If the waste was landfilled, 1 ton of MSW would produce approximately methane via the anaerobic decomposition of the biodegradable part of the waste. Since the global warming potential of methane is 34 and the weight of 62 cubic meters of methane at 25 degrees Celsius is 40.7 kg, this is equivalent to 1.38 ton of CO2, which is more than the 1 ton of CO2 which would have been produced by incineration. In some countries, large amounts of landfill gas are collected. Still the global warming potential of the landfill gas emitted to atmosphere is significant. In the US it was estimated that the global warming potential of the emitted landfill gas in 1999 was approximately 32% higher than the amount of CO2 that would have been emitted by incineration. Since this study, the global warming potential estimate for methane has been increased from 21 to 35, which alone would increase this estimate to almost the triple GWP effect compared to incineration of the same waste.