Sewer systems have long been assumed to be negligible sources of methane, yet emerging evidence suggests that they represent a previously overlooked contributor to greenhouse gas emissions. This study shows that global sewer networks emit ~1.2–2.0 Tg CH4 yr−1, substantially increasing wastewater-sector methane emissions and challenging the IPCC zero-emission assumption.
- Keshab Sharma
- Jiuling Li
- Zhiguo Yuan