An updated bottom-up inventory and global estimates for CF4
(University of Bristol, Cantock\'s Cl, BS8 1TS)
Tetrafluoromethane, (CF4, PFC-14) is a potent greenhouse with an atmospheric half-life of approximately 50,000 years with a global warming potential over a 100-year time horizon (GWP100) of 7390 (Cicerone, 1979; Ravishanakara et al., 1993; Morris et al., 1995; Jain et al., 2000; Hurley et al., 2005; Clerbaux et al., 2007; Forster et al., 2007; Myhre et al., 2013). CF4 emissions are almost entirely anthropogenic (Deeds et al., (2015), Harnisch et al. 1996a, 2000, Harnisch and Eisenhaur (1998)) and three industries have been identified so far as primarily contributors to this rise in CF4: the aluminium, rare earth smelting and semiconductor industries. Global top-down emissions estimates using data from the Advanced Global Atmospheric Gasses Experiment (AGAGE) found that only around 50% of CF4 could be accounted for using the available bottom-up estimates for aluminium production and semiconductor manufacture (Mühle J. et al., 2010; Kim J. et al., 2014). Significant fractions of the global top-down emissions of CF4 remain unaccounted for in the bottom-up emissions (Mühle et al. (2010), Kim et al., (2014), Worton et al., (2007)). We will present the first part of an updated, inclusive bottom-up inventory and we attempt to close this gap by producing a new bottom-up global emissions estimate. To do this, we make use of newly available activity data from the aluminium and semiconductor industries, and incorporate information on rare earth smelting, which has largely been omitted from previous top-down comparisons. Additionally, we will present our top-down results in the form of case studies for the areas of Australia and East Asia.