The role of the North Atlantic Oscillation for projections of winter
mean precipitation in Europe
Abstract
Climate models generally project an increase in the winter North
Atlantic Oscillation (NAO) index under a future high-emissions scenario,
alongside an increase in winter precipitation in northern Europe and a
decrease in southern Europe. The extent to which future forced NAO
trends are important for European winter precipitation trends and their
uncertainty remains unclear. We show using the Multimodel Large Ensemble
Archive that the NAO plays a small role in northern European mean winter
precipitation projections for 2080-2099. Conversely, half of the model
uncertainty in southern European mean winter precipitation projections
is potentially reducible through improved understanding of the NAO
projections. Extreme positive NAO winters increase in frequency in most
models as a consequence of mean NAO changes. These extremes also have
more severe future precipitation impacts, largely because of mean
precipitation changes. This has implications for future resilience to
extreme positive NAO winters, which frequently have severe societal
impacts.