the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Climatic signatures in early modern European grain harvest yields
- 1Department of History, Stockholm University, 106 91 Stockholm, Sweden
- 2Bolin Centre for Climate Research, Stockholm University, 106 91 Stockholm, Sweden
- 3Swedish Collegium for Advanced Study, Linneanum, Thunbergsvägen 2, 752 38 Uppsala, Sweden
- 4Danish Meteorological Institute, Lyngbyvej 100, 2100 Copenhagen Ø, Denmark
- 5Department of Geography, Johannes Gutenberg University, 551 28 Mainz, Germany
- 6Global Change Research Institute (CzechGlobe), Czech Academy of Sciences, 603 00, Brno, Czech Republic
- 7Institute of History, University of Bern, 3012 Bern, Switzerland
- 8Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
- 9Department of Historical Studies, University of Gothenburg, 405 30 Gothenburg, Sweden
- 10Chair of Forest Growth and Dendroecology, Institute of Forest Sciences, Albert Ludwig University of Freiburg, 791 06 Freiburg, Germany
- 11Department of Botany, University of Innsbruck, 6020 Innsbruck, Austria
- 12Division of Agrarian History, Department of Urban and Rural Development, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden
- acurrent affiliation: Upplands-Bro Municipality, 196 81 Kungsängen, Sweden
- 1Department of History, Stockholm University, 106 91 Stockholm, Sweden
- 2Bolin Centre for Climate Research, Stockholm University, 106 91 Stockholm, Sweden
- 3Swedish Collegium for Advanced Study, Linneanum, Thunbergsvägen 2, 752 38 Uppsala, Sweden
- 4Danish Meteorological Institute, Lyngbyvej 100, 2100 Copenhagen Ø, Denmark
- 5Department of Geography, Johannes Gutenberg University, 551 28 Mainz, Germany
- 6Global Change Research Institute (CzechGlobe), Czech Academy of Sciences, 603 00, Brno, Czech Republic
- 7Institute of History, University of Bern, 3012 Bern, Switzerland
- 8Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland
- 9Department of Historical Studies, University of Gothenburg, 405 30 Gothenburg, Sweden
- 10Chair of Forest Growth and Dendroecology, Institute of Forest Sciences, Albert Ludwig University of Freiburg, 791 06 Freiburg, Germany
- 11Department of Botany, University of Innsbruck, 6020 Innsbruck, Austria
- 12Division of Agrarian History, Department of Urban and Rural Development, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden
- acurrent affiliation: Upplands-Bro Municipality, 196 81 Kungsängen, Sweden
Abstract. The association between climate variability and grain harvest yields has been an important component of food security and economy in European history. Yet, inter-regional comparisons of climate–yield relationships have been hampered by locally varying data types and use of different statistical methods. Using a coherent statistical framework, considering the effects of diverse serial correlations on significance, we assess the temperature and hydroclimate (precipitation and drought) signatures in grain harvest yields across varying environmental settings of early modern (c. 1500–1800) Europe. An unprecedentedly large network of yield records from northern (Sweden), central (Switzerland) and southern (Spain) Europe is com- pared with a diverse set of seasonally and annually resolved palaeoclimate reconstructions. Considering the effects of different crop types and time-series frequencies, we find within regions consistent climate–harvest yield patterns characterised by a significant summer soil moisture signal in Sweden, a winter temperature and precipitation signal in Switzerland, and spring and annual mean temperature signals in Spain. The regional scale climate–harvest associations are weaker than the recently revealed signals in early modern grain prices, albeit similar to those observed in modern climate–harvest relationships on comparable spatial scales.
Fredrik Charpentier Ljungqvist et al.
Status: open (until 14 Mar 2023)
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RC1: 'Comment on cp-2022-88', Anonymous Referee #1, 09 Dec 2022
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This is a very solid work to examine the climate-harvest linkage which will have a wide academic impact. I applaud the findings and great effort made by the authors. To improve the paper, I would like share some of my comments as below.
The issue of representativeness in space is my first question. The paper has selected several sites to indicate the harvest in Sweden, Switzerland, and Spain. Could the authors give more explanations how these sites are representative to show the harvest conditions of these three countries?
Second, I understand the data processing before the statistical analysis, such as detrend and smooth. I just wonder how large is the difference between the results raw data and processed data? If the authors use raw datasets, it will be also interesting to show human factors behind the climate-harvest linkage.
Third, the harvest conditions are investigated by two indicators, tithe and yield ratio, which have improved the findings currently made only according to yield ratios. However, I would suggest the authors to add more explanations on these two indicators to which extent they could be compared with each other.
Fourth, the authors used Granger Causality Analysis. This is a method very useful to check the temporal patterns. Furthermore, the authors use correlation analysis as well. Is there any other method potentially suitable for the study on climate-harvest linkage?
Fifth, I am very curious about the implication from your study on the past to current societies under the warming threat. May I suggest the authors to share their views on the practical implications to modern era?
I hope my comments could be useful. Thank you.
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AC1: 'Reply on RC1', Fredrik Charpentier Ljungqvist, 19 Dec 2022
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Reviewer comment #1: The issue of representativeness in space is my first question. The paper has selected several sites to indicate the harvest in Sweden, Switzerland, and Spain. Could the authors give more explanations how these sites are representative to show the harvest conditions of these three countries?
Answer: We only have data from the areas shown in Fig. 1. Note that for Sweden and Switzerland we use county and canton level data which should be more representative than point data. In addition to the series for Sweden, Switzerland, and Spain, we use harvest data from other sites in Europe (including England, France, Italy and Germany), but we pay less attention to these series as we have only one or a handful of series from these locations. The choice to mainly focus on Sweden, Switzerland, and Spain is made for two reasons: (1) most yield (ratio) series and tithe series are available from these countries for the early modern period, and (2) these countries, representing a north-to-south gradient in Europe, are representative for the climate–harvest relationship in northern, central and southern Europe, respectively. For both Sweden, Switzerland, and Spain the harvest series come from major agricultural regions. Thus, we consider them representative for the harvest conditions in the three countries although we note a large environmental heterogeneity within all three countries.
Reviewer comment #2: Second, I understand the data processing before the statistical analysis, such as detrend and smooth. I just wonder how large is the difference between the results raw data and processed data? If the authors use raw datasets, it will be also interesting to show human factors behind the climate-harvest linkage.
Answer: As seen in the correlation results, there is a dependence on the type of detrending and filtering applied – hence, the results from ‘raw data’ are expected to also yield differing results. We do not want to look at raw data as the low-frequency variability in harvest data is most likely influenced by factors more or less unaffected by climate (e.g., labour force availability, market access changes, wars etc.). That said, we actually did perform exploratory data analysis, at an early stage of our work, using ‘raw’ data for some data subsets. This yielded, in cases without a strong long-term trend, results rather similar to when using linearly detrended data.
Reviewer comment #3: Third, the harvest conditions are investigated by two indicators, tithe and yield ratio, which have improved the findings currently made only according to yield ratios. However, I would suggest the authors to add more explanations on these two indicators to which extent they could be compared with each other.
Answer: We think that we actually discuss this issue rather extensively both in the Data and Method Section (2.1) and in the Discussion Section (4.6). Furthermore, we are not really sure what the reviewer refers to with “findings currently made only according to yield ratios”. As further addition to the text, about tithe vs. yield ratio data, would make our already long article even longer, we would prefer to leave it to the editor to decide whether additional text about tithe vs. yield ratio data is needed.
Reviewer comment #4: Fourth, the authors used Granger Causality Analysis. This is a method very useful to check the temporal patterns. Furthermore, the authors use correlation analysis as well. Is there any other method potentially suitable for the study on climate–harvest linkage?
Answer: A few other methods could have been used in addition to the correlation and Granger Causality analyses applied, such as multivariate regression, linear or nonlinear. Extraction of leading patterns of variability by use of Principal Component Analysis (PCA) could also be applied, and if there are episodic excursions in the climate these would be expected to impact harvest data and could thus be revealed by so-called Superposed Epoch Analysis (SEA). The article is already very long as it is and we do not plan to add such additional analyses. SEA can well be applied in situations where, e.g., volcanic forcing events are expected to impact climate and/or climate-dependent things such as harvests, and we are working on such an analysis for another (unrelated) article at the moment.
Reviewer comment #5: Fifth, I am very curious about the implication from your study on the past to current societies under the warming threat. May I suggest the authors to share their views on the practical implications to modern era?
Answer: Modern agricultural practices are different from what was used during our study period (c. 1500–1800). We choose these limits in order to have many overlapping records as well as avoiding the period after fertilisation, mechanisation and new seed types became widespread, as this insulates harvest yields (and hence tithes) from climate and weather excursions to some extent. The modern climate–harvest relationship can be expected to be different from the one prior to 1800. That said, we note that the drought-sensitivity of the harvest yields in parts of the study domain (e.g. Sweden) are surprisingly similar to the modern ones. We will nevertheless explain the limitations with comparing historical and modern climate–harvest relationships more clearly in the Introduction (e.g. line 97). The question from the reviewer is indeed very interesting, but somewhat beyond the scope of this article – nevertheless, we will consider adding one or a few sentences about the issue brought up by the reviewer in the Discussion. We also note that we already actually mention something about modern climate–harvest relationships in the Introduction (lines 84–95).
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AC1: 'Reply on RC1', Fredrik Charpentier Ljungqvist, 19 Dec 2022
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Fredrik Charpentier Ljungqvist et al.
Fredrik Charpentier Ljungqvist et al.
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