ABSTRACT
In the present chapter, potential climatological proxy data for winter severity in medieval Sweden found in documentary sources are assessed and explored. Geographically, the documents cover the greater Baltic Sea area. A four-grade index classification of the documentary proxies is suggested and applied. The results should be seen as preliminary, but indicate a visible consistency with the periodization proposed for large parts of Europe of a pronounced warm period until the mid-1300s and two centuries thereafter of a cooling trend, both for winters and summers, with shortened growing seasons, harvest failures and cold winters. At the same time, consistency with European indices for the 14th century seems to be somewhat weaker. Severe or long winters have been recorded for 21 years between 1306 and 1496 and mild or short winters for 16 years between 1396 and 1492. In particular, the 1430s, the 1450s and the 1490s stand out as periods with accentuated longer winters. In case of Sweden, the variability on inter-annual and decadal scales is particularly significant for the seasonally and inter-annually very variable Baltic Sea area, and can explain some of the deviations from the general European pattern.
