Exploring the climate-society nexus with tree-ring evidence : Climate, crop yields and hunger in medieval and early modern north-east Europe

(1)

uef.fi

PUBLICATIONS OF

THE UNIVERSITY OF EASTERN FINLAND Dissertations in Social Sciences and Business Studies

ISBN: 978-952-61-2562-6 ISSN: 1798-5749

Dissertations in Social Sciences and Business Studies

PUBLICATIONS OF

THE UNIVERSITY OF EASTERN FINLAND

Adverse climate and resulting harvest failures are commonly seen as the main cause of hunger in medieval and early modern north-

east Europe. Yet, the lack of written sources has for a long time hindered the research on the topic. This thesis introduces a novel approach how to use tree-ring data as source

material in historical research. By analysing tree-ring evidence together with traditional historical sources, this thesis concludes that the relationship between climate and hunger in

medieval and early modern north-east Europe was not as direct as it has been previously

presumed.

HELI HUHTAMAA

DISSERTATIONS | HELI HUHTAMAA | EXPLORING THE CLIMATE-SOCIETY NEXUS WITH TREE-RING EVIDENCE | No 152

HELI HUHTAMAA

EXPLORING THE CLIMATE-SOCIETY NEXUS WITH TREE-RING EVIDENCE

Climate, Crop Yields, and Hunger in Medieval and Early Modern North-East Europe

(2)

EXPLORING THE CLIMATE-SOCIETY NEXUS WITH TREE-RING EVIDENCE

CLIMATE, CROP YIELDS, AND HUNGER IN MEDIEVAL AND EARLY MODERN NORTH-EAST EUROPE

(3)

(4)

Heli Huhtamaa

EXPLORING THE CLIMATE-SOCIETY NEXUS WITH TREE-RING EVIDENCE

CLIMATE, CROP YIELDS, AND HUNGER IN MEDIEVAL AND EARLY MODERN NORTH-EAST EUROPE

Publications of the University of Eastern Finland Dissertations in Social Sciences and Business Studies

No 152

University of Eastern Finland Joensuu

2017

(5)

Juvenes Print - Suomen Yliopistopaino Oy Tampere, 2017

Sarjan vastaava toimittaja: Kimmo Katajala Sarjan toimittaja: Eija Fabritius Myynti: Itä-Suomen yliopiston kirjasto

ISBN: 978-952-61-2562-6 (nid.) ISBN: 978-952-61-2563-3 (PDF)

ISSNL: 1798-5749 ISSN: 1798-5749 ISSN: 1798-5757 (PDF)

(6)

Huhtamaa, Heli

Exploring the climate-society nexus with tree-ring evidence. Climate, crop yields, and hunger in medieval and early modern north-east Europe, 59 p.

Joensuu: University of Eastern Finland, 2017 Publications of the University of Eastern Finland

Dissertations in Social Sciences and Business Studies, no 152 ISBN: 978-952-61-2562-6 (print)

ISSNL: 1798-5749 ISSN: 1798-5749

ISBN: 978-952-61-2563-3 (PDF) ISSN: 1798-5757 (PDF)

ABSTRACT

The relationship between adverse climate, crop failure, and hunger in medieval and early modern north-east Europe is commonly considered to be direct. Moreover, it is believed that crop failure and hunger events became more common with the shift to the cooler climatic regime of the Little Ice Age (LIA). Yet, lack of written sources has hindered investigation of these assumptions to date. In order to bridge this gap, this study derives additional evidence of past climate and crop yield variability from tree-ring material. By analysing this new source material alongside written sources, it can be shown that the causality between climate and hunger was not as straightfor- ward as previously considered.

This study introduces a novel method to reconstruct past crop yield responses to climate variability from tree-ring material. In addition to indicating severe crop failure events, the reconstruction provides valuable source material for studying agricultural history at large in the region. The results demonstrate that agricultural changes, which have previously been attested in pollen analyses and archaeological and historical studies, were connected to larger scale climatic shifts.

Whereas the relationship between climate and yield variability is shown to be rather generic, the relationship between crop failures and hunger is more complex.

The human consequences of bad harvests vary over space and time as well as within the peasant community, due to varying capacity to adapt to and cope with adverse climate and related yield decline. Accordingly, the results of the present study do not support the argument that hunger became inevitably more frequent with the shift to the LIA, as people’s responses to the cooling climate varied considerably across the study region.

Keywords: Climate, Agriculture, Hunger, Crop Failure, Tree Rings

(7)

Huhtamaa, Heli

Puun vuosilustot lähteinä. Ilmaston, satovaihteluiden ja nälän yhteys keskiajan ja uuden ajan alun Koillis-Euroopassa, 59 s.

Joensuu: Itä-Suomen yliopisto, 2017.

Publications of the University of Eastern Finland

Dissertations in Social Sciences and Business Studies, no 152 ISBN: 978-952-61-2562-6 (nid.)

ISSNL: 1798-5749 ISSN: 1798-5749

ISBN: 978-952-61-2563-3 (PDF) ISSN: 1798-5757 (PDF)

TIIVISTELMÄ

Ilmaston, katovuosien ja nälän yhteys keskiajan ja uuden ajan alun Koillis-Euroopas- sa on usein oletettu olevan suora, jopa monokausaalinen. Lisäksi kato- ja nälkävuo- sien on katsottu yleistyneen siirtyessä pikkujääkaudeksi kutsuttuun kylmempään ilmastovaiheeseen keskiajan ja uuden ajan taitteessa. Kirjallisten lähteiden vähyys on kuitenkin estänyt näiden oletuksien kriittisemmän tarkastelun. Tässä työssä puun vuosilustoaineistoa käytetään menneisyyden ilmasto- ja satovaihteluiden lähteinä.

Tutkimalla tätä uutta lähdeaineistoa kirjallisten lähteiden ohella, tämä työ esittää et- tei ilmaston ja nälän kausaalisuhde ole ollut niin suora kuin aikaisemmin on oletettu.

Tämä tutkimus esittelee uuden metodin rekonstruoida satovaihteluita puun vuosilustosarjoista. Satorekonstruktion avulla menneisyyden ankarat katovuodet voidaan ajoittaa vuoden tarkkuudella. Tämän lisäksi satorekonstruktio auttaa tutki- maan maatalouden historiaa myös laajemmin. Tämä työ osoittaa aikaisemman tutki- muksen tunnistamat maatalouden murroskaudet tutkimusalueella olevan yhteydes- sä laajempiin ilmastovaihteluihin.

Satovaihtelut osoittautuvat olevan riippuvaisia ilmastosta mutta kato- ja nälkä- vuosien yhteys osoittautuu monimuotoisemmaksi. Vaikutus ihmisen hyvinvoin- tiin vaihteli sekä ajasta ja paikasta riippuen että talonpoikaisyhteisön sisällä, koska sopeutumis- ja selviytymiskyky epäsuotuisaan ilmastoon ja laskeviin satotasoihin vaihteli. Tämän vuoksi työn tulokset eivät myöskään tue oletusta, että nälkävuodet olisivat yleistyneet pikkujääkauden vuoksi. Sen sijaan, väestön kyky vastata kylme- nevään ilmastoon vaihteli huomattavasti tutkimusalueella.

Avainsanat: Ilmasto, maatalous, nälkä, kato, puun vuosilustot

(8)

Huhtamaa, Heli

Eine Untersuchung zum Zusammenhang von Klima und Gesellschaft unter Einbe- zug von Baumringdaten. Klima, Ernteerträge und Hunger im mittelalterlichen und frühneuzeitlichen Nordosteuropa, 59 p.

Joensuu: Universität Ostfinnland, 2017

Publications of the University of Eastern Finland

Dissertations in Social Sciences and Business Studies, no 152 ISBN: 978-952-61-2562-6 (Band)

ISSNL: 1798-5749 ISSN: 1798-5749

ISBN: 978-952-61-2563-3 (PDF) ISSN: 1798-5757 (PDF)

ZUSAMMENFASSUNG

Der Zusammenhang zwischen ungünstiger Witterung, Missernten und Hunger im Nordosteuropa des Mittelalters und der Frühen Neuzeit gilt gemeinhin als sehr eng.

Zudem wird davon ausgegangen, dass mit dem kühleren Klima der Kleinen Eiszeit öfter Missernten und Hungersnöte auftraten. Da nur ungenügend schriftliche Quel- len vorhanden sind, konnten diese Annahmen bisher allerdings weder bestätigt noch verworfen werden. Die vorliegende Arbeit kombiniert deswegen die schriftlichen Quellen mit Baumringuntersuchungen zum Klima der Vergangenheit. Dadurch wird deutlich, dass der Zusammenhang zwischen Klima und Hunger nicht so direkt ist, wie ursprünglich angenommen.

Die vorliegende Untersuchung präsentiert eine neue Methode, wie der Einfluss von Klimaschwankungen auf Ernteerträge in der Vergangenheit mit Baumringen rekonstruiert werden kann. Mit dieser Methode und den dazugehörigen Quellen lassen sich sowohl schwere Missernten aufzeigen, als auch agrargeschichtliche Er- kenntnisse für einen grossen Raum gewinnen. Die Resultate zeigen dabei auf, dass landwirtschaftliche Umbrüche, die bereits in älteren Pollenanalysen und archäologi- schen Untersuchungen sichtbar waren, mit langfristigen Klimaschwankungen ver- bunden waren.

Im Gegensatz zum direkten Zusammenhang zwischen Klima und den Ernteer- tragsschwankungen präsentiert sich die kausale Verbindung von Missernten und Hungersnöten komplexer. Die Folgen für die Menschen variieren abhängig von der Region und im Verlaufe der Zeit sowie innerhalb der Agrargesellschaft stark, weil sich auch die Möglichkeiten der Bewältigungs- und Anpassungsstrategien an Klima- wandel verändern. Entsprechend liefern die Resultate dieser Untersuchung keinen Hinweis darauf, dass Hungersnöte während der Kleinen Eiszeit zwangsläufig häu- figer auftraten, da die Gesellschaften – über die Zeit und den geographischen Raum gesehen – sehr unterschiedlich auf das kühlere Klima reagierten.

Keywords: Klima, Landwirtschaft, Hunger, Missernten, Baumringe

(9)

(10)

ACKNOWLEDGEMENTS

Conducting a double doctorate degree in joint supervision in two countries to two different disciplines has provided insight to interdisciplinary research that I could have never expected when I started my journey with the PhD. These years have been both a scientific and personal challenge, which would not have been possible without the encouragement and help of several people.

First and foremost I would like to thank my supervisors. My grateful thanks to Jukka Korpela, whose motivational – and sometimes provocative – teaching and supervision have greatly influenced where I am as a historian today. I also wish to express my sincere gratitude to Christian Rohr, who welcomed me to Bern and provided me with this unique opportunity to conduct a double doctorate degree. Without his enthusiasm and support, compiling this dissertation would have not been possib le. Moreover, I express warm thanks to Samuli Helama, who introduced me to the world of natural sciences. His patient supervision, encouraging words and inspiring questions have been invaluable throughout the PhD process.

I wish to pass my sincere thanks to Bruce Campbell, who acted as the pre-examiner and opponent of this dissertation, and to Jussi-Pekka Taavitsainen, the second pre-examiner, for their valuable and insightful comments on the manuscript. I would also like to thank Jari Holopainen for his collaboration and thoughtful remarks on the articles included in this dissertation.

I wish to express kind acknowledgements to Harri Siiskonen, Minna Tanskanen, Riikka Myllys and to other colleagues and friends at the Department of Historical and Geographical Studies at the University of Eastern Finland. Moreover, my warm thanks to Christian Pfister, Daniel Segesser, Chantal Camenisch, Melanie Salvisberg and to everyone at the WSU team and to Martin Grosjean and the Oeschger Centre for Climate Change Research at the University of Bern.

Over the last five years I have had the fortunate opportunity to visit different research groups and participate numerous workshops and conferences. Through these visits and events I have gotten to know many inspiring scholars in the field, many of whom have then become dear friends. Exchange of ideas with Matthew Hannaford has been essential. Thanks also to Dominik Collet, Maximilan Schuh and the ‘Facing Famine’ team at the University of Heidelberg and the ‘Hunger Years’ team at the University of Turku, among others, for the fruitful discussions over the years.

Compiling this double doctorate project would have not been possible without the support and encouragement of my friends and family – in Finland and Switzer- land alike. My warmest thank to all of you. Last but not least, thanks to Michèle, who has made me laugh and remember life outside of the PhD over these years.

Bern, 17 July 2017 Heli Huhtamaa

(11)

(12)

LIST OF FIGURES

Figure 1. Map of the study area and places mentioned in the text . ... 25 Figure 2. Finnish crop yield ratio, April-August mean temperature, and averaged

southern and northern tree-ring MXD series 1866–1905 ... 28 Figure 3. Reconstructed climate-mediated yield ratio anomalies 760–2000 and

periods of agricultural transformation in Finland ... 35 Figure 4. Simplified model illustrating the link between spring and summer

temperatures and the frost damage on crops ... 38 Figure 5. Reconstructed climate-mediated yield ratio anomalies ... 40 Figure 6. Time-series of crop failure and hunger from 17th century

Southern Ostrobothnia. ... 44 Figure 7. Uneven hunger ... 46

LIST OF ABBREVIATIONS

EPS Expressed population signal LIA Little Ice Age

MXD Maximum latewood density NAF National Archives of Finland NOA North Atlantic Oscillation OSF Official Statistics of Finland SYF Statistical Yearbook of Finland TRW Tree-ring width

(14)

1 INTRODUCTION

Adverse climatic conditions, weather, and resulting crop failures are commonly seen as the main cause of hunger in medieval and early modern north-east Europe (modern day Finland and north-west Russia).¹ On the other hand, it is well known that dynamic, local and society-specific factors, like trade networks, food prices and en- titlements, political stability, and storage capacity, among other things, have likely contributed to every hunger crisis.² Moreover, the direct causal relationship between climate and hunger in north-east Europe is merely a widely-agreed assumption. This is mostly because reliable and continuous written source material indicating variations in climate, harvest and human well-being are scarcely available from the area during this period. However, additional material on climate and grain yield fluctuations can be derived from tree-ring series. In this thesis, therefore, tree-ring based climate and grain yield reconstructions are explored alongside written source material to better understand the dynamic nexus between climate and human well-being.

The question of causality between climate and hunger is approached through five different case studies. The first article statistically quantified crop yield responses to climate variability. The second article qualitatively assessed the possible linkages between climate and food crises in medieval Novgorod and Ladoga. The third article developed a novel method to reconstruct temperature sensitive crop yield variations from tree-ring density data. The fourth article traced the agricultural and societal consequences of climate extremes resulting from volcanic forcing in the 17th century Ostrobothnia, Finland. And lastly, the fifth article discussed the spatial synchrony of crop failure and hunger events in north-east Europe using the case study of the crises of the early-14th century.

These separate case studies focused on different areas and time-periods in medieval and early modern north-east Europe. The studies utilised diverse methods and sources and focused on different research questions. Yet, the nexus between climate and hunger was the unifying research theme and the tree-ring data the common source material in all of the studies. Therefore, this thesis demonstrates how tree-ring data can be used as supplementary source material in historical research by exploring whether the causality between climate and hunger in medieval and early modern north-east Europe was as direct as has been previously supposed.

Atmospheric variability is characterised as weather (high-frequency variability) and climate (low-frequency variability).³ Climate can be considered as the average of prevailing weather patterns of a given region over a long period of time,⁴ whereas weather is the experienced short-term (hourly to daily) variations of these elements.

This thesis focuses mostly on climate fluctuations: shifts and annual deviations from

1 Myllyntaus 2009, 81.

2 Slavin 2016, 439–441.

3 Lovejoy 2013, 1.

4 From decadal to millenial time-scales.

(15)

the long-term seasonal mean, although the possible significance of short-term weather events is also briefly discussed.

Over recent decades, in light of the growing awareness of anthropogenic climate change, interest in integrating paleoclimate records into historical research has grown.⁵ Paleoclimatology is the study of past climate variability and change on seasonal to multicentennial time scales. Climate proxy records, indirect data sensitive to climate variability, is transformed in paleoclimatological studies into estimations of past climate variability. These climate proxy data can be derived from man-made written sources, like annals, weather diaries and phenological observations, or from natural archives, where climate and weather anomalies have left signals, for example, in tree rings and cave speleothems. Some paleoclimate records are clearly better suited for historical research than others.⁶ Tree-ring records are one of the most im- portant sources of paleoclimate data due to their excellent temporal resolution and accuracy. Tree ring records are dated to absolute calendar years, which, in practice, allows direct comparison with historical events. Tree-ring records are also especially valuable over eras and regions where written sources are scarce, as in medieval and early modern north-east Europe, where reconstructing past climatic variability from documentary sources may not be possible.

Tree-ring data, commonly measurements of the width (TRW) or maximum density (MXD) of the annual growth layers of arboreal growth, are widely used as climate proxy data to reconstruct variations in past climate. Chronologies of TRW or MXD can be transformed into annually resolved reconstructions of temperature and precipitation variability.⁷ By combining overlapping chronologies of living trees, tim- bers from historic buildings and archaeological sites, and subfossil trees preserved in bogs and lakes, these tree-ring series can extend over entire millennia.⁸ The availability of multi-centennial tree-ring series is exceptionally good in north-east Europe, spanning from the heart of medieval Novgorod to southern Finland and northern Lapland.⁹

In north-east Europe, the chronologies of historical and climatic events are considered to be closely correlated, mostly because the area overlaps with the northernmost limit of crop cultivation.¹⁰ The whole period from the Middle Ages to the early-20th century is considered as one of traditional agriculture in the region, mostly due to the rather stationary state of agricultural practices and methods.¹¹ The bread crop cultivation was commonly restricted to two principal grains tolerant of the short growing season, that is, winter rye (Secale cereale L.) and spring-sown barley (Hordeum vulgare L.). The agrarian population aimed to minimize the agricultural risks caused by the cool climate by combining different cultivation methods, like slash-and-burn and ar-

5 McCormick et al. 2007, 865; Caseldine & Turney 2009, 88; Pfister 2010, 29; Dearing et al. 2015, 222; Izdebski et al. 2016, 18–19.

6 Caseldine & Turney 2009, 2.

7 Wilson et al. 2016, 2.

8 Fritts 1976, 2–4.

9 Kolchin 1967; Tarabardina 2001, 2009; Helama et al. 2005, 2009, 2014a, 2014b, 2017; Holopainen et al. 2006;

Esper et al. 2012; Melvin et al. 2013; Matskovsky & Helama 2014.

10 Holopainen & Helama 2009, 213–214; Klimenko 2016, 337.

11 Soininen 1974, 13.

(16)

able cultivation, as well as by balancing the cultivation of the two grains.¹² Neverthe- less, medieval and early modern agriculture in the region is considered unproduc- tive and climate-sensitive.¹³ The shift to the generally cooler conditions of the Little Ice Age (LIA) in particular is believed to have caused more frequent crop failure and hunger crises in the 16th and 17th centuries.¹⁴ Agriculture was close to subsistence level,¹⁵ and it is therefore commonly believed that a single poor harvest could make all the difference between survival and death by starvation.¹⁶

Commonly, food shortages in medieval and early modern times are regarded as famines in the sources and literature alike.¹⁷ But famine refers to a catastrophic crisis where scarcity of food is so severe that loss of population becomes widespread.¹⁸ In this respect, data on population fluctuations would be required to define whether a crisis was a famine or not, and these data are not available from medieval and early modern north-east Europe. Therefore, this study approaches food crises through the concept of hunger. Hunger is defined as an involuntary condition, when the mini- mum level of food is not available, or people do not have the access to it, to maintain their well-being.¹⁹ To a certain degree, assessment of such conditions is possible from the available contemporary sources. Hunger can be either acute or chronic. Whereas the former is detectable from the medieval and early modern sources, the latter is commonly not. However, chronic hunger is known to take the form of acute out- breaks.²⁰

12 Smith & Christian 1984, 26; Solantie 2012, 73–84.

13 Shaw 2006, 38–39; Jespersen 2016, 206–207.

14 Kujala 2003, 39; Myllyntaus 2009, 80–81.

15 Smith 1977, 86–95; Holopainen & Helama 2009, 216.

16 Jespersen 2016, 207.

17 For furter discussion, see, e.g., Vanhaute 2011; Slavin 2016.

18 Ó Gráda 2009, 6.

19 Millman & Kates 1990, 3.

20 Dirks 1993, 29–30; Sanchez & Swaminathan 2005, 357. For further discussion on the definition of hunger, see, Krämer 2015, 99–105.

(17)

2 RESEARCH FRAMEWORK

2.1 RESEARCH TRADITION

2.1.1 Tree-ring data in historical research

As early as 1914 Andrew Ellicott Douglass proposed that climate-sensitive tree-ring records provide novel material to study the environmental conditions of certain historical events.²¹ Yet it took several decades before tree-ring data were included in historical research, and where this was the case historians tended to consider den- dro-sciences mainly as a dating method.²² In his early works, Emmanuel Le Roy Ladurie, one of the pioneers of climate history, was sceptical of the suitability of tree-ring material in historical research, and especially its ability to reflect past grain yield fluctuations. This was mostly because of the poor temporal and spatial distri- bution of tree-ring measurement series available from Europe at the time.²³ Over the last four decades, the growing number, sophistication, and easier accessibility of tree-ring based reconstructions have opened up new archives for historians. How- ever, integrating human history with the information captured in the tree rings is a task that has largely been left to natural scientists.²⁴ Historians, although referring increasingly to tree-ring studies in their work, commonly treat tree ring material more as supplementary information than as source material.²⁵ Yet, the full potential of including tree-ring material in historical research was demonstrated to the historical community by Bruce M.S. Campbell, first in his study on the connections between environment and society in pre-modern England (2010) and later in his monograph

‘The Great Transition’ (2016).

In addition to reconstructing past climate variability, tree-ring series have been successfully used to reconstruct rain-fed agricultural production and food reserves in America.²⁶ In Finland, too, Ilmari Hustich found already in 1947 the existence of a strong correspondence between the annual variations of Scots pine (Pinus sylvestris) growth and crop yields.²⁷ A few years later Peitsa Mikola (1950) noted that years of crop failure, especially those that were caused by frost damages, were also poor in terms of tree growth.²⁸ However, although generally agreeing that adverse weather and climate were the primary cause of the various hunger years of the country, Finn- ish historians have questioned the reliability of the tree-ring data as source material, particularly in research on pre-industrial crop failures.²⁹ Eino Jutikkala (1994), for ex-

21 Douglass 1914, 322.

22 Kolchin 1967, 30–31; Bannister & Robinson 1975, 210–211.

23 Le Roy Ladurie 1972a, 2–3; 1972b, 142–148.

24 See, e.g., Baillie 1999; Holopainen & Helama 2009; Büntgen et al. 2011, 2016; Schmid et al. 2015.

25 See, e.g., Behringer 2010; White 2011.

26 Burns 1983; Andersson et al. 1995; Therrell et al. 2006; Maxwell & Knapp 2012; Maxwell et al. 2013;

Bocinsky & Kohler 2014.

27 Hustich 1947, 9–10.

28 Mikola 1950, 205.

29 Tornberg 1989, 59; Keränen 1989, 226–227.

(18)

ample, doubted whether tree growth and agriculture are sensitive to the same climatic factors. He was especially suspicious of tree-ring material corresponding to grain yield fluctuations resulting from short-term weather events, like night-frosts during harvest time.³⁰ Mirkka Lappalainen elaborated Jutikkala’s argument by rationalizing that whereas tree rings are indicative of the average growing conditions over the whole summer season, a single fatal frost night over the harvest time – which does not affect tree-ring growth – can destroy the whole harvest.³¹

2.1.2 Grain yields and hunger in the northern margin

Fluctuations in climate can be expected to have a considerable impact on peasant societies in the marginal areas of agriculture, where either temperature or precipitation is clearly the principal yield-limiting factor.³² In areas near the thermal limit of crop cultivation, like in north-east Europe, the rate of plant growth is strongly regulated by temperature, and lower temperatures reduce growth speed.³³ In these areas even small temperature departures can potentially cause severe crop failures. Severe crop failures, in turn, can be expected to have considerable impacts on the medieval and early modern peasant population, as their food availability was heavily based on local, self-sufficient agricultural production.³⁴

However, Le Roy Ladurie noted in his essay ‘History and Climate’ that we should not naïvely assume the effects of any given meteorological conditions, for instance the alter- nation of wet and dry cycles, on crops.³⁵ Therefore, instead of relying on general assumptions, crop yield responses to climate variability should be carefully evaluated and defined in the region and period of study, as demonstrated by Christian Pfister.³⁶ Lit- erature on yield responses to climate variability in the northern margin of agriculture is widely available.³⁷ Yet, statistical data for the research on the relationships between climate and crop yields have been gathered commonly from the most recent decades alone. It may not be feasible to derive the understanding on the relationships solely from the era of industrial agriculture when aiming to understand medieval and early modern yield responses to climate variability because of technological and method- ological developments which have taken place in agricultural practices during the recent past. Moreover, the genetic plant material changed after the World Wars.³⁸ For example, breeding has brought new crop varieties that are more resistant to weather stress and (weather-related) plant pests and diseases. Thus, industrialisation of agriculture has not only increased the yield but may have also altered the crop responses to climate variability.

30 Jutikkala 1994, 11.

31 Lappalainen 2012, 32.

32 Parry & Carter 1985, 97; Toohey et al. 2016, 408.

33 Rantanen & Solantie 1987, 19.

34 Orrman 2016, 161.

35 Le Roy Ladurie 1972b, 146.

36 Pfister 1978, 224. See, also, Le Roy Ladurie 1972a, 289–292.

37 See, e.g., Mukula & Rantanen 1987, 1989; Carter & Saarikko 1996; Kaukoranta & Hakala 2008; Pelto- nen-Sainio et al. 2009a, 2009b, 2011, 2016a, 2016b, 2016c; Himanen et al. 2013.

38 Holopainen & Helama 2009, 217.

(19)

Moreover, it is known that all food shortages – or crop failures – do not inevitably lead to hunger. In addition, not only declines in food availability but also entitlement failures, which are caused by human and institutional actions, are known to cause hunger.³⁹ This entitlement approach was pioneered by Amartya Sen in his work ‘Poverty and Famines’ (1981). Since then, the economic nature of hunger has gained profound intrest among scholars of famine.⁴⁰ However, a strong economic focus may not be the most fruitful approach to better understand hunger among self-sufficient peasant societies.⁴¹ For example, in western Finland, only one out of six years of elevated mortality over the period 1750–1850 coincided with a year of high grain prices.⁴² Furthermore, I have proposed earlier that if grain prices were associated with food shortages in early modern Finland, rising prices were most likely the consequence of – rather than the cause for – food shortage. This is because the price peaks commonly lagged crop failures by a couple of years.⁴³ An entitlement approach might be only applicable if an institution or other actor can control the entitlement to food, for example through exchange, markets, or trade.⁴⁴ In the northeastern periphery over the study period this was not always the case.⁴⁵

An alternative approach, following Thomas Malthus’s theory, is to see hunger (and related mortality) as inevitable consequence of population growth when human population grew faster than food production.⁴⁶ This approach long dominated the international famine studies focusing on pre-industrial societies.⁴⁷ And last, hunger can also be considered as a hazard, when exposure to an event, like extreme climate, has harmful consequences.⁴⁸ In Russia and Finland, medieval and early modern hunger has been largely understood through the latter approach, primarily as a consequence of production failure due to adverse climate and weather.⁴⁹ However, this generally agreed conception of hunger as a ‘natural hazard‘ originates from rather old literature, and has been hardly revisited.

2.1.3 The ‘Kingdom of Frost’

Miikka Voutilainen noted sharply in his recent study on the Finnish hunger years of the 1860s that the international literature published after the 1970s has had little impact on Finnish famine studies.⁵⁰ Indeed, the main discussion in Finland has focused on whether malnutrition or diseases were more fatal for the pre-industrial population during

40 Voutilainen 2016, 67.

41 See, Soininen 1974, 351–365, for the discussion on the little impact market economy had on the livelihood and subsistence of pre-industrial peasant in Finland.

42 Jutikkala 2003, 504.

43 Huhtamaa 2018, 56.

44 Sen 1981, 155.

45 See, Korpela 2014b, 185–188.

46 Malthus 1798, 44.

47 Slavin 2016, 434.

49 See, Melander & Melander 1924 (Finland) and Kahan 1968 (Russia).

(20)

the hunger years.⁵¹ Yet, the initial cause of hunger has not received careful analysis.

Instead, food shortage, more precisely crop failure due to harvest time night-frost, is seen almost unanimously as the primary trigger for hunger in medieval and early modern Finland. Dramatic titles like ‘The Constant Danger of Frost’, ‘Land of the Frost-Devil’, and ‘The Kingdom of Frost’ are common in the literature.⁵² The direct causality between frost, crop failure and hunger is such a well-established hypothesis in the Finnish literature that records of frost year, year of scarcity, and hunger year (hallavuosi, pulavuosi, and nälkävuosi in Finnish, respectively) are commonly regarded as indications of crop failure years.⁵³

The research on pre-1700s hunger in Finland has focused almost solely on the famine of the 1690s.⁵⁴ In these studies, the interpretations on the role of the institu- tions, authorities, population pressure, economic factors, and disease, inter alia, in contributing to the development and severity of the famine differ. Yet there is a con- sensus that severe crop failure due to night-frost was the decisive trigger of the crisis.

However, these studies are not simply works of environmental determinism, as all of these consider the significance of pre-crisis socio-economic conditions and possible relief measurements. Nevertheless, the relationship between crop failure and hunger is rather unidirectional.⁵⁵

Research on crop failures and hunger extending prior to the 1690s is scanty. Viljo Voipio (1914) explored the severity and human consequences of the 1601 crop failure in south-west Finland. Väinö Johanson (1924) assessed the frequency and causes of crop failures in Finland from the 17th century onwards. Matleena Tornberg (1989) examined yield ratio variability in the 16th and 18th centuries south-west Finland.

To date, Kurt Reinhold Melander’s and Gustaf Melander´s (1924) work is the only overview on the topic that extends back to the medieval period (to the 14th century) from Finland. Because of the lack of early sources from the region, the catalogue included some known Swedish and Russian famines as indicators of crop failure years in Finland over the earlier centuries. However, no references to any primary sources are given in the chronology. In their chronology of Finnish crop failures, three crop failure years in the 14th century, ten in the 15th, 16 in the 16th, and 33 crop failure years in the 17th century were identified. The catalogue was later reproduced largely in Timo Myllyntaus’s study (2009). These works saw harvest time night-frost as the most common reason for severe crop failures in Finland. Yet other factors like drought or excessive precipitation were also suggested to have caused considerable yield damages and hunger.⁵⁶

The increasing number of recorded crop failure events in the 17th century has been further connected to the cooler climatic conditions of the Little Ice Age (LIA),

51 See, e.g., Turpeinen 1986; Jutikkala 1987, 2003; Soikkanen 1991; Häkkinen 1994; Kallioinen 2005; Lappa- lainen 2014a. For further review on the ‘malnutrition-disease’ dabate, see, Voutilainen 2016.

52 Jutikkala 2003, 292; Solantie 2006, 185; Lappalainen 2012, 47, respectively.

53 See, e.g., Melander & Melander 1924; Myllyntaus 2009.

54 Jutikkala 1955, 2003; Neumann & Lindgren 1979; Mäntylä 1988; Muroma 1991; Katajala 1994; Lappalainen 2012, 2014a.

56 Melander & Melander 1924, 352–353; Myllyntaus 2009, 81.

(21)

especially in more recent reseach.⁵⁷ However, the occurrence of night-frost, the most commonly named cause of crop failure in Finland and Russia,⁵⁸ is more dependent on weather than climate. In the studied area, harvest time night-frosts are usually radiation frosts. These result because of temperature inversion, which occur under clear sky and calm winds. In this situation, radiant heat rapidly rises after sunset, and cold air, being heavier, flows down and stays trapped below the warmer inversion layer.

The topography of the fields affects the frost prevalence, valleys and depressions being the highest risk areas, whereas a close proximity to waterbodies decreases the likelihood of frost occurrence. These radiation frosts are local and short-term weather phenomena, lasting only hours over the night.⁵⁹ Therefore, instead of long-term mean temperature, the occurrence of night frost in the region is mainly dictated by daily weather: calm, clear and dry atmospheric conditions. Thus, perhaps previous historical research has failed to make clear distinction between short-term whether phenomena (like radiation frost) and long-term climatic regimes (like the LIA).

In Finland, the relationship between crop failures and hunger is commonly seen as generic.⁶⁰ Solely the fact that records of hunger and famine from Finland, or even from Sweden or Russia, have been used as proxy data for crop failure years sug- gests that these two variables are seen inherently connected. Consequently, based on the crop failure chronology by Melander and Melander, Myllyntaus proposed that during the early modern period at least part of the population faced a famine every third year during those two [17th and 18th] centuries.⁶¹ The frequent famines are associated with the cool climate of the LIA. However, the frequency of early modern crop failure and hunger years was soon challenged by Jari Holopainen and Samuli Helama (2009), who noted that the information on past crop failures has been gathered from spatially fragmentary sources. By analysing the spatial synchrony of early modern yield ratios, they suggested that the early modern crop failures listed in these cata- logues might have been much more local than previously assumed. Consequently, they have suggested that the Finnish famine history may actually not be as dark as as- sumed based solely on the listed years [by Melander and Melander].⁶²

2.2 OBJECTIVES

The brief literature review above revealed considerable research gaps in the history of crop failures and hunger in medieval and early modern north-east Europe. The knowledge on the causality between adverse climate and hunger is based on general assumptions that have not been critically reviewed. Most likely, the lack of medieval and early modern written sources from the region documenting harvest fluctuations or human well-being explains the scarcity of research on the topic. Therefore, this

57 Tornberg 1989, 68 Keränen 1989, 221; Kujala 2003, 39; Myllyntaus 2009, 80–81.

58 Melander & Melander 1924; Kahan 1968; Myllyntaus 2009.

59 Kalma et al. 1992, 5. Tikkanen 2006, 13; Saukkonen 2008, 41.

60 For discussion on the topic, see, Voutilainen 2016, 96.

61 Myllyntaus 2009, 80.

62 Holopainen & Helama 2009, 222.

(22)

thesis derives novel evidence of past climate and grain yield variability from tree- ring material.

The thesis critically explores whether the generalisations prevailing in the literature are valid. The focus is on five of the main generalisations:

i) The hypothesis that harvest time night-frosts were the main reason for crop failures.

ii) The assumption that tree-ring data are not suitable to study crop failure history, or agricultural history at large, because harvest time night-frosts are not captured in the tree-ring data.

iii) The notion that hunger resulted from food shortage caused by crop failure

iv) The interpretation of hunger events, taking place either in Finland or ad- jacent regions, as an indicator of simultaneous crop failure in Finland.

v) The idea that episodic hunger became more frequent because of the cooling conditions of the LIA.

By addressing these generalizations, this thesis aims to review whether the relationship between climate, crop failure, food shortage, and hunger in medieval and early modern north-east Europe was as direct as previously proposed.

In order to critically explore these generalisations, the relevance, reliability, and validity of using tree-ring material to study the relationship between climate and crop yields are first explored. Next, pre-industrial crop yield responses to climate variability are defined and quantified. This is done with statistical data from the late- 19th and early-20th centuries. The climate-crop yield relationship from this era can be expected to correspond to the relationship of the medieval and early modern period because changes in agricultural practices and crop species were rather minor from the Middle Ages to the 19th century. This is especially so when compared with the leap from the traditional agriculture of the late-19th century to the industrial agriculture of today.⁶³ Moreover, the industrialisation of agriculture did not arrive in Finland until the beginning of the 20th century, which is much later than, for example, in western Europe.

After the relationship between climate and pre-industrial grain yield fluctuations has been defined, the study explores the causality between climate, crop failures, and hunger. This is mostly done by focusing on medieval (1100–1500) Novgorod and Ladoga and on 17th century Southern Ostrobothnia in western Finland (Figure 1). Special emphasis is given to the spatial and temporal synchrony of crop failure and hunger events. After briefly stating the main findings, the results are further discussed in the context of previous literature.

Although the need for research originates largely from the generalisations of the Finnish literature, it is essential to include medieval north-west Russia in the exam- ination. This is because the better source availability of the region and because the interpretations on crop failures and their causes and consequences in medieval Fin-

63 Rasila 2003, 490–492.

(23)

land rely largely on the Russian example due to this better source availability. As this thesis aims to explore whether these generalisations are valid or not, the analysis does not go into depth on any specific event. Instead, the thesis aims to identify long- term patterns, developments and regularities.

2.3 SOURCES

2.3.1 Tree-ring, crop yield and meteorological data

This thesis uses several published tree-ring width (TRW) and maximum density (MXD) series.⁶⁴ Paleoclimate reconstructions based on these data can explain c. 60%

of the observed summer temperature and 40% of precipitation variance.⁶⁵ If possible, MXD series instead of TRW are selected, as the TRW parameter is known to con- tain considerable biological memory.⁶⁶ This might translate into an overestimation of the persistence of climate anomalies. In this thesis, two mean MXD chronologies, one from southern Finland and one from northern Finland, are used as principal source material (Figure 1).⁶⁷ These data were also used in Article III to reconstruct climate-mediated yield ratios. In addition, tree-ring based precipitation reconstruction from western Europe and temperature reconstructions from central Sweden and Po- lar Siberia were used for comparison in Article V.⁶⁸ All the reconstructions have been corrected for the biological influence of tree ageing and site-related noise.⁶⁹

Data on annual provincial rye and barley yield fluctuations in Finland are collected from statistical reports that are available from the 1860s onwards.⁷⁰ The yield data were used in assessing crop yield responses to climate variability (Article I) and in reconstructing a climate-mediated yield ratio (Article III). For Article I, the yield data were linearly detrended to avoid spurious correlation coefficients that could arise because of the long-term increasing development of the grain yields. For Article III, the missing values for the year 1876 were infilled by adopting an arithmetic mean of the annual yield ratio over the five preceding and five following years of both grains (rye and barley) in each province. The mean yield ratio used in the reconstruction was calculated from the provincial series with a weighted arithmetic mean, where the weights dependend on the share of the grain and the provincial yield of the total harvest.

Monthly mean temperature and precipitation sum measurements from Finland are available from six weather stations (temperature) and two stations (precipitation) from the mid- to late-19th century.⁷¹ The data have been corrected for inhomogeni-

64 Helama et al. 2005, 2009, 2014a, 2014b, 2017; Matskovsky & Helama 2014.

65 Helama et al. 2009, 176, 2014b, 272; Matskovsky & Helama 2014, 1480.

66 Frank et al. 2007, 3302.

67 Helama et al. 2014a; Matskovsky & Helama 2014, respectively.

68 Büntgen et al. 2011; Gunnarson et al 2011; Briffa et al. 2013, respectively.

69 Briffa et al. 1992, 114; Helama et al. 2017, 172.

70 Official Statistics of Finland (OSF); Statistical Yearbook of Finland (SYF).

71 Finnish Meteorological Institute.

(24)

ties.⁷² The meteorological data were used in Article I for exploring the yield response to climate variability.

2.3.2 17th century administrative sources

Prior to the keeping of official yield statistics, tithe payments which were dependent on the amount of harvested grain can be used to estimate agricultural output.⁷³ How- ever, two tithe systems, ‘fixed tithes’ and ‘grain tithes’, were in simultaneous use in Finland. Only in the province of Ostrobothnia was the amount of collected tithes based on the quantity of annual harvest throughout the early modern period.⁷⁴ In addition to indicating year-to-year harvest fluctuations, the Finnish tithes may indicate also storage reserves as the tithes were commonly collected on the following spring.

The tithe data in Article IV was first collected from each parish of the province and adjusted to correspond to the harvest year.⁷⁵ Next, the parish series were normalised into z-scores. Last, the normalised parish data were averaged into a mean provincial tithe index series and the variance of the mean record was stabilized (see Article IV for details).

To study the possible human consequences of adverse climate and crop failures, the numbers of farms and deserted farms were collected from the same province of Southern Ostrobothnia.⁷⁶ In the Nordic countries, registers of deserted farms are common source material to assess societal hardship over the early modern period.

If a farmstead failed to pay taxes for three consecutive years, the farm was marked as deserted in the land registers. Also, farms that were abandoned, or whose inhab- itants had perished, were marked as deserted. Thus, the increase in the number of deserted farms can be expected to indicate increased impoverishment, perhaps even elevated mortality.⁷⁷ The number of farms is given here as the farm taxation unit at the time, as mantal.

In addition to the Crown keeping records of peasants’ tax paying ability, the peasant could appeal for a tax reduction from the Crown. In these petitions the peasants give a reason for the wished reduction, which was often crop failure or hunger. The catalogue of early modern peasant petitions until 1720 has been published by Ludvig Mårtensson (1952). The 17th century administrative sources were used alongside the tree-ring data to examine climate-driven agricultural crises and their possible societal aftermaths in Article IV.

72 Klingbjer & Moberg 2003; Tuomenvira 2004.

73 See, e.g., Pfister 1978; Kain 1979; Le Roy Ladurie & Goy 1982; Dodds 2004.

74 Muroma 1991, 15; Seppälä 2009, 102.

75 Finnish national Archives (NAF): Bailiff’s Accounts, Tithe Registers and Verification Books 1598–1634;

NAF: Provincial Accounts, Tithe Registers and Verification Books 1635–1704.

76 NAF: Bailiff’s Accounts, Land and Verification Books 1598–1634; NAF: Provincial Accounts, Land and Verification Books 1635–1704.

77 Kujala 2003, 39.

(25)

2.3.3 Medieval narrative sources

For the medieval period, north-west Russian chronicles and annals provide the best written source material to study crop failure and hunger in the north-east. Two chronicle compilations are used here, the 1914 edition of ‘The Chronicle of Novgorod’ and the ‘Utdrag ur ryska annaler’ which is a selected collection of Russian chronicle text focusing on the north-eastern Baltic region. ‘The Chronicle of Novgorod’ is based on the annals of the city of Velikii Novgorod, which were kept year by year from the early twelfth to the fifteenth century.⁷⁸ The ‘Utdrag ur ryska annaler’ was compiled by Matthias Akiander (1849) from tens of Russian contemporary and non-contemporary chronicles. Akiander paid special attention to the remarks on food crises, diseases, weather, and various natural phenomena when collecting the records from the Rus- sian sources.⁷⁹ The compilation can be criticised as fragmentary, however, since the records were not collected systemically.⁸⁰

The chronicle records are commonly of both descriptive and explanatory charac- ter, i.e. the event itself and its cause is stated. Nevertheless, these narrative sources usually lack information on the extent and severity of the events. Annalists and chron- iclers could also exaggerate the horrors of the famine. Alternatively, all crop failure or hunger events might not have been considered worth writing down. Chronicles served contemporary religious and political agendas and do not necessarily provide accurate descriptions of bygone events. Some annals and chronicles were written from first-hand knowledge, whereas others were compiled decades, or even centuries, after the events had taken place. As such, sources may include misdatings. Thus, entries of crop failure, food shortage and famine from contemporary sources cannot be taken as comprehensive lists of past events.⁸¹ The medieval narrative sources were analysed qualitatively in Articles II and V.

For the various methods used to analyse the statistical data and the administrative and narrative sources, see the details in the original articles.

78 Guimon 2010, 1158–1159.

79 Akiander 1849, 7.

80 Korpela 2014a, 20–21.

81 Helbling 2007, 431; Rohr 2007a, 223–226, 2007b, 100; Camenisch 2015, 40–49.

(26)

0 200 400 600 800 km

Tornio Artic Circle

N

Ladoga Helsinki

Novgorod S

Figure 1. Map of the study area and places mentioned in the text. The shading indicates the approximate study area of the thesis. The triangles indicate the average sampling sites of the southern (S) and the northern (N) MXD chronologies used in this study. The dark grey area indicates area of 17th century Southern Ostrobothnia.

(27)

3 RESULTS

3.1 TREE-RING DATA AS SOURCE MATERIAL IN HISTORICAL RESEARCH

3.1.1 Critical source assessment and tree rings

Through five different case studies, all the articles included in this thesis demonstrate that tree-ring data can provide valuable source material on past climate and yield fluctuations for historical research. However, historians should assess the relevance, reliability, and validity of the tree-ring data as carefully as they evaluate their written sources. Article V outlined that critical source assessment of the tree-ring material should include, at least, consideration of the response window, the indication of reconstruction skill, the spatial domain, and the sample replication of the used climate reconstruction or other dendrochronological data. Moreover, it should be considered how well a tree-ring chronology based on a limited number of trees represents the hypothetical perfect chronology. If it is demonstrated that the selected tree-ring data are relevant, reliable, and valid considering the studied era, location, and matter, tree-ring material can be considered as a primary source, as with any other sources.

3.1.2 Yield ratio reconstruction

Article I demonstrated that Scots pine (P. sylvestris L.) latewood maximum density data (MXD) can be used as indirect source material for reconstructing past yield fluctuations in the northern margin of agriculture. The common limiting factor, growing season temperature, largely explains the strong correspondence between the MXD and crop yield series (Figure 2). Consequently, Article III used the MXD data to reconstruct climate-mediated yield ratios (harvested grain in relation to sown) for central and northern Finland (i.e. above 62°N) since ad 760. A standard calibration-verification approach was applied to reconstruct the yield ratio fluctuations. The reconstruction explains 50% of the variance in recorded yield ratio variability over the calibration period (1866–1922).

The full reconstruction (760–2000) indicated five distinct intervals of potentially low and high yield ratios. The intervals were statistically defined using Rodionov’s (2004) sequential algorithm. The period of highest yield ratios was 760–1106. This period of high crop yields was followed by three periods of further lowering ratios.

The period of lowest yield ratios was 1695–1911. After that, the yields rose to values comparable to the period of highest yield ratios of 760–1106 (Article III; Figure 3).

The yield ratio reconstruction corresponds with the known large-scale crop failure events over the calibration period (Article III; Figure 2). Moreover, when the reconstructed series were compared with the 17th century grain tithe data from Ostroboth-

(28)

nia (western Finland) both series portray variations that are in general agreement with each other (Article IV). Importantly, both of the series identify certain common years having notably low yield output, i.e. years of severe crop failure. Thus, the yield ratio reconstruction can provide valuable source material to explore medieval and early modern crop failure history in Finland.

3.2 CLIMATE, CROP FAILURES AND HUNGER 3.2.1 Climate-sensitivity of the northern agriculture

Article I examined the relationships between monthly mean temperatures and provincial crop yields of rye and barley in Finland over the period 1861–1913 using a correlation analysis. Overall, yields of both crops correlated positively with spring and summer (April-August) mean temperatures in large parts of the country. Warm- er temperatures were consistently associated with higher crop yields, emphasising the importance of temperature as a yield-limiting factor in pre-industrial agriculture in the region. In addition to spring and summer mean temperatures, the onset of the growing season was found to have a decisive impact on the crop yields. The onset of the growing season, in turn, was partly dictated by the winter severity (temperature and snow cover). Evidence of precipitation playing a significant role in controlling crop yields in pre-industrial Finland was not found (Article I).

The crop yield sensitivity to temperature was found to vary spatially within 19th century Finland. Crop cultivation was most temperature-sensitive in the northern provinces, whereas the temperature linkage almost disappeared in the most south-eastern parts of the country. Additionally, the crop yields of rye correlated positively with January mean temperatures in southern Finland (Article I, Figure 2).

Although considerable spatial differences in the temperature response were found, both crops failed in large parts of the country in 1867, 1877, 1881, 1892, 1899, 1902. These years of countrywide crop failure coincided systemically with the years of low April-August mean temperatures (Figure 2). Because of the low temperatures, the ripening of the crops was delayed to a period when the first autumn night-frosts commonly occur (Article I). Thus, the low spring and summer temperatures explain the extent and severity of the frost damage on crops. In most cases, the low temperatures directly affected the same year’s harvest. Alternatively, when the adverse conditions affected also the quantity and quality of the seed grain, the crop response could lag one year.

Article II further analysed the climate-sensitivity of crop cultivation in medieval Novgorod and Ladoga (1100–1500) with qualitative analysis. These results were largely in agreement with the findings of the statistical analysis of the 19th century data. Also in medieval north-west Russia, most of the severe crop failures resulted from harvest time night-frosts and these failures happened in years when adverse climatic conditions had delayed the ripening of the crops. Similar to the findings of

(29)

Article I, delayed onset of the growing season and cool summers were considerable threats to crop cultivation. Yet, in addition to low temperatures, precipitation variability was also shown to influence harvest success in Novgorod (Article II).

6 7 8 9 10 11 12

-4 -3 -2 -1 0 1 2

1870 1880 1890 1900

Yield ratio Tree ring Temperature

Yield ratio and tree-ring (z-scores) April August temperature (°C)

Crop faulure

Figure 2. Finnish crop yield ratio, April-August mean temperature (averaged from Helsinki and Tornio stations), and averaged southern and northern tree-ring MXD series 1866–1905. The grey shadowing indicates years of countrywide crop failures. The close correspondence between the different series illustrates how tree-ring data can be used as both climate and yield proxy data.

Source: Article I; Klingbjer & Moberg 2003; Tuomenvirta 2004; Helama et al. 2014; Matskovsky

& Helama 2014.

Note: See Article I for information on the missing values. The yield ratio was calculated with weighted arithmetic mean from the provincial crop yield data, where the weighting was deter- mined by the share of the provincial grain (rye or barley) harvest to the total harvest

3.2.2 Crop failures and hunger

The analysis carried out in Article II found that adverse climate or weather was at least a contributing factor in 90% of the recorded hunger events in medieval Novgorod and Ladoga. Similarly, the time series analysis in Article IV found that each time contemporaries witnessed hunger in early modern Ostrobothnia, the climatic conditions were considerably unfavourable for crop cultivation over the preceding years.

(Article IV). Thus, there is strong evidence that climate-driven crop failures underlay the recurrent hunger experienced in medieval and early modern North-East Europe.

However, the significance of adverse climate underlying hunger varied over the studied period and area (Article II, V). For example, the role of climatic factors underlying acute hunger was less evident in 14th and 15th century Novgorod (Article II) than in 17th century Finland (article IV).

Moreover, the situation did not evolve into a hunger crisis each time the tree-ring data or narrative sources indicated climate and weather conditions potentially unfavourable for crop yields (Article II, IV, V). Commonly, the most severe hunger crises

(30)

followed after at least two back-to-back harvest failures (Article II, IV). Despite the considerable climate-sensitivity of the crop yields in the region, the results suggest that the hunger crises in the north-east were almost never caused by climate-driven production failures alone. The harvest success did not solely determine the well-being of the population. Consequently, the relationship between climate and crop failures appears to be generic, whereas the relationship between crop failures and hunger was more complex in the medieval and early modern north-east.

3.2.3 Resilience to adverse climate and crop failures

Resilience, the ability to anticipate, cope, or recover from the crop failures, explains the more complex pathways from crop failure to hunger.⁸² First of all, the people on the northern margin of agriculture anticipated that climate and weather posed a risk to crop cultivation and that crop failures were likely. Consequently, they favoured high-yielding methods, like slash-and-burn cultivation, to maximize the yield in a good year (Article II, III). The contemporaries must have had some grain storages, as Article IV demonstrated that the peasants commonly faced the greatest hardships one to three years after the first crop failure event. Furthermore, the worst climate-driven hunger crises examined in the articles, the famines of 1127–1128 and 1230–1231 in Novgorod and 1601–1603 and 1695–1697 in Ostrobothnia, culminated during the second or third successive year of adverse climate and crop failure (Article II, IV).

Second, the wilderness, forests and waters, provided alternative – and often cru- cial – sources of nutrition. Fish in particular might have had a decisive role whether grain shortage evolved to a hunger crisis (Article II, V). Moreover, cultivation of other crops and vegetables, like millet and root vegetables, provided supplementary sources for subsistence (Article II). And lastly, people had learned to cope with frequent crop failures and prepared substitute foods, like birch- and pine-bark bread (Article II).

The level of resilience, however, varied within the studied peasant populations.

The poor were the most vulnerable. For example, in the 17th century Ostroboth- nia, the landowning peasants were more resilient than the tenant farmers. Article IV demonstrates that the social consequences of severe crop failures, like impoverishment, were considerably profound among the tenant farmers.

3.2.4 Spatial and temporal differences

Climate-driven crop failures are commonly more local than regional because of the spatial variability in climate and weather patterns, soil types, and agricultural practices (Article IV). Article V discusses how the food systems differed from place to place over the north-east. For example, when considering medieval times, in many

82 Cardona et al. 2012, 75.

(31)

areas of the north-east, the daily source of nutrition came from fishing, herding and hunting.⁸³ In many areas, crop cultivation acted only as a supplement for sustenance.

Thus, only the people whose livelihood depended on crop cultivation were affected by the adverse weather and climate conditions described above. Therefore, severe crop failures, like the one in 1314, only impacted severely on part of the population (Article V).

However, over the studied time the importance of crop cultivation as the main livelihood strategy increased notably among the population. Article IV found that climate extremes, like those resulting from volcanic forcing, could cause simultaneous crop failures and food shortages across north-east Europe. These shortages could then escalate into pan-regional subsistence crises, like after the 1601 and 1695 crop failures.

83 However, climate variability is known to influence fish and game populations. Yet, the responses are commonly slower and more moderate than the agricultural responses. See, Article V for further discussion.

Exploring the climate-society nexus with tree-ring evidence : Climate, crop yields and hunger in medieval and early modern north-east Europe

uef.fi

Dissertations in Social Sciences and Business Studies

HELI HUHTAMAA

HELI HUHTAMAA

EXPLORING THE CLIMATE-SOCIETY NEXUS WITH TREE-RING EVIDENCE

EXPLORING THE CLIMATE-SOCIETY NEXUS WITH TREE-RING EVIDENCE

Heli Huhtamaa

EXPLORING THE CLIMATE-SOCIETY NEXUS WITH TREE-RING EVIDENCE

ABSTRACT

TIIVISTELMÄ

ZUSAMMENFASSUNG

ACKNOWLEDGEMENTS

CONTENTS

LIST OF FIGURES

LIST OF ABBREVIATIONS

1 INTRODUCTION

2 RESEARCH FRAMEWORK

2.1 RESEARCH TRADITION

2.1.1 Tree-ring data in historical research

2.1.2 Grain yields and hunger in the northern margin

2.1.3 The ‘Kingdom of Frost’

2.2 OBJECTIVES

2.3 SOURCES

2.3.1 Tree-ring, crop yield and meteorological data

2.3.2 17th century administrative sources

2.3.3 Medieval narrative sources

3 RESULTS

3.1 TREE-RING DATA AS SOURCE MATERIAL IN HISTORICAL RESEARCH

3.1.1 Critical source assessment and tree rings

3.1.2 Yield ratio reconstruction

3.2 CLIMATE, CROP FAILURES AND HUNGER 3.2.1 Climate-sensitivity of the northern agriculture

3.2.2 Crop failures and hunger

3.2.3 Resilience to adverse climate and crop failures

3.2.4 Spatial and temporal differences