How to adapt vineyards to keep up with climate change

In France, wine is of the upmost eco­nom­ic and cul­tur­al import­ance. Before the Cov­id-19 pan­dem­ic, the industry was gen­er­at­ing as much as ~€14bn turnover as the country’s second largest after aerospace. The wine industry is also key to attract­ing tour­ism and pro­mot­ing the country’s repu­ta­tion. Value cre­ated by wine­mak­ing is closely tied to the notion of region (of “terroir”), reli­ant on the fine bal­ance of soil and cli­mate con­di­tions, grape vari­et­ies, expert­ise and product qual­ity; all of which are guar­an­teed by geo­graph­ic­al indic­a­tions (AOP, “appel­la­tion d’ori­gine protégée” or IGP “indic­a­tion géo­graph­ique protégée”). How­ever, depend­ency of the wine sec­tor on cli­mate con­di­tions makes it par­tic­u­larly vul­ner­able to cli­mate change. 

In 2021, we launched the Lac­cave research to study the effects of glob­al warm­ing on wine and to research pos­sible means of adap­tion. Lac­cave brings togeth­er 24 labor­at­or­ies, mainly from INRAE and CNRS, as well as uni­ver­sit­ies in agri­cul­tur­al sci­ence. Over­all, around 90 research­ers and PhD stu­dents are involved in the pro­ject from a vari­ety of sci­entif­ic dis­cip­lines such as cli­mate sci­ence, eco­nomy, genet­ics, agro­nomy, oen­o­logy and geo­graphy. The pro­ject is also open to key French gov­ern­ment insti­tu­tions like the INAO (Nation­al Insti­tute of Ori­gin and Qual­ity) or FranceAg­riMer, to fore­cast changes in the run up to 2050.

Dur­ing the ini­tial phase from 2012 to 2016, the Lac­cave pro­ject made it pos­sible to share and cla­ri­fy our know­ledge on the impacts of cli­mate change on vine­yards and wine. For starters, due to mild win­ters and rising aver­age tem­per­at­ures, all stages of vine matur­ity occur earli­er: bud­ding, blos­som­ing, ripen­ing (known as “verais­on”) and grape matur­ity. As such, har­vests now begin sev­er­al weeks earli­er than in the 1980s. Vine­yards are also con­fron­ted with drier sum­mers, faced with an increase in hydric stress – espe­cially in the South of France – impact­ing yield, grape com­pos­i­tion and char­ac­ter­ist­ics of the wine they pro­duce. Wines con­tain more alco­hol, are less acid and aromas dif­fer; not­ably the taste is said to have less com­plex notes and hint­ing more towards stewed fruits than fresh ones. 

For wine ama­teurs and wine­makers, these phe­nom­ena are already notice­able. For example, the har­vest of Château­neuf-du-Pape now begins late August/early Septem­ber, where­as in the 1950s it would have taken place between Septem­ber 20^th to Octo­ber 5^th. In Gru­is­san, in the Aude region, annu­al rain­fall has dropped by ~25% since the 1990s, caus­ing issues. Extreme weath­er events are on the rise, too, such as the heat­wave in 2003. Dur­ing June 28^th 2019, in the Langue­doc region sev­er­al vine­yards lit­er­ally burnt. Finally, the aver­age degree of alco­hol for wines pro­duced in Langue­doc increased from 11% in 1984 to more than 14% in 2017, while their pH has decreased, thereby redu­cing their acid­ity and freshness.

In France, these events have par­tic­u­larly affected south­ern regions. They also affect the Bor­deaux region, par­tic­u­larly the Mer­lot vari­ety, and to a less­er degree the north­ern vine­yards. But every­where wine­makers and research­ers have been exper­i­ment­ing to address these issues. Pos­sible solu­tions have been stud­ied since the begin­ning of the Lac­cave pro­ject and in 2018, the second phase star­ted con­duct­ing new stud­ies with par­ti­cip­at­ive approaches focused on strategy devel­op­ment. Four areas of action are involved, which will later be com­bined to devise strategies.

The first area con­sists of modi­fy­ing grape vari­et­ies and their root­stocks by favour­ing late sea­son vari­et­ies. These are more tol­er­ant to drought and high tem­per­at­ures, more res­ist­ant to dis­ease and pro­duce less sug­ar with high­er acid­ity. Genet­ics and eco­physiology help us under­stand the mech­an­isms involved in these traits and to reas­sess exist­ing grape vari­et­ies or cre­ate new ones by hybrid­isa­tion. We study these hybrids in vine­yards or exper­i­ment­al plots with wine­makers and their organ­isa­tions. We are also turn­ing to grape vari­et­ies from warm­er regions (Italy, Greece) or vari­et­ies that were over­looked in the 19^th cen­tury. These “for­got­ten”, “ancient” or “loc­al” vari­et­ies were neg­lected because were less effi­cient, but this is not the case today. The INAO now author­ises wine­makers to plant new grape vari­et­ies under the same “label” for cli­mate-related reas­ons; up to 5% of land sur­face and 10% of volume in produce.

The second sphere of action involves the growth of vines and the change of agri­cul­tur­al prac­tices: vary­ing the size or the dens­ity of plots to reduce hydric stress; arran­ging foliage to pro­tect grapes from the sun; man­aging soil com­pos­i­tion, with cov­er plant­ing or by adding organ­ic mat­ter to favour water reten­tion; increas­ing agro­forestry and nat­ur­al hedges around plots to cap­ture CO2 and mit­ig­ate micro­cli­mat­ic con­di­tions. This even includes drip irrig­a­tion, already in devel­op­ment in vine­yards in South of France. Oth­er research stud­ies aim to man­age water effi­ciently, for instance by imple­ment­ing pro­jects which re-use water from treat­ment plants.

The third means of action is oen­o­logy. Indeed, we can cor­rect the effects of cli­mate change by redu­cing the alco­hol level in the wine by using mem­brane sys­tems, without modi­fy­ing the struc­ture or the aro­mat­ic pro­file. For example, this could be used to decrease alco­hol con­tent from 15% to 12% in a giv­en wine. We also use acid­i­fic­a­tion tech­niques to extract cations in order to lower the pH level through elec­tro­lys­is. This pro­cess is already author­ised, espe­cially on white wines for which qual­ity is con­nec­ted to acid­ity. Dur­ing vini­fic­a­tion, the reg­u­la­tion of tem­per­at­ures is also sub­ject to import­ant innov­a­tions (dry ice, isol­a­tion) to lim­it the risks of oxid­a­tion and to improve fer­ment­a­tion. Finally, cer­tain yeasts make it pos­sible to decrease eth­an­ol levels whilst increas­ing acidity.

The fourth area involves the reor­gan­isa­tion of crops. Inside the same “terroir”, the object­ive is to recon­sider soil diversity and expos­ure of plots to pos­i­tion new plant­a­tions. Or increase alti­tude to where the tem­per­at­ures are cool­er, as is the case for pied­mont vine­yards: Bany­uls, Ter­rasses du Lar­z­ac and Côtes-du-Rhône. Like­wise, small vine­yards are cre­ated in warm­er regions, for example in Bretagne (~100 acres), in Poland, Den­mark, and more sig­ni­fic­antly in the South of Eng­land, where 1,000 addi­tion­al acres are planted every year (spark­ling and white wines).

The adapt­ive solu­tions in these four fields must be accom­pan­ied by a change in reg­u­la­tions, espe­cially regard­ing spe­cific­a­tions and the delim­it­a­tion of des­ig­na­tions of ori­gin. As well as by organ­isa­tion­al and fin­an­cial innov­a­tions to cov­er cli­mate-related risks. Tak­ing con­sumer expect­a­tions into account is also fun­da­ment­al. Wine is still per­ceived as a product of both nature and cul­ture; we must bear that in mind when imple­ment­ing innov­a­tions. But above all, adapt­ive solu­tions must be com­bined with cli­mate strategies at the scale of com­pan­ies, regions, and pub­lic policies. These strategies must also include actions to reduce green­house gas emis­sions, by optim­ising con­tain­ers and logist­ics, as well as lim­it­ing the use of fossil fuels and man­aging waste. Vine­yards can also be organ­ised so as to cap­ture car­bon, by increas­ing the organ­ic mat­ter in the soil, cov­er­ing the ground in plants or by plant­ing trees.