A proxy for air quality hazards under present and future climate conditions in Bergen, Norway

• A link between local air pollution and large scale atmospheric blocking events.
• Prediction of the future occurrence of high air pollution events in Bergen, Norway.
• Comparison to large-scale atmospheric circulation indices.

This study reports a statistical analysis of air quality observations in Bergen, Norway over 2003–2013. We linked high levels of air pollution (NO2 concentrations >150 μg m−3) to the regional atmospheric circulation through a meteorological proxy index. We used the proxy index to characterize the potential for air quality hazards in Bergen using: (i) ERA-Interim for the period 1979–2013; and (ii) climate change simulations with the Norwegian Earth System Model (NorESM) for the period 1950–2100. We found that the recent air quality hazards in 2009–2011 were rather exceptional in the historical reanalysis data and the climate simulations over the considered 150 years. The atmospheric conditions favourable to frequent air quality hazards on seasonal time scales were observed in ERA-Interim only for 7 (out of 34) winters. The climate simulations with NorESM do not project a significant change in the frequency and persistence of the potential air quality hazards until 2100. The NorESM simulations suggest a significant role of the decadal (10–15 years) variations in the regional atmospheric circulation. If the timing of those variations is controlled by the anthropogenic forcing, the simulations project on average less frequent air quality hazards up to the mid 2020s.