Methane is a potent greenhouse gas and, according to the Intergovernmental Panel on Climate Change, “plays a crucial role in regulating Earth’s surface temperature.” As such, understanding methane and how it interacts with the environment is essential for understanding climate change.
In this post we will explore methane's role in climate change, its sources and sinks (those substances that take up or release gas), as well as techniques for mitigating its emissions to limit future warming.
Methane plays a major role in the greenhouse effect. As the Earth warms, some of its water evaporates into the atmosphere where it releases heat energy in the form of radiation. Methane is a very strong greenhouse gas, and as a result traps heat that would otherwise escape to space. In fact, each pound of methane gas traps 20 times more heat than each gallon (3.79 liters) of gasoline does.
Methane has not always been such a potent greenhouse gas, though. Methane has been around since organic matter first began to decompose millions of years ago, but the amount it contributes to warming is different now than it was then.
Fossil fuels, such as coal, oil, and natural gas, are sources of carbon. Carbon from these fuels can be released into the atmosphere when we burn them for fuel. While burning these fuels releases heat to us humans, it also releases carbon to the atmosphere where it forms methane. This methane in turn causes additional warming throughout the globe. Use of fossil fuels is a major source of human-made greenhouse gases and is one of the largest contributors to global warming.
Organic matter in landfills is another source of methane emissions. When organic material gets buried in a landfill, oxygen in the air cannot get through that area because of all the garbage on top (the air needs somewhere for all that oxygen to go). Without oxygen, organisms that would normally break the organic material down cannot do so.
Aerobic decomposition is the type of decomposition where oxygen is present (as opposed to anaerobic decomposition, which does not require oxygen). Aerobic decomposition occurs when bacteria feed off of organic matter. This type of decomposition releases methane as a byproduct. Again, we humans are receiving benefits from this process: methane can be used for fuel or in fertilizer production. However, when it escapes into the atmosphere it has a warming effect on our planet.
Cow belching and flatulence are also sources of methane emissions for our fossil-fuel burning society. Methane is an important greenhouse gas. Methane is also the second-most plentiful greenhouse gas. An increase in methane levels in our atmosphere will have an effect on climate change, but a global decrease will have a much bigger impact.
The main human source of methane emissions is agriculture, the production and transportation of coal and gas, landfill waste, biomass burning and the production of oil. The natural sources are wetlands and inland seas, permafrost and wildfires. Man-made emissions are responsible for 55 to 60 percent of the methane in our atmosphere today; most of these come from coal and natural gas systems.