He methane is a greenhouse gas that begins to be on everyone’s lips, although on many occasions it remains a mere anecdote as cow flatulence (the technical term is enteric fermentation). Currently, methane is beginning to be relevant. Largely because on November 3, 2021, during COP26, more than a hundred countries (including the United States and the European Union as promoters) agreed to reduce methane emissions by 30% by 2030.
This is good news, everything adds up, but it must be taken into account that the objective that the UN saw as feasible during the spring of 2021 was 45%, which would mean avoiding 0.3ºC of global warming by 2045. As usually happens , the goodwill of the parties does not reach the real objectives.
Methane is not an anecdotal greenhouse gas though does not reach the level of concern that CO2 emissions entail. As we will see below, the greenhouse effect potential of methane is much higher than that of CO2, the effect of cutting methane emissions into the atmosphere can be observed much more quickly than that of reducing CO2 emissions.
The permanence of CO2 in the atmosphere is thousands of years according to the IPCC report, while that of methane is just over a decade (12 years). Therefore, if we were to reduce methane emissions today, the effects of this reduction would be visible after the twelfth year.
Sin embargo, eIn the case of CO2, although its potential as a greenhouse gas is lower, its long persistence in the atmosphere means that all the CO2 emissions that have been produced since the industrial era are accumulating. There is more and more carbon dioxide in the atmosphere, and it will continue to be so if they are not stopped soon or CO2 capture technologies start to become a reality soon.
He Methane is a gas with the formula CH4, which means that it is a carbon molecule surrounded by four hydrogen atoms. which is in the form of a gas at room temperature. Its danger is due to the fact that it is a highly flammable and explosive gas and that, being colorless, odorless (it does not smell like anything) and insoluble in water, it is not easily detected.
Methane is produced by the degradation of organic matter by the action of microorganisms under anaerobic conditions (ie, in the absence of oxygen).
Methane gas is the majority component of natural gas that can contain between 80% and 97%. Natural gas comes from the decomposition of organic matter (plants and animals) under conditions of intense heat and pressure for millions of years below the Earth’s surface. As a curiosity, the firedamp from coal mines is methane.
What is CH4 used for?
The uses of methane are basically two:
- As power source: As we have commented in the previous section, it is the fundamental component of natural gas, which is one of the most important sources of energy, as we are currently seeing with the news of possible cuts in the gas supply and the concerns of the Ukraine-Ukraine conflict. Russia.
- How mgreat meal to obtain chemical compounds such as hydrogen, methanol, acetic acid and acetic anhydride that are used in industry.
In nature there are natural methane emission sources, as well as many other greenhouse gases to which artificial sources must be added. As always, the key lies in the increasingly rapid rate of emission of these gases by human action.
Natural sources
The natural sources of methane are basically two.
- Fermentation of organic matter: Wetlands are natural ecosystems that emit large amounts of methane due to the degradation of organic matter that occurs in these environments. They account for around 25% of global CO2 emissions.
- He other natural sources are termites and oceans with much lower percentages than wetlands.
- Los volcanoes they can also be a source of methane to the atmosphere.
artificial sources
Fossil fuels always appear as the main culprits in the emission sources of most greenhouse gases, but on this occasion they are surpassed (by little) by livestock and agriculture.
Fossil fuels: 35%
Extractions of oil and natural gas, especially from deep reservoirs, emit CH4
Livestock and agriculture: 40%
Livestock and agriculture account for 40% of methane emissions of human origin. In particular, there are two sources that are responsible for most of the emissions: rice fields that account for 8% and cattle due to enteric fermentation (the famous cow farts) and manure that account for 32%.
Beef cattle have a higher carbon footprint than other foods that we have already seen in this post here.
Waste: 20%
Waste is another source of CO2 emissions both due to its dumping in landfills and the degradation that occurs from the waste, as well as when organic waste is used to obtain energy in the combustion of biomass.
When we talk about the greenhouse effect potential of the different greenhouse gases (GHG), it is always done based on the greenhouse effect potential of CO2 to which 1 is assigned and the time spent in the atmosphere.
As we said, the residence time of methane in the atmosphere is approximately 12 years and its heat absorption capacity is around 26 times the capacity of CO2.
The most significant difference is its permanence in the atmosphere since carbon dioxide lasts for thousands of years, while methane only lasts 12. However, its emissions have been increasing in large amounts since 1983.
This means that the effect on the reduction of methane emissions is faster and therefore allows time to be saved in the decarbonisation of the economy. However, it is still essential to reduce CO2 emissions because current emissions will remain in the atmosphere for thousands of years.
A worrying trend
Until 2006, a trend towards a reduction in the amount of methane emissions into the atmosphere had been observed, a trend that changed as of 2007 and which concerned the scientific community since the cause of this increase was unknown.
After studies by analyzing the carbon isotopes that make up methane, it has been concluded that the increase in methane emissions is due to natural sources, due to the decomposition of organic matter by microbes, which can account for 85% of the increase in methane emissions into the atmosphere. Despite this, humans are still responsible for 62% of CO2 emissions.
Concern over microbes and methane
What worries scientists about this increase in methane emissions by microorganisms is that this is due to a feedback effect from climate change. The melting of the poles, especially the permafrost, can be an important source of methane that feeds back global warming and that brings us to a point of no return.
For this reason, the agreement to reduce methane emissions (Global methane pledge) by 30% by 2030 is essential to buy time.