Long overshadowed by the issue of CO2, the fight against methane emissions is gradually gaining a place in public policy. This gas has a much greater warming power than carbon dioxide. In October 2021, during COP26 in Glasgow, around a hundred countries notably announced a 30% reduction in their methane emissions by 2030 compared to 2020, first targeting those from the energy sector.
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In fact, while 40% of emissions are of natural origin, the rest – 60% today – is of human origin. The fight to contain it is also based on the observation that it disappears after a dozen years in the atmosphere. So much so that by reducing our emissions by 40 to 45% by 2030, nearly 0.3°C of warming could be avoided by 2040, according to a United Nations report. While every tenth of a degree counts, this potential is not negligible.
A third of energy-related emissions
Emissions related to oil, gas and coal (35% of human emissions) are often the most targeted by public policies. “This is the sector in which emissions can be reduced most easily, summarizes Marielle Saunois, teacher-researcher at the University of Versailles-Saint-Quentin-en-Yvelines. Emissions are often concentrated in specific locations, and maintenance measures or infrastructure are often inexpensive to implement. »
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Behind the methane of energy origin comes that of waste. In this sector, the decomposition of organic matter, combined with a lack of oxygen, contributes 20% of man-made emissions. The problem mainly comes from open landfills or certain methods of wastewater treatment. “The solutions are known, explains Marielle Saunois. The brakes come rather from the difficulties of setting up national policies, infrastructures and waste management methods. »
As for agriculture, the main source of methane emissions of human origin, it is divided between livestock (32% of emissions) and rice growing (8%). “Emissions are more diffuse than in other sectors, which makes their mitigation more difficult”, specifies Marielle Saunois.
According to the previously cited United Nations report, part of the reductions needed by 2030 could be achieved through targeted measures (improvement of ruminant feed, treatment of animal waste). But to drastically reduce emissions, behavioral changes will be necessary, foremost among which are the adoption of less meat-based diets and the reduction of food waste.