How winemakers in France combat the effects of climate change

Vigneron Jonathan Hesford explains how he deals with more heat and less rain in the vineyard

Grape bunches can suffer sunburn if the temperatures rise too high before they change colour and become more heat-resistant

Until about 2015, when people asked me about which were the best vintages in the Roussillon (where my vineyards are), I used to say that there was little variation between years.

However since then, almost every vintage has posed its own problems and the variation from one year to the next has become more noticeable. Much of this can be put down to the effects of climate change.

Heatwave every summer now

It’s a common misunderstanding that an increase in temperatures leads to more alcoholic wines. The main reason why there are more higher-alcohol wines on the market is because consumers prefer ripe-flavoured, smooth-textured wines.

The easy way to achieve that is to pick grapes when they are over-ripe and that means more sugar, which translates into more alcohol.

Improvements in viticulture and the use of new, more effective pesticides, have allowed grape growers to leave their fruit to hang later into the year without the risks of rot and insect damage.

Even without any increase in average temperatures, the average alcohol levels of Bordeaux would have risen by about 1% compared to those common in the 1990s.

Read more: Bordeaux winegrowers demand money to uproot vines

Having said that, there have been noticeable changes in the weather patterns in recent years, driven by global warming.

Every summer now we get a prolonged period of intense heat, called a canicule in French.

Grapes lost to downy mildew

Annual rainfall has decreased and, in my region, the heavy November rains which replenished the ground water (and reservoirs) have almost disappeared. However, there have been some years with a pretty wet, warm spring.

The effects on the vines of those changes are several and interconnected.

A warm wet spring increases the risk of downy mildew enormously.

For vignerons trying to reduce their pesticide usage or relying on the copper-based fungicides approved for organic and biodynamic certification, that can mean disaster.

Read more: What is the future of organic wine in France and do consumers care?

In 2020, three of my vineyards lost all of their grape bunches to downy mildew.

Therefore vignerons are going to have to be more vigilant, looking ahead at weather forecasts and modifying their anti-fungal spray programmes in order to avoid catastrophic losses.

Alternatively, they could replace their vines with newly developed hybrid varieties which are much more tolerant to downy mildew.

For example, I have replaced my susceptible Muscat vines with the disease-tolerant Souvignier gris variety, which was authorised for Indication Géographique Protégée (IGP) wines only a couple of years ago.

When to harvest is a dilemma for growers

A heatwave in early summer, while the shoots and leaves are still tender, can cause scorching which destroys the young shoots.

Grape bunches can also suffer sunburn if the temperatures rise too high before véraison, when the grapes change colour and become more heat-resistant. Therefore leaf-trimming may have to be delayed or avoided to protect the grapes.

Late summer heatwaves can increase the rate of grape ripening, provided there is enough water in the soil.

However, that accelerated ripening can be uneven, increasing the sugar levels before the skins of the grapes have had chance to transform their astringent, green flavours into smoother, riper ones.

That poses a dilemma to the grower. Do they harvest as soon as they have the appropriate sugar level in order to avoid high-alcohol wines or do they wait until the skins have ripened fully?

Too little water means smaller berries

In France, it is prohibited to add water to the juice to dilute the sugar level (but I’m sure it does happen).

Drought is probably the most worrying aspect of climate change. Vines are notoriously hardy plants which can survive on pretty dry soils.

The beneficial impact of dry, stony soils on wine quality has been written about in hundreds of wine books. However, the vines still need a certain amount of water to grow and produce a decent yield.

A combination of heat and drought can cause wilting and slows down the ripening process as the vines reduce their rate of transpiration, by closing their stoma, in order to preserve water.

Too little water over a long period of time will also result in smaller berries.

That means the wines from a drought year can be more acidic and tannic – as well as producing fewer bottles per hectare.

Read more: Tannins can make red wine undrinkable or delicious – what are they?

Hoping for rain to come before harvest can be dangerous

If the rain is too heavy or too long, it can cause the grapes to swell too quickly and the skins to split, leaving them exposed to fungal and bacterial infection and forcing the vigneron to pick them quickly, before they have had a chance to use the rainwater to ripen the fruit.

In dry areas of the New World, vineyards are irrigated using dripper systems but in France, this is prohibited for any vineyard producing Appellation d’Origine Protégée (AOP) wines.

If you see dripper lines or the more wasteful water cannons, those vines can only make wines labelled IGP or Vin de France. The philosophy being that the best wines come from vineyards which don’t need irrigation.

Irrigation can be used judiciously to counter the effects of drought and many great wines from the New World indeed come from irrigated vineyards.

But in France, a strong belief in terroir and the view that irrigation is primarily used to boost quantity, mean that its use is frowned upon.

Irrigation also requires a nearby source of water.

The dry wine regions of France have seen an increase in fruit orchards and production of salads and vegetables that have a high water requirement. There has also been a 20% increase in housing over the last 20 years, many with swimming pools and irrigated gardens.

Competition for water is becoming a political issue

I think the introduction of irrigation for AOP wines, which is being talked about in the South of France, will come with a lot of rules and regulations and will probably take many years to be accepted by the wine industry for the production of high quality wines.

Any AOP deciding to authorise irrigation runs the risk of being denigrated by the French trade and press, not something that the AOPs of the Languedoc-Roussillon can easily deal with, given its historically poor reputation as the source of the wine lake.

Change to drought resistant varieties is risky and slow

There has been some research done on planting more drought-resistant grape varieties, such as those found in southern Italy and Greece, but whether the French consumer would buy those wines is unknown.

The chances are that those grapes would only end up in generic regional wines at the lower end of the market, unless the producer has a high enough reputation to create a super-cuvée.

The wine market is traditionally resistant to change and it takes many years before a replanted vineyard produces wine. Therefore changing to new varieties is both risky and slow.

Unfortunately, I believe that it is more likely that the vineyards most at risk to climate change will simply cease to exist. On the plus-side, other areas that have been too wet or cold for wine production may make the grand crus of the future.

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