Meat & Livestock Australia has created a simple animation that explains the difference in the environmental impact of methane from cows and carbon dioxide from fossil fuels. Methane is part of the natural carbon cycle that after 12 years breaks down into natural CO2 and water.
Grass absorbs the CO2 by photosynthesis and the cycle starts again. CO2 from fossil fuels is new and does not come from this natural carbon cycle, so remains in the atmosphere for potentially 1,000 years.
The difference between methane from livestock and CO2 from fossil fuels is widely misunderstood and misreported - this animation makes it easy to understand.