Further refinements are made in the method of calculating amounts of carbon dioxide released to the atmosphere through the combustion of fossil fuels. Data available in the UN Statistical Yearbook are used as the basic sources rather than the summary, World Energy Supplies, U.N. Statistical Papers, Series J because the most recent data are available several months earlier in the yearbook and because data are included for natural gasoline, natural gas liquids, and cement production. Coal, lignite, crude petroleum, “marketed” natural gas, flared natural gas, and cement are itemized separately and revised CO2 emission estimates are made for each year from 1960 thru 1971. These estimates average 2.3% higher than Keeling's with the carbon dioxide production from flared gas being the largest difference. Natural gas which is flared at the well accounts for over 2% of the total CO2 produced from fossil fuels.