PARADIGM SHIFT: CLIMATE, TERROIR & WINES OF THE FUTURE

Roger C. Bohmrich, Master of Wine

September 5th, 2021

           Wine by its very nature is a kaleidoscope through which myriad influences, fixed and changeable, are reflected. One of the most consequential is the weather of each vintage year. As new patterns take hold, they are likely to be echoed in the fruit and, afterward, the finished wine. In Part One of this discussion (Does a Warming Climate Mean Better Wine?), we looked in the rearview mirror and left off on a positive note. In recent decades, previously cool, marginal wine regions have been experiencing more regular grape maturity and better quality across vintages. Wine drinkers have in fact been enjoying the pluses of climate change. Our attention shifts now to the future as we grapple with looming questions. To what extent will wine growing and making be able to adapt to a transformed ecosystem? How hot is too hot for grape varieties currently grown in vulnerable locales? Will grapes offering greater tolerance of heat and drought replace those intimately associated with pedigreed appellations? The answers seem to lead to an inescapable conclusion: If present trends continue, there is nothing less than a paradigm shift awaiting us by the end of the 21st century.

There is no doubt among informed scientists concerning the gravity of the worsening crisis. A well-known academic, Dr. Elizabeth Wolkovich, has said that “climate change is a wave you must ride or be swept away by” (Brooks, 2019). The Intergovernmental Panel on Climate Change (IPCC), the United Nations body which released its first Assessment Report in 1990, advised this past decade: “Warming of the climate system is unequivocal…the atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen” (IPCC, 2014). In a 2019 Special Report, the IPCC indicated that the mean land air surface has increased by 1.53°C from 1850-1900 to 2006-2015 (IPCC, 2019). In 2020, the Alliance of World Scientists issued a statement from more than 11,000 scientists warning that “planet Earth is facing a climate emergency.” They pointed out that greenhouse gas emissions “are still rising rapidly, with increasingly damaging effects on the Earth’s climate” (Ripple et al., 2020). Gases, led by carbon dioxide together with methane and nitrous oxide, are triggering rising temperatures. The latest IPCC Working Group report (IPCC, 2021) warns of “widespread, rapid, and intensifying” climate change.

It so happens that the grapevine is highly susceptible to changes in growing-season temperatures. A well-known Bordeaux researcher puts it this way: “Temperature is the major driver of vine phenology” (Van Leeuwen, 2019). Climatologist Gregory V. Jones, Director of the Evenstad Center at Linfield University, said recently that “a 1º F [0.56º C] increase in average temperature would shorten the season from budbreak to harvest by between five and 15 days” (Greenspan, 2020). That alone would shift the ripening phase to a hotter part of summer, in turn altering the chemical composition of the fruit.

One educated observer, Dr. Bruce Zoecklein, suggests that, in technical language, we are likely to see intensifying “asynchrony” between primary and secondary metabolites in the future (Zoecklein, 2018). This means disharmony between rising Brix levels, on the one hand, and other compounds, on the other, as conditions heat up. Simply put, higher temperatures boost sugars while lessening desirable aromas, flavors and phenols. The ratio of anthocyanins to skin tannin at harvest is different in hot as compared to temperate zones. “The more anthocyanins there are relative to tannins,” Zoecklein explains, “the ‘finer’ the tannins in fermented juice.” This presages an altered and, very likely, disrupted balance of flavor characteristics. The pleasure we experience from a glass of Cabernet or Syrah could be compromised, particularly if the wine comes from a region already experiencing hot growing seasons.

            While climatologists are understandably troubled by rising temperatures driven by dramatic increases in greenhouse gases, the world is seeing other signs of a disordered climate. Debilitating frosts struck vineyards in waves in 2021 in several parts of Europe, first in April and again a month later. While Champagne and Chablis are known for spring freezes, the larger Burgundy region was devastated in the latest incidents.  Some reports indicate losses from 20% to 100% of buds, although actual crop shortfalls will not be known until the grapes are picked (Mustacich, May 2021). Bordeaux, Languedoc, the Rhône Valley and other regions were also affected. How does this relate to a changing climate? Quite simply, Europe’s warmer winters signal the grapevine to produce buds and vegetation ahead of the typical timetable.  This leaves vineyards far more vulnerable to normal spring frosts, to say nothing of repeated assaults by freakish subfreezing weather (which may itself be part of larger climatic forces).

Evidence of an altered climate can be found across France. In Champagne, harvesting never took place in August until 2003; yet it has since occurred six times in that peak summer month. Another record was set in 2020: the first grapes were picked on August 17 (Stelzer, 2020). The following chart (Fig. 1) covering 1892-2014 lays out harvest dates in five French districts where picking has advanced 4.4 days per decade from 1964 to 2014 (Delorme).

Figure 1. Harvest dates in France from 1892-2014. Five districts listed in the legend are plotted in different colors, with a solid line to indicate the trend since 1964. The solid black line is a composite of all regions. (Delorme-Agence française pour la biodiversité | Wikimedia Commons)

Higher maturity – more sugar, less acid – could improve meager, sharp still wines, but it is not necessarily advantageous for Champagne, which relies on a precise equilibrium. Fortunately, the practice of using several grape varieties and many vineyard origins, in proportions each house desires, is a bulwark against a warming climate. Additionally, the final dosage or sweetening can easily be reduced or eliminated if the base wine is riper. This is certainly a reason houses have been able to offer more low- or zero-dosage Champagnes. Over the long term, however, this celebrated region may no longer enjoy the very cool climate which has been integral to its reputation for elegant, nuanced effervescent wines. (Champagne’s still wines, on the other hand, stand to benefit.) Will the advantage shift to Britain, where warmer weather is providing a longed-for boost to grape maturity? England is already making some exceptional sparklers with a remarkable resemblance to their French cousins.

What can be done to counter a changing climate in the near term? There are strategies which can be implemented with varying degrees of disruption and cost before temperatures break through the ceiling a grape variety can tolerate. Picking some varieties or vineyard parcels earlier, altering the selection of lots and varieties, blocking the malo-lactic (for white wines) or acidifying the must, and/or employing a spinning cone to remove unwanted alcohol from finished wine are all viable practices. Water can be added to dilute excessively rich musts as vintner Michel Chapoutier suggested, to the shock of many, as a simple remedy for Châteauneuf-du-Pape crossing the 16% alcohol threshold. In fact, he boldly claimed: “It’s the future of wine” (Robinson, 2014).

In the vineyard, mulching will hold moisture, and irrigation could be introduced or recalibrated to counter increased vine water stress. Later pruning might delay phenology, and the leaf area to fruit weight ratio could be fine-tuned to maintain optimum ripening of white wine grapes (Van Leeuwen, 2019). Harvesting can be done in the cool of night or early morning. These corrective measures are relatively affordable and most involve a minimum of disturbance and expense, certainly when compared to more drastic strategies. As a further step, replanting with a new cultivar, clone and rootstock as well as, possibly, relying on a different form of vine training, could become necessary if circumstances worsen. Unless regulations are rewritten, however, growers in rule-bound European appellations will not be at liberty to introduce modifications such as these, no matter the practicality.

Climate researchers are providing a glimpse into the future of viticulture beyond 2050. One study examined the viability of grape growing in Europe and predicts significant shifts (Cardell et al., 2019). The details differ according to the bioclimatic index, but, fundamentally, the results redraw the map of European vineyards. An altered climate will reshuffle the terroir cards and deal  a new hand.  Southern Europe and the Mediterranean will be “negatively affected” owing to “a future increase in cumulative thermal stress and dryness during the growing season.” In some locales, “the vine may cease to be viable” without “adaptive measures.” Higher rates of evapotranspiration associated with warming will have a tendency to increase pressure on water supply. Southern Greece, central Spain and the Middle East are especially vulnerable. Using the Winkler Index, as set out in the mapping below (Fig. 2), Rioja and Piedmont may be transformed by 2046 – 2070 from a Region III to Region V while Bordeaux is realigned from a Region II to Region IV. At the same time, “high-quality areas for viticulture will significantly extend northward in western and central Europe” toward southern England, Belgium, Germany, Poland, and the Czech Republic. This highlights the often-overlooked duality of a changing climate, which has both negative and positive repercussions.

Figure 2. Winkler Index depictions of the temperatures in ºC from 1981-2005 (left) and projections of increases in ºC for the period 2046-2070 (right).(Cardell MF et al., 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019)

If there is further warming of 2° C by the mid-21st century, a conservative scenario, academics such as Elizabeth Wolkovich predict that some cultivars will no longer be suitable for their present viticultural addresses. These researchers speak of “intraspecific diversity,” referring to the varied requirements of grape varieties. The title of a 2020 article on this subject, which sent shock waves through the popular press, suggests how substituting more suitable varieties could be an answer: “Diversity buffers winegrowing regions from climate change losses” (Morales-Castilla et al., 2020). Their models say that swapping cultivars could reduce global vineyard loss from 56% to 24%, should temperatures rise by 2º C. It is nevertheless evident from these figures that planting new vine types is not a panacea.

This is not just theoretical. Alternative grape varieties have already been approved for the Bordeaux and Bordeaux Supérieur appellations, albeit with restrictions. For now, at most 5% of the vineyard surface may be planted with such “alien” varieties, and they cannot exceed 10% of wine blends. These newcomers are, in reds, Marselan, a cross of Cabernet Sauvignon and Grenache; Touriga Nacional, the admired grape of Portugal; Castets, a nearly extinct grape of southwest France resistant to many common vine maladies; and Arinarnoa, a cross of Cabernet Sauvignon and Tannat. In whites, the new arrivals are Alvarinho of Portugal (or Albariño in Spain) and Liliorila, a cross of Chardonnay and Baroque (Cahier des charges, 2021). The taste of Bordeaux is set to change, if only by small increments at the outset.

In Napa Valley, a farsighted winemaker, Dan Petroski of Larkmead Vineyards, is preparing for the day Cabernet Sauvignon may no longer be suited to the Valley. He has planted a research block of three acres with grapes such as Petite Sirah, Zinfandel, Aglianico, Tempranillo, and Touriga Nacional. He believes that each could be a successful blending partner for Cabernet Sauvignon “as a supporting actor until Cabernet can’t be used anymore” (quoted in Rebmann, 2020). [Watch this 2-minute video by The Economist about California’s fast-moving climate: https://www.linkedin.com/company/the-economist/videos/native/urn:li:ugcPost:6816753012057354240/]

        Using Pinot Noir and Grenache as representative of varieties matched to cool or hot climates, respectively, the researchers exploring intraspecific diversity explain how there could be both losers and winners in the climate sweepstakes (Fig. 3).

Figure 3. An illustration of intraspecific diversity using the contrasting examples of Pinot Noir and Grenache to project gains and losses of vineyard plantings in selected regions. (Graph: Ignacio Morales-Castilla reprinted in Fecht, 2020)

Places which are already warm to hot will suffer most, simply because they have little room to maneuver. They point to Spain, Italy, Southeast Australia and California. Even in France, cool-climate grapes, Pinot Noir among them, are set to lose ground. Similarly, Australian research predicts that by late century climatic conditions in parts of cool-climate Tasmania may resemble today’s Coonawarra and Rutherglen (ACE CRC, 2010). If that occurs, Shiraz will be more suitable than Pinot Noir.

Among the possible winners in a grape-switching scenario will be Germany, New Zealand and the Pacific Northwest. Winning varieties such as Grenache which prosper in hotter, drier environments could include Tempranillo, Mourvèdre and Carignan. As Burgundy starts to perspire, Germany will bask in new-found warmth, and Spätburgunder (Pinot Noir) just might become a star of the future.

Many suggest vineyards could escape heat by migrating to higher latitudes. Relocation, of course, would be a radical option. Moving one isotherm Celsius toward the North Pole for each degree of temperature increase may be a useful guide (Kenny & Shao, 1992). There are vineyards of grapevine crosses in Sweden and Norway well above the 50th parallel, long seen as the climatic ceiling for Vitis vinifera in the Northern Hemisphere. Elsewhere, vintners may seek out high-altitude locations. Grapevines have been planted at 7,000 to 10,000 ft. in Chile, Argentina and China. Many more are being cultivated at somewhat lower elevations which are nevertheless well above previous norms. Lake County, with several viticultural areas reaching above 3,000 ft. – an exception in California – may become a refuge for Cabernet if Napa proves inhospitable.

        It seems inconceivable to us now, but academics are already asking if, by the end of this century, Pinot Noir will still find a home in Burgundy and Cabernet Sauvignon will remain intimately associated with Napa. Discovering new habitats for these and other grapes which are better suited in terms of climate is a deceptively simple idea. Merely transplanting Pinot Noir to the cool-climate zones of the future does not mean the results will taste like a Chambolle-Musigny or Vosne-Romanée. The wines might be similar in some respects, but certainly not identical. The world of wine as we know it is very likely to undergo a metamorphosis as climate evolves. The fabled terroirs romanticized in books, the ones we view as immutable and eternal, may well be turned on their heads. 

REFERENCES

References

[NB. Certain citations also pertain to Does a Warming Climate Mean Better Wine?]

 

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Brooks, L (Jan 2019), Climatologists Say Cabernet’s Days as King in Napa are Numbered, Wine Business Monthly.

 

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Cahill, K N & Field, CB (2008), Future of the Wine Industry: Climate Change Science, Practical Winery and Vineyard.

 

Cardell, MF; Amengual, F; Romero, R (4 May 2019), Future effects of climate change on the suitability of wine grape production across Europe, Regional Environmental Change 19:2299–2310, https://doi.org/10.1007/s10113-019-01502-x © Springer-Verlag GmbH Germany, part of Springer Nature 2019.

 

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September 5th, 2021