FORM · Quantification of FOssil methane emissions using Radiocarbon measurements of atmospheric Methane

With FORM the experience researcher (ER) will develop and apply a novel tool to investigate methane (CH4) sources and estimate their emissions through the measurement and modelling of radiocarbon (14C) in atmospheric CH4. CH4 is the second most important anthropogenic greenhouse gas but CH4 emissions, and particularly their attribution to specific sources, are not well-constrained. 14C measurements provide the most accurate way of identifying fossil fuel-derived methane (from natural gas leaks, coal mining, and petroleum refining) vs biogenic methane (agriculture, waste and wetlands). Fossil carbon has lost all 14C after millions of years of radioactive decay during burial underground and it is entirely depleted in 14C. When emitted into the atmosphere, fossil-derived methane will cause a strong decrease into the atmospheric ratio of radiocarbon to total carbon in methane (Δ14CH4). By measuring variations in Δ14CH4, the fossil fraction of methane emissions can be quantified. Despite their incredible usefulness, there are presently very few Δ14CH4 measurements made anywhere in the world, because there is no available system for sampling atmospheric methane for radiocarbon analysis that is easy-to-use and versatile. This challenge has been addressed by the latest work of the ER, who has developed a unique sampling method for high precision Δ14CH4 measurements. The ER’s sampling system is currently a laboratory prototype. To realize its potential, she will further develop the system at the Laboratory of Ion Beam Physics (LIP) at the Swiss Federal Institute of Technology (ETH). She will make Δ14CH4 measurements easier to perform, ultimately enabling systematic Δ14CH4 measurements to be produced. The new Δ14CH4 measurements will be integrated into a modelling framework as a further constraint on the contribution from different methane source categories and for verification of local inventories.