What are the main sources of Methane emissions?

Methane (CH₄): As with CO₂, there are both natural sources of methane as well as ones that come from human activities. Again human-related sources create the majority of methane emissions, the 3 main sources are:

• Fossil Fuel Mining/Distribution
• Livestock
• Landfills

Figure 1:Source: Inventory of U.S. Greenhouse Gas Emissions and Sinks (2008), EPA.

• Fossil Fuel Mining/Distribution:

  Methane is always found wherever there are fossil fuels. It is released whenever fossil fuels are extracted from the earth whether it is natural gas (which is mostly methane anyway), coal or oil. Also during any type of handling, transportation (through pipeline or truck delivery) or refinement there are additional methane emissions created for every type of fossil fuel. By simply buying/using any fossil fuel whether it is coal, natural gas or petroleum you contribute to the most important source of methane emissions worldwide.

• Livestock:

  Farm animals create methane emissions in 2 ways. Animals like cows, sheep and goats are examples of ruminant animals and during their normal digestion process they create large amounts of methane. What is called enteric fermentation occurs in the stomach of these animals and produces methane as a by-product.

  The second way that livestock create methane emissions is from their manure. When cows, pigs and chickens are raised in an industrial way, there are obviously large quantities of manure that get produced by these animals everyday so farms have to have a way to manage and treat all of this manure. Livestock manure management is done by using large waste treatment systems and holding tanks. In these tanks the manure decomposes but because the tanks are closed there is no oxygen. When organic material decomposes anaerobically (without oxygen) great quantities of methane are produced.

  It's not the animals themselves that are at fault, it's the way and the amount of livestock that is raised that should be evaluated. The meat that we eat everyday contributes significantly to total methane emissions because of these 2 reasons.

• Landfills:

  As with manure, landfills and open garbage dumps are full of organic matter from our garbage (things like food scraps, newspapers, cut grass and leaves). Everytime new garbage comes in it is pilled over the old garbage that was already there. The organic matter in our garbage gets trapped in conditions where there is no oxygen (anaerobic) and because of this large amounts of methane is created.

To go back to the main page for the sources of emissions click here