National Oceanic and
Atmospheric Administration
United States Department of Commerce


(A) Time series of the northern hemisphere surface concentrations (expressed as partial pressure in parts per trillion) of CFC-12 (solid) and SF6 (dashed) in equilibrium with the atmosphere.  (B) The CFC-12 curve is shifted +14 years to demonstrate the similarities of the two curves. (C) The growth rate of SF6 and CFC-12 (shifted 14 years). The SF6 concentrations are scaled by a factor of 89 in all panels (Tanhua, et. al. 2013).