One of the most fascinating aspects of winemaking is how the climate and geological changes impact the quality of the grape harvest. The combination of these factors can directly impact whether one year’s vintage will be a classic or a complete failure.
For wine enthusiasts it pays to understand more about these influences as it can help to decide which vintages to focus on. Knowing more about the impact of weather and climate also gives us an insight into the relative abilities of different wine makers.
Some wine makers are better at adapting to the changing conditions year on year. Even when the conditions are poor, the best makers will still make the right production decisions for the grape varieties they’re growing.
How climate and soil conditions affect the wine we drink
Wine enthusiasts and wine makers use one word to cover the particular climate and soil types of a vineyard: ‘terroir’. Terroir therefore describes the unique combination of factors that includes the climactic, geological and topographical conditions in which a wine is made. The concept of the terroir is important because wine is a natural product, and it is the core of a wine’s unique identity.
How does climate affect the quality of a wine?
We can break down the impact of the climate on a wine harvest into three key elements: heat, cold and rain.
Temperature is one of the biggest factors that affects how well a wine harvest will grow. Warm weather and lots of sunshine help grapes to ripen. In areas benefiting from a warm and sunny climate, we therefore see grapes with higher sugar levels and lower acidity.
New World wines are typical of the kind of wines produced in warmer climates. They tend to be full-bodied and packed with rich fruit flavours.
It’s harder for grapes to ripen in cooler climates, which results in wines with higher acidity. They tend to be lighter bodied and not as alcoholic because of lower sugar levels in the grapes.
It’s not all about temperature though, as sunlight also affects how grapes ripen. If there’s a lot of cloud cover one season, even in a warm climate, the ripening process can slow.
Finally, the cold is a fundamental part of the production process for some wine types. For example, German Eiswein makers rely on extremely cold conditions to freeze the grapes and create their unique tasting wine. Too warm and this process simply won’t happen.
Rainfall also impacts the growth of wine grapes. Obviously, vines need rain to grow and too little will hamper them. But too much can cause the resulting harvest to be watery and lacking in flavour due to less sugar in the grapes.
Too much rain also increases the chances of fungal disease and mildew. Finally, rain can also make it harder for the wine makers to access the vines without damaging the surrounding soil.
Why is soil type so important?
The type and condition of the soil also impacts the quality of the wine. While it’s important the soil is moist, it also needs to be well drained to avoid the risk of the vine roots becoming water-logged.
Less fertile soils create better wine harvests as the vines are forced into creating more concentrated fruits., Chalky soil is one of the best for wine making as it stores water well and drains efficiently. Vines also ripen relatively quickly in warmer chalk soils and the roots find it easy to grow through.
Conversely, clay soils drain less well but are rich in minerals which some makers argue add to the unique flavour of the terroir. These soils also tend to be cooler (or at least warm up less quickly), resulting in a slower ripening process.