Methane is the second-largest greenhouse gas after carbon dioxide. According to the Climate and Clean Air Coalition, anthropogenic methane emissions account for nearly 45% of current net warming, making it an important factor in global warming. An international research team led by a scholar from City University of Hong Kong (CityUHK) has broken through the overlooked role of sewers as a source of methane, developing the first-ever globally applicable estimation tool and offering a new perspective on mitigating climate change.

cross-posted from: https://slrpnk.net/post/37101017

According to the Climate and Clean Air Coalition, anthropogenic methane emissions account for nearly 45% of current net warming, making it an important factor in global warming

It is generally assumed that the limited residence time of wastewater in sewer networks is not conducive to methane formation, and that the overall emissions are difficult to monitor and quantify. Therefore, in current greenhouse gas inventories by the IPCC and various countries, urban sewers are considered a negligible source of methane emissions, assumed to be zero.

The team estimates that sewers worldwide emit 1.18 to 1.95 million tons of methane annually. This reveals that global wastewater management has a far more significant impact on greenhouse gas emissions and global warming and is crucial for improving greenhouse gas emissions accounting and promoting global emissions reduction.

Composting toilet + food forest revolution?