Abstract :
The atmosphere-ocean model ECHO-G, run with solar, volcanic and greenhouse gas forcing for the past millennium, is
used to analyse winter and summer temperature variability in Scandinavia. Relationships with atmospheric circulation,
North Atlantic SSTs and Northern Hemisphere (NH) temperatures are investigated at timescales longer and shorter
than 10 yr. The simulated response to volcanic forcing is also analysed. Realistic relationships with the atmospheric
circulation, with some deficiencies in summer, are found. High-frequency co-variations with SSTs and NH temperatures
are too weak, but low-frequency co-variations with NH temperatures in winter are apparently too strong. The summer
cooling response to volcanic forcing is realistic, but the expected winter warming is absent. The simulated long-term
temperature evolution agrees broadly with proxy data. Combinations of several forcing factors can lead to decadal
and multidecadal anomalies from the centennial trends. Decreased solar forcing can account for cold intervals in both
summer and winter. A systematic negative North Atlantic Oscillation (NAO) phase can explain the coldest winter
temperatures during 1590–1650. Several strong volcanic forcing events can have contributed to a simultaneous summer
cooling. Proxy data also indicate cold summers and winters, and a negative NAO in winter, in the same period.
