Global increase of SF6 observed in the atmosphere

Abstract

High precision long‐term observations of the trace gas sulphur hexafluoride (SF₆) in background air at Neumayer station, Antarctica (1986–1991), and at Izaña observatory, Tenerife (1991–1992), are presented. Since the very first measurements in 1970 (0.03 pptv), the purely anthropogenic greenhouse gas SF₆ has increased by two orders of magnitude to a global mean value of 2.8 pptv in 1992. The observations can best be fitted by a quadratic curve with a recent increase rate of 8.3% yr⁻¹. A significant north‐south gradient of 0.29 pptv is observed. From this gradient an interhemispheric exchange time of 1.4 years is derived. A modeled atmospheric budget history agrees reasonably well with estimates of global SF₆ production rates and leads to an extrapolated SF₆ concentration of about 20 pptv for the year 2030.