In the past, the greenhouse gas methane has appeared much less frequently in the public spotlight than its “big brother” carbon dioxide. This is largely due to the fact that methane degrades chemically in the atmosphere, and only remains there for about twelve years. Carbon dioxide, on the other hand, does not break down easily. It must be extracted from the atmosphere, either by plants, the ocean or through the weathering of rocks. These natural extraction processes proceed much more slowly than the rate of carbon dioxide emissions, so newly released carbon dioxide will continue to impact the climate as a greenhouse gas for millennia.
But for more than ten years now, researchers have been observing the increase in the methane content of the atmosphere with great concern. Since 2014, they have been referring to it in terms of a strong increase. The concentration of methane is still significantly lower than that of carbon dioxide, but it possesses a much greater heat potential. Calculations indicate that it retains about 30 times more heat in the atmosphere than carbon dioxide. This leads to the estimation that methane is responsible for around 30 per cent of the warming observed on Earth to date.
It is not yet precisely known why methane emissions have increased so sharply in recent years. Methane is released by natural processes as well as by human activities. Around two-fifths of the emissions originate from natural sources such as moors and wetlands. Three-fifths of the emissions can be attributed to human activity. They escape from oil and gas production facilities or from old coal shafts, or are released from waste dumps and by the burning of organic material. But they can also be released through agricultural activity, for instance in rice farming or by cattle herds.
Population growth in the tropical regions may be one explanation for the rise in methane concentrations. Where there are more people, more agriculture has to be carried out to produce sufficient amounts of food. Through the use of improved observation technology such as drones and satellites, however, researchers are gaining much better insights into the enormous amounts of methane that are being released by waste dumps and oil production facilities.
The one ray of hope in the present situation is the short-lived nature of methane. If humans are able to drastically reduce their methane emissions within a short period of time – and the knowledge to achieve this goal is available – the concentrations will decline noticeably within a decade.
With carbon dioxide, however, there would be a wait of centuries to millennia before extensive reductions in emissions could result in a measurable decline in the atmospheric concentrations.