The impact of Swedish SO2 policy instruments on SO2 emissions 1990-2012

Sulphur dioxide (SO2) emissions cause acidification and human health problems which are, despite present policy instruments, projected to remain even after 2030 in Europe. Additional instruments are needed to solve the problems, and impact analysis of already used policy instruments would contribute to the development of new effective instruments. We present a study on how much of the decoupling of SO2 emissions from economic growth 1990-2012 that was due to SO2 policy instruments in general and to what extent it is possible to estimate the impact of individual instruments. Focus is on Sweden, a country with problems reaching its SO2-related environmental policy targets and with detailed data available. We applied decomposition analysis combined with an analysis of the chronological development of emission factors and mandated emission limits. Our use of official emission inventory data and publicly available data on the development of SO2 policy instruments increase the usefulness of our results to policy makers. The results indicate that at least 26-27% (corresponding to similar to 35-36 ktonne annually) of the decoupling 1990-2012 was due to SO2 policy instruments. 4-5% (similar to 6-7 ktonne) of the decoupling was caused by one environmental permit decision and stricter sulphur emission limit for marine oils. Most of the total impact of SO2 policy instruments could not be causally connected to an individual instrument, because many events and developments overlap in time. The implications of the results are that: a) SO2 policy instruments should still be important to reduce SO2 emissions in many countries; b) a lower boundary total emission impact of SO2 policy instruments can be estimated, but with current knowledge and data the impacts of individual instruments are rarely possible to estimate. Research on how to increase the precision in total impact estimates of SO2 policy instruments is needed to improve future impact analyses. More detailed emission inventory data would improve impact analysis of individual instruments.