Vulnerabilities

Main factors: precipitation and temperature

The main regional climate variables are precipitation and temperature:

• Temperature: the grape’s maturation capacity and the development of sugar and flavours are all determined by the average temperature during the growing season (10). Higher temperatures can lead to over-ripening, dryness, higher acidity and greater vulnerability to pest and disease, all of which affect wine quality (11).
• Precipitaton:  the style of a wine depends on its water content and how this evolves throughout the growing season, with or without irrigation. Nevertheless, it is a crop that is able to adapt to water deficit, and an excess can actually lead to pest and disease (12). At the same time, low water levels can reduce the yield and alter the style of the final product (13).

Chilling and forcing: cold and heat requirements

There are usually two main thermal factors influencing plant development: cold (chilling) and heat (forcing) requirements (19). Chilling refers to an extended accumulation of cold weather, which enables plants to leave the dormancy stage and allowing them to properly set buds and produce fruit when warmer temperatures arise. Following this stage, heat accumulation plays a major role, forcing plant phenological development and growth. A certain accumulation of warm temperatures is indeed necessary for plants to achieve a proper ripening. Higher winter temperatures may be detrimental, as insufficient chilling may cause delayed budding and foliation, resulting in low fruit set/yields (20). Additionally, increased temperatures during the growing season may result in faster and unbalanced fruit ripening, which may lead to implications in fruit quality, fruit set and yields (17).

Grapevines are not a high chill-demanding crop (21); for grapevines, thermal (heat) forcing is the main driver of crop development. In the course of this century, most of the current European viticultural regions are still projected to achieve these minimum chilling thresholds, thus triggering normal budbreak. This was concluded from simulations with a large number of models based on a moderate and high-end scenario of climate change (RCP4.5 and RCP8.5 scenarios) (17). Some grape varieties may struggle more than others, however (22). Regarding thermal (heat) forcing, future warming will likely lead to an advance of the phenological stages, thus impacting grapevine yield and quality. More heat stress will have detrimental impacts on grapevines.

Suitability decrease

If global warming exceeds 2°C, half of current global wine-growing regions would become climatically unsuitable for today’s major wine grapes (24). Top-producing countries, particularly in Southern Europe, are predicted to sustain major declines of suitable winegrowing areas. For example, Spain and Italy are expected to lose 65% and 68%, respectively, of climatically suitable areas, under a 2°C warming scenario. Changing the varieties of cultivated wine grapes may offset this loss by only 5% and 9% for Spain and Italy, respectively. For France a change of varieties may compensate the losses for current varieties under a 2°C warming scenario. Losses at 4°C are predicted to be particularly high in countries that are already warm; this includes losses reaching 90% in Spain and Italy (24).

Wine production in Europe accounts for more than 70% of the global total (23). The countries with the largest areas of vineyards in Europe are Spain (33% of the total area in Europe), France (26%), Italy (23%) and Portugal (6%) (18). In the second half of this century wine grape growing will be negatively affected in southern Europe. A reduction in table quality vines and wine grape production in this region is expected due to a future increase in the cumulative thermal stress and dryness during the growing season. Furthermore, the projected precipitation decrease, and higher rates of evapotranspiration due to a warmer climate will likely increase water requirements. On the other hand, high-quality areas for viticulture will significantly extend northward in western and central Europe (23).

Reductions in suitability for grapevine are expected in most of the wine producing regions (3). Wine grape suitability is projected to decline in 2050 (mean of 2041–2060) compared with 1961–2000 in many traditional wine-producing regions (e.g., the Bordeaux and Rhône valley regions in France and Tuscany in Italy) and increase in more northern regions in Europe, with high agreement among the results of 17 global climate models. Estimates of the reduction of the area suitable for viticulture in major wine producing regions by 2050 are 25-73% and 19%-62% under high and low climate change scenarios, respectively (1). In western and central Europe, projected future changes could benefit wine quality, but might also demarcate new potential areas for viticulture (5). A significant variation in climate conditions, as predicted for the near future, could alter the current geography of high-quality wine production, especially in southern Europe (9).

Impact on biodiversity

Climate change may cause establishment of vineyards at higher elevations that will increase impacts on upland ecosystems. Attempts to maintain wine grape productivity and quality in the face of warming may be associated with increased water use for irrigation and to cool grapes through misting or sprinkling, creating potential for freshwater conservation impacts (1).

Redistribution in wine production may also occur within continents, moving from declining traditional wine-growing regions to areas of novel suitability, as well as from the Southern Hemisphere to large newly suitable areas in the Northern Hemisphere. The actual extent of these redistributions will depend on market forces, available adaptation options for vineyards, and continued popularity of wine with consumers. Even modest realization of the potential change could result in habitat loss to viticulture over large areas (1).

Potential ecological footprint is projected to increase most strongly in Mediterranean Europe (upper estimate: +342%), where suitability expands upslope into remaining montane areas containing some of Europe’s most natural lands. Large increases in ecological footprint are also projected in Northern Europe (upper estimate: +191%) (1).

Frost risk impacts on future grapevine distribution in Europe

Warmer temperatures will lead to an earlier occurrence of grapevine bud break and flowering. This may have a negative impact on grape yield and quality (15), and, therefore, on the suitability of the most famous wine-producing regions. Consequently, a shift may result from current suitable areas towards new ones in the future (16). 

The timing of phenological stages, like bud break and flowering, is different for different grape varieties. The vulnerability of grape varieties to climate change, therefore, also varies from one variety to another. Frost risk will be larger for varieties with early bud break, the moment when grapes start their annual growth cycle, than for those with late bud break. The effect of frost events at bud break stage is the most important factor for the selection of grape varieties. In a warmer climate the likelihood of frost events will reshape the distribution of grapevine varieties in Europe (14). 

The impact of climate change on different grape varieties was studied for grapes characterized by very early, early, middle-early and late cycles of bud break and flowering (14). For all these varieties bud break and flowering will occur earlier in future decades. The study shows that this shift is more pronounced in central and eastern regions of Europe than in others parts of Europe. 

In Germany a shift of 28 to 31 days earlier bud break is estimated for the end of this century (time slice 2066 - 2095) compared with the present (time slice 1980 - 2010) under a high-end scenario of climate change (RCP 8.5) for all grape varieties considered. In Spain this estimated bud break shift is 7-11 days. The estimated spring advancement of flowering is a little less than the advancement of bud break, with the largest shift in France: up to 18-21 days at the end of this century for all varieties under the high-end scenario of climate change (14).

For grape yield and quality, frost risk at the moment of bud break is particularly critical. The likelihood of a frost event during bud break depends on the speed of advancement of warmer temperatures relative to the predicted earlier bud break. For central Europe this frost risk is estimated to increase under a moderate scenario of climate change (RCP 4.5) and decrease under the high-end scenario of climate change. For Atlantic Europe, notably France, Spain and the UK, a marked reduction of frost risk is predicted under both scenarios of climate change (14).

According to this study a warmer climate leads to a general decrease of frost events frequency especially in Mediterranean regions and on the northern fringes of Europe, while in eastern regions (such as Germany) these events are expected to occur more often (14).

Critical level of 2 °C

If global warming does not exceed 2 °C, over half of traditional vineyards on a global scale should not be at risk of severe consequences of climate change. In fact, approximately 25% of current wine regions might benefit from a temperature increase capped at 2 °C. In addition, around 26% of current wine regions are likely to maintain their current suitability with proper management practices. However, almost half of traditional vineyards are under serious pressure of climate change (26).

A completely different situation will arise once global warming exceeds 2 °C. Under those circumstances, the future of 70% of existing winemaking regions, globally, is at risk. Main threats are excessively high temperatures and increased water scarcity. On the other hand, wine production could expand to new suitable areas at higher latitudes and altitudes. This is evident from a global review of the scientific literature on ‘climate change impacts and adaptations of wine production’ (26).

Shifting geographies of wine production

At the global scale, traditional wine regions in southern Europe are most vulnerable to global warming. The review concludes that ‘about 90% of traditional wine regions in coastal and lowland regions of Spain, Italy, Greece and southern California could be at risk of disappearing by the end of the century because of excessive drought and more frequent heatwaves with climate change’ (26).

More than half of global wine production is produced in southern Europe. Even at global warming levels below 2 °C, the future of current wine regions in southern Europe depends on adaptation measures. A further increase of irrigation may no longer be an option because of widespread water scarcity in these regions. At global warming levels beyond 2 °C, the climate in most Mediterranean regions may no longer be suitable for wine production. Shifting vineyards to higher altitudes in mountainous areas will be an option for only a minor part of these regions (26).

Wine regions further north will face lower risks. Here, several adaptation strategies can be effective to cope with higher temperatures and more drought. By introducing later-ripening grape varieties, for instance, ripening of the grapes can be delayed, bridging the hottest and driest part of the summer. It is important for grapes to ripen under ideal temperatures: when temperatures are too high or too low, the alcohol and acidity levels may be too high or too low, affecting the quality of the wine. Also, new wine regions are expected to expand northward. The review shows that the expansion of newly suitable viticultural areas in Europe may greatly outpace losses. Theoretically, based solely on climate conditions, the expansion could be a net increase of as much as 40% by the end of the century (26).

Adaptation strategies

Potential to improve economic performance wine farms

The adaptive capacity and vulnerability of wine production under climate change and fluctuating market forces was analysed for France, Italy, Spain, Germany and Portugal, including the 39 major wine regions of these main European wine-producing countries (9). According to the results of this study wine farms show considerable potential to improve their economic performance, and thereby ease their situation in a global change scenario. The results reveal high levels of technical inefficiency, despite substantial efficiency improvements over the period of analysis (1989–2008). It was concluded that on average, European wine farms realise only 57.8 % of their maximum output potential with proper use of available resources. The potential for production improvement is greater in southern regions of France and Portugal, and practically all regions of Italy and Spain, where the highest levels of inefficiency can be observed (9). According to experts, wine makers in Southern Europe are not fully aware of the consequences of climate change for their companies and their adaptation to the changing climate is still inadequate (27)

Examples of adaptation strategies

There are examples of adaptation strategies where wine growers maintain productivity and quality as well as minimize freshwater withdrawals and terrestrial footprint (1):

• Integrated planning for production and conservation is emerging in several prominent wine-producing regions, where wine producers and conservationists have joined together to plan vineyard expansion and protect biodiversity by avoiding areas of high conservation importance.
• Investment in new varieties that would give similar flavors but with altered climate tolerances may avoid unfavourable land or water use outcomes. Marketing in anticipation of change can build consumer interest in new varietals. “Managed retreat” to new varieties may reduce water use and upland habitat loss that might be associated with attempts to retain varieties.
• Innovation in vineyard management may benefit conservation. Improved cooling techniques such as water-efficient micromisters or strategic vine orientation/trellising practices to control microclimates at the level of individual grape clusters can greatly reduce water use demands (2).

In addition, vineyards may be displaced geographically beyond their traditional boundaries (‘terroir’ linked to soil, climate and traditions) (6).

Changing the varieties of cultivated wine grapes can reduce the negative outcomes of climate change, but this reduction declines under greater warming (24). Currently, little of the diversity of 1,100 planted varieties is exploited. Many countries plant 70–90% of total hectares with the same 12 varieties, representing 1% of total diversity (25).

According a review of global literature, ‘grapevine varietal diversity is probably the most promising adaptation lever for climate change’. Other options include increasing the shading of grapevines to mitigate heatwave damage, decreasing planting density and using drip irrigation to reduce water use, and using wind machines and over-vine sprinklers for frost protection to mitigate the effect of advancing budbreak dates (26).

Barriers to the adaptation measures and strategies

There are barriers to the adaptation measures and strategies summarized above, however:

1. Such technical solutions do not account for the unique characteristics of wine production cultures and consumer perceptions of wine quality that strongly affect the prices paid for the best wines (6,7). Consumers may not be willing to pay current day prices for red wines produced from other grape varieties (6).
2. Wine is usually produced within rigid, regionally-specific, regulatory frameworks that often prescribe, amongst other things, what grapes can be grown where, e.g., the French AOC or the Italian DOC and DOCG designations (8).

Traditions and rules that often determine which grape varieties can be grown in a certain area and which cultivation practices must be used, could seriously hinder the adaptation of viticulture to the changing climate. Those traditions and rules lead to rigidity while flexibility is necessary. The increasing impacts of climate change are likely to make the current rigid system based on a limited number of grape varieties, traditionally established vineyard management practices and strict geographical boundaries a thing of the past in the coming decades (28).

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Europe.

1. Hannah et al. (2013)
2. Nicholas and Durham (2012), in: Hannah et al. (2013)
3. Hall and Jones (2009); White et al. (2009); Jones et al. (2010), all in: IPCC (2014)
4. Goode (2012), in: IPCC (2014)
5. Malheiro et al. (2010), in: IPCC (2014)
6. Metzger and Rounsevell (2011), in: IPCC (2014)
7. White et al. (2009), in: IPCC (2014)
8. IPCC (2014)
9. Bardaji and Iraizoz (2015)
10. Jones et al. (2005); Jones and Alves (2012), both in: Bardaji and Iraizoz (2015)
11. Metzger and Rousenvell (2011), in: Bardaji and Iraizoz (2015)
12. Deloire et al. (2004), in: Bardaji and Iraizoz (2015)
13. Vink et al. (2012), in: Bardaji and Iraizoz (2015)
14. Leolini et al. (2018)
15. Fraga et al. (2016); Hannah et al. (2013); Jones et al. (2005); Moriondo et al. (2013); White et al. (2006), all in: Leolini et al. (2018)
16. Hannah et al. (2013); Moriondo et al. (2013), both in: Leolini et al. (2018)
17. Fraga et al. (2019)
18. OIV (2017), in: Fraga et al. (2019)
19. Benmoussa et al. (2017); Ruiz et al. (2007), both in: Fraga et al. (2019)
20. Campoy et al. (2011), in: Fraga et al. (2019)
21. Dokoozlian (1999); Santos et al. (2018), both in: Fraga et al. (2019)
22. Fila et al. (2012); Fraga et al. (2016); García de Cortázar-Atauri et al. (2017), all in: Fraga et al. (2019)
23. Cardell et al. (2019)
24. Morales-Castilla et al. (2020)
25. Wolkovich et al. (2017)
26. van Leeuwen et al. (2024)
27. Prada et al. (2024)
28. Tscholl et al. (2024)