Persisting Modulation of Interdecadal Pacific Oscillation on Near‐Future Winter Precipitation Projections in Northern Europe

Abstract European winter precipitation profoundly influences regional hydroclimate, yet the relative roles of internal variability and external forcing in its decadal changes remain elusive. Using large‐ensemble climate simulations, we identify the Interdecadal Pacific Oscillation (IPO) as a potential driver of interdecadal changes in winter northern European precipitation. During the 1980–2014 IPO phase transition, internal variability induced a drying trend of −0.07 mm day −1 (35 years) −1 , offsetting a concurrent externally forced wetting trend of +0.19 mm day −1 (35 years) −1 . This influence arises from IPO‐related modulation of atmospheric circulation and moisture transport. The persistence of IPO–WNEP linkages into 2015–2050 suggests that internal variability may continue to shape near‐future hydroclimate. Accounting for IPO‐related influences reduces projection uncertainty by 30% historically and 20% in the near future. These results highlight the critical role of internal variability in long‐term European precipitation trends and emphasize its relevance for regional water resource planning.