1.3 Methane and Contribution to global warming

According to the Global Methane Assessment 2021 Report 2017, approximately 596 million tonnes of methane were released into the atmosphere. Anthropogenic emissions from fossil fuel production and use, agriculture, wastewater and waste, and biofuel contributed around 60% (358 million tonnes of CH₄).

Recent estimates suggest that global methane emissions from non-sewered sanitation systems in 2020 caused an average of 377 million tonnes of CO_2eq (Shikun C., 2022) or 13.46 million tons accounting for 4% of global anthropogenic methane emissions, with increasing tendency, as we are all working towards an Open Defecation free world.

Even if our global sinks can reduce the accumulation of methane in the atmosphere by 571 million tons, an annual surplus of 25 million tons will accumulate in the atmosphere for the next century and is 28 times more potent for warming potential than carbon dioxide.

However, reducing human-caused methane emissions is recognised as one of the most cost-effective strategies to rapidly reduce the rate of warming and contribute significantly to global efforts to limit temperature rise. This is stated in the Global Methane Assessment 2021 from UNEP and reflected in the COP 26 pledge, where the international community committed to reducing methane emissions to combat the climate emergency. All sectors, including sanitation, must contribute to decreasing greenhouse gas emissions to meet the targets.

Implementing anaerobic digestion processes with biogas recovery for non-sewered sanitation systems offers a cost-effective approach to reducing overall methane emissions.

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