Anthropogenic sources of atmospheric methane

Slightly over half of the total emission is due to human activity. Since the Industrial Revolution, humans have had a major impact on concentrations of atmospheric methane. As a result, humans have aquired the ability to affect the concentration of other gases in the atmosphere as well. For example, because methane traps heat in the atmosphere, increased methane emissions increase the temperature of the atmosphere. And, because warmer climates hold more water vapour, through methane emissions humans can also indirectly increase the amount of water vapour in the atmosphere as well.

Ecological conversion:

Conversion of forests and natural environments into agricultural plots increases the amount of nitrogen in the soil, which inhibits methane oxidation, weakening the ability of the methanotrophic bacteria in the soil to act as sinks.

Farm animals:

Farming also acts to increase atmospheric methane through ruminant farm animals, e.g. sheep/cows. Two reasons explain this: firstly, the mass collection of cattle that are needed to supply the meat industry and secondly, changes in natural feeding habits. In order to reduce the costs associated with large amounts of feed needed to support livestock, humans have begun adding more nitrogen to cattle feed. The addition of nitrogen to the feed causes the cattle to need less food to feel full. However, this increase in nitrogen feeds not only the cattle, but also the microorganisms in their stomachs. More methane producing microorganisms means higher methane emissions.

A 2006 UN FAO report stated that livestock generate more greenhouse gases in CO2 equivalents than the entire transport sector. Livestock accounts for 9% of anthropogenic CO2.

Rice agriculture:

Due to a growing world population, rice agriculture has become one of the largest anthropogenic sources of methane. With warm weather and water-logged soil, rice paddies act like wetlands, but are generated by humans for the purpose of food production. When the water table is higher, the methane produced in the soil can diffuse…