Structural and Spatial Shifts in the Viticulture Potential of Main European Wine Regions as an Effect of Climate Change

Round 1

Reviewer 1 Report

Dear Authors,

The article titled "Structural and spatial shifts in the viticulture potential of main European wine regions as an effect of climate change" aims to evaluate the impacts of climate change and propose adaptation strategies for wine regions such as Bordeaux, Loire Valley, Rheingau, La Rioja, Cotnari, and the East Sussex area of the UK. This assessment is conducted by analyzing multi-year averages of viticultural bioclimatic indices, including AvGST, HI, and IAOe, spanning the periods of 1951-1990 and 1991-2010.

While the article presents valuable insights into the subject matter, there are several areas that require attention and clarification. Namely:

- Line 167-169 (Table 2): The complete HI formula is not provided. It is recommended that all HI classes be categorized into their respective subclasses {HI-3, HI-2, ..., HI+2, HI+3}, accompanied by their corresponding significance.

- Line 183-185: Please clarify the phrase for better understanding. "The average annual temperature (AAT) of the 1991-2010 time period recorded higher values by 0.6...1.3 °C, with an absolute average of the AAT increase, for all six areas, of +0.735°C."

- Line 192: Precipitation during the growing season (GSP) is not defined in Material and Methods. Please add the definition of GSP to Table 2 and define the reference record period.

- Line 202-203: Please clarify "(...) the GSP values are maintained in the range considered optimal, however, the increase in evapotranspiration in the context of climate change (...)"

Note that: One crucial point is that evapotranspiration will only increase if there is available soil water. Otherwise, an increase in reference evapotranspiration may occur without a necessary corresponding increase in actual evapotranspiration. Since no information is added about soil water content...

Nonetheless, these areas remain vulnerable to an increased potential exposure to water stress.

- Line 221-238: Please rewrite the entire paragraph. Make it shorter for better understanding.

- Line 247-249 (Table 3 and remaining article): Please change the comma to a point as the decimal separator. Keep the significant decimal number within the allowed measurement resolution.

- Line 250-252: "The analysis of the correlations between the latitude at which the studied areas are located and the difference between the averages of the climatic variables for the two periods (Figure 2), (...)". Figure 2 does not illustrate the correlation between the variables. Please revise the paragraph.

- Line 262: Figure 2 does not illustrate the correlation between the variables. Please check the Figure title.

- Line 274-275: Please enhance Figures quality. It is impossible to read the legends within the figures.

- Line 308-310: A major doubt arises from the result "(...) Cotnari wine region, (...) new climate classes appeared: the warm class (HI+2) (...)".

I wonder if these calculations are correct. It's hard to believe that a region with an average GST of 16.8 ºC can achieve such an high Huglin Index class. Despite the Cotnari region having a k value of approximately 1.05, the average GST required to reach such class should be around 19 - 20 ºC. Please provide evidences for the presented result.

- Line 337-339 (Table 5): Column "% classes". Does this column refers to the frequency of the class within the viticultural area? or the percentage of area within each class? Please name it.

- Line 346-348: Please enhance the Figures quality for better reading.

- Line 370-372: Please rewrite "The results of our research reveal the fact that the growth of AAT differs between wine regions, in relation to their positioning on the latitude, there being a tendency of temperatures increase to diminish from the south to north (...)". The phrase is to long and hard to follow.

- Line 409-410: Please clarify accordingly to the statement made in Line 308-310, and vice-versa, "for Cotnari, we find similar results for the period 1961-2013, indicating the transition of HI to the temperate class [28]."

- Line 480-483: "A higher relief allows a better adaptation of the wine region to climate changes, by maintaining specific climate suitability, which moves to a higher altitude (...)". The authors should be mindful that the proximity to the ocean can exert a comparable influence on the low-elevation wine regions in the southern viticultural areas.

- Line 489-490: "Our research provides information that winegrowers and policymakers can use to establish effective measures to adapt each wine region viticulture to climate change.". Remind that the results presented in this study are far from representative of all the regions analysed. Despite the evidence, some caution should be exercised when extrapolating the results to all wine-growing regions.

Other detailed questions and suggestions for improvement have been provided in the attached PDF.

Best regards

Comments for author File: Comments.pdf

Author Response

Please see the attachment. 

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript concerns climate change and its consequences on the European viticulture and wine sector. The authors compared the value of temperature-related bioclimatic indices for viticulture such as the Average Annual Temperature, the Average Temperature of the Growing Season, the Huglin Index and, secondarily, the Oenoclimate Aptitude Index, for two periods - 1951 -1990 (as the period before climate changes) and 1991-2010. The advantage of the manuscript is the comparison of these indicators for six wine regions in Europe, which allowed for a clear demonstration of common regularities. In line with the expectations and reports of many authors, the value of the discussed indicators has clearly increased. Authors are not limited to ascertaining the state of the climate, but in the discussion and conclusions they indicate how to adapt to changes - to changing the traditional structure of the types of wine production of wine regions (changes in the range of recommended varieties in accordance with knowledge regarding their agrobiological characteristics and thermal requirements), the appearance of new suitable areas for viticulture and the expansion of the suitable area for grape growing towards higher altitudes and more northern latitudes. The selection of bioclimatic indicators, the method of using climate data and their processing, taking into account data on altitude and latitude, are correct. The conclusions are justified and supported by the results. The manuscript was written very carefully, in perfect English. The article deserves to be referred for further editorial work.

Comments for author File: Comments.pdf

Author Response

Please see the attachement. 

Author Response File: Author Response.pdf

Reviewer 3 Report

In this study authors investigate the impact of climate change on different climatic indexes in six European wine regions, and the structural and spatial shifts in the viticulture potential during the period 1991-2010 vs. 1951-1990 according to the data obtained.

Although this thematic has been widely investigated by other authors and for other regions during the last decade, the present manuscript brings new insights in understanding the changes that occur in major European wine regions and the data are presented very clearly, so I recommend to publish it in Horticulturae journal after the following issues have been addressed.

Line 39 (and on other places in the manuscript): The term ‘relief’ may eventually be changed to some other terms regarding the context in the text (altitude in some cases, topography in other cases, or similar), as the term ‘relief’ is not widely used in viticultural literature (but this is just a suggestion, not an obligation).

Lines 71-72: Improve the sentence ‘The values of climatic factors suitable to wine production are generally similar in different climates…’ according to the original thought.

Line 167: In Table 2. for Huglin Index include the classes (H-3, H-2,…) which are mentioned in the text.

Line 167: In Table 2. for Huglin Index the equation is not entirely visible (one part is missing).

Line 167: In Table 2. for Oenoclimate Aptitude Index and for Average Annual Temperature try to make a more clear distinction for the classes in the last column.

Line 184 (and on other places in the manuscript): What do you mean when you write ‘by 0.6…1.3 °C’? You mean ‘from 0.6 to 1.3 °C’, or? Please correct this type of writing to make it better understandable.

Line 183-185: If this difference is referred to years 1991-2010 compared to 1951-1990, then include this information in the text.

Lines 206-239: For the AvGST and HI please include the reference for the suitability of varieties for each class of AvGST and HI (which you used to arrange the varieties according to classes).

Lines 247-248: Include the abbreviations used in the Table in the Table heading.

Line 275: In Figure 3 it is not seen the text of the legend as it is too small.

Line 275: In Figure 3 for Bordeaux it is a suggestion to denote the sea on the map.

Line 427: I suggest to change the term ‘assortment’ with ‘the choice of variety’ or similar.

Author Response

Please see the attachment. 

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors have revised the manuscript according to the given comments and I suggest to accept it for a publication.