Extreme droughts and human responses to them: the Czech Lands in the pre-instrumental period

Rudolf Brázdil,Ladislava Řezníčková,Petr Dobrovolný,Lukáš Dolák,Oldřich Kotyza,Miroslav Trnka

doi:10.5194/cp-15-1-2019

Abstract

Abstract. The Czech Lands are particularly rich in documentary sources that help elucidate droughts in the pre-instrumental period (12th–18th centuries), together with descriptions of human responses to them. Although droughts appear less frequently before 1501, the documentary evidence has enabled the creation of a series of seasonal and summer half-year drought indices (Standardized Precipitation Index, SPI; Standardized Precipitation Evapotranspiration Index, SPEI; Z index) for the Czech Lands for the 1501–2017 period. Based on the calculation of return period for series of drought indices, extreme droughts were selected for inclusion herein if all three indices indicated a return period of ≥20 years. For further analysis, only those from the pre-instrumental period (before 1804) were used. The extreme droughts selected are characterized by significantly lower values of drought indices, higher temperatures and lower precipitation totals compared to other years. The sea-level pressure patterns typically associated with extreme droughts include significantly higher pressure over Europe and significantly lower pressure over parts of the Atlantic Ocean. Extreme droughts with a return period ≥ 50 years are described in detail on the basis of Czech documentary evidence. A number of selected extreme droughts are reflected in other central European reconstructions derived from documentary data or tree rings. Impacts on social life and responses to extreme droughts are summarized; analysis of fluctuations in grain prices with respect to drought receives particular attention. Finally, extreme droughts from the pre-instrumental and instrumental periods are discussed.

Highlights

Droughts and floods constitute two extreme aspects of the water cycle
Seasonal and summer half-year series of drought indices since 1501 were used to select extreme droughts according to calculated N-year return period
The calculation of return periods (N ≥ 20 years) in the reconstructed series of drought indices in the Czech Lands from the 1501–2017 period was used for the selection of extreme droughts

Summary

Introduction

Droughts and floods constitute two extreme aspects of the water cycle. while floods are typified by sudden onset, loss of human lives and immediate material damage, the onset of droughts is much slower, without direct loss of human lives and result in a more chronologically extended range of impacts, especially on agriculture (agricultural drought) and water resources (hydrological and underground water droughts), and usually with a greater delay in their broader socio-economic consequences (socio-economic droughts). Several extreme drought events with significant human impacts and consequences are known worldwide from the more recent instrumental period, occurring, for example, in Europe in 2003 (Fink et al, 2004), in Russia in 2010 (Shmakin et al, 2013; Kogan and Guo, 2016), in the US Great Plains in 2012 (Hoerling et al, 2014; Kogan and Guo, 2016), and in Kenya in 2016–2017 (Uhe et al, 2018). Recent global warming, arising from the intensification of the greenhouse effect due to anthropogenically enhanced concentrations of greenhouse gases, may well have contributed to an increase in the frequency and severity of drought episodes (Dai, 2013). Naumann et al (2018), in an analysis of drought conditions corresponding to a global warming of 1.5, 2 and Published by Copernicus Publications on behalf of the European Geosciences Union

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Conclusion