Methane, whose emissions the United States and the European Union intend to reduce, is a very harmful gas for the climate. It is largely linked to human activities (agriculture, energy, waste) on which it is possible to act.
What is methane?
Methane (CH4) is a very common gas, which exists naturally on Earth since it is the main component of natural gas, widely used as an energy source. It is also the second greenhouse gas of anthropogenic origin (linked to human activity) after carbon dioxide (CO2). But its warming effect is 28 times greater per kilogram than that of CO2 over a 100-year horizon.
However, its lifespan in the atmosphere is relatively short (around ten years, against decades or even hundreds of years for CO2). Methane also participates in the production of ozone, a pollutant dangerous for humans, which also affects ecosystems.
Global methane emissions increased by 9% between 2006 and 2017, according to a study conducted by more than 100 international researchers under the aegis of the Global Carbon Project and published in 2020.
Where do the emissions come from?
Around 40% of its emissions are of natural origin, particularly in wetlands. Permafrost also contains immense volumes of methane, which could be released into the atmosphere if this frozen ground continues to melt as a result of global warming. Human activities are directly responsible for the remaining 60%.
Agriculture is, according to the researchers, at the origin of the majority of these anthropogenic emissions of methane, with 30% coming from breeding herds (digestive fermentation and manure) and 8% for the cultivation of rice. In terms of fossil fuels, the exploitation of oil and gas represents 22% of anthropogenic emissions and the extraction of coal 11%.
Solid and liquid waste management accounts for 18% of emissions and biomass and biofuel fires 8%, the rest of the emissions being linked to transport and industry.
Is it possible to act?
The United States and the European Union are working together on a draft agreement that promises to reduce anthropogenic methane emissions by at least 30% by 2030 from 2020 levels. “Reduce methane pollution is the fastest and most effective strategy we have to reduce the rate of warming. The benefits will be almost immediate ”, reacted Fred Krupp, president of the NGO Environmental Defense Fund (EDF).
In a report released this year, the United Nations Environment Program (UNEP) estimated that it was possible to reduce methane emissions by 45% – or 180 million tonnes per year – by 2030. This would allow to avoid 0.3 ° C of global warming by the 2040s.
What can be done to limit them?
In the field of oil and gas, the International Energy Agency (IEA) estimates that three-quarters of methane emissions can be removed – and much of it at no additional cost. It therefore suggests replacing the equipment (for example valves) which now allow gas to escape on hydrocarbon extraction and transport installations, and installing equipment for recovering or detecting leaks.
In agriculture, it is possible to change the diet of ruminants, which produce methane during their digestion, or to select the most productive breeds to limit herd size, UNEP lists. The EU also suggests reducing the consumption of meat and dairy products. Rice fields can benefit from better water management or the addition of certain products that limit gas production.
On the waste side, reducing emissions involves improving the sorting and treatment of waste. It is also recommended not to resort to landfill for biodegradable waste.