  The warming trend of the last decades is now so strong that it is discernible
in local temperature observations. This opens the possibility to compare the
trend to the warming predicted by comprehensive climate models (GCMs), which up
to now could not be verified directly to observations on a local scale, because
the signal-to-noise ratio was too low. The observed temperature trend in
western Europe over the last decades appears much stronger than simulated by
state-of-the-art GCMs. The difference is very unlikely due to random
fluctuations, either in fast weather processes or in decadal climate
fluctuations. In winter and spring, changes in atmospheric circulation are
important; in spring and summer changes in soil moisture and cloud cover. A
misrepresentation of the North Atlantic Current affects trends along the coast.
Many of these processes continue to affect trends in projections for the 21st
century. This implies that climate predictions for western Europe probably
underestimate the effects of anthropogenic climate change.
