Wine vs climate change: how global warming is affecting the grapes vineyards grow
- Warmer weather has already had an impact on the flavour profile of popular wines, such as New Zealand’s Marlborough sauvignon blanc
- From 2021, Bordeaux winemakers will be permitted to use ‘accessory grapes’ adapted to hotter, drier conditions
With the planet getting warmer, the wines we enjoy now may not be the ones we will drink in the future. Climate change is having a major effect on grapes. As sea levels rise, the salinity of soils in coastal wine-growing regions increases, which stresses the vines and raises the risk of a proliferation of pests and diseases.
Warmer temperatures are also a problem in regions that rely on winterfrosts to kill insect larvae in the soil and reduce the pest population in warmer weather.
In the short term, hot weather may be beneficial in some regions. But if it lasts too long, it leads to wines that are too sweet and high in alcohol. When red-wine grapes ripen too quickly, the wine’s complexity and quality are compromised because the sugar content, acidity and tannins are affected.
For example, we are familiar with the tart lime and gooseberry flavours of sauvignon blanc produced in New Zealand’s cool Marlborough region, but warmer weather has changed its profile to more mellow pineapple and lime juice.
To some extent, winemakers can adapt: by implementing controlled irrigation (permissible only in certain regions); by replanting vines in shallow soil to reduce water consumption (although this can weaken the vines at the roots); and by shading the grapes from the sun (which is expensive).
Currently, 12 grape varieties comprise almost 80 per cent of the market, and much research is being undertaken to find grapes better suited to hotter climates.
One region seeking to adapt is Bordeaux, in France. To prepare for change,French wine authorities recently announced that smaller chateaux, those producing everyday bordeaux and Bordeaux Supérieur wines, will be permitted to use non-bordeaux “accessory grapes” from 2021.
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These grapes will be allowed to make up no more than 5 per cent of a winemaker’s vineyard, and no more than 10 per cent of the wine blend.
Grapes under consideration include two bordeaux crossbred varieties – marselan (cabernet sauvignon and grenache) and arinarnoa (cabernet sauvignon and tannat, from the hotter south of France) – as well as castets, a rare grape from the south of France that doesn’t need much water, and two Portuguese grapes, touriga nacional and alvarinho. Consumers won’t see accessory grapes listed on the back label, however.
Authorities will not allow them to be named, to preserve the traditional identity of Bordeaux, even though the region’s winemakers have started listing their grapes to be more user-friendly.
Such a change is a significant investment for any winemaker who is – or is likely to be – affected by climate change. It is a gamble as new vines do not produce a crop for four years.
A first vintage can be made from vines that are six years old, but it takes about 20 years to determine if a vine is truly suited to a site.
The choice is to either invest in new practices and experiment with new grapes, or stay the course and hope for the best.
