Complex sentence: In some countries, large amounts of landfill gas are collected, but still the global warming potential of the landfill gas emitted to atmosphere in the US in 1999 was approximately 32% higher than the amount of CO 2 that would have been emitted by incineration.
Split into simpler sentences: In some countries, large amounts of landfill gas are collected. 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 CO 2 that would have been emitted by incineration.