Methane (CH4) is predicted to cause as much global warming as carbon dioxide (CO2) over the next 20 years. Traditionally the global warming potential (GWP) of methane has been measured over 100 years. The IPCC’s Fourth Assessment Report (IPCC 2007) warns that this underestimates its immediate impact. Viewed over 20 years it has 72 times the GWP of CO2.The current study was prompted by concern about these emissions, and by a recent Government policy study in Melbourne, Australia, which recommended composting of municipal waste. The mass composting of waste would reduce landfill gas, currently used as a fuel. This study uses recent information (2006 IPCC Guidelines) with local data to estimate:- How much greenhouse gas is emitted to the atmosphere from best practice landfill with methane capture Pipes? How much can be captured to use as fuel? - Is aerobic composting or incineration better at controlling emissions than landfill with gas capture?