A Contribution to the History of European Winters: Some Climatological Proxy Data from...

A CONTRIBUTION TO THE HISTORY OF EUROPEAN WINTERS:SOME CLIMATOLOGICAL PROXY DATA FROM EARLY-SIXTEENTH

CENTURY SWEDISH DOCUMENTARY SOURCES

D. RETSÖ

Institute of Latin American Studies, Stockholm University, 10691 Stockholm, Sweden

Abstract. In this paper, the potential is explored for climatological information on winter weatherin a hitherto largely neglected category of historical documentary sources (correspondence letters)covering two decades of the less studied intermediate stages between the proposed warm High Mid-dle Ages and what has been termed ‘the Little Ice Age’. A discussion concerning some problemsof interpretation is presented from a historical methodological point of view. Content analysis, withspecial attention paid to contemporary terms and expressions linked to transport and travel, showsthat winters in Sweden during the first decades of the sixteenth century, in comparison with theaverage of the late twentieth century, were on the whole somewhat shorter in duration. Two of thewinters studied can be said to display some extreme characteristics; one exceptionally mild, and onewith an unusually early onset. On the whole, the result diverges slightly from previously publishedwinter severity indices and confirms regional disparities in the middle phase between a possible warmHigh Middle Ages and the so-called ‘Little Ice Age’.

1. Introduction

Knowledge concerning climatic conditions in the pre-instrumental period is partlydependent on proxy data from historical sources. However, it has long been recog-nized that the reliability of these, particularly narrative sources, is often difficultto assess, and that they must be treated with caution.1 More precisely, it is theunverifiable presence of interpolated secondary material and a strong observer biasthat can lower their reliability. The uncritical acceptance of such sources, and theiruse for conclusions on past climate has increasingly been subject to criticism, withthe point frequently made that they require careful analysis.2 However, there is onecategory of historical source which suffers less from these weaknesses – correspon-dence letters. It is remarkable to what a small degree they have hitherto been usedas climatological sources.3 Understandably, attention has primarily been focusedon historical documents with a much more explicit or unquestionably climatolog-ical content, such as annals, chronicles, monographies, diaries, weather diaries,log books, manorial account rolls, etc. Most compilations of weather data fromEuropean historical sources have no references to correspondence letters, and theyare quite often omitted or pass uncommented in lists of documentary sources ofpotential climatological interest.4 One difficulty with correspondence letters is, ofcourse, that they are to a large extent unprinted, and that relevant climatological

Climatic Change 52: 137–173, 2002.© 2002 Kluwer Academic Publishers. Printed in the Netherlands.

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information is scattered throughout an enormous mass of documents of a dis-parate nature. This renders access to it difficult, and requires a time-consumingand patient reading of original documents. It can also be argued that they veryseldom contain explicit weather observations. Nevertheless, their advantages overother historical source types are considerable, for a number of reasons. Insteadof meteorological observations of a quantitative numerical character, they do havequalitative information about parameteorological and phenological phenomena.5

Furthermore, the fact that such information generally appears in passing, and notas the main message of the text, makes them more credible. The letters are alsogenerally exactly dated, or datings can be inferred by careful comparison withother dated documents, and thus have a very high time resolution, normally tothe day, which is particularly important for the establishment of synoptic mapsand the determination of year-to-year variations during periods of change from oneclimatic regime to another.

The main focus of this paper is as a contribution to the history of European cli-mate by the analysis of early-sixteenth century Swedish documents. In particular,the study described here is intended as a response to the recent call for renewedefforts in examining documentary sources as well as expanding the spatial dimen-sion of climatic change. Further to this, it is written in the context of the needfor more information on regional and annual variations and temporal anomaliesregarding climatic changes that have been proposed to have occurred sometimebetween the fourteenth century and the mid-sixteenth century.6 In addition, it isintended to encourage investigation into a relatively unexploited type of historicalsource still awaiting its deserved attention.7 Some observations on the differencebetween these and other source types will also be made. In these latter sources therecan be a tendency to stress extreme climatic events like droughts, floods and frosts,whose significance for long-term climatological development can be difficult toassess in the absence of other evidence.

The limitations of the paper should also be clearly stated. Although the studyof past climates by nature is interdisciplinary, the present author does not pretendto transcend the disciplinary borders of the historical field. All climatological evi-dence as such should in the end be scrutinized not by historians but by professionalmeteorologists and climatologists. For that purpose, these scholars need to be pre-sented with information whose usefulness in the form of climatological data, whenextracted from nonquantitative historical accounts, is dependent on procedureswithin the domains of the historian’s craft; for example, such as the establishingof correct datings and interpretations of content. Although rich in information,these letters, as historical sources, must first be the object of historical scientificscrutiny in order to establish their degree of reliability. Only by passing throughthe historical methodological apparatus can their content safely be handed downto the scholars of adjacent disciplines for further processing and quantificationtowards genuine knowledge.8 Consequently, attention will be paid here to the his-torical methods proper, more particularly textual criticism, which will be treated

A CONTRIBUTION TO THE HISTORY OF EUROPEAN WINTERS 139

in detail. Neither will any attempt at quantification or calibration of the data bemade, another reason for which is, as will be seen, the detailed character of theevidence, which does not allow for generalizations on any other time-scale thanthe annual, or rather, the seasonal. Although Lamb has warned against a too strictapplication of historical critical methods9, it is held here that they are an absoluteprerequisite and an irreplaceable tool for a correct handling of the sources. Thepaper may thus be seen as a contribution to the ever-ongoing accumulation ofweather data from all parts of the world and all times, of which there can scarcelybe enough, and the value of which must be seen against the background of twofacts. First, the more general, ever-present need for all kinds of information thatcan shed light upon the weather conditions of previous times, and thus upon thoselong-term climatological changes which also affect our own times, and, second, thespecifically climatological discussion concerning global variations in climate.10

2. Introductory Description of the Sources

In a general sense, the number of surviving written sources from the Middle Agesin Sweden is quite small, especially if compared to European standards; only about20,000 original letters on parchment and paper, with an additional 20,000 medievaland post-medieval transcripts.11 Within that context, however, the archives of thetwo late medieval regents Svante Nilsson (1504–1511) and his son and succes-sor Sten Sture the younger (1512–1520) stand out as relatively rich sources ofinformation on a variety of topics.

Though archivistically two distinct bodies, the two archives are commonlyreferred to as one single collection under the label "the Sture Collection’ (Sturear-kivet). It comprises in total around 2,000 original documents dated roughlybetween 1498 and 1520, and are complemented by two contemporary copy-books,now kept in the Swedish National Archives under the signa A4 and A5, containingabout 250 additional letter texts in transcript, mostly from lost originals.12 Takentogether, they constitute a collection of texts which within the Swedish context isunique in many ways. Though not absolutely intact or homogenous – some 127letters can be verified to have disappeared from the collection at some point andthere are a number of documents with other origins than the Regents, though themajority stems from persons in their immediate vicinity – it is by far the largestand most complete single collection of letters from the Swedish Middle Ages. Inaddition, it is the only surviving archive that has belonged to the central power ofthe medieval period. The time period covered by the letters is the last two decadesof the so-called Union Era of Scandinavian history, whose character in part ex-plains the collection’s composition. This was a period characterized by the rise ofthe Danish kingdom as a major regional power and by repeated conflicts betweenSweden and Denmark, ultimately caused by the reluctance on the part of a sub-stantial group of the Swedish aristocracy to accept a Danish king as stipulated by

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the Scandinavian Union Treaty of Kalmar (1397) as well as numerous subsequenttreaties. As a consequence, Sweden was to an increasing extent only sporadicallyruled by nominal kings, whether Danish or Swedish, and the power of the nationalcouncil increased accordingly. During the period 1470–1523 Sweden was almostexclusively ruled by regents (riksföreståndare), who, while acting very much in themanner of viceroys, were elected by the national council and therefore subject toits control and dependent on its consent. In practice, Sweden was therefore to alarge extent an aristocratic republic. As a further consequence, there was no centralroyal chancery where records were kept. Instead, a functional division regardingthe handling of documents relevant to the proceedings of the council developed be-tween the branches of government. In this agreement the responsibility for keepingspecific categories of documents seems to have been assigned in a quite detailedway to each of: 1) the Regent (the foremost secular member of the council); 2)the Archbishop (the foremost clerical member of the council and its præses, orpresident) and; 3) the Bishop of Strängnäs, who, at least from the early 1470s, inaddition to being keeper of the national seal, acted as cancellarius regni, the chan-cellor of the realm.13 Each of these three persons of course kept their own, privatearchives, all of which at some later stage have disappeared, with the exception ofthe documents once belonging to the Regent during the period 1504–1520. A largepart of the archives of the other two branches of central government was destroyedin the devastating fire at Stockholm castle in 1697. However, the political archivesof the Regents’ earlier fifteenth-century predecessors are also lost; only remnantsare left.14

3. The Character of the Sources

The character of the sources is determined by the Regent’s dual role of, on theone hand, a private person, reflected by documents concerning his private estatebusiness as well as letters from his wife, and on the other, an official person. Inthe latter capacity two further functions can be distinguished; administrator of theroyal fiefs in the name of the council and the realm, and representative of royalpower within the council and its most prominent secular member. In fact, while thetexts in the two copy-books mostly deal with strictly political matters, especiallyforeign policy, thus reflecting the latter official function, the major part of the StureCollection is connected to the former.

Within that group, it is the incoming cover letters from crown sheriffs in chargeof the local administration, reflecting the first function, which are of primaryconcern to us. These letters, often accompanying tax remittals, contain importantinformation about day-to-day fiscal and administrative matters – dealings with thetax-paying peasantry, collection of ordinary and extraordinary taxes, furnishingand maintenance of the royal castles, etc. – as well as comments on matters ofa more personal character. As immediate residues of a historical process and of the


administration, the amount of manipulated or subjective tendencies such as foundin contemporary chronicles and other narrative sources is negligible. The totalnumber of identifiable individual letter authors in the Sture Collection is around450, of which 48 have contributed with climatological proxy data in 97 letter texts.More than 50% of these data come from three individuals, the Archbishop JakobUlfsson, the elected (but never confirmed) bishop of Linköping Hemming Gad,and the Sheriff of Stockholm castle Jon Jönsson. The overwhelming majority ofthe remaining letters is also issued by nobles; perhaps only six are written bynon-nobles. Three fifths, 29 letters, are from local sheriffs. All relevant letters arewritten by native Swedes (or Scandinavians, if we include Svante Nilsson’s Danishwife Mätta Ivarsdotter), except two, which were written by Germans. From a cli-matological point of view, it can thus be observed that the letters are written over afairly short period of time by a relatively small number of individuals from roughlythe same social group who are firsthand observers and whose descriptive vocabu-lary thus can be expected to be quite uniform. The influences from their social andintellectual environment, their personal taste and prejudices should therefore bedistributed quite evenly in the material.15 Interpolation of secondary information,a difficulty known to be common in other historical sources, especially descriptiveones, is virtually absent, and it seems that where it is existent it is expressly stated.16

Furthermore, as stated above, most of the writers are native Swedes, familiar withtheir immediate geographical environment, its meteorological ‘normality’ and pe-culiarities, and the ‘alien perspective factor’ can be regarded as negligible.17 Theirinformation on a number of topics is, in short, highly reliable as regards contempo-raneity, propinquity and faithful transmission and therefore complies with some ofthe most important demands on a useful historical source.18 Moreover, the periodcovered by the letters takes place in the intermediate stage between the supposedwarm High Middle Ages and the so-called and much-discussed ‘Little Ice Age’19,which can be regarded as an advantage, especially since scholarly attention hastended to concentrate on these two latter climatological regimes, and since theglobal synchronicity of these and their power as general frameworks for interpreta-tions have increasingly been questioned.20 It can be noted that Gustaf Utterström,who in his famous study has come closest to the period and the material in concern,also jumped over the half-century around AD 1500, concentrating on GustavusVasa’s reign.21

On the other hand, it must be noted that the temporal distribution of the lettersis highly uneven. In general, Svante Nilsson’s regency is quite well documented,with a peak during the years 1506–1508, but for Sten Sture the younger’s regencythere are some gaps, particularly the years 1514–1515 and after 1518, the reasonsfor which remain unexplained,22 but the consequences are clear; the ground forsafe conclusions of any kind diminishes accordingly. Furthermore, the geographi-cal scope of the letters is limited as compared to the configuration of present-daySweden. Until the mid-seventeenth century the western and southern provinces ofBohuslän, Halland, Skåne and Blekinge as well as the island of Gotland and the

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Figure 1. Southern Scandinavia and the Baltic Region.

northern provinces of Jämtland and Härjedalen belonged to the Danish-Norwegiankingdom. None of these areas, nor the thinly populated northern two-thirds ofSweden, has left more than a few traces in the source material. On the otherhand, Finland formed part of the Swedish kingdom. So, the core zone of medievalSweden where most people lived and ran their business and to which the avail-able information consequently is concentrated, was confined to an area stretchingfrom the more densely populated areas around Turku in southwestern Finland overthe Åland Sea to the agricultural areas around the lakes Mälaren and Hjälmaren,in Västergötland, Östergötland and Småland, and finally the mining district inDalecarlia.

A first superficial glance at the content of the letters from a climatological pointof view is disappointing. As may be expected from this type of source, there arealmost no explicit weather observations, no mentions of sunny or cloudy days, noinformation on precipitation, not even direct information about, for example, ex-treme heat or extreme cold (not to speak of ‘normal’ temperatures), nor snow cover.As a whole, useful climatological information, particularly on summer weather,seems to be scant. Instead, the true validity of the sources derives from the well-known fact that it was climatological and meteorological factors that determinedthe modes and speed of transport and travel in pre-industrial northern Europe. More


Figure 2. Central Sweden in the Late Middle Ages.

precisely, it is the dominance of sledges and sleighs for winter transport in Scandi-navia, together with the trivial fact that sleigh-rides require snow-covered ground,that concern us here. The predominance of sleighs in transportation of heavy andbulky goods such as tax items in kind, together with the large number of lettersin the Sture Collection dealing precisely with tax collecting, give good reasonsto expect that snow and ice conditions would be reflected in the contemporaryletters in one way or another. Other fortunate circumstances connected to the basicconditions for transport in medieval Sweden is that meteorological factors by thesame logic also determined the conditions of warfare and maritime trade, and thattwo other main themes in the Sture Collection are precisely the armed conflictswith Denmark and the trade with the commercial ports of the south Baltic – Tallinn,Lübeck, Danzig, etc. For example, since frozen waters constituted avenues of mil-itary land transport, the artificial breaking up of lake ice by hand so as to obstructthe enemy’s troop movements developed as one defensive measure in winter war-

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fare. The same principle was applied around castles surrounded by water. The factthat Sweden north of the 61st parallel is virtually absent in the sources is in thiscontext no great loss. It can safely be assumed that since snow and sleighs weremore commonplace at these Arctic and sub-Arctic latitudes, mentions of them,had we been in possession of more sources from these regions, would not havecontributed much to our knowledge about climatic change, and even less aboutclimatic anomalies; they would only have confirmed previous assumptions. It is inthe south of Sweden, where sleighs were less common, that indirect evidence of iceand snow conditions take on a special significance, as does the information fromthat region. The method required is thus one of critical content analysis in whichthe incidence of certain key terms require particular attention – in the present casethe most important ones are före and första öppna vatten.23

4. ‘Före, Menföre, Oföre’ and Other Terms Indicating Snow Conditions

Före is a noun which in modern Scandinavian languages refers to the degree offriction on a snow-covered surface for modes of winter transport such as skis andsleighs. Ultimately it derives from the verb föra – ‘to lead’, ‘to guide’, ‘to carry’, ‘totransport’ – and is also related to the adjective för which today almost exclusivelyappears in the variant arbetsför – ‘fit to work’. It is virtually impossible to translateit faithfully into English, and therefore the Swedish word will be retained here. Inmedieval sources it normally appears with a negative modification, preceded eitherby the adjective ont (‘bad’) or by one of the prefixes men- and o-, more or lesscorresponding to the English prefixes ‘un-’ and ‘in-’. Thus, all three expressions(ont före, menföre and oföre) refer to weather conditions unfit for sleigh rides, forexample, while gott före would indicate suitability. Some incidences of the wordföre indicate a much broader significance in medieval language, though, and makeit seem simply synonymous with ‘snow’, particularly when it appears without anyadjectivization. The Sheriff of Turku castle reported once that the peasants of theTavastland province were reluctant to hand over a particular tax payment ‘untilthe före comes’, and on another occasion Regent Svante ordered a sheriff to sendbutter and pork to Stockholm ‘while there is före’.24 The general impression is,though, that the word should be understood as synonymous with trafficability ingeneral, and that its qualification as an indicator of snow conditions is determinedby the date of the letter in which it appears. A confirmation of that is a conspicuousexample from the autumn of 1511 when one of Svante’s servants blamed ‘greatmenföre, because there were deep ditches’ for not having been able to execute anattack on the manor of one of the Regent’s political enemies.25 It is clear, bothfrom the description and from the date and place for the event, that menföre inthis case had nothing to do with snow. Another example shows that even in moredoubtful cases one can conclude that the mention refers to something other thansnow. One of Svante’s sheriffs reported in April 1508 to his lord that he was unable


to obey an order to send some horses to him ‘until the före gets better’.26 It seemsunreasonable to believe that anyone would expect improved trafficability throughsnow at such a late time of the year as the month of April, and even more soas it regards the transport of horses who would be helped neither by snow norsnow vehicles like sleighs. The conclusion in this case must be that thaw probablyprevailed at the time of the writing of the letter and that the ‘better före’ must referto bare (or perhaps rather dry) snowless ground. It should be noted that the processof melting in the spring can have ambiguous effects. Open snow-covered roadswould of course be subject to a higher degree of exposition to the spring sun andthus a higher pace of melting than the shadowed snow patches in the forest. On theother hand, the snow on frequently used avenues of communication would have ahigher density resembling ice due to the constant traffic on it which would slowthe pace of melting down. It is therefore not uncommon in the late winter monthsthat the conditions of trafficability are inverted, and that roads are too icy to beused while bare ground is found deeper in the forests. A corresponding case fromthe autumn season is constituted by a letter from late November 1504, in whichthe sender apologized for his and his wife’s inability to attend Svante’s wedding inStockholm, since they had been forced to interrupt their journey due to ‘quite bad,sudden före’ (ganska ont brått före).27 Again considering the time of the year, itseems unlikely that the ‘bad före’ in this case could have been caused by a suddenthaw, melting good sleigh snow away. Instead, it would rather mean rain turningthe road into mud. When similar expressions appear in letters from mid-wintermonths, special caution has to be used. On February 20, 1501, for instance, oneof Svante’s servants regretted that he could not travel to Stegeborg castle due tolack of horse fodder at the moment, and ‘probably neither during the winter at allby sleigh’.28 The latter expression is somewhat vague, but considering the date itseems over-confident to interpret it as a pessimistic view of the amount of snow forthe remaining winter. Rather than lack of snow, it is more probable that it aims atan estimated continuous shortage of fodder for the drought horses, or perhaps eventhat the Sheriff had no sleighs at his disposal.

5. ‘First Open Water’ and Other Terms Indicating Ice Conditions

The second term, ‘first open water’ (första öppna vatten), is less problematic. Itobviously refers to the break-up of the ice in the spring. It appears occasionallyin letters from ports in the Mälar Valley (Västerås, Köping), but also from portsalong the Baltic coast (Stockholm, Nyköping, Norrköping and Söderköping), andparticularly in letters dealing with matters in Finland, separated from the Swedishhalf of the kingdom by the Gulf of Bothnia. The background of the occurrence ofthe expression in these latter cases is of course primarily the fact that the Baltic Seaoccasionally freezes due to the low salinity (7–9� in the surface layer which makesit freeze at −0, 35 ◦C) in combination with the extremely complicated geography

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of the Swedish and Finnish coastlines. The sheltered waters of the numerous bays,inlets and straits between the thousands of islands and islets scattered along thecoast stretching from Kalmar to Turku are among the first to freeze in the earlywinter and the last to break up in the spring. The freezing of the inner watersbetween Åland and Turku in particular is an established historical event that hasoccurred repeatedly into modern times, constituting an obstacle to sea transportsin the winter. In medieval sources, there are many references of different kindsto these freezings. For instance, in the letter of safe-conduct for Nils Bosson, aSwedish nobleman in Danish service, a special clause was included stating that ifhe, due to ‘ice and menföre’ – hence in one breath equalizing the impeding naturefor travel of both – did not manage to return to his castle Borgholm within thesafe-conduct period (November 21, 1507 to January 23, 1508), the safe-conductwould automatically be prolonged until he did so.29 Therefore, in medieval timesall transfers of taxes from Finland were carried out during the summer, and the term‘first open water’ generally appears in future tense in letters from the Sheriff of thecentral Finnish castle of Turku (which was a royal fief) under whose supervisionthese tax remittals were executed, to the Regent answering previous requests byhim. Its incidence in the letters is therefore an important indicator of ice conditions,or more precisely, of when the sea was not navigable due to the ice cover. This isalso reflected by the monthly frequency of letters with Finnish origin. For the wholeperiod, 40% of them are dated in the ice-free months of July through September,while only 14% are dated in the winter months December through February. Thereis also a peak in the month of March, with a total of 25 letters, which seems toreflect suddenly easier transportation in connection with the break-up of the ice.Interestingly, the frequency to a certain extent corresponds to the recommendationsfor travel and conveyance of messages found in old peasants’ weather-books.30

Some cases, in which the term appears in letters written in November and Decem-ber, can be disregarded, since they obviously are written too far in advance to haveany information about break-up of the ice in the spring. But letters written in thelate winter months or early spring months, obviously give a datum terminus postquem for the spring break-up of sea ice in the Finnish Archipelago, or at least inthe vicinity of Turku.

In this context, a letter dated on April 7, 1505, should be mentioned becauseof an interesting but puzzling formulation. The Sheriff of Västerås regretted thatSvante’s order to send all tax iron to Stockholm ‘with the first open water’ couldnot be obeyed because it had not arrived due to ‘lack of water’ (watwløse skwl).31

It must be assumed that this concerns the water level in the rivers furnishing waterpower for the iron works further north. However, it is difficult to determine whetherwhat is actually being described is a delayed spring flood due to persistent frost inthe headwaters, and that we can deduce something about the normal date for theiroccurrence, or, whether this is an expression of an exceptionally small spring floodat the normal time, in other words an indication of a mild winter in the headwatersof the river. Instinct may incline us towards the latter. There would be no apparent


reason for Svante to order transfers of tax in kind at a time when water would beknown to be scant, especially if we suppose that he was informed about the normallevels of water at different times of the year, an assumption for which there aregood grounds – Svante spent his childhood and adolescence at Västerås castle, andshould be well aware of local conditions. It should be noted that the main river ofthe mining area in modern times is known for quite substantial spring floods.32 Thepresent evidence, however, precludes any conclusion.

6. The Siege of Kalmar

Concerning winter warfare, another fortunate conjunction of events results in valu-able climatological information. This is the sieges of the seaboard Kalmar andBorgholm fortresses, a major, prolonged historical event which encompassed thefirst decade of the sixteenth century and thus coincides in time with precisely thoseyears during which the Sture letters are most numerous. These castles, which wereheld by Denmark, are situated on each side of the Kalmar channel which separatesthe island of Öland from the mainland in the southeast of Sweden. The Regent,Svante Nilsson, spent much energy and resources to seize them. That was partlymotivated by their important strategic position along the trade routes of the southBaltic Sea, partly by the highly symbolic value of controlling Kalmar, the site of thesigning of the Scandinavian Union Treaty in 1397 – the political agreement aboutwhich much of the late Nordic medieval conflicts revolved – as well as of numerousNordic summit meetings. All of this is reflected in the great number of letters in theSture Collection originating from the Swedish commanders of the besieging forcesoutside the fortress. In particular, these reports contain quite detailed informationabout ice conditions around the fortress since it had military significance both forattackers and defenders. An ice cover on the channel constituted an obstacle toships with reinforcements and necessities for the fortresses, while it at the sametime facilitated mutual attacks, and made it possible for the besieged Danes atKalmar to cross the channel to Öland and plunder farmsteads in search of food.Correspondingly, open water meant a forced slackening of war activities and re-inforcements for the Danes, eventually prolonging the siege. These circumstanceswere put clearly in a letter from Regent Svante in late September 1507, in whichhe stated that his departure from the vicinity of Kalmar was dependent on whether‘the ships and the enemies of the realm leave the channel, which I hope will happensoon because of the approaching winter days’.33 After all, the idea of fluid wateras a defensive device is of course reflected in one of the main characteristics ofmedieval fortification architecture – the moat. Some parallels are found in reportsabout the crew of the castle keeping the waters around it ice-free, which of coursehas a great significance for our present purpose since it means that it indicates thepresence of ice. Thus, frozen water and open water served different purposes forthe people involved and this is reflected in the sources. One curiosity that should be

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mentioned is the absolute absence in the sources of mentions of fog, a phenomenonwhich is very common along the southeastern coast as well as north of Stockholmduring autumn and winter in modern times.34

7. Rye Crops

Data on harvest as a function of the length and character of the growing seasonis correlated with the length and character of winter. It is commonly known thatbad autumn harvests in Scandinavia are normally due to the thermal deficits inthe growing season with cold and cloudy spring-summers or even in the precedingwinter.35 Unfortunately, such data are rare in the letter material. One example ofevidence of a dearth of barley from May 1503 may point to a bad harvest in 1502.It is one of the Regent’s sheriffs who reported that the barley in Kalmar was moreexpensive than it had been in almost a hundred years (which should not be takenliterally), and he proposed that the Regent not collect cereals taxes ‘now when thesoil lies unsown and the peasants eat bark’.36 On the other hand, from the year 1513we have information about ‘the greatest rainfall in six or eight years’ and a goodforecast for the barley harvest, but also ‘the greatest scarcity of fish in a hundredyears, according to the old people’.37 Of particular interest are the rye crops, a ce-real which to an increasing extent was used in Sweden mainly as a hibernating cropsown in the autumn and reaped in the spring, reports on which are somewhat morenumerous and therefore could be important indicators of winter severity during therelevant years. In late June 1508, for example, the Sheriff of Turku in Finland hadto reject the Regent’s request for a remissal of rye on the grounds that he had noneafter he had been forced to pay the workmen of the castle in rye instead of money,and he added that last year’s (i.e. 1507) harvest was not good enough as seed. TheDean and the burghers of Turku could not help him out since ‘the peasants starveand eat more bark than ever this year’.38 A possible confirmation of the poor qualityof the seed of 1507 also in Sweden is perhaps a statement by one of the Regent’sintimates in Kalmar who claimed that ‘the seed sown this year cannot be harvestedand ground in two years’.39 Similarly, in another letter from April the same year itis said that the peasants in the vicinity of Stockholm had not sown so little rye inmany years.40 The effect of that is seen in a letter from late March 1509, when theSheriff of Stockholm reported that famine in the coastal and interior areas northof Stockholm was so widespread that the peasants ate bark and was unable to paytheir due taxes.41 There are also a number of other letters with similar interestingclimatological information but which at the present state of research unfortunatelycannot be utilized since they lack a more precise time resolution. That is the casewith one letter which speaks of a season with exceptional wetness (probably from1504 or 1507), and one from a peasant community complaining about their povertyand dispair due to the weather (from 1504–1511).42


The reports on famine and low quality of rye seed during these years shouldbe seen against the background of seed being one of the major agricultural invest-ments in the Middle Ages, sometimes constituting up to 1/3 of the harvest.43 Giventhe inverted cumulative effect over time produced by such a low seed/yield ratio,a shrinkage of one single season would produce a chain reaction with a down-spiralling devastating effect on the peasant economy. It seems obvious that thesereports actually describe a situation derived from another geometric and chronolog-ical scale than the single mention of a frozen water at a particular place and thushave a greater scope of significance. It could be argued that a prolonged parame-terological event is not necessarily the result of a prolonged weather situation, butcan have relatively instant causes such as a sudden and severe frost during a crucialphase of the growing season. In the case of rye, that is less probable, however.Apart from the apparent difficulty of explaining the absence of any mention ofsuch an extreme event in the contemporary sources, the south boreal climate zonewhich encompasses almost half of Sweden’s surface presents very good conditionsfor the cultivation of rye, which is also known to grow relatively well even underunfortunate conditions such as severe winters. On the other hand, it is not com-pletely resistant to persevering frost.44 It may therefore be tempting to ascribe tothe winter preceding the first report on rye crop failure, i.e., that of 1506/7, a long,severe character affecting the sowing and harvest of the following. But these dataare difficult to reconcile with, for example, tree-ring data from northern Swedenwhich suggest that the summers of 1506–1509 fell in a period encompassing thefirst decades of the sixteenth century with positive anomalies in Europe, perhapsup to +1 ◦C.45 It could be possible that we are dealing with regional-seasonaldisparities with positive summer anomalies in the north and negative winter anom-alies further south, suggesting a more accentuated continental climatic character.However, all the evidence from the winter of 1506/7 presented below points to thecontrary – an unusually mild winter, according to Easton’s index even the warmestof the decade.46 One possibility is that the chain reaction of bad seed started evenearlier, for example, the winter 1505/6 which at least around Kalmar and on theEuropean continent seems to have been severe.47 But even though the interrela-tionship between low quality of seed and famine can be established, a strict causalconnection between climate and the rye crops cannot. It should be remembered,as Le Roy Ladurie has pointed out, that the background of such data can be ofmany kinds and unless the precise cause of crop failures is stated one should nota priori connect them with climate factors at all.48 It is also obviously clear thatfurther proxy data can be obtained by further analyses of, for example, the timingof mentions of storms and shipwrecks (as well as their frequency), the coming ofherring and salmon, sowing, reduction of taxes as well as agricultural productivityfrom particularly well-documented manors.

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8. Problems of Interpretation

Even when the term före and its variants, as well as other similar terms and ex-pressions, can be relied upon as references to snow-covered ground or ice-coveredwater, there are additional problems of interpretation. Since their appearance inthe sources is connected to transport, in particular transports of taxes in kind, itwould not seem far-fetched to suspect that a person in charge of collecting andremitting such taxes might invent weather problems if he had been negligible inperforming his duty.49 On the other hand, it can be argued that such a person wouldbe anxious to be close to the truth if the weather really had been an obstacle, soas not to risk a stain on his reputation. It is quite apparent in the surviving sourcesthat there was constant gossip, complaints and rumours about alleged negligence,highhandedness and unauthorized measures among the sheriffs and the personnelof the castles as well as among the peasants, and that it sooner or later reachedthe Regent’s ears and occasioned rebukes and even quite severe punishment. Ingeneral, it must be assumed that the terms referring to snow and ice conditionsin connection with fiscal activities describe a meteorological reality of the past.A different case, however, is when high politics was involved. There is a goodexample from April 1518. To a request from the Regent Sten Sture to meet with himin Stockholm, Bishop Mats of Strängnäs answered that he would be glad to do so assoon as the ice had broken up.50 Although it is perhaps possible that Lake Mälarencould be intrafficable due to ice at this season of the year, the time is a little late forthat. In fact, a closer look at some other letters from the same time shows that travelin the region was in no way impossible. For instance, a letter written on April 19in Uppsala, arrived at the Regent in Stockholm, 60 kms away, only two days later,and Sten’s reply to him arrived even faster, in one single day.51 Although we lackdetails on the route used for the delivery of these letters, the length of the day’sjourneys strongly indicate that the messengers have travelled the shortest way, overthe lake. Even more significant, two men from the Uppsala Bishopric, whose arrivalin Strängnäs on April 19 the Bishop himself had reported, had, according to anotherreporter, already returned to Uppsala on April 21.52 Since Strängnäs and Uppsalaare situated on each side of Lake Mälaren and they have covered the 65 kms as thecrow flies between them in such a short time, it can be concluded that they mostdefinitely have travelled over the lake, whether frozen or not, and hence it is alsoclear that travels in the Mälaren Valley could indeed be made, and quite fast, too.Summing up, one should distrust the Bishop’s assertion that he was prevented fromgoing to Stockholm because of ice. The political context probably elucidates hisimpediment better. The Bishop was at this time a candidate for the Archbishopricfollowing the dramatic deposition of Gustav Trolle the previous year, but he wasreluctant to accept the candidacy since the procedure was possibly a violation ofcanonical law, and he first wanted to deal with the matter in the presence of theother bishops and the National Council.53 The result is that the Bishop’s statement,


from a critical point of view, is useless as an indicator of ice conditions on LakeMälaren in April 1518.

The example mentioned also points to another limitation. Since the modes andspeed of travel and winter transport is dependent upon meteorological factors likesnow cover and ice cover it could be tempting to also use the available informationabout speed of travel as a proxy data for weather conditions. Travel could, forinstance, be expected to have been faster during the winter through the use ofsleighs and the shortening of travel routes over frozen lakes and snow-coveredfields. It could thus be assumed that a particular journey performed at a high speedin the winter has been undertaken in a sleigh through a winter landscape – a pa-rameteorological proxy datum. In the case above, the speed with which the lettersbetween towns around Lake Mälaren were delivered could, for instance, suggestthat the waters of the lake were indeed covered with a thick and reliable cover of iceon which messengers on horseback could move fast. However, this is obviously achicken-and-egg question. It must be remembered that ‘winter’ is at the same time achronological and a meteorological term. It is not possible to assume a priori that ajourney taking place during the chronological winter (December–March), has beencarried out in a sleigh through a meteorological winter landscape. In order to knowwhether there was snow at the particular time of a journey, and thus enabling us todraw a climatological conclusion, we would have to know whether the journey wasmade by sleigh, and in order to know whether the journey was made by sleigh, wewould have to know whether there was snow. So, at present we will have to limitourselves to the hard core of more explicit information furnished by the mentionsof the key terms already analyzed.

9. The Evidence

The evidence retrieved from the Sture Collection and the codices A4 and A5derives from a thorough reading of all 2,250 letters, and is presented here inchronological order.

THE WINTER OF 1501/2

On 14 December 1501, a ship arrived in Stockholm from Lübeck, indicating thatthe passage was free of ice.54 On January 20, the Sheriff of Stegeborg castlereported that the water around the castle was being kept free of ice.55


Sometime before April 24 ships arrived from Lübeck to a Swedish port whosename is not mentioned but which can be assumed to have been Stockholm.56

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The body of the deceased Sten Sture the elder was transported in a sleigh fromJönköping (probably all the way to Stockholm) in late December 1503.57 On April9 and 10 there was still ice in Stockholm.58


On December 8, there is still no snow suited for sleighs in Stockholm.59 There wasice in Turku on February 13 as well as on April 4, but in Kalmar Danish forceswere able to arrive before April 3.60 In a letter to Regent Svante written on March18, the Knight and Counsellor Knut Eskilsson denied an alleged earlier promise tocome and see him on Nyköping castle ‘as soon as the ice on [the Bay of] Bråvikenbears’ since he did not know whether it would be strong enough.61


In mid-December a storm ravaged the southern Baltic Sea delaying or sinking upto 15 ships.62 Around December 22, the garrison of the Kalmar fortress was ableto get reinforcements, but by early February, according to exaggerated but tellinginformation, an ice cover which was said to be strong enough to support ‘a thousandhorses’ had been formed.63 On April 10, Svante’s wife Mätta Ivarsdotter, then atthe Eksjö manor, regretted to her husband that she was unable to meet him by theNydala monastery as agreed since she had no saddle for her accompanying maidand the horses’ shoes had to be made first.64 Considering that women preferredtravel in sleighs when possible and that horses’ shoes usually were taken off whenthere was snow, it points to a relatively thin or inexistent snow cover. By April13, there was busy traffic in the waters around Stockholm. According to one letter,ships can navigate freely, and one item of information can be interpreted to meannavigability as early as around March 1.65 On April 20, as well as five days later,there were several ships at Tyresudden ‘by the Finnish route’ (finskeleden), unableto get into the harbour due to a strong westerly wind.66 It seems possible to connectthat with a notice from April 29 when it is reported that a ship that Regent Svantehad ordered the Sheriff of Västerås castle to send to Arboga - thus westwardsand possibly against the wind - had not sailed due to the weather and because thecurrent in the Arboga creek was too strong.67 The latter information is especiallyinteresting since it points to a substantial spring flood, for which the Arboga creekis not known, and therefore gives an indication of the date for the onset of springthaw as well as of a snowy winter in the area around its sources located in themountains of southern Dalecarlia. The modern maximum usually occurs in thefirst half of May.68 Unusual evidence concerning ice conditions further north isfound in a letter dated June 4 in which the sheriff of the Korsholm castle in Finlandreported that he soon would go north to take care of Svante’s fisheries, which hehad been unable to do before ‘due to the ice’.69 The apologizing tone of the letter


suggests that it should have been done earlier and that ice had lingered on longerthan normal.


There are several indications of a ‘frail and weak’ (klen och veker) winter, thatas late as the end of January the ice had not yet covered the Kalmar channelas expected and that the ice around Öland a month later ‘not yet could supporthorses’.70 This can be compared with the statement from the previous year men-tioned above. Judging from a report from March 1 on a number of new Danishtroops having arrived at the fortress, the Kalmar channel was still navigable shortlybefore that time.71 Already by December 22 ships with reinforcements arrived atthe castle, and there were other ships near the island of Jungfrun in the northernpart of the channel.72 A Swedish envoy to Poland reported on December 19 fromReval (Tallinn) in Estonia that his departure was being delayed by the weather.73

Central and western Sweden also seem to have had a mild winter with little snowand relatively high temperatures that year. Shortly before Christmas (i. e. January30, New Style) three ships arrived in the port of Söderköping, situated in a long,narrow bay, and possibly also some in Nyköping.74 When the Danish Duke Kristian(the future King Kristian II) and his followers travelled through Bohuslän towardsAkershus fortress in Norway towards the end of January, the Swedish Knight TureJönsson complained that ‘there was no winter’ so that he could attack him.75 SvanteNilsson’s wife Mätta Ivarsdotter complained in mid-February to her husband thatshe had not been able to fulfil her intentions to leave Vadstena for the family manorUlvåsa in northern Östergötland, ‘either by wagon or sleigh’ due to menföre. Thefact that she deemed both sorts of vehicle useless is no doubt an indication of aparticularly slushy thaw - two weeks later she had still not been able to travel.76

It is also worth noting that she mentions nothing about the possibility of goingon horseback, something which she, through other letters, is known to have beencapable of. There was not much snow in the area around Jönköping either. TheSheriff reported on February 19 that the peasants there refused to pay their tax‘until better före and weather comes’.77 At the same time further north, the Ham-rånge Bay, some 180 kms north of Stockholm, was frozen; one of the Regent’ssheriffs, while crossing the bay on the ice his way south, was hit by a storm shortlybefore February 18, lost one horse in a crack in the ice and just barely managedto save another from the same fate.78 In late March the military commander ofthe siege of Kalmar reported that it finally had become colder, that the ice in thechannel had strengthened and he even suggested another military expedition toÖland.79 About the same time, however, the Knight Åke Hansson in southeasternVästergötland, explaining the reasons for not having attacked the Danes, blamed insomewhat vague words ‘unstable’ weather rendering troop movements impossible,and hoped that it would become warmer so that the roads become trafficable.80 Inearly April the weather had improved to the degree that Mätta had finally managed

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to carry out her long postponed journey to Ulvåsa and was even preparing for thereturn to Vadstena.81 According to a notice in the Book of Acts of the StockholmMagistrate, the Chieftain of Kastellholm fortress on Åland left the town on April 6for his fief, from which it seems that the route out of Stockholm to the open sea wasfree of ice.82 About the same time, the port of Norrköping was free of ice as wellas Kalmar, where the arrival of ships by Easter (i. e. April 14, New Style) indicatesfree water, and the thaw had reached Dalecarlia by April 19 when difficulties incollecting tax iron due to the ‘bad före’ was reported.83 Shortly before April 30there were several battles around Kalmar involving ships.84


Around December 12, six ships from Danzig arrived in Stockholm.85 In Kalmar,the taxes had not been collected to the desired extent by Christmas (i.e., January4, New Style) due to the peasants’ refusal to pay ‘with the present före’ (swadanthföre som nw aer) and wanted to postpone it until ‘different weather than thepresent’ (wederacth en nw aer) set in. In another letter with news about dramaticevents near the castle, the Commander reported that a ship had arrived from Ölandon Christmas Eve, and had been attacked by the Swedes – a testimony of navigablewater in the channel.86 By mid-January an ice layer had been formed but wasobviously quite thin, as it was also around March 7 and 10.87 On March 21 therewas still ice but it was expected to break up soon. One of the commanders claimedthat once he got the timber he needed for the strengthening of a barge it wouldbe ready to be used as a blockade of the castle within 8 days. It was important toplace the barge there as soon as the ice broke up because there were several shipswaiting by Öland to furnish the castle with reinforcements. He gave thanks to Godthat the harbour (of the castle) was all covered with ice and prayed that it wouldfreeze rather than melt.88 However, two weeks later, shortly before April 12, thewaters around the castle must have been free of ice as seven Danish ships werereported to have arrived there.89 It is remarkable that in Öregrund (115 kms northof Stockholm), a much more northerly part of the country, some burghers as late asNew Year’s Day (i.e., January 10, New Style) were still ‘awaiting the first före’ totravel to the north of Sweden with their sleighs - obviously there was insufficientsnow cover.90 Also in Västergötland, the winter had been mild up to at least shortlybefore Christmas (i.e., January 4, New Style), but turned relatively snowy beforeEpiphany. It is again the Knight Åke Hansson who on January 17 in commentingan assault on a priest in the district of Mark around Christmas, says that if ‘theföre at that time had been as it is now. . . , I would have done something about it’.91

In a letter to Regent Svante, written in Uppsala on February 29, the Archbishopdeclared himself prepared to come to the meeting of the council in Vadstena onAsh Wednesday (March 18) ‘if the före permits’.92 It seems obvious that there musthave been enough snow at that time in Uppsala for him to make such a promise. Buteleven days later, on March 10, he wrote another letter from his residence Arnö to


the counsellors assembled in Vadstena, regretting that he was now unable to come,due to the great menföre that had occurred, making it impossible for him to use hissleigh, and he also added that he was too weak to ride on his horse.93 On March27, there was still ice around the town of Köping at the extreme end of the LakeMälaren; the Sheriff there promised to send the remaining tax with ‘the first openwater’.94


According to several letters from the latter third of November the winter seemsto have set in early; there are predictions of a ‘harsh winter’ simultaneously inÖstergötland and in Finland, and in Finland even of a ‘sudden’ winter.95 No detailsare given but evidently there must have been cold northern winds and probablysnowfall. In two interesting letters dated November 18 and 19, the Archbishopreminded Regent Svante about an agreement to convoke a meeting of the council inEnköping to discuss the sending of a delegation to Denmark for peace negotiations.Answering Svante’s recent suggestion to hold the meeting in Stockholm instead,the Archbishop tried to persuade him to stick to the former agreement, giving asreasons that his ships were ‘laid up for the winter’, that ‘the straits around Stäket[the Archbishop’s castle] are beginning to freeze’ and that he was ‘too weak toride long distances’.96 The fact that he rules out a trip on water on the groundsthat winter was approaching, while omitting any mention of sleighs, constitutesanother confirmation of an early, albeit so far snowless, winter. One of the envoyseventually sent to Denmark for negotiations asked Svante in a letter dated at theEkholm manor on November 22, to arrange a new letter of safe-conduct for himand his fellow travellers, since their departure had been delayed, and it would beimpossible to reach the border within the time limits of the current safe-conduct‘especially in the prevailing före’.97 Obviously then, the first thrust of the winterhad ceded to milder weather. The waters of the archipelago outside Stockholmas well as the Kalmar channel, Bråviken, and the Gulf of Finland, seem for in-stance to have been navigable during the whole month of November and well intoDecember.98 Still, around St Anne’s Day (December 19, New Style), ships wereable to sail the Kalmar channel and on January 19, ships which had been waiting forthe ice to break up in the Stockholm archipelago just a week before, had arrived inthe town itself.99 On February 21, a request from the Regent for an attack on Ölandwas discouraged, one of the grounds of which was that the ice in the channel wassaid to be ‘treacherous’.100 On the next day, another person on the spot in Kalmarsuggested sending ships with provisions to the town.101 On April 3, the Archbishopreported to the members of the council in Finland that a meeting recently had beenheld in Arboga, which he again had been unable to attend due to menföre.102 Themeeting was held around March 20-21, at which time hence there was little snowin Uppsala where the Archbishop stayed.103 About the same time, the Sheriff ofStockholm asked Regent Svante, at that time presumed to be in Arboga for the

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meeting, to send cereals ‘as soon as the ice breaks up’. Since the Sheriff himself hadbeen in the Västerås area around mid-February, it is reasonable to believe that hisexpression derives from his own observations of the ice conditions at that time.104

On April 29 ships were able to leave the port of Söderköping.105


By March 17, ships arrived in the port of Stockholm, and judging from the Arch-bishop’s stated inability to travel due to the ‘great oföre’, spring thaw set in in theUppsala area shortly before March 27.106 It seems possible to put that in connectionwith two subtle indications in a letter dated April 9 of strong southern winds in thesouthern Baltic area, bringing warmer air over southern Sweden. The messengerwho brought the threat of war from the Duke of Mecklenburg to the Danish kingtravelled the 180 kms between Rostock and Copenhagen in two days – a recordspeed of 90 kms per day obviously furnished by extremely favorable winds – whilea delivery of meat from Söderköping (thus in the opposite compass direction) hadnot been able to be carried out at all due to adverse wind.107 By April 29, whenthe Archbishop expressed a wish to hold a meeting of the council in Stockholminstead of Tälje since the ‘unstable weather’ made it uncomfortable ‘for old men tocamp’ (ligga på marken), the waters between Uppsala and Stockholm apparentlywere free of ice.108 Sometime before March 31 the Regent’s sheriff in Söderköpingreceived a letter from his lord who asked him to send butter and pork to Stockholm‘while the före is good’.109 Obviously this is another case in which the author ofthe letter has chosen his words on the basis of the prevailing conditions in hisimmediate vicinity. It can therefore be assumed that there was still winter and ‘goodföre’ in the Västerås-Arboga area where Svante himself was at the time.110


Three days before Christmas (i.e., January 1, New Style), some Danish ships vis-ited the vicinity of Borgholm, and the reporter adds that a ship would be sent tothe Hanseatic towns after Christmas, indicating expectations of navigable watersfor the nearest future.111 On commenting rumours of an imminent Danish attackon southwestern Västergötland, the Knight Ture Jönsson on January 23 suggestedthe Regent to assist the peasantry in breaking up the ice as a defensive measure.112

Other rumours of imminent Danish attacks on Kalmar and Öland in February 1511indicate a sufficiently thick ice cover in the channel.113 ‘Bad före’ is mentioned onMarch 19 at Penningby northeast of Stockholm, and the following day there wasstill ice in Turku.114


In the third week of December 1512 the Archbishop tried to persuade the newRegent Sten Sture to hold a meeting in Enköping or at Svinngarn (45 kms from


Arnö) instead of Vadstena since he, due to the menföre, could not travel so far.It is clearly stated that he intended to go there on horseback.115 Hence, the snowdoes not seem to have come yet at that moment. It should be noted in passing thatthe messenger who delivered the letters between them over the 55 kms betweenArnö and Stockholm travelled very fast in one day. Already on December 16, theArchbishop had received an answer to a letter he wrote the day before.116 On March31 there was still ice in Viborg.117


There is evidence of rough weather in the Baltic in late November – early De-cember 1516. A citizen of Stockholm reported that Regent Sten’s ships had beenready to sail from Lübeck on November 19, but had by December 13 probably notreached further than Kalmar, due to ‘the weather that has been’. The same storm issaid to have stranded two ships on their way from Prussia and forced another one togo to Reval (Tallinn).118 At the end of December, the Tiveden forest was trafficablefor snow vehicles, according to a letter from a noblewoman who intended to borrowsome sledges from the Regent for her moving, and on January 7 she wrote anotherletter with the same content.119 Sometime before Easter (i.e., April 22, New Style)a dozen yachts and ships sailed the archipelago of Tjust.120

10. Discussion

Before any conclusions can be drawn from this material it should be noted that theevidence on which generalizations would be based amount to less than 100 pointsof information, and derives from some 30 localities concentrated in a few regions,and to the peak years of the Sture Collection. Obviously this raises the questionof their representativity. The episodic character of the evidence is of course in partexplained by the sheer quantity of surviving sources, and the fact that the archiveshave been worn down through history. This has particular consequences for thevalue of the indications of ice cover, the formation of which in temperate areas likesouthern Sweden is not a continuous and uniform process. Due to various factors,predominantly the double effect of wind, which at the same time facilitates iceformation by cooling down water, and delays it by setting it in motion and mixingcold and warm water, ice formation can pass through several phases and retakesin one single season and in the early winter even during one single day.121 For ex-ample, in the winter 1996/97, considered as generally mild, twenty-three switchesbetween freezing and melting were recorded along the entire Swedish coast, thefirst melting occurring as early as December 1 and the last freezing as late as May24.122 Therefore, although it would be tempting to construct a regressional thermalcurve backwards from dated and localized ice data, it cannot be done on the basisof the present evidence alone. Furthermore, air temperature, while being the main

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determinant of ice formation, is by no means the only element involved; among thevarious factors included in the extremely complicated interplay of ice formationthere are several which ‘disturb’ it, and some crucial ones which elude our knowl-edge. Although we possess knowledge about some hydrographical variables likedepth and surface area (i.e., water volume and degree of wind exposition) and watercurrents, and geographical ones such as altitude, latitude and the configuration ofthe coastline, others are unknown to us. Examples of these may be meteorologicalones such as air temperatures, wind conditions and force (in relation to coastlineconfiguration), precipitation, cloudiness prior to an ice indication etc. In the presentcontext where several ice indications concern Baltic ports, one can also add salin-ity which varies according to water circulation and supply from the saltier seasin the west. Some factors constituted by the combination of primary factors arealso incalculable since they require exact values such as degree of wind exposition(determined by the compass direction of a lake – a known geographical factor)and wind direction and force (an unknown meteorological factor). For the Baltic,even the temperature before the southward passing of the 0 ◦C isotherm must betaken into consideration, as well as the number of days with positive degrees afterits withdrawal northwards in the spring to calculate the rate of melting.123 On theother hand, far fewer factors influence the break-up of the ice in the spring, mainlywind and altitude.124 Nevertheless, if both the indications of ice and snow cover atour disposal and the workings of ice physics are instant, momentaneous, what doa few mentions of ice cover in a particular place actually tell us about the winter asa whole?

A second observation is that the evidence retrieved here is mostly of a ‘negative’kind – indeed more than two-thirds of the data speak of ‘non-wintry weather’,which cannot be wholly accounted for by the mutilated character of the archivesat our disposal today. Had we had intact records, the proportions would probablyhave been the same. Instead, the emphasis on such information derives from thefact that the meteorological observations have passed through another filter; theselective minds of the contemporary writers of the letters. It must be rememberedin what context the present evidence has passed down to us. As parameteorologicalphenomena mostly connected to transport, evidence will be present in the sourcesonly to the degree that meteorology put constraints on transport activities. Hence,the meteorological winter would in most cases set in before our first dated evidenceof it, and cease after our last. We must assume that the ice and snow season perse was much longer than indicated by the evidence and that large areas outsidethe main avenues of transport were long covered with snow or ice without beingmentioned. It is, for example, obvious that the expression ‘first open water’ is areference strictly to trafficability and not the absolute absence of ice, and that shipswould leave Finland for Sweden as soon as the sea passage was considered safe,while pockets of ice could very well be found in narrower straits in the leeward.125

Likewise, the messengers who brought letters over the half-frozen sea in the win-ter usually travelled partly on ice (between the Finnish mainland and Åland),


partly on open water (between Åland and the Swedish mainland).126 Thereforeit cannot be regarded as a weakness of the sources that reporters would considerdepartures from normal winter weather, in particular when it had consequences fortransport and communication, as deserving of mention while winter according toexpectations would pass unnoticed. To expect anything else would be to demand apremature, pre-Renaissance interest in meteorology in its own right and a disregardof the essential character of different categories of documentary sources.

In this context it is also worth noting that while the late medieval letters of theSture Collection give the impression of mild winters, narrative sources seem tostress their contrary, severe winters.127 For example, one of the most extraordinarymeteorological events of the late Middle Ages, the famous repeated freezings ofthe open sea surface of the Baltic, evidence of which is found in several accounts,is not mentioned at all in contemporary Swedish letter sources. On the other hand,a point in common is that precisely those extreme events are referred to in thesame parameteorological terms that have been the focus of this article, transportand communication – the point of reference for the amazement about a frozen seawas that one could travel by horse or on foot on it.128

All of this raises the question of the representativity of the sources. It is, forexample, clearly wrong to conclude a priori from the first impression of the evi-dence that the winters during the period have been exceptionally mild. Lamb too,has noted that quantity and quality of reports from a particular winter seem to berelated – the fewer reports, the milder winter.129 Of course, no single historicalsource is continuous in time and space or gives a complete picture. But, howeversporadic, irregular and accidental the climatological evidence of winter weatheris, selected for us by other powers than our own inquiring mind, it is consideredhere that it does go beyond the purely episodic or extreme, and can support certaingeneralizations. Furthermore, other supplementary proxy data exist, albeit with aless marked ‘instant’ character which have the potential to fill the gaps to a certaindegree, and to enlarge the fragmented picture.130 Moreover, the weather in Swedenof the early sixteenth century was of course governed by physical and chemicalmechanisms which are still present, and which are subjects of precise knowledgetoday. Concluding this article, some considerations will be discussed within thiscontext.

As regards the reliability of ice and snow indications it is clear that, althoughboth ice and snow can come and go several times during a single winter, a cover ofsnow or ice sufficiently thick to meet the requirements for transport does not formand vanish overnight. Due to the ultimate dominance and impact of air temperature,this is even more true in central and northern Sweden (north of the 59th parallel),where the southward progress of the 0 ◦C isotherm in early winter is more con-tinuous and definite than further south. Therefore, when we find direct or indirectevidence of strong ice south of the 59th parallel, such as in Kalmar on February7, 1506, around March 25, 1507, and on March 21, 1508, we can be sure thattemperatures below zero had prevailed for some time. Furthermore, it should be

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noted that the formation and melting of early winter growth of ice is connected tothe different speeds at which the formation and recession of ice normally occur.The consequence is that autumn ice is tougher, able to support a human safelyat a thickness of 4–5 cms, while spring ice whose break-up is swifter and moredefinite, is notoriously brittle, not even considered safe at a thickness of 10 cms. Ifthe temperature stays below zero, ice will be safe already a week after cold weatherhas set in, and will continue to strengthen arithmetically, a process only interruptedwhen air temperature rises above zero. Therefore, when we are told that the ice atKalmar was ‘treacherous’ on February 21, 1509, we can be sure that not much wasleft of the winter there, especially considering the structural weakness of salineice. For the same reason, together with the fact that the supportive power of iceincreases with the square of the thickness, we can be certain that the ice at Kalmaron February 7, 1506, claimed to be able to support ‘a thousand horses’ must haveexceeded 10 cms and was a result of a prolonged period of very cold weather.

Although the evidence retrieved is unsatisfactorily sparse, it carries another typeof information beyond simple instances of weather occurrences. It is obvious thatcontemporaries of the time lacked any awareness of large-scale climatic changes,but they of course possessed some notion of ‘weather normality’. They also defi-nitely knew that this was not a static but a dynamic condition; they were familiarwith variability of weather as such. Mentions of, for example, menföre, thereforedo not necessarily imply anything abnormal for contemporaries and should notbe equalized with extreme events. Sudden changes in weather within certain pa-rameters were expected and regarded as inevitable, just as they are for us. Peoplewere used to them and responded to and adapted themselves to different condi-tions according to a well-established mental routine which would not necessarilyleave any traces in the written sources. This is especially true for Sweden, whoselocation within the boreal forest zone between the Eurasian continental block andthe Atlantic Ocean could be expected to experience great thermal swings betweenRussian-Siberian continental and Atlantic maritime climate, but whose climate in-stead, due to the interaction of these conditions, tends to a somewhat more maritimecharacter than its latitudinal position would otherwise have given it. This is furthergenerated by the joint formation of relatively warm southern and southwesterlywinds, and further accentuated by its topographical and hydrographical constitu-tion – the numerous lakes and the peninsular configuration of Scandinavia.131 In theabsence of great thermal oscillation deviations from normal temperatures, definedthrough latitudinal and altitudinal criteria, are therefore mainly accounted for bythe delaying effects of the surrounding seas and rarely exceed 1 ◦C in modern times.It could be added that, as a consequence of the historically determined size of thearea in consideration for this article, the relevance of two other determinants ofweather, altitude and latitude, is small. The southern part of Sweden is remarkablyflat, with no great topographical contrasts – the only major high plateau, that ofinner Småland, only rises to a maximum height of 378 ms – and extends onlybetween the parallels 56◦ 30′ N and 61◦0′ N. The thermal differences caused by


altitude, the annual average of which is calculated at 0.5 ◦C/m, can thus be dis-regarded, while that of latitude of course is somewhat greater (1.1 ◦C per parallelin the winter and 0.1 ◦C per parallel in the summer). The only exception is innercentral Sweden including the great lakes area. There, some marginal influence isexerted by the westward lying Scandinavian mountain range in Norway, servingas an orographic shelter from the Atlantic, as well as the altitude of the miningarea in southern Dalecarlia (between 200 and 500 ms), producing a relatively morecontinental character. But it is also of marginal significance for the core zone ofmedieval Sweden treated here, and diminishes towards the east as the influence ofthe Baltic water-masses increases accordingly.

The parameters of normality produced by these basic meteorological charac-teristics can be the object of knowledge. One could perhaps speak of ‘normaldepartures from normality’ which, as such, forms part of a dynamic normalityitself. Furthermore, the contemporary conception of normality as expressed in thesources can be relied upon as being based on the sum of personal experiences andknowledge about weather through practice. As such, they not only inform us aboutmedieval mentality but also give a mean value, albeit not numerical, of medievalclimate on a greater time-scale than the pure diurnal of the correspondence letters.

A good example of this is a letter dated April 25, 1502, from Knut Skrivare,one of Svante Nilsson’s servants in Stockholm, in which he asked his lord to sendsome goods to him from Stegeborg castle ‘with the first open water’. It is obviousthat we cannot conclude anything about the ice conditions around Stegeborg, aboutwhich Knut, 120 kms away, of course could know nothing. It would be temptingto suspect that there was ice around Stockholm, and that Knut was inspired toinclude that formulation by observing ice conditions outside his own window. Butin the same letter he mentions the departure of a ship to Germany, and speaks ofa defensive barrier across one of the straits in the town (the castle in Stockholmwas at this time, like that of Kalmar, besieged by the Swedes).132 So, there wasdefinitely no ice in Stockholm, and we do not know anything about Stegeborg. Butit is also quite obvious that Knut had a reason to include that formulation, and thathis expression reveals something of his knowledge about his own meteorologicalenvironment. Through his own mental set of meteorological knowledge he simplyknew that ice around Stegeborg was a quite possible phenomenon at that time ofthe year. It could of course be argued that his wording was an expression of alax routine, but it is held here that even such a routine must be established onconcrete experienced conditions and worked within the framework of a climato-logical reality. It would for example have been considered an obvious absurdity toinclude similar expressions in letters from the meteorological summer season. Inthe present case, it can be added that Stegeborg is located in a narrow strait whereice would linger longer than on more open water surfaces with a higher degree ofwind exposition, as it does still today around the same latitude. For example, themodern mean date for the break-up of the ice in the Södertälje inlet, very similarto that of Stegeborg, is around April 12.133

162 D. RETSÖ

In some cases, we are even able to follow the line between personal experi-ences and their transformation into expressions of expectations. When one of thecommanders in Kalmar in 1508 hoped that the ice on the channel would thicken atsuch a late point as late March, it seems to be quite over-optimistic. But in fact thesame person was on the spot in Kalmar the previous winter when a thrust of coldweather did set in at precisely that same time, strengthening the ice considerablyand thus also the commander’s expectations for the same thing to occur again. Inthis case they probably failed, but there are also cases of the contrary. When theArchbishop declared himself willing to come to a meeting of the council on March18, 1508, he added a condition: if the snow conditions permitted. The good reasonsfor his proviso are proven by the fact that menföre actually did occur and eventuallystopped him from travel. The Archbishop knew that by that date the winter wouldhave entered a stage which was critical from a trafficability point of view and inwhich a satisfactory snow cover could not be counted on. Another letter from theArchbishop, dated at Arnö on December 15, 1512, presents another conspicuousexample. He proposed that Regent Sten Sture hold a meeting of the council ata location more near-by than the originally settled Vadstena because of the badwinter, i.e., insufficient snow cover for sleigh-rides. The verbal expression he usedto describe the nature of the winter, förföga sig does not exist in modern Swedishbut can be interpreted as ‘to be late’ or ‘to loiter’ as well as ‘to be deficient’ (anapproximate literal translation into English would be ‘to fall short of itself’). Bythe Archbishop’s choice of words it is obvious that the letter was written after thedate on which he expected winter weather to set in, although it is impossible toconclude whether it had done so at a smaller degree than he expected or not at all.

In this way, evidence of different climatic regimes can be compared. For exam-ple, in 1270, more than 200 years before the period treated here and in the middle ofthe proposed warm High Middle Ages, King Valdemar wrote to the inhabitants ofa district in southwestern Småland urging them to deliver their tithes due to the Ny-dala monastery to their parish churches during the winter, more specifically beforepurificationis mariæ (i.e., February 12, New Style) when ice and snow facilitatedfurther transport by the monks.134 The fact that the delivery of tithes is explicitlyput in connection with terms of trafficability makes the date seem to indicate theend of the trustworthy winter trafficability season and the beginning of the periodof more unreliable winter weather. Compared with modern times, the date seemsvery early; the 1961–1990 mean value for the last day with snow cover in that areais April 15135, very close to the date on which, according to a letter from RegentSvante’s wife mentioned above, the snow season of 1506 seems to have ended(April 10). Even allowing for one month of spring menföre it is apparent that thereliable snow season in the thirteenth century – that is, in the middle of the warmHigh Middle Ages – was much shorter than now and even than that of the lateMiddle Ages.


11. Conclusion

The period analyzed here falls in between the proposed warm European HighMiddle Ages and ‘the Little Ice Age’. It thus forms part of a period from themid-fifteenth century to mid-sixteenth century which has been characterized asrelatively mild and climatologically stable with predominantly westerly or south-westerly winds and receding glaciers.136 The picture emerging, based on a contentanalysis of reports in contemporary letters from a geographically wide range oflocalities with special attention paid to the terms före and ‘first open water’, is thatthe winter 1506/7 was a mild, ‘bad’ winter, the following having a duration moreor less from January 10 to the end of March but without indications of unusual coldor mildness, while the winter of 1508/9 seems to have struck quite hard and unex-pectedly in mid-November but on the whole was not very severe. Taken together,they thus to a certain extent diverge from European winter-severity indices con-firming regional variabilities within the general timeframe of climatic transitionssince the Middle Ages. The 1506/7 winter has been characterized as very mild oreven the mildest of the decade while the following has been classified as severeor even the most severe of the decade, which does not seem to have been the casefor Sweden.137 Apart from these three winters, the remaining winter evidence iseither too sporadic or too isolated in time and space to support generalizations. InLamb’s view, for example, fewer than three reports from a single winter would beconsidered as unsatisfactory.138 But it can be noted for the winter of 1503/4, thatthe indication of trafficability on snow by late December and the late ice indicationon April 10, point towards a quite cold winter season, while the following seems tohave been relatively mild at least in southern Sweden. Reports of westerly winds,suggested to be responsible for generally warmer conditions in northern Europein the early sixteenth century139, have only been found for the winter of 1505/6.Over the whole period considered, mentions of menföre, interpreted as evidenceof spring thaw or slush, appear between February 15 (1507, Vadstena) and April19 (1507, Dalecarlia). The extreme dates for freezing are mid-November (1508,Stäket), and shortly before June 4 (1506, Gulf of Bothnia), but the way in whichthe former is commented and the latitude of the latter hardly make them repre-sentative. The earliest indication of ‘normal’ freezing is from January 19 (1508,Kalmar) and the latest April 10 (1504, Stockholm). The latest date for Kalmar isaround March 25. At this point of research, then, winters in early 16th-centurySweden, in comparison with modern mean values (1961–1990) for last day withsnow cover and freezings, seem to have had a somewhat shorter duration, but adefinite confirmation of that will only be provided by further research.140

Acknowledgements

The author would like to thank the reviewers for their suggested improvementsduring the review process.

164 D. RETSÖ

Appendix

Schematic view of evidence of winter weather in Sweden 1501–1517 (datesaccording to New Style)

Winter Last mention of Mentions of oföre, Others

season ‘first open water’ menföre, ont före

1501/2 Dec 14: no ice in Stockholm

Jan 20: ice around Stegeborg

1502/3 bf Apr 24: no ice in Stockholm

1503/4 Dec 25: snow in the Jönköping-Gränna area

Apr 9 (Stockholm)

Apr 10: ice in Stockholm

1504/5 Nov 22 (Borg) Dec 8: little or no snow in Stockholm

Feb 13: ice in Turku

bf March 18: weak ice on Bråviken bay

bf Apr 3: no ice in Kalmar

Apr 4 (Turku)

1505/6 Dec 22: no ice in Kalmar

bf dec 30: storm in the southern Baltic Sea

Feb 7: strong ice in Kalmar

c March 1: no ice in Stockholm?

Apr 10: little or no snow at Eksjö

Apr 13: no ice in Stockholm

Apr 20: no ice in Stockholm archipelago, hard west

wind

Apr 25: no ice in Stockholm archipelago, hard west

wind

Apr 29: hard west wind at Västerås

bf June 4: ice in inner Gulf of Bothnia

1506/7 Dec 19: strong western winds at Reval (Tallinn) ?

bf Dec 22: no ice at Kalmar nor Jungfrun island

Jan 30: no ice at Kalmar, Söderköping and possibly

also Nyköping

Jan 31: ‘no winter’ at Falem

Feb 10: ‘frail and weak winter’ at Kalmar

Feb 15 (Vadstena)

Feb 18: ice on Hamrånge Bay

Feb 19 (Jönköping)

Feb 28 (Vadstena) Feb 28: no ice at Kalmar and weak ice around Öland

March 22: ‘unstable weather’, probably thaw, at Ettak

c March 25: colder and stronger ice at Kalmar

Apr 6: no ice in Norrköping nor in Stockholm and

probably bare ground in Östergötland

c Apr 14: probably no ice in Kalmar

Apr 19 (Dalecarlia)

c Apr 30: no ice in Kalmar




1507/8 March 27 (Köping) c Dec 12: no ice in Stockholm

Jan 3–5: neither ice nor snow at Kalmar, little

Jan 5 (Kalmar) or no snow in Mark

Jan 7 (Kalmar)

Jan 10: little or no snow in Öregrund

Jan 17: snow in Mark

Jan 19: weak ice at Kalmar

Feb 29: snow in Uppsala

March 7: weak ice at Kalmar

March 10 (Arnö) c March 10: weak ice at Kalmar

March 21: ice at Kalmar, relatively strong by the

castle

Apr: thaw in Småland

c Apr 12: no ice at Kalmar

Nov 13: waters outside Stockholm still

navigable

Nov 16: no ice in Kalmar channel

Nov 18–19: straits freezing at Stäket

Nov 20: signs of harsh winter at Stegeborg

c Nov 20: no ice on Bråviken

Nov 22 (Ekholm) Nov 22: omitted tax due to winter at Turku

Dec 8: no ice on Gulf of Finland

Dec 19: little or no snow at Kalmar

Jan 19: no ice in Stockholm

c Feb 19: ice in Västerås?

Feb 21: ‘treacherous’ ice in the Kalmar

channel

Feb 22: weak or no ice in Kalmar

c Feb 25: ice in western Lake Mälaren

c March 21 (Uppsala)

Apr 29: no ice in Söderköping

1509/10 bf March 17: no ice in Stockholm

c March 25: snow in Västerås-Arboga area

March 27 (Uppsala) c March 27: strong southern winds in southern

Baltic and in Söderköping

bf Apr 29: thaw in Dalecarlia

Apr 29: ‘unstable weather’ but no snow nor ice in

Uppsala-Stockholm area

1510/11 March 20 (Turku) Nov 21: no snow in Tavastland

c Jan 1: no ice at Borgholm

Jan 23: ice on lakes in sw Västergötland

Feb: thick ice in the Kalmar channel

March 19 (Penningby)

166 D. RETSÖ



1511/12

1512/13 March 31 (Viborg) Dec 16 (Arnö)

1513/14

1514/15

1515/16

1516/17 Early Dec: strong northern

winds in the southern Dec 31: snow in Tiveden

Baltic Sea Jan 7: snow in Tiveden

Feb 2: snow in Turku

bf Apr 22: no ice in the Tjust archipelago

Notes

1. Le Roy Ladurie, 1971; Alexandre, 1987; Bell and Ogilvie 1978; Ingram et al., 1981; Pfister,1984; Munzar and Pejml, 1990; Ogilvie, 1995.

2. Bell and Ogilvie, 1978; Wigley, 1978; Ingram et al., 1981; Hughes and Diaz, 1994; Ogilvie,1995.

3. However, see e.g. Ogilvie 1995.4. Norlind, 1914, pp. 47–53; Weikinn, 1958, pp. 487-531; Lamb, 1982, pp. 73–81.5. See Ogilvie, 1995.6. Lamb, 1977, p. 463; Lamb, 1982, p. 74; Bradley, 1985, p. 413; Lamb, 1988, p. 228-9; Grove,

1988; Guiot, 1992; Hughes and Diaz, 1994 p. 137; Pfister, 1995, p. 139; Bradley and Jones,1995a, p. 660; Bradley and Jones, 1995b, pp. 674–675; Ogilvie and Farmer, 1997, p. 130.

7. Although see Ogilvie, 1995.8. See Le Roy Ladurie, 1971; Ingram et al., 1978; Bell and Ogilvie, 1978; Pfister, 1984; Ogilvie

and Farmer 1997.9. Lamb, 1988, p. 49.

10. See Le Roy Ladurie, 1971; Ingram et al., 1978; Oliver, 1991; Hughes and Diaz, 1994.11. Fritz, 1976/77, p. 68.12. For a general description of the collection and the copy-books, see Schück, 1976, pp. 412–416.

A more detailed analysis of the composition of the A5 codex is found in Wieselgren, 1949, pp.425ff. A corresponding analysis of codex A4 has not been made; see Schück 1976 pp. 415–416.

13. Schück, 1976, pp. 386–406.14. Schück, 1976, pp. 391, 400; Fritz, 1998, p. 523. The Sture Collection’s preservation into modern

times is probably in part due to the fact that it was, at an unknown date and under unclearcircumstances, captured by the Danes as war booty and transferred to Denmark, where it waskept for about four centuries. It attracted no attention from historians until the early eighteenthcentury, and since the nineteenth century more than half of the letters has been printed in a num-ber of historiographical editions, predominantly in Edward Grönblad’s Nya källor till Finlandsmedeltidshistoria (1857) (almost all of which was reprinted in volumes 6 and 7 of ReinholdHausen’s Finlands medeltidsurkunder, 1930–1935), Volumes 4 and 5 of Carl Gustaf Styffe’sBidrag till Skandinaviens historia (1875–1884), Lars Sjödin’s Arvid Siggessons brevväxling


(1937) and volume 39 of Historiska handlingar (1967-1969), also edited by Sjödin. All theletters once belonging to and issued by regent Svante’s wife Mätta Ivarsdotter have also beenpublished as an appendix to a philological dissertation, Utterström 1968. The two copy-books,which in contrast to the letter collection had remained in Sweden, were printed in Handlingarrörande Skandinaviens historia, volumes 19, 20 and 24 (1834–1835, 1840). The letter collectionwas returned to Sweden and the National Archives in 1929.

15. For a similar standpoint, see Rodrigo et al., 1994, p. 401; cf. Ingram et al., 1981.16. Cf. Oliver, 1991.17. See Kupperman, 1982.18. See Bell and Ogilvie, 1978.19. See e.g. Ogilvie and Johnson, 2001.20. Le Roy Ladurie, 1971; Hughes and Diaz, 1994; Bradley and Jones, 1995a.21. Utterström, 1955.22. See Schück, 1976, pp. 414–416.23. On content analysis from a climatological viewpoint, see Baron, 1982.24. Sturearkivet nos. 1145 (FMU 7:5486) and 1099. See also Sturearkivet no. 1322 (FMU 7:5907).

References in brackets indicate printed editions.25. Sturearkivet no. 456 (printed and dated by Styffe in BSH 5:381). All letter datings referred to in

this article are presented according to the New (Gregorian) Style.26. Sturearkivet no. 418 (dated by Sjödin in ASB p. 535, n. 2).27. Sturearkivet no. 432 (‘Tuesday after St. Martin’; year dating supplied by Sjödin in ASB p. 499).28. Sturearkivet no. 653 (‘scolastice virginis’ without year; year dating supplied by Sjödin in ASB,

p. 150).29. Parchment diploma 13 September 1507 (BSH 5:156), Nils Bosson’s safe-conduct (BSH 5:168

after an original parchment in the Library of the Diocese of Lund).30. See for instance Läke - och örteböcker från Sveriges medeltid p. 461f.31. Sturearkivet no. 557 (ASB p. 189–190).32. Ångström, 1958, Fig. 38, p. 90. A similar case in the Jura Mountains of France is reported by Le

Roy Ladurie (1971, p. 236).33. RA A4 fol 113r–114r (HSH 20 pp., 196–200). See also Sturearkivet no. 96 (BSH 5:182) where

Svante orders his commanders to prepare for an assault on the fortress ‘if the ice in the channelis strong enough’, Sturearkivet no. 133 (BSH 5:260), a draft from January 1509 of a letter tothe peasants in a Småland district where Svante puts the outcome of the siege in direct relationwith the ‘winter’ and the ice in the straits, and Sören Norby’s letter to King Kristian of Denmarkdated 5 October 1519 (BSH 5:492), in which he forwards a rumour that Sten Sture the youngerwas awaiting the freezing of the channel in order to launch an attack on Öland.

34. Ångström 1958 Figs 34b and 35, pp. 86–87.35. Le Roy Ladurie, 1971, pp. 286, 289.36. Sturearkivet no. 255. The precise time for the writing of this letter, which lacks any time indi-

cation, is difficult to estimate. It is one among many undated in the Sture Collection issued bya certain Per Månsson whose scribe obviously did not care much about chronological precision.But an approximate dating is furnished by its content. Hammarström’s dating to early spring1502 (Hammarström, 1956, p. 60, n. 63) is not convincing. It is clear that it is written beforeSvante’s election to the regency in January 1504, since he is addressed with title ‘chieftain’(hövitsman) of Stegeborg, a title he bore prior to his election. But a detail overlooked by Ham-marström is that Per uses the preposition i in referring to Kalmar, definitely a reference to thetown and not the castle, in which case he would have used the preposition på. The letter musttherefore be written after the reconquest of the town which occurred on 19 May 1503 (Script.Rer. Svec. 3:1, p. 85).

37. Sturearkivet nos. 1379, 1278 (FMU 7: 5685).38. Sturearkivet no. 988 (FMU 6: 5324).

168 D. RETSÖ

39. Sturearkivet no. 1583 (BSH 5: 229).40. Sturearkivet no. 573 (ASB, pp. 295–296).41. Sturearkivet no. 541 (ASB, pp. 336).42. Sturearkivet nos. 650 and 485. The latter was due to a misreading of the place name attributed

by Edward Grönblad to deal with Åland but is actually from a parish in Östergötland (Åtvid).The mistake was reproduced by Hausen in FMU 6:5276.

43. Myrdal, 1985, pp. 64, 103.44. Myrdal, 1985, p. 64, Solantie, 1988.45. Schove, 1954, Fig. 3, p. 55; Bradley and Jones, 1995b, Fig. 34.2, p. 674; Karlén and Rosqvist,

1995, Fig. 4, p. 57.46. Lamb, 1977, App. 5, Table 5, p. 566.47. Le Roy Ladurie, 1971, App. 15, p. 378.48. Le Roy Ladurie, 1971, pp. 275–276. See also de Vries, 1981.49. For some general considerations of these difficulties in historical sources, see Lamb, 1982, p. 75.50. RA A5 fol 70v (HSH 24, p. 118).51. RA A5 fol 72r, 72v, 73r (HSH 24, pp. 120–121, 122–123, 123–125).52. RA A5 fol 70v, 73r (HSH 24, pp. 117, 123).53. Wieselgren, 1949, pp. 298ff.54. Sturearkivet no. 31 (BSH 4:196).55. Sturearkivet no. 257 (ASB, pp. 154–155).56. Sturearkivet no. 42 (‘bona sexta feria’ without year; printed and year supplied by Styffe in BSH

4:226).57. Sturearkivet no. 1501 (BSH 4:237).58. Sturearkivet nos. 1431 (FMU 6:5012) and 622a (FMU 6:5013).59. Sturearkivet no. 626 (ASB, p. 182, Utterström 1968, p. 201).60. Sturearkivet nos. 881 (FMU 6:5099), 884 (FMU 6:5110), and 343 (BSH 5:33).61. Sturearkivet no. 688.62. Sturearkivet nos. 700 and 713.63. Sturearkivet nos. 718 (BSH 5:57) and 499 (dated ‘Wednesday after St. Paul’s Day’, year supplied

by Styffe in BSH 5 p. LXV n. 3).64. Sturearkivet no. 737 (Utterström 1968, pp. 203–204). See also Olaus Magnus, p. 534.65. Sturearkivet no. 793.66. Sturearkivet nos. 813 and 758. See also no. 896 (BSH 5:67).67. Sturearkivet no. 1102b (printed and dated by Sjödin in ASB, p. 205).68. Cf. Ångström 1958, Fig. 38, p. 90, Gotthardsson, 1995, p. 125, 128.69. Sturearkivet no. 899 (FMU 6:5184).70. Sturearkivet no. 1531 (BSH 5:110), no. 524 (dated in Carlsson 1915, p. 154) and no. 454

(‘Thursday after Ash Wednesday’ without year; printed and year supplied by Styffe in BSH5:113).

71. Sturearkivet no. 590 (dated and printed BSH 5:114).72. Sturearkivet no. 1527 (BSH 5:103).73. Sturearkivet, unnumbered December 19, 1506 (FMU 6:5119).74. Sturearkivet no. 812.75. Sturearkivet 518b (‘Thursday after St Henry’s Day’ without year; year supplied by Sjödin in

ASB, p. 520, n. 1, and extract printed in Dipl. Norv. 22:1:56).76. Sturearkivet no. 814 (Utterström 1968 p. 206ff) and no. 213 (ASB, p. 247, Utterström, 1968, pp.

231–232).77. Sturearkivet no. 880a.78. Sturearkivet 588b (‘Monday before fastegången [i.e., domini esto mihi]’ without year; year

supplied in Hammarström, 1956, p. 68 n. 91).79. Sturearkivet no. 1624 (printed and dated by Styffe in BSH 5:120).


80. RA A4 fol 85v (HSH 20, p. 110), Sturearkivet no. 828. On April 28 she was planning to continueto Örebro.

81. Sturearkivet no. 215 (printed and dated by Sjödin in ASB p. 253, also printed in Utterström 1968p. 233ff).

82. Stockholms stads tänkeböcker, Vol. 2: 4, p. 181.83. Sturearkivet nos. 853, 22 and 55 (BSH 5:122, 130 and 151).84. Sturearkivet nos. 1534 (BSH 5:127), 1535 (BSH 5:128, Utterström, 1968, pp. 260–1), 1536

(BSH 5:129) and 1669.85. Sturearkivet no. 933 (Utterström, 1968, pp. 249–250). The letter is an undated postscriptum on

a separate slip of paper belonging to Mätta’s letter of 12 december 1507 (see ASB, p. 526, n. 2).86. Sturearkivet nos. 1555, 1556 and 1557.87. Sturearkivet nos. 968 (BSH 5:179), 971, 446 (dated in Gillingstam, 1952, p. 553). See also

Sturearkivet no. 1667.88. Sturearkivet no. 1563 (BSH 5:192).89. Sturearkivet no. 327 (BSH 5:196).90. Sturearkivet no. 965 (HT, 1881, p. 398).91. Sturearkivet no. 967 (BSH 5:183).92. Sturearkivet no. 1442.93. Sturearkivet no. 1443 (BSH 5:187).94. Sturearkivet no. 978 (ASB, p. 134).95. Sturearkivet nos. 1022 (BSH 5:248), 562 (dated and printed by Hausen in FMU 6:5347), and an

unnumbered letter dated 12 January 1509 (FMU 6:5359).96. Sturearkivet nos. 1448 and 1449 (BSH 5:244 and 245).97. Sturearkivet no. 574 (‘Sunday after St Martin’s Day’ without year; year supplied and printed by

Styffe in BSH 5:249).98. Sturearkivet nos. 1020 (ASB, p. 320), 1021 (BSH 5:243), 1023 and 1028 (FMU 6:5352).99. Sturearkivet nos. 580 (dated in Carlsson 1915 p. 196 n. 1, ASB p. 535 n. 2), 1038 (ASB p. 323)

and 1039.100. Sturearkivet no. 1612 (printed and dated BSH 5:265).101. Sturearkivet no. 1406 (BSH 5:266).102. Sturearkivet no. 1454 (BSH 5:271, FMU 7:5379).103. There are two letters indicating the time of the meeting; one issued by the Swedish council in

Arboga on March 21 adressed to the Danish council (Sveriges traktater 3:2, p. 548) which isalso preserved in the form of a contemprary copy in the Danish National Archives (Missiver2:210) and a draft in the Swedish National Archives (Sturearkivet no. 92), and a second from theSheriff of Arboga (Sturearkivet no. 512, dated ‘Saturday before Dominica oculi’ with no year;year supplied and printed in ASB, p. 335).

104. Sturearkivet no. 541 (printed and dated by Sjödin in ASB, p. 336). Cf. Sturearkivet nos. 390(dated and printed by Sjödin in ASB, p. 328), 1044 (BSH 5:262) and 1045 (ASB, p. 325).

105. Sturearkivet no. 337 (printed and dated by Styffe in BSH 5:273).106. Sturearkivet nos. 1098 (BSH 5:294) and 1465.107. Sturearkivet no. 1584. The precise time of delivery of the letter from Mecklenburg is unclear.

The original, now lost, has been presumed to have been issued in February, printed in extract inHanserecesse 3:5 pp 634-5.

108. Sturearkivet no. 1468 (BSH 5:299).109. Sturearkivet no. 1099.110. Svante’s wehereabouts at the time are deduceable from a number of entries between March 22

and 30 in the Book of Acts of the Arboga township (Arboga stads tänkebok, Vol. 3, pp. 233–236).111. Sturearkivet no. 479.112. Sturearkivet no. 1164 (BSH 5:337).

170 D. RETSÖ

113. Sturearkivet no. 47. That this undated letter is from the year 1511 should be deduceable fromanother letter from the council members gathered in Uppsala to the council members in Finlanddated January 2 (Sturearkivet no. 1160, printed FMU 7:5497) as well as Erik Turesson’s letterof March 2 (Sturearkivet 1178, printed FMU 7:5502) in which some of the same informationis contained. As Svante at the time of the issuing of this letter seems to be in Stockholm itmust be from the first half of February at the earliest; the whole month of January he spent inVästergötland and still the first week of February in Dalecarlia or near Västerås (cf Sturearkivetno. 1168, printed in Utterström 1968 pp 222-3).

114. Sturearkivet nos. 1196 and 1180 (FMU 7:5505).115. Sturearkivet no. 1480 (BSH 5:413).116. Cf Sturearkivet no. 1479 (BSH 5:412).117. Sturearkivet no. 408 (FMU 7:5642).118. Sturearkivet, unnumbered December 13, 1516 (HH 39:327).119. Sturearkivet nos. 1383 (‘St Thomas’ Day’ without year) and 1384 (‘Innocents’ Day’ without

year; printed and year supplied for both by Sjödin in HH 39:330 and 333).120. Sturearkivet no. 591 (HH 39:377, dated in Westin 1957 p. 498 n. 26).121. Eriksson, 1920, p. 3.122. Lundqvist and Asp, 1997, pp. 8–21.123. Rodhe, 1952, p. 176, Ångström, 1958, pp. 8–21.124. Eriksson, 1920, pp. 36-37, n. 54.125. For a discussion of semantics of breaking-up of the ice, see Kajander 1990.126. Medin, 1952, p. 30.127. However, this does not seem to be the case for Icelandic annals, see Ogilvie, 1995, p. 113.128. The same transport-related expressions describing parameteorological phenomena are found in

e.g. 17th century Icelandic annals (see Ogilvie, 1995, pp. 108, 110). It should be noted that theSwedish 16th century author Olaus Magnus, citing the German geographer Albertus Crantziusas his source, mentions the freezings of the Baltic in 1323, 1399 and 1423 as well as that ofSkagerrak in 1294. He interestingly adds that this has also happened later but that it has not beenrecorded since it was nothing unusual (Olaus Magnus, 1909–1925, p. 59). The information on thewinter of 1423 is repeated in the work of Olaus Petri, probably based on the same source (OlausPetri, 1917, p. 148). Note too that neither of these authors, nor Olaus Magnus’ statement thatrivers froze in England in the year 1300, are included in Weikinn’s compilation (cf. Weikinn,1958, pp. 322–325, 185–186). Some of Olaus Magnus’ accounts of exotic winter weather arebased on firsthand personal experiences – he was among the first to describe Lapland after a visitthere in 1518–1519.

129. Lamb, 1987, p. 134. See also Kupperman, 1982.130. See Appendix.131. Ångström, 1958, pp. 22–8.132. Sturearkivet no. 264 (BSH 4:211).133. Lundqvist and Asp, 1997, p. 31.134. Transcript dated 22 December 1270 (Dipl. Novevallensia, no. 48, p. 123).135. Dahlström, 1995, p. 94.136. Ångström, 1958, Fig. 59, p. 137; Lamb, 1977, p. 461; Lamb, 1982, Fig. 30, p. 76; Lamb, 1988,

pp. 45–46; Guiot, 1992; Karlén and Rosqvist, 1995, p. 57.137. Le Roy Ladurie, 1971, Appendix 15, p. 378; Lamb, 1977, Table 5 in Appendix 5, p. 566.138. Lamb, 1987, p. 134.139. Cf. Lamb, 1982, p. 201.140. Cf. Dahlström, 1995; Lundqvist and Asp, 1997.


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(Received 8 November 1999; in revised form 21 May 2001)

A Contribution to the History of European Winters: Some Climatological Proxy Data from...

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