Methane (CH4) is emitted naturally and through human sources. Natural sources make up 36% of all Methane emissions and this includes wetlands, turmite and the oceans. The remainder is emitted via human activities; this includes landfills, livestock farming and use of fossil fuels. Methane can be removed from the atmosphere through natural processes in soil. But for a long time now human activities have been creating methane emissions much more rapidly than the Earth can remove them, increasing global methane levels.
Methane's lifetime in the atmosphere is shorter than carbon dioxide, but "animals produce 37 percent of methane, which has more than 20 times the global warming potential of carbon dioxide." Additionally, as shown in the pie chart below, the human sources of methane are predominantly due to livestock farming and fossil fuel production. This is indicative of the importance and detrimental impact of methane emissions.
So how exactly do livestock emit methane?
If you want the short answer to how animals emit methane, look no further, we do it all the time: burps, farts and breathing.
No kidding.
And the long answer goes like this.Cows come under a the mammal group called ruminants which acquire nutrients from plant based products. They have four stomachs; where the food is digested. The stomach is filled with bacteria, and when food is digested, methane is also manufactured in the process.
(If only I had four stomachs...)
Furthermore, in the animal manure storage tanks, methane is produced. Imagine the extent of methane produced;
- Britain has millions of ruminants, including 10 million cows. Cows contribute 3 percent of Britain's overall greenhouse gas emissions and 25 to 30 percent of its methane.
- Methane is the second most prevalent greenhouse gas emitted in the United States from human activities. In 2012, CH4 accounted for about 9% of all U.S.greenhouse gas emissions from human activities.
How to train a ruminant:
Give your cow some garlic to reduce methane emissions, apparently...
Happy Meatless Monday! Tune in next Monday for a new post on Nitrous Oxide emissions.