More projected warming in Europe due to neglected regional aerosol changes

Regional climate models provide information at much higher resolution than their global counterparts, and hence form the backbone of national climate services for several European countries, including Switzerland. Most of these models, however, do not consider that after peaking at around 1980, human-induced aerosols over Europe have been on the decline. 

Impact of Declining Aerosols

Human-induced aerosols dampen the primarily greenhouse-gas induced warming by attenuating shortwave radiation. As such, declining aerosol emissions in recent decades and expected future reductions imply that the cleaner air will mask the warming to a lesser and lesser extent. Since this is not represented in a majority of available regional climate model simulations, the accelerated warming through aerosol reductions is not captured, causing an underestimation of the 1980–2022 summer warming by about 0.5 ℃. 

Seasonal Variation and Regional Implications

Because this effect depends on insolation, it is evident in all seasons except for winter in Europe, and manifests most clearly in summer. The underestimation of the warming is only becoming more pronounced, reaching about 1 ℃ in 2100 based on a high carbon emission scenario. The study focuses on Western Europe, but since aerosol emissions in Eastern Europe are still higher than further west in the continent but have declined from a higher level, the warming mismatch is even stronger there. 

This is reported by climate researchers around ETH Professor Sonia Seneviratne at the Institute for Atmosphere and Climate in a recent study in the journal "Communications Earth & Environment". Dominik Schumacher, lead author of the publication, is presenting the results today at a media conference organised by the European Geoscience Union (EGU) in Vienna.  

Underestimation of Heatwaves

The intensification of heatwaves is underestimated even more than mean summer temperature changes: currently by about 1 ℃ and reaching 2 ℃ towards the end of the century. Such strong discrepancies imply that assessments dominated by currently available regional climate models with constant aerosol representations are too optimistic.