The Importance of Accounting for the North Atlantic Oscillation When Applying Observational Constraints to European Climate Projections

Abstract Variability in the North Atlantic Oscillation (NAO) has contributed to recent multidecadal trends observed European climate, especially winter precipitation over Northern Europe. However, current generation of coupled climate models struggle reproduce NAO's contribution trends, which important implications for deriving constraints based on comparison and modeled trends. An observational constraint attribution results, both with without variability associated NAO, is applied projections temperature, NAO shown lead a that overestimates future forced changes. Only after removing change consistent model simulations, tighter, unbiased signal (without NAO) can be projections.