“Atmospheric concentrations of methane (1774 ppb) in 2005 exceed by far the natural range over the last 650,000 years.”
Together with the gases it forms in the atmosphere, methane has been responsible for 36.7 percent of radiative forcing between 1750 and 2011.
Methane by itself has caused 24.3% of global warming, and warming from its ‘downstream’ gases are: carbon dioxide (0.7%), ground level ozone (9.1%) and stratospheric water vapour (2.6%)
Two thirds of methane emissions are human-caused, the greatest source (responsible for 37 percent of emissions) being ruminant livestock (cattle, sheep and goats)22, followed by leakage of methane (natural gas) form oil and gas production, livestock waste, landfill and coal mining,
“The global production of cattle and sheep is responsible for 19 to 48 times more greenhouse-gas emissions, based on pounds of food produced, than the global production of protein-rich plant foods like beans or soy products.”
“A 50% reduction in methane emissions by 2050 maintained until 2100 could help reduce global temperature by about 0.55°C or 1°F.”
“ Reducing meat consumption as a demand side mitigation action offers greater greenhouse gas reduction potential. Livestock emissions include enteric fermentation, manure emissions, feed crop emissions, deforestation and associated burning. The accompanying reduction in grazing intensity could also allow regrowth of forests and other natural vegetation, resulting in additional carbon sequestration in both biomass and soils with beneficial climate feedbacks.”