Biomethane and biogas are increasingly turned to as alternatives for fossil gas. However, their production and distribution can still result in climate damaging methane (CH4) emissions, the magnitude of which remains unclear. A new study from the Imperial College London finds that emissions along the supply chain are much greater than previously estimated. Mitigating CH4 throughout not only fossil gas, but also biomethane and biogas supply chains is urgently needed. Lisa Tostado investigates.