There are plenty of climate change sceptics, but it is a fact that alcohol levels in wine are increasing, and some grape varieties ripen, where they wouldn’t have 20 years ago.
Why is alcohol level an indication of higher temperatures?
Higher temperatures produce riper grapes, which have more sugar. During fermentation, the sugar turns to alcohol, so more sugar leads to more alcohol. There is an associated decrease in acidity.
Different grape varieties prefer different temperatures
The diagram shows that some grape varieties need longer heat exposure to ripen than others.
- If the temperature is higher than ideal, the grapes will ripen, but the wine will lack freshness and acidity.
- If the temperature is lower than ideal, then the grapes won’t ripen properly, and the wine will be tart and acidic.
- If the temperature is much higher than ideal, then the vine simply shuts down, and nothing happens.
Which countries are most affected?
Those at the current extremes of temperature for growing vines:-
- Much of Australia and Spain, for example, have vineyards in regions with high temperatures. They will have to adapt to survive.
- Countries further from the Equator with more marginal climates, such as England, will now be able to grow a much wider range of grape varieties.
What can the adversely affected regions do about it?
- Plant different grape varieties, which are more tolerant of the hot weather.
- Train the vine branches so that leaves physically shade the grapes.
- Allow plants to grow between the vines, as this lowers the soil temperature, and there is less reflected heat from any stones.
- Plant new vineyards at higher altitude.