Methane and Climate Change

Greenhouse gases are gases in earth's atmosphere that trap solar radiation and warm the atmosphere in the same way that a greenhouse increases the temperature within its bounds.

Carbon dioxide is probably the most well-known greenhouse gas and the burning of fossil fuels has led to an increase in carbon dioxide which is often blamed for human induced climate change. However, methane is a far more potent greenhouse gas; 21 times more effective at trapping solar radiation than carbon dioxide.

Human activity is increasing the production of methane as well as carbon dioxide and is potentially a major problem for the global climate.

There are a number of sources of methane.

I guess that most of us know that methane is a gas but here is an extract from the Wikipedia entry for Methane to tell us a little more about it.

"Methane is a chemical compound with the molecular formula CH4. It is the simplest alkane, and the principal component of natural gas. Burning methane in the presence of oxygen produces carbon dioxide and water. The relative abundance of methane and its clean burning process makes it a very attractive fuel."

Before expanding on the sources of methane, anyone wanting to know more about "global warming" and climate change can do a lot worse than read or watch An Inconvenient Truth.

Remember, it isn't the final word on climate change, but it is an accessible book/movie to get some ideas of the issues involved.

The stomachs of cattle and other grazing livestock contain large numbers of bacteria which break down the cellulose in the plants they eat. These bacteria excrete methane which enters the atmosphere via the livestock's mouths and bottoms!

Whilst this is a natural process, the numbers of cattle, sheep and goats on earth now are man-made. As humans have cleared forest and created pasture the demand for meat has increased and with it the numbers of methane-belching livestock. Wild ruminants also produce methane but the numbers that would inhabit the natural environments destroyed by intensively cultivated pasture would be much lower.

In this rather strange way mankind has increased the production of methane - a very powerful greenhouse gas.

As undeveloped countries become more developed, the demand for meat increases. This means that unless humans begin to eat less meat the production of methane through livestock is likely to increase.

Measures such as changing cows' diet or breeding new varieties of cattle could reduce this problem.

Termites produce methane in the same way as livestock; the bacteria in their gut help them break down wood and they excrete methane. In fact they excrete a lot of methane, as much as five liters per minute for one termite mound. But how are humans responsible for this?

Well, in the same way that humans have artificially increased livestock numbers, so termite numbers have increased because of human activity. As forests are logged open country habitats replace them and often becomes more arid - ideal termite habitat has been created and so they thrive. At first the relationship between man and termites may seem tenuous, but this is a side effect of deforestation that rarely is discussed. Deforestation results in the release of carbon dioxide as stumps are burned, reduce sequestration of the same gas, extinction of populations of animals and plants, soil erosion, reduced rainfall and now we can add the increased production of methane from the resultant boom in termite populations to this list.

Read more about this issure here: Termites emit methane.

Habitats low in oxygen, such as marshy waters, have always been full of the methane-producing bacteria but the huge area under rice cultivation, which is often kept irrigated year round where naturally it would be dry for part of the year, produces huge amounts of methane and rice appears to speed up the process of venting it into the atmosphere.

As the world becomes more populated and demand for rice increases, the area under rice agriculture grows, year round rice production is introduced to more regions and the amount of methane produced in this way continues to increase.

Apparently, draining the paddies once during the growing season could reduce methane emissions by 30%.

In the region of 30% of all waste which ends up in landfills is capable of rotting. As it rots, methane is produced - that is what can sometimes be seen burning from small chimneys at old landfill sites.

In some places this methane is put to good use and pumped into houses for use as domestic gas. However, in most places around the world this does not happen; the methane gas simply seeps out into the atmosphere, contributing to the greenhouse effect 21 times more efficiently than carbon dioxide.

Permafrost is ground which is permanently frozen. However, as the climate warms, either naturally or as a result of man's actions, this permafrost begins to melt. Within this permafrost is locked an enormous amount of methane; this begins to be released into the atmosphere to further increase the greenhouse effect, increasing temperature, melting more permafrost, releasing more methane - a feedback loop which runs out of control.

In similar fashion, methane which is locked in the mud of the continental shelves of the oceans becomes free as the waters warm through climate change. This mud may hold trillions of tons of methane which if released would be catastrophic for the Earth's climate.

The oil and mining industries release large amounts of underground methane when they penetrate into fossil fuel deposits. In some countries with large operations in these industries the amount of methane released is larger from other sources, but on a worldwide level this source of this greenhouse gas is lower than many other sources and certainly lower than all the biogenic sources put together.

These industries do create a large amount of methane but it is surprising that it is not the world's largest source. Although with the increase in "fracking" this source of methane is increasing and there are lots of other environmental problems surrounding this industry including including huge amounts of waste material, pollution, habitat destruction and others.

There are many publications available for those that want to know more about global warming and climate change. Here are just two of the more simple ones available.

It is worth mentioning here that although a large number of scientists agree on the mechanisms of climate change and after many, many years they have succeeded in getting politicians to accept their views, there are still a number of respected scientists who disagree.

Although many of the arguments put forward against human-induced climate change can be relatively easily countered, it is always good to get both sides of the argument before forming an opinion.

Whilst the sceptics can often use inflammatory language to argue their point, equally environmentalists are prone to overstating their case. Reading some of the following in conjunction with books supporting the human-driven climate change theory may help to form a balanced opinion.