The main sources of methane gas emission are:
Breeding animals: their digestive process produces this gas, and because the production of these animals is very large across the world, it's a considerable amount of this gas to take into count.
Fossil fuel: the methane is emitted during the extraction of petroleum, gas, or carbon.
Landfill: the organic matter is decomposed in anaerobic conditions (without oxygen) and a product of this reaction is methane gas.
