Everyone has heard of global warming. But have you thought about the consequences of climate change on viticulture? So, are the consequences beneficial or worrying? We'll explain!
To begin with, surveys show that the average air temperature has increased by approximately 1.4°C over the past century or so (1900-2010). In addition, over the last fifty years, there has been an increase in the amount of rainfall in northern France and a significant decrease in precipitation in the southern regions. This process is likely to accelerate further with forecasts of +2°C by 2050!
Wine-growers can already identify these changes at crucial moments in a vine's life cycle. In fact, stages of development such as bud break (bud emergence), flowering and veraison (the onset of ripening, when the grapes change colour) are tending to appear earlier and also with increasingly high temperatures during the ripening of the grapes.
MORE SEVERE WEATHER EVENTS
Wine-growers and scientists agree that the sky is ultimately more threatening than the earth. We are seeing and continue to fear terrible climatic episodes with less frost but more hail (as in spring 2019 in the Rhône). Hail can devastate the harvest in a vineyard plot in a few seconds, and is still extremely unpredictable.
Climate change is also responsible for the emergence of new insects and parasitic diseases that destroy the grapes.
And heat waves can be a significant cause of concern during the vines' ripening cycle. If they occur when the grapes are young (in July and August), they can cause the bunches to scorch. Scorching is like sunburn, and it roasts the young grapes and stops their development. On the surface, the grapes are crumpled, dried out. Fortunately, the very hot days of June 2019 impacted upon the previous stage of the cycle where the grapes were not yet formed and were more resilient. Later in the year, the thin skin of the grapes becomes fragile and sensitive, and heat can easily cause damage.
Finally, the dates for harvesting are also becoming earlier and earlier, forcing some wine-growing regions to pick the first bunches from mid-to-late August. This is no longer uncommon in continental regions such as Alsace and Champagne, for example.
HOW WILL THIS AFFECT THE WINE?
Clearly, all these changes have an impact on the final product, and its composition is bound to change, leading to more alcoholic and less acidic wines. It is, in fact, the sugar content of the grapes at the time of harvesting that will determine the degree of alcohol in the wine. The sugar/acidity balance required to trigger the grave harvesting operation is changing, and the alcoholic potential of the wines is increasing significantly.
Speaking in practical terms, the disruption of the seasons causes faster maturation of the grapes, which become laden with sugars, which will subsequently be transformed into alcohol. Although this is positive for those professionals who wish to produce more powerful and potent red wines, these temperature increases can cause a threat to the production of white wines with imbalances in the alcohol-sugar and acidity combination depriving some of those wines of their freshness and lightness. In regions where ripening the grapes was a challenge in some years (Champagne, Chablis, Alsace...), we can breathe a sigh of relief. On the other hand, further south, concerns are mounting.
From the point of view of flavour, the aromas of the wines are also changing, from fresh red fruits, such as strawberry or raspberry to more deeply developed notes of candied fruits. In general, professional wine-growers fear that the flavours specific to the regions will diminish as the climate warms the wines.
WHAT ARE THE SOLUTIONS FOR TOMORROW?
Obviously, the primary solutions are nothing new! A significant reduction in global CO2 emissions is crucial for the protection of the environment. Many other factors need to be reviewed too, such as the production and recycling of bottles, the transport of goods, the energy used by agricultural machinery, the oenological instruments and chemical components used, and even the design of buildings.
Put simply, changes to the way we work in the vineyard are not out of the question. In particular, we are looking at rootstocks and grape varieties that are more resistant to climatic conditions and diseases. The modification of viticultural practices with organic supplements is essential, as well as better soil and water management, and even a reorganisation of plantations (exposure, altitude) with a possible restructuring of the map of regions and wine appellations.
We can also consider correcting the effects of global warming by adopting different wine-making techniques (choice of yeasts, temperature control, de-alcoholisation or acidification).
Ultimately, we will have to amend the specifications of the designations and to involve consumers in these changes and decisions.
Would you like to know more? Take a look at this french infographic, which will explain the impacts of global warming in figures.