Final answer:
Industry, landfill, refrigerants, and agriculture are all sources that introduce methane in the atmosphere.
Step-by-step explanation:
Methane in the atmosphere is introduced by several sources, including industry, landfill, refrigerants, and agriculture.
Industry contributes to methane emissions through activities such as natural gas drilling and the use of petroleum and coal. Landfills release methane as the organic waste undergoes anaerobic decomposition.
Refrigerants, specifically hydrofluorocarbons (HFCs), are potent greenhouse gases that contribute to methane emissions. Finally, agriculture, specifically the microbiomes of ruminants and rice cultivation in anoxic compost and shallow ponds, also produces methane.