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.