Title: Bridging the gap between bottom-up and top-down approaches for the global CF4 budget
(University of Bristol, Bristol, UK)
CF4, also known as carbon tetrafluoride (or tetrafluoromethane), is a very stable gas with an atmospheric half-life of 50,000 years, and a global warming potential of 7390 (Forster et al., 2007). CF4 is the most persistent greenhouse gas yet discovered and its emissions are almost entirely anthropogenic (“man-made”). Three main sources have so far been identified: a) the aluminium (AL) industry and b) the semi-conductor (SC) industry and c) rare earth smelting (RE). Emissions inferred by a combination of measurements from the Advanced Global Atmospheric Gases Experiment (AGAGE) and inversion modelling (a top-down method) show that only around 50% of global CF4 emissions can be explained by current emissions inventories (Kim et al., 2014). Given the continuous growth of all three industries mentioned above, it is of great importance to understand the reasons behind the emission discrepancies despite efforts from the industries to reduce their emissions and update their inventories. To that end, we are working on construction of a bottom-up inventory that includes the AI, SC and, for the first time, the RE industries. Initial data on Australian emissions will be presented in which top-down and bottom-up emissions are compared. Initial findings for a semiconductor and flat-panel-display-centric example will also be discussed. The ultimate goal of this project is to: a) quantify and localise the emissions of CF4 for each industry and, b) bridge the gap between bottom-up and top-down approaches for the global CF4 budget.