my estimated greenhouse gas emissions were of 7.8 tons of carbon dioxide (CO2) equivalent per year, which is below the U.S. national average. Lastly, my carbon footprint on http://www.bp.com is approximately 10.4 tonnes CO2 per year…