The greenhouse gas methane has a huge impact on the course of climate change. More than 150 countries have therefore committed to reducing methane emissions by 30 percent this decade. But so far, very few seem to have implemented this promise. New research shows that global methane emissions have increased faster than ever before in the last five years. The main sources of methane are agriculture and landfills, followed by the use of fossil fuels.
Methane (CH4) is a highly effective greenhouse gas. Although it is shorter-lived than carbon dioxide (CO2), it warms the atmosphere almost 90 times faster in the first 20 years after it is released. Some of the methane comes from natural sources such as wetlands, but large amounts also come from man-made sources such as agriculture, landfills and fossil fuels. These emissions are avoidable and reducing them would help to limit global warming in the near future. In November 2021, over 150 countries committed to reducing their methane emissions by 30 percent by 2030 in the so-called Global Methane Pledge. But what about implementation?
Humans release more methane than nature
Scientists from the Global Carbon Project have now checked how much methane has actually been released into the atmosphere in recent years. To do this, the team led by Robert Jackson from Stanford University measured global methane concentrations and evaluated them using refined models. The analysis showed that annual methane emissions increased by a total of 20 percent in the two decades between 2000 and 2020. The increase was particularly strong between 2019 and 2023. “Methane concentrations have risen faster in the last five years than at any time since records began,” the team writes. As a result, atmospheric concentrations of methane are now more than 2.6 times higher than in pre-industrial times – the highest they have been for at least 800,000 years.
Around two-thirds of this value is primarily due to an increase in methane emissions from human activities, the analysis showed. The methane comes primarily from coal mining, oil and gas production and their use, cattle and sheep farming, and the decomposition of food and organic waste in landfills. Agriculture and waste are responsible for about twice as many emissions as the use of fossil fuels. The lockdowns of the corona pandemic also contributed indirectly to this increase, as data from 2020 show. During this time, fewer goods were transported and thus fewer nitrogen oxides (NOx) were released. These normally cause dirty air, but also mean that less methane accumulates in the atmosphere. In the pandemic year of 2020, a particularly high increase in methane was therefore recorded.
Gloomy climate forecast
“At the moment, the goals of the Global Methane Pledge seem as far away as a desert oasis,” says Jackson. “We hope they are not a mirage.” According to the study, most of the countries have not yet adequately fulfilled their self-imposed commitments. “Only the European Union and possibly Australia appear to have reduced methane emissions from human activities over the past two decades,” says co-author Marielle Saunois of the University of Paris-Saclay. “The largest regional increases came from China and Southeast Asia.” However, China has not signed the agreement either.
Overall, global methane emission rates have been rising steadily recently, the study shows. This trend “cannot continue if we want to maintain a habitable climate,” write the researchers. Based on the current growth rates, climate scientists expect global warming of three degrees by the end of the century. This would have noticeable consequences and would, among other things, lead to even more extreme weather. With a view to the record summer of 2024, which will be marked by storms and heat waves, the authors emphasize: “The world has reached the threshold of a 1.5 degree Celsius increase in the global average surface temperature and is only beginning to feel the full consequences.”
Source: Stanford University; Article: Environmental Research Letters, doi: 10.1088/1748-9326/ad6463