Emissions of CO2 - from Cement Production (CDIAC) is the amount of C02 created by the conversion of calcium carbonate to calcium oxide inside the kilns, and by burning large quantities of fossil fuels to heat the kilns to the 1450 C necessary for roasting limestone. The sum of emissions estimates for all countries is not equal to the estimate of global total emissions because : 1. The global total includes emissions from bunker fuels (i.e., fuels used by ships and aircraft during international trade) whereas these are not included in any national totals. 2. The global total includes estimates for the oxidation of non-fuel hydrocarbon products (e.g., asphalt) whereas national totals do not. 3. National totals include annual changes in fuel stocks whereas the global total does not. 4. Due to statistical differences in the international statistics, the sum of exports from all exporters is not identical to the sum of imports by all importers.