The atmospheric methane burden has grown rapidly since 2007, with remarkable increases in the 2020s . The parallel sharp isotopic decline in the proportion of 13CH4 suggests growth is primarily driven by biological sources, including climate-warming feedbacks from natural wetlands and also human-driven agricultural sources (Michel, et al. PNAS 121: e2411212121. 2024). New radiocarbon monoxide results (Morgenstern et al. Nature Comm 16: 249, 2025) imply increasing atmospheric oxidizing capacity and thus higher methane emissions. There may be evidence a major climate transition is already in progress (Nisbet et al. Glob.Biogeo.Cycl. 37: e2023GB007875, 2023).
The Union session will outline the scientific evidence for recent changes in the methane budget, and summarise progress in quantification and mitigation methods. Methane’s rapid new growth challenges the Paris Agreement. Rapid progress is being made in quantifying oil and gas, coal, and landfill emissions, and in learning how to mitigate them. Less progress is being made in reducing emissions from agriculture.
Presentations from James France, Semra Bakkaloglu, Thomas Röckmann, and Euan Nisbet will consider why growth is taking place, the impact of climate feedbacks, and what our mitigation responses should be, in the context of the Paris Agreement and the Global Methane Pledge. The symposium will also include a panel discussion with speakers and convenors, and a 30 minute Q&A session for audience discussion.