The European drought of 1921 is assessed in terms of its impacts on society and in terms of its physical characteristics. The development of impacts of the drought are categorized by a systematic survey of newspaper reports from five European newspapers covering the area from England to the Czech Republic and other parts of Europe. This is coupled to a reconstruction of daily temperature and precipitation based on meteorological measurements to quantify the drought severity and extent, and reanalysis data are used to identify its drivers. This analysis shows that the first impacts of the drought started to appear in early spring and lingered on until well into autumn and winter, affecting water supply and agriculture and livestock farming. The dominant impact in western Europe is on agriculture and livestock farming while in central Europe the effects of wildfires were reported on most often. The peak in the number of reports is in late summer. Preceding the first impacts was the dry autumn of 1920 and winter 1920–1921. The area hardest hit by the drought in the following spring and summer was the triangle between Brussels, Paris and Lyon, but a vast stretch of the continent, from Ireland to the Ukraine, was affected. The reported impacts on water supply and water-borne transport in that region were matched by an analysis of the hydrological situation over the Seine catchment. On average, the 1921 summer was not particularly hot, but the heatwave which was observed at the end of July saw temperatures matching those of the heatwaves in modern summers. Similar to modern droughts, an anticyclone was present roughly over the British Isles, maintaining sunny and dry weather in Europe and steering away cyclones to the north. Its persistence makes it exceptional in comparison to modern droughts.
The 1921 drought stands out as the most severe and most widespread drought in Europe since the start of the 20th century. The precipitation deficit in all seasons was large, but in none of the seasons in 1920 and 1921 was the precipitation deficit the largest on record. The severity of the 1921 drought relates to the conservative nature of drought which amplifies the lack of precipitation in autumn and winter into the following spring and summer.
Drought is one of the most costly natural disasters
Droughts are often viewed from a climatic perspective where a host of indicators are available based on meteorological parameters
(e.g.
The principal motivation to focus on 1921 is that this 100-year old climatic extreme is the driest year since the start of the 20th century for Europe in
terms of area affected
This section describes the 1921 drought in terms of its
consequences on socioeconomic and environmental systems, i.e. its negative impacts
A systematic effort was made to review the impacts of the 1921 drought. This was done by collecting text-based reports from five digitized newspapers
which reported drought impacts. The period for which the newspapers were reviewed was from 1 January to 31 December 1921. Different selected newspapers were explored through their digital archives by means of the search term “drought” (in each of the native languages). Text-based reports from the following digitized newspapers were used: the
The newspaper clippings were classified into major impact categories, each of which had a number of subtypes. The classification follows the pioneering work of
In addition to this systematic effort, a more ad hoc approach was taken for Ireland, northern Italy and the Alpine region, France, and Poland. Newspaper-based reports on impacts and reported impacts in scientific publications from that period were used to identify impacts which were prominent in the reporting.
Recently,
Graphs showing reported impact type for the United Kingdom, the Netherlands, Belgium, Germany and the Czech Republic (top to bottom). The vertical axis shows the number of reports, the horizontal axis shows the date associated with the publication of the text-based report. Below each impact graph, the weekly sum of rainfall, averaged over the country and as the ratio with the corresponding climatological period, is shown where brown relates to lower-than-expected values. In the background, daily maximum temperatures, averaged over the country, are shown as deviations from the climatology. Temperature and precipitation data are based on the E-OBS dataset introduced in this study.
Figure
The most reported impacts that occur the earliest in the year are different among the countries, but both Belgium (BE) and Germany (DE) report the earliest on effects on waterborne transportation. Photograph
The period with the largest number of reports is in July 1921. For the United Kingdom and Belgium this peak takes place in the week of 17 July,
the Netherlands (NL) has the largest amount of reports in the week of 24 July, and Germany and the Czech Republic (CZ) in the week of 31 July,
showing a clear west–east time shift. The timing of these reports coincides with the heatwave peak in Europe, with temperatures peaking in London around July 19 and in Paris (and in about 75 % of France) on 28 July to 38.4
Impacts on waterborne transportation are reported on relatively often in Belgium and especially Germany and not so much in the Netherlands. Although the water
level in the Rhine (where it enters the Netherlands) was at an all-time low from spring to autumn 1921, it remained possible to navigate the Dutch part of the river (Boris Teunis, Rijkswaterstaat, personal communication, 2019). However, the Meuse, with its catchment in France, Belgium and the Netherlands, was completely dry in the
southeastern part of the Netherlands
Earliest and latest reported impacts for the five countries, and the top three of the most reported impacts for 1921.
Reported impact types in public water supply
The impact categorization scheme
In many reports, particularly those from the Netherlands and England, the late spring frost of 1921 was mentioned as an additional setback for farmers. However, an analysis of the Julian day with the last night with frost using the meteorological station data did not show a significant difference between the 1921 last spring frost and 1981–2010 climatological mean values of the last spring frost.
The 1921 drought in Italy was preceded by dry conditions in 1920, and
the first reports on its impact appeared in mid-November 1920 as a lower harvest for some products, especially cereals, due to the persistent drought.
The dry conditions starting in autumn 1920 led to a dramatic decrease in water levels in Italian rivers, streams and lakes, especially those that came from the Alps. Recently, a reconstruction of monthly precipitation of the Abba basin in northern Italy for the period 1800–2016
Interestingly, the dry winter 1920/21 in Switzerland was reflected in an impact on the tourism sector; the
In January 1921, hydro-powered electricity production was scarce because of the low water levels in dam reservoirs, and the problem intensified in autumn 1921
and winter 1921/22. Several provinces of northern Italy established severe reductions on the use of electrical energy, for industries, homes, cinemas,
public/private offices and shops. This meant that major cities in northern Italy were without light or light was rationed and industries and transportation (locomotives) ceased operation. The water shortages at the start of 1921 affected the agricultural sector: cattle were sold before they died of thirst and lack of fodder. Drinking water became scarce, with queues for public fountains, and villages were without water, requiring marches of several kilometres to
fetch water. A review in
At the end of April and early May, reports began to appear in the Irish newspapers that water reservoirs and rivers were lower than normal for the time of year, and the public were urged to economize water usage as much as possible. By June the drought had started to affect livestock, grass growth was poor and crops in many parts of the country were reported to be suffering. In the second half of June there continued to be anxiety over the development of crops due to the almost entire absence of rain, the late spring frosts and the low night temperatures. There were reports of water supplies being shut down in some parts of the country at night and by the end of the month there were serious concerns in Dublin that the Vartry reservoir would run dry. In July, newspaper reports stated that the drought still prevailed in all parts of the country and there were fears of water famine. Further appeals were made for citizens to be strictly economical in the use of water. Ponds and rivers that had not been seen dry by the oldest inhabitants were completely dried up in some areas. Thousands of cattle had to be driven for miles daily to be watered, and many cows in all parts of the country were ceasing to give milk.
The sunny and stable weather made for an early harvest. In some cornfields bordering the sea in the Hook, Co. Wexford district, the oat production was so poor owing to the great drought that the crop had to be cut and gathered up like hay. However, the drought did not affect the winter wheat crop, contrasting with the situation of the pastures which was hardly short of disastrous, particularly for grazers.
The dry period which started in the last quarter of 1920 had the consequence of a general lowering of groundwater tables and a significant decrease in the flow
of rivers. An example is the Seine basin where the small rivers in the Champagne region ran dry and in particular the Somme, the source of which was dry
since 20 September 1920
The succession of rainfall deficits for five consecutive quarters in France, with the autumn of 1921 being particularly dry, had repercussions on the production of
hydroelectric energy and on the supply of drinking water for large cities like Grenoble, Chambéry, and Gap due to rapid and significant drops in underground
aquifers deprived of recharge
The dry conditions in summer 1921 coincided with a heatwave, which will be quantified in Sect.
Publications following the 1921 drought highlight the scale and severity of this event. The rainfall deficiencies for 1921 in eastern and southern England amounted to between 50 % and 60 % of the normal value
The overview of London weather from 1841 to 1949
The film news of Pathé
A striking impact of the 1921 drought in Poland were its many fires, the largest of which occurred in August. These include the one on 7 August in the town of Pińsk (population in 1921: 23 497), eastern Poland, where loss of life was reported and a third of the town, predominantly built of wood, was destroyed, including the town centre and an almost 1000-year-old synagogue. The losses were so great that the Polish Government decided to move the authorities of the region to which Pińsk belongs to Brest, located 150 km westward. On the same day, the smaller town of Kłodawa (population in 1921: about 2200) in central Poland saw a large part of the town completely destroyed by fire, and at least 130 buildings burned down. The town of Rudnik on the San (population in 1921: 2959) in the southern part of Poland was densely covered in smoke from the fires in the surrounding bogs, meadows and forest, making it difficult to breathe.
Between 9–16 August 1921, forest fires raged in the Sandomierz Forest in the southern part of Poland. At least a dozen square kilometres burned down in this fire. For 13 August, reports on forest fires in the region of Upper Silesia are found. The fires have been estimated as the biggest ones in the region of Silesia for at least several dozen years. Not only many square kilometres of forests but also suburban districts of the town of Mikołów (formerly: Nikolai) were burned down. The railway traffic on the route Zabrze/Gliwice–Kȩdzierzyn (formerly: Hindenburg/Gliwitz–Kendrin) was temporarily suspended due to the risk of flames.
An assessment of the production of annual crops in western Poland on 1 August 1921 showed that many crops for human consumption or fodder rated between “medium” and “poor” up to “bad” for potatoes, sugar beet and pastures. Widespread deficits in the availability of dairy products due to a strong reduction in milk production was reported, as well as low availability of meat and sausages, which resulted in price increases, particularly in western and central Poland. Restrictions in drinking water were issued in Poland as well.
To further develop and complement the qualitative assessment of impacts related to the 1921 European drought, we now provide quantitative assessment of this climatic event using new datasets and methods.
An initial assessment of the number of stations in the European Climate Assessment and Dataset (ECA&D)
Three approaches are used to increase the station coverage for 1920–1921 in ECA&D.
Within the ERA4CS INDECIS project The data portals of the European national meteorological services (NMSs) were accessed in search of data for 1920 and 1921 that were not already included in the ECA&D database. This approach was directed mainly at the Scandinavian countries, Germany and the UK. Inquiries were made at the NMS contacts of ECA&D with a request for additional data. The Czech Hydrometeorological Institute (CHMI) provided data from 8 stations which continued from 1920 to 1960. In addition, CHMI provided a set of 359 discontinued stations with data from 1920 and 1921. A set of 187 rain gauge stations were provided from the Dutch NMS. These latter data provisions are for stations that are now no longer operational.
All data were subject to a quality control
Figure
Map with the stations for daily temperature
The aforementioned station dataset is used to develop the E-OBS dataset for 1920 and 1921. The gridding procedure was developed by
Figure
In the analysis, long-term daily precipitation series from ECA&D are used
There are numerous ways to quantify drought (e.g.
A common meteorological drought index to analyse drought conditions is the Standardized Precipitation Index (SPI;
The evaporation of water from the soils is principally driven by radiation which provides the energy for evaporation. As the observation-based
reconstruction of the 1920–1921 climate lacks an estimate of daily global radiation sums, a commonly used alternative approach uses the Hargreaves equation for
potential evaporation ET
The form of the
Moisture availability and transport were evaluated by using the vertically integrated water vapour transport (IVT), based on ERA20C data, which is defined as the
horizontal transport of specific humidity, integrated for a vertical column of the troposphere (between 1000 and 300 hPa), as follows:
The heatwave index used here is the Warm Spell Duration Index (WSDI) defined by the CCl/CLIVAR/JCOMM Expert Team on Climate Change Detection and Indices
(ETCDDI)
The SPI indicator computed for the accumulation period of 12 months is shown in Fig.
Monthly SPI12 values of the Uccle (Belgium) series for the period 1900–2019. Positive values (blue) show conditions wetter than usual, negative values (red) show conditions drier than usual with values below
Diagram showing the drought severity of major European cities in 1921. The horizontal axis gives the number of months in 1921 that SPI3 values were below
The combination of the length of the dry period with the maximum value of the precipitation deficit relates to “drought severity”. The overview of drought severity of major European cities is given in
Fig.
Figure
Maps with SPI values showing the evolution of the drought from autumn 1920 to autumn 1921. The panels show SPI3 values for September–November 1920
The assessment of the drought conditions on a monthly basis (not shown) shows that the driest months of 1920 were October and November, whereas the driest
months of 1921 were March and July. There were, however, a lot of subsequent dry months in 1921, and only August showed somewhat normal conditions. The
remarkable nature of 1921 is made clear in Fig.
Probability-scaled map of the number of rainy days for 1921, using the 1981–2010 period as a base period to calculate the expected value. The map shows the probability to observe the same number of rainy days in the 1981–2020 climate as was observed in the 1921 drought.
In the inventory of impacts of the 1921 drought, the limitations in the water supply for drinking and sanitation purposes and to a lesser extent the limitations
in waterborne transport ranked high. An assessment of the remarkable nature of the 1921 drought can be made by making a cumulative distribution of the daily
rainfall, integrated over a river catchment. In an effort to assess the loss of evaporation to the atmosphere, a similar integral measure over a river catchment of potential evaporation is made. Figure
Cumulative distribution of daily rainfall aggregated over the Seine catchment
The 1921 drought coincided with high temperatures across Europe, parts of which were affected by a heatwave which occurred in July. While the European-average July temperature was not remarkable in the 100-year period 1920–2019 (mean daily average temperature ranks 47th), the hottest day in summer 1921 was remarkable. When compared to all other hottest summer days in the period 1920–2019, 1921 ranks in the top five for the area between Paris, the eastern half of Belgium, southwest Germany and into Switzerland. The hottest day of 1921 also ranks in the top five of the past 100 years in western Poland, the Black Sea coast of Romania, western parts of the Ukraine, parts of Ireland and the North Sea coast of northern England.
Figure
Maps showing
One of the hottest days in the heatwave that affected France was 28 July 1921. Figure
Map showing the daily maximum temperature for 28 July 1921 at the peak of the heatwave in France. Based on the E-OBS dataset.
In this section, we explore the atmospheric circulation conditions associated with and contributing to the 1921 drought. Figure
Monthly precipitation totals for January to December 1921 as the ratio of the corresponding 1981–2010 climatology. Contours show the Z500 anomalies (solid lines for positive, and dashed lines for negative, in 20 m intervals).
Figure
Figure
Although smaller than its Atlantic counterpart, the Mediterranean storm track also contributes to the total number of storms and rainfall accumulated
over southern Europe. Mediterranean cyclones are generated on preferred cyclogenesis areas such as the lee of the Alps, the Gulf of Lyon and the Gulf
of Genoa, where the land–sea contrast provides the right conditions for storm growth
The poleward displacement of the storm track is also well reflected in moisture transport anomalies. Figure
There are several aspects that make the 1921 drought stand out from other droughts. Perhaps the most intriguing is that this drought can be regarded as a “compound event”
The impacts of the 1921 drought are assessed by a systematic review of text-based reports from selected papers in five countries where the reported drought impacts were classified into major impact categories, and by a more ad hoc approach highlighting the major impacts in some other European countries. The focus on the impact is coupled to a reconstruction of daily temperature and precipitation of the 1920 and 1921 situation based on observations. This study shows the following:
The drought had its first major impacts in autumn 1920 over the Alpine region and affected north Italy by reduced streamflow and low water levels in lakes. Dry conditions started to affect other parts of Europe in spring 1921. The type of impact which was experienced first varies across Europe. There is more agreement on the type of impact which lingered on the longest, that is the impact on water supply, and on agriculture and livestock farming. The impacts on agriculture and livestock farming are reported on most frequently, except in the Czech Republic where wildfires (followed by problems with the water supply) were more dominant. This was also the case in Poland, where towns were completely or partially destroyed by fires. The epicentre of the drought was observed in the area including Brussels, Paris and Lyon, but a broad band from Ireland and the UK, including the Low Countries and the Greater Alpine area, to the east over Poland and the Ukraine. The reported water shortage is confirmed by the reconstruction of precipitation and (potential) evapotranspiration; over the catchment of the Seine river the number of rainy days was well below anything observed in the 1981–2010 baseline period while (potential) evapotranspiration values were up to twice as high as in the baseline period. While the average summer or annual temperature in 1921 was not really remarkable for modern standards, the hottest days in the summer of 1921 ranked in the top five of hottest days of the last 100 years for parts of western and central Europe. The soil desiccation will have been instrumental in generating the 1921 extreme temperatures in Europe, a mechanism which is shown to be a key player in more recent heatwaves as well Instrumental to the 1921 drought was a persistent high-pressure area situated roughly over the British Isles, although it moved around slightly from month-to-month. This synoptic situation steered away cyclones, shifting the Atlantic storm track northwards.
The examined newspaper reports from the UK and the Netherlands suggest a late spring frost in 1921, but this could not be confirmed in the meteorological measurements. A possible reason for this intriguing mismatch is that temperature measurements in 1921 in the Netherlands were made at 2.2 m height whereas modern measurements are done at 1.5 m. While this may bias this comparison, ground temperatures are hardly correlated to the air temperature at both these heights when stable conditions in the atmospheric boundary layer occur. Our interpretation is that the newspaper reports probably relate to temperatures close to the ground which can be considerably lower than those at thermometer screen height. The persistent high-pressure situation in spring 1921 favours calm and cloudless nights and the development of stable conditions in the boundary layer, leading to ground frost. In addition, crops may have developed faster because of the high afternoon temperatures of spring 1921 and may have been in a critical stage when the late frosts occurred, giving greater damage to the crop.
From the perspective of climate dynamics, there are similarities between the 1921 drought and other major droughts, especially in the atmospheric circulation patterns that give rise to the stable, sunny and dry weather found during spring and summer of 1921. Similar atmospheric conditions occurred in the 1976 and 2018 droughts. The north Atlantic sea surface temperature pattern of 1921 showed alternating cold and warm areas, but a clear similarity with the patterns of the more recent major droughts seems absent.
The relation between cold anomalies in the North Atlantic surface waters and warm weather over Europe was the focus of
The drought of 1921 illustrates that a long historical perspective is valuable in assessing the full range of climatic variability. The remarkable nature of the 1921 drought – where a dry spring and summer was preceded by a dry autumn and winter – make this year a candidate for benchmarks in the design or tests of water resource management strategies
Photograph from the British illustrated newspaper
The Rhine Falls near Neuhausen (Switzerland) at low water in 1921. Photograph made on 22 March 1921 when the water level reached a historically low level. Source and copyright: Schweizerisches Socialarchiv.
Photograph from the Dutch newspaper
Photograph from the Dutch newspaper
Photograph from the Dutch newspaper
Photograph from the British illustrated newspaper
Photograph from the British illustrated newspaper
Photograph from the British illustrated newspaper
Maps indicating the number of days per year with available data for 1920 and 1921 and for temperature and precipitation.
The E-OBS dataset documented here is available from the Copernicus Climate Change Service at
Meteorological station data used in the analysis and the production of the E-OBS were provided by RC, AAP, OP, MC, MM, JF, PŠ and PZ. These authors also provided impact information on the 1921 drought in their home countries. The E-OBS is produced by EJMvdB. Surveys of newspaper articles were performed by HVdV, BVS, RB, LŘ and GvdS. The analysis of the atmospheric circulation from the reanalysis was done by AO, PMS and RPA. Analysis on the E-OBS data were performed by HVdV, BVS and GvdS. The text was written by RPA, AO, PMS, HVdV, RB, GvdS, RT and EA.
The authors declare that no competing interests are present.
Publisher’s note: Copernicus Publications remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Petr Štěpánek, Pavel Zahradníček, Rudolf Brázdil and Ladislava Řezníčková were supported by the Ministry of Education, Youth and Sports of the Czech Republic for the SustES – Adaptation strategies for sustainable ecosystem services and food security under adverse environmental conditions, project ref. CZ.02.1.01/0.0/0.0/16_019/0000797. The Project INDECIS is part of ERA4CS, an ERA-NET initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR), and BELSPO (BE) with co-funding by the European Union (grant no. 690462).
The newspapers articles from
Olga Solomina and an anonymous reviewer are thanked for their comments. Christoph Albers (Staatsbibliothek zu Berlin) is thanked for pointing our attention to some of the digital newspaper archives.
This research has been supported by the Joint Programming Initiative More Years, Better Lives (grant no. CZ.02.1.01/0.0/0.0/16_019/0000797). This research has also received financial support from the project INDECIS, which is part of ERA4CS initiated by JPI Climate, and funded by FORMAS (SE), DLR (DE), BMWFW (AT), IFD (DK), MINECO (ES), ANR (FR) and BELSPO (BE) with co-funding by the European Union (grant no. 690462). The production of E-OBS is funded by the Copernicus Climate Service through contract C3S_311a_Lot4.
This paper was edited by Jürg Luterbacher and reviewed by Olga Solomina and one anonymous referee.