Changes in future synoptic circulation patterns: consequences for extreme event attribution

Anthropogenic emissions can modify the frequency and intensity of extreme weather events such as cold-spells, heatwaves and heavy precipitations. A major challenge is to detect changes in the atmospheric circulation patterns associated to those extreme events. The emergence of patterns depends on the chaotic behavior of the atmospheric flow and can also be modified by anthropogenic emissions. By embedding the circulation patterns observed during selected extremes into historical climate simulations and projections based on emission scenarios, we find major changes in probability, predictability and persistence of atmospheric patterns observed during extreme events using an analog based method. The results highlight the need to take into account the role of atmospheric circulation in attribution studies.