| 22 Jul 2025
Wine must yields as indicators of May to July climate in Europe, 1416–1988
Abstract. Narrative historical records of wine production in Central Europe date back to 1200. The extent to which such data can be used as proxy data for summer temperatures is being explored. Here, we investigated taxes paid to the authorities in the French-Luxembourg Moselle region, Germany and the Swiss Plateau over the last few centuries drawing on 11 regional series from the early 15th merged into three supra-regional series: (1) the Moselle series, starting in 1416 and consisting of data from the former city-republic of Metz (France) and the Grand Duchy of Luxembourg; (2) the series for Germany, starting in 1511 and mainly originating from the former city-state of Heilbronn; and (3) the third series, starting in 1529 and representing production on the Swiss Plateau. The residuals of the supra-regional yield series were averaged, divided into seven classes, and multiplied by five quality classes. Yield quality indices (YQI) varying between 35 (large and excellent) and 1 (small and undrinkable) century to 1988. We detrended the data to compensate for longer-term biases. The homogenised series were significantly correlated with temperatures between May and July. Regression analysis of the composite series revealed that yield and quality primarily depend on the climate conditions from May to July as well as on those in June of the previous year. Crops with a YQI > 28 (rated "good" by traditional winegrowers) were related to above-average May–July temperatures, early grape harvest dates and high tree-ring maximum latewood density resulting from frequent anticyclonic weather situations. Crops with YQI > 10 could not be uncritically assigned to cold summers since winter, and spring frosts often reduced yields without affecting quality. Severe crop failures sometimes triggered witch hunts. In summary, narrative evidence on wine production allows reconstructions based on tree-rings to be specified and verified.
Review of manuscript ‘Wine must yields as indicators of May to July climate in Europe, 1416–1988’ submitted to the journal Climate of the Past.
Authors of the manuscript: Christian Pfister, Stefan Brönnimann, Laurent Litzenburger, Peter Thejll, Andres Altwegg,Rudolf Brázdil, Andrea Kiss, Erich Landsteiner, Fredrik Charpientier Ljungqvist, Thomas Pliemon.
Dear Authors,
Please consider my comments below, which have been formulated to enhance the manuscript in a positive and constructive manner.
The manuscript addresses relevant scientific questions within the scope of the journal Climate of the Past, presenting novel concepts, ideas and data. However, data analysis was only completed until 1988.
The abstract provides a concise and complete summary.
The scientific methods and assumptions are valid and clearly outlined. The results are sufficient to support the interpretations and conclusions. Substantial conclusions are reached, but the conclusion section of the manuscript could be improved.
The authors give proper credit to related work and clearly indicate their own new/original contribution.
The overall presentation is well structured and clear, and the language is fluent and precise.
The number and quality of references are appropriate (see exceptions in the specific comments section below).
No supplementary material provided.
Title: I suggest slightly changing the title to reflect the contents of the paper clearly: Wine must yields as indicators of May to July climate in Central Europe, 1416–1988’. Use Central Europe or a better designation for the study area in the title. The use of Europe in the title can be misleading, as many wine regions (e.g. Southern and Mediterranean Europe) are not included in the analysis.
Abstract - Line 17: “Narrative historical records of wine production in Central Europe date back to 1200.” This sentence requires a reference; therefore, it must be removed from the abstract and included elsewhere in the manuscript (e.g. Introduction). In addition, only data from 1416 is being used as a proxy.
It must be clearly stated why there is no analysis of data after 1988. What are the reasons? Data availability? It would be interesting to include the recent warmer decades in the analysis if data are available.
Make sure to add the references: Lines 39-40, 44, 57-58, 75-76, 536-537.
Use different references instead of Wikipedia: Lines 158, 495-496, 510.
Line 76: briefly specify the relevant results.
Section 3. Sources – It would be great to include a few figures of the original sources to highlight a few examples.
Section 5. Statistical methods. Please make sure to use a statistical textbook/peer-reviewed publications to add references to the used methodologies: low order polynomial, ordinary least squares, orthogonal polynomials, Kolmogorov–Smirnoff test and detrending techniques. Adding references is important to ensure the description of experiments and calculations is sufficiently complete and precise to allow their reproduction by fellow scientists (traceability of results).
It would be great to cross-reference the results of the analysis of the historical data with references on future effects of climate change on wine grape production in terms of quantity, quality, and resilience of the wine regions included in the study area.
Line 38: Europe, not Europa.
Line 40: table, not Table.
Line 265 (table): Luxembourg.
Moselle is written in the text, but it is spelt as Mosel in the graphs.
Figure 8: Decimal points must be used instead of commas in the Y axis.
I hope my comments are viewed as positively constructive and will assist the authors in enhancing their manuscript. I wish the authors well as they consider these comments and edit their manuscript for possible publication in the Climate of the Past.