Kathleen Pribyl

The year-long unprecedented European heat and drought of 1540 – a worst case

The heat waves of 2003 in Western Europe and 2010 in Russia, commonly labelled as rare climatic anomalies outside of previous experience, are often taken as harbingers of more frequent extremes in the global warming-influenced future. However, a recent reconstruction of spring–summer temperatures for WE resulted in the likelihood of significantly higher temperatures in 1540. In order to check the plausibility of this result we investigated the severity of the 1540 drought by putting forward the argument of the known soil desiccation-temperature feedback. Based on more than 300 first-hand documentary weather report sources originating from an area of 2 to 3 million km2, we show that Europe was affected by an unprecedented 11-month-long Megadrought. The estimated number of precipitation days and precipitation amount for Central and Western Europe in 1540 is significantly lower than the 100-year minima of the instrumental measurement period for spring, summer and autumn. This result is supported by independent documentary evidence about extremely low river flows and Europe-wide wild-, forest- and settlement fires. We found that an event of this severity cannot be simulated by state-of-the-art climate models.

Reconstructing medieval April-July mean temperatures in East Anglia, 1256–1431

This paper presents the first annually resolved temperature reconstruction for England in the Middle Ages. To effect this reconstruction the starting date of the grain harvest in Norfolk has been employed as a temperature proxy. Using c. 1,000 manorial accounts from Norfolk, 616 dates indicating the onset of the grain harvest were extracted for the period 1256 to 1431 and a composite Norfolk series was constructed. These data were then converted into a temperature series by calibrating a newly constructed comparison series of grain harvest dates in Norfolk from 1768 to 1816 with the Central England Temperature series. These results were verified over the period 1818–1867. For the British Isles no other annually resolved proxy data are available and the onset of the grain harvest remains the only proxy for assessing April-July mean temperatures. In addition, this is the first time-series regarding the onset of grain harvests in medieval Europe known so far. The long-term trend in the reconstructed medieval temperature series suggests that there was a cooling in the mean April-July temperatures over the period 1256 to 1431. Average temperatures dropped from 13°C to 12.4°C, which possibly indicates the onset of the Little Ice Age. The decline in values was not steady, however, and the reconstruction period contains decades of warmer spring-early summer temperatures (for example the 1320s to the early 1330s and the 1360s) as well as colder conditions (for example the late 1330s, 1340s and the 1380s). The decline in grain-growing-season average temperatures would not have been a major problem for medieval agriculture, rather the phases of very high interannual variability partly found in the medieval time-series, such as 1315–1335 and 1360–1375, would have proved disruptive.

Tree-rings and people – different views on the 1540 Megadrought. Reply to Büntgen et al. 2015

Buntgen et al. (2015; hereinafter B15) present the result of new research which question the results of Wetter et al. 2014, (hereinafter W14) and Wetter et al. (2013, hereinafter W13)regarding European climate in 1540. B15 conclude from tree-ring evidence that the results based on documentary data of W14 probably overstated the intensity and duration of the 1540 drought event. W14 termed it Megadrought because of its extreme duration and spatial extent compared to other drought events in central Europe, although they note that the term is generally used for decadal rather than for single-year droughts (Seneviratne et al. 2012). We take the opportunity to recall the following issues. Firstly, when dealing with drought the complexity of this phenomenon should be kept in mind. Meteorological drought defined as a large negative precipitation anomaly during a certain period can trigger agricultural, hydrological, groundwater and socioeconomic droughts. Lloyd-Hughes (2013] and references cited herein) concluded that any workable objective definition of drought does not exist. To quantify droughts, various indices based on precipitation, temperature and evapotranspiration are used such as the Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), Z-index and PDSI. Their calculation depends on different periods (seasons, combination of months) and so different indices may classify the same drought episode differently (e.g. Brazdil et al.2014).

European Middle Ages

This chapter introduces the state of the field in the historical climatology of the Middle Ages in Europe. This region and era witnessed significant human historical changes, as well as climatic phases identified as the Medieval Warm Period and the beginnings of the Little Ice Age. Starting with the work of Hubert H. Lamb and Emmanuel Le Roy Ladurie in the 1960s, the field has seen a continual extension and refinement of research. Historical climatologists of medieval Europe have drawn on both narrative and administrative sources, which have provided both qualitative weather descriptions and information on climate proxies. Use of these sources poses particular methodological challenges, but historical climatologists have developed seasonal temperature and precipitation indices and long phenological records covering parts of medieval Europe.

Climate and the Plague, 1348–1500

This chapter investigates the role of temperature and precipitation in the outbreaks of plague in late medieval England. For allowing a meaningful quantitative analysis the time frame is extended to 1500; well-known major plague outbreaks are listed and the evidence for the less well studied plague waves, particularly those of the fifteenth century, is reconsidered. In England the majority of large-scale plague waves falls into a meteorological pattern of warm and dry summers, which followed on average or slightly colder than average winters as well as on runs of summers of one to three years of average or slightly below average temperature and probably average to above average precipitation levels. Between the middle of the fourteenth century and 1500 the frequency and severity of plague declined, nonetheless national or regional plague outbreaks occurred about every decade over this period. The regularity of plague outbreaks and the triggering of major outbreaks by clearly defined meteorological parameters indicate the persistence of plague outside the reservoir of urban Black rats as sylvatic plague in an unknown wild rodent host. On the example of field voles this chapter reviews the (climatic) conditions needed for a mass rodent proliferation in Europe north of the Alps. For England the existence of a potential reservoir of sylvatic plague was confirmed by a number of cases of plague in rural eastern Suffolk in the early twentieth century, when Black rats were extinct. Hence the recurrence of plague waves between the arrival of the Black Death and 1500 must have been largely due to the involvement of a wildlife reservoir of Yersinia pestis; plague was most likely not being constantly reintroduced to the country after 1350.

The Medieval Grain Harvest

This chapter investigates the relationship between climate, phenological state of the crop and the grain harvest. Only under exceptional circumstances as during plagues or in times of war might the phenological signal in the grain harvest be disturbed. The grain harvest constituted the climax of the agricultural calendar and would provide the people with the bulk of the food supply for the coming year. Hence its economic, social and cultural importance can not be overestimated. This chapter outlines the management and work organisation of the medieval grain harvest. Data safety is high with regard to the harvest, because the information on the harvest of a manor is recorded at various points in the manorial accounts, allowing cross-checking. Additionally the harvest information comes from a variety of manors and landowners, so that dates and trends can be compared. The setting of the harvest date within the possible time window of the phenological state of the grain with the help of the ecclesiastical calendar and in the working week are analysed.

Temperature Extremes 1256–1431: Independent Evidence and Context

This chapter acts as a catalogue for extremely hot and cold spring/summer seasons in late medieval England. For the years of extremely high or low reconstructed East Anglian April–July mean temperatures independent evidence on weather from documentary sources from the British Isles and the climate information for the Low Countries is assembled. The focus is laid upon the impacts of extreme weather on agriculture and agricultural productivity, the formation of subsistence crisis and the occurrence of disease. The meteorological characteristics of the years of the agrarian crisis 1314–1323, including the time of the Great Famine 1315–1317 and the cattle plague 1319–1320, and the difficult years around 1350, the time of the arrival of the Black Death in Europe and also England, are described in detail.

Harvest Length – An Indicator of Late Summer Precipitation

The length of the grain harvest reflects the amount and frequency of rainfall during the harvest. The aim is always to harvest as speedily as possible for reducing the risk of the standing corn to the vagaries of the weather. However, the duration of the harvest is also linked to the availability of labour, the bulk of the harvest and the harvesting method. Thus the harvest length can be used for an index, but not a reconstruction, of rainfall shortly before and during the grain harvest, i.e. the months July, August and September. The East Anglian precipitation index is compared to other precipitation-responding proxy data. The index is valuable for identifying interannual fluctuations in rainfall, phases of higher and lower rainfall and extremes. For harvesting, and also agriculture in general under England’s maritime climate, high and highly variable precipitation levels were linked to lowered harvest success.

Farming in Norfolk Around 1800

The grain harvest was little changed from the Late Middle Ages to the nineteenth century. This is demonstrated in this chapter through an analysis of information contained in a selection of eighteenth and nineteenth-century farming diaries from across Norfolk. Even though the county was at the forefront of the agricultural revolution and one of the most productive regions of England around 1800, a time of agricultural improvement and change, harvest method and technology had remained stable over the past centuries. A number of independent harvest date series from Norfolk are compared, they display similar harvest dates and trends, and hence as in the Middle Ages the grain harvest was triggered by a non-human factor, the phenological state of the grain development. The longest and most complete series from Langham, northern Norfolk, serves as a modern comparison series for the medieval harvest dates in the temperature reconstruction analysed in Chap. 5.

The Keeping of Agricultural Records in Late Medieval England

The documentary sources, manorial accounts, employed throughout this book come from northern East Anglia, mostly from Norfolk, and were drawn up for the estates of a number of medieval landowners. Manorial accounts record the revenues and expenses of a manor as well as the strategies used in the agricultural and pastoral sectors and their outcome. The majority of manorial accounts in England survive in the archives of ecclesiastical institutions, who had recourse to the knowledge necessary for making the accounts and could provide the material and institutional surroundings needed to preserve medieval documents. The most comprehensive collection of manorial accounts used in this study comes from the estates of Norwich Cathedral Priory and dates to the years between 1256 and 1431. For providing a background to the study of the impact of climate on the agriculture, economy and society, the economic and estate history of the cathedral manors is outlined, it is interwoven with the more general trends in agrarian economy across England in the Late Middle Ages.