According to projections, almost 600 million tons of methane (CH4) entered the earth’s atmosphere in 2017, more than half of it through human activities. The greenhouse effect of the gas is enormous. Throughout 100 years methane has a greenhouse effect 28 times stronger than carbon dioxide, over 20 years the effect is even 86 times stronger than that of CO2. As a result, methane is responsible for around a quarter of the global warming caused by greenhouse gases.
Methane sources are difficult to identify
To determine the causes of the methane emissions, these are measured from known sources, and extrapolations are made from them. However, these calculations are fraught with major errors because not all methane sources, such as swamps, oil explorations, fracking systems, and leaks in gas pipes, can be analyzed. As a result, the global increase in the atmosphere can be measured very precisely, but it is not possible to say exactly how much methane is produced where.
The natural breakdown process of methane and its problem
Just as there are natural ways in which methane is produced, there are natural processes that remove methane from the atmosphere. What is important here is the so-called hydroxyl radical, a very short-lived combination of oxygen (O) and hydrogen (H). About 90 percent of the methane is broken down by OH radicals in the lower atmosphere. If CH4 reacts with an OH radical, it results in water and, via a few intermediate steps, ultimately CO2.
On average, methane remains in the atmosphere for around nine years. Since methane emissions are increasing worldwide, the level of OH radicals decreases because the oxidation reaction with methane takes place more frequently. The methane that follows will only be broken down after a long period and will fuel global warming until then. And that is exactly what could become a big problem in the future if emissions are not reduced.
A serious climate threat
If methane emissions are not reduced significantly, we all have a big problem. The climate targets will be missed by far. In addition, one is also forced to make much more drastic savings on CO2 and other greenhouse gases. This will hit the economy and citizens hard, as they will have to be restricted if action is not taken quickly.
A reduction in methane emissions of over 30% would be necessary by 2050. Right now, however, exactly the opposite is happening and emissions are increasing.
What can be done?
Rice farmers could flood their fields for shorter periods, and major leaks in gas and oil transport systems could be closed.
Farmers could change their cattle feed mixes. The ruminant is one of the largest sources of methane in the world, which cattle produce during digestion. As an example: According to projections, cattle farming leads to methane emissions that have the same global warming effect as CO2 from 350 million cars.
Methane emissions from the thawing of permafrost soils
So far, no major methane emissions have been observed due to the thawing of permafrost in colder regions. However, with temperatures rising around the world, this should only be a matter of time. The quantities of greenhouse gases stored in soils are enormous. If these thaws and release methane, the process could develop a dynamic that can no longer be stopped by humans.
Global methane emissions represent a major climate risk, and action should be taken as quickly as possible because not only CO2 is climate-relevant. Politicians, industry, and private individuals are therefore required to make more conscious decisions that reduce emissions.