[audio:http://wamcradio.org/EarthWise/wp-content/uploads/2012/04/EW-05-29-12-Methane.mp3|titles=EW 05-29-12 Methane]
Methane concentrations are rising in Earth’s atmosphere, more than doubling since the beginning of the Industrial Revolution. Like carbon dioxide, methane contributes to global warming. In fact, it is 25 to 35 times more effective at warming our atmosphere than carbon dioxide. Trouble is, we’re not sure what’s causing methane levels to rise.
Some methane comes from the ground, where it is known as natural gas and the subject of our pursuit as a fuel for heating and the generation of electric power. When we drill for natural gas, we increase methane leakage.
Wetlands are also a source of methane, where it is produced by soil bacteria that are busy decomposing organic material. And each year cattle, sheep, and other ruminants contribute some 25% of methane emissions, which are produced by stomach bacteria that help them digest plant material.
Like all gases in our atmosphere, methane concentrations are maintained as a balance between “sources” and “sinks,” processes which remove gas from the atmosphere. Methane’s largest sink is a reaction with a gas called hydroxyl radical, which has been dubbed ‘the detergent of the atmosphere’ for its ability to remove a variety of pollutants.
Some scientists believe that methane concentrations are rising because we’ve increased its sources. Problem is: many of them, like cows, are so dispersed and it’s hard to envision how to engineer a cap for their emissions. Other scientists believe that the rise in methane is due to the loss of hydroxyl radicals in our atmosphere.
Whatever the cause, stemming the rise in methane in the atmosphere will be an important step to preventing global changes in our climate.
Photo, taken on November 28, 2009, courtesy of Ari Moore via Flickr.