Have you ever wondered why your wine tastes the way it does? Why Loire sauvignon blanc is so zesty and refreshing? Or why that Primitivo from Puglia is full-bodied and ripe? Climate and environmental factors play a key part. Here I explain what these factors are and how they affect wine styles
There are many factors which affect a wine’s style and taste. One of the pleasures of studying wine (at least for me) is to appreciate just how many variables are in the equation. How they contribute, to define style, flavours and quality level in a particular wine.
You may or may not be a wine geek, but if you are reading this article it means you enjoy wine. You might ask why you need to know about the factors that affects a wine style? I’ll give you three reasons:
- Practical reason: If you’re in a shop, it will help you choose your next bottle of wine. You will be able to predict what a wine will taste like by knowing where it’s grown or how it is produced
- Predictive reason: You’ll figure out what new wines you are likely to enjoy based on what you tasted and liked in the past. For example, if you found out you like white wines from cold climates – you can try a Chablis or a riesling from Mosel?
- Semi-serious reason: If you want to fulfil your dream and buy a vineyard, you know which environmental characteristics to look out for!
The elements that affect wine style can be roughly divided into two macro-categories:
- Nature: the factors defining the vine growing environment
- Humans: viticultural and winemaking decisions
In this article I will focus on the natural elements. In another article I will outline the human-based decisions affecting wine style and quality. Now, if you bear with me, we need a short botanical class as an introduction…
Wine and vines
Our praised beverage (wine) comes from grapes, the fruit of a particular species of vines. Vines, like everything in the green realm, have an annual lifecycle. Through photosynthesis, plants transform sunlight, water and carbon dioxide into glucose and oxygen. The latter is liberated into the atmosphere. Glucose, the other product of photosynthesis, is the plant’s food, together with nutrients found in the soil.
Vines need five things to thrive: heat, sunlight, carbon dioxide, water and nutrients. Out of the five, carbon dioxide is more or less always present in the same quantities everywhere. However, it is the availability of the other four elements that shape the style and quality of wine. Now we’ll see how.
Temperature
The amount of heat in the vineyard is probably the most defining factor to influence wine. The average temperature determines the grape varieties that can be successfully planted in a specific location. For example, grapes like sauvignon blanc, riesling and pinot noir normally thrive in cold climates. Whereas grenache, zinfandel/primitivo prefer much warmer areas. However, there are a number of grape varieties that are quite versatile and can prosper in a range of climates (though with differing results), these include chardonnay, cabernet sauvignon and merlot.
Sunlight
Sunlight allows photosynthesis to take place. The greater the light, the more the vines will photosynthesise and accumulate glucose (sugar) in their grapes. Since sugar is converted into alcohol during fermentation, grapes containing more glucose produce wines with higher alcohol content and a fuller body.
There is a relationship between sunlight and heat. As a rule of thumb, the more the sunlight the higher the temperature. But sunlight and heat are not actually the same thing! For example, Cafayate in Argentina is a region quite close to the Equator, characterised by a very high altitude. The availability of sunlight there is very high, but temperatures are cooler due to the high altitude. Another example is Central Otago in New Zealand. It has a cool climate but a very high level of sunshine. The former allows pinot noir to flourish, the latter results in a high level of sugar and alcohol content in the wines from that area.
Water
Vines need water for two main reasons: to allow photosynthesis and to swell their berries. Ideally, vines need more water in the early stages of their development. Once the vegetative growth is complete, reducing water availability is beneficial for the grapes. This might seem mean but if the vines have limited water during the ripening phase, they will direct all their energy towards their berries. As a result, a scarcity of water results in wine growers getting more concentrated and flavoursome berries from which to make wine.
Environmental factors affecting a vine’s needs
There are several environmental factors affecting the variables just mentioned (temperature, sunlight and water). Now I will briefly describe how some of these environmental factors can impact the style and nature of wine.
Latitude
Latitude is the main factor affecting heat. Most vineyards in the world are planted between the latitude of 30o and 50o. Latitude also affects sunlight. During summer, days are longer the further you move from the Equator.
Altitude
Higher altitudes mean lower temperatures. Sometimes altitude can be beneficial, especially in hot regions. For example, Cafayate in Argentina or Mount Etna in Sicily allow the growth of grapes that otherwise wouldn’t survive at such latitudes. Altitude normally ensures a higher temperature diurnal range (I explain this later).
Aspect and slope
The term aspect means the direction in which a slope faces. Of course vineyards sitting on a flat land have no aspect, so this factor is only relevant at a higher altitude. In the Northern Hemisphere, south-facing slopes get the most warmth (in the Southern Hemisphere, the north-facing aspect is the warmest one). At more extreme latitudes sunlight does not fall perpendicular to the ground, therefore a favourable aspect can be the difference in getting enough heat to make viticulture possible. For example, the best vineyards in German regions such as Mosel and Rheingau are located on steep south-facing slopes.
Vineyards sitting on slopes have a few advantages, especially in moderate and cold regions. As mentioned above, if oriented with the right aspect these vineyards receive more sunlight compared to the ones on flat lands. The cold air tends to sink as low as possible, therefore vineyards on a slope minimise the risk of spring frost. Beyond that, being on a slope, the soil has better drainage.
All these reasons explain why, for example, all the Premier Crus and Grand Crus in Burgundy are located in the middle-section of slopes with optimal aspect.
Ocean currents
Ocean currents can have a localised warming or cooling effect. For example, the cold Benguela Current in South Africa cools down the hot regions on the Western Cape. The Gulf Stream (a warm ocean current) increases the temperature in the north-west Europe (mitigating the Bordeauxclimate, among other things).
Fog
Fog is another cooling effect, decreasing local temperatures. In California, for example, fog helps cool down scorching heat.
Soil
Soil composition affects vineyard temperature. In particular, stone and dark soils retain heat and increase the local temperature. This is why, for example, the Left Bank of Bordeaux (whose soil is rich in gravel) is warm enough to allow late ripening varieties (such as cabernet sauvignon) to thrive.
The draining capability of the soil has a huge impact on the mesoclimate of an area. It also has a great influence on the style of the resulting wine. In fact, soil nature is one of the defining elements of the so-called terroir of a wine (check my article What it terroir? for more info about this fascinating concept).
Soils with bigger particles (stones, pebbles, sand) have great draining capacity. Clay-based soils, whose particles are the smallest, do not hold water well and therefore can become waterlogged in case of excessive rainfall. For the same reason, these soils require more energy to heat up and are defined as “cold”.
The interplay between soils, geology and viticulture is complex, and the exact implications of soil composition on wine is far from fully understood. As a general rule, the best soils for winegrowing are those that retain enough water and release it to the vines when needed. Anyway, the best soil in absolute terms does not exist due to the interdependencies of many other factors.
Continentality
The continentality of a region is the average difference in temperature between the hottest and the coldest months. Continentality determines the length of the growing seasons and ultimately the amount of heat available throughout the year. This in turn affects which grape varieties are more suitable for a particular region.
In areas with a high continentality, the seasons are well defined: the summers are hotter and the winters colder. As a result, the growing season for grapes is shorter. Usually regions further inland, far from large water masses, experience a high continentality.
When the difference between hottest and coldest months is limited, the region it said to have a low continentality. The season differences are less defined, and the growing season longer. This is beneficial for grapes that ripen late. The proximity to the sea or other large water masses generally favour a lower continentality.
Diurnal range
Diurnal range is the difference in temperature between day and night. A higher diurnal range tends to be beneficial for grapes, especially in warm or hot climates. Cold nights allow the grape to rest and have a break from the heat of the day. At the same time, slowing down the loss of flavour compounds and acidity drop. This is why wines from higher altitudes are generally more elegant and aromatic, resulting in a fresher and higher acidity and a more defined character.
Weather and climate
Temperature, sunlight and rainfall are the three factors that shape the overall weather and climate of a region.
Weather defines the particular climatic conditions (temperature, sunlight, rain) in a specific year. Some regions experience more or less the same weather year in year out. For these areas, vintage is not usually a particular concern. Warmer wine regions and almost the whole New World fall into this category.
In other areas, weather can differ greatly from one year to another. In these circumstances vintage is important. Bordeaux, Burgundy, Germany, Douro are regions where vintage really counts.
Climate usually indicates the average annual pattern of temperature, sunlight and rainfall throughout the year. Every region has its own climate and it does not change from year to year.
All the factors just outlined affect climate. Some of these might be more relevant, but it’s important to have the overall picture of all the environmental conditions.
For example, Casablanca Valley in Chile stands at a latitude closer to the Equator than any European wine region. But the vineyards are cooled down by the cold Benguela oceanic current. As a consequence, Casablanca Valley experiences a cold climate, allowing the production of high quality sauvignon blanc and pinot noir.
Climate levels
In the wine world, people usually use three levels to refer to climate, with different degrees of granularity: macroclimate, mesoclimate and microclimate.
Macroclimate is the broad climate of an entire wine region. Usually an appellation defines a macroclimate. For example, an AC (in France), a DOC/DOCG (in Italy) or an AVA (in US). When talking about “climate” (without adding any prefix to the word), we generally refer to macroclimate.
Mesoclimate has a finer granularity, usually defining the conditions of a particular vineyard. Tens/hundreds of metres are the reference scale for a mesoclimate.
Microclimate has the finest granularity. It describes the conditions of a very small area, often in the order of one or few rows of vines.
Climates based on temperature
The average temperature during the growing season is used to classify wine regions into four climates: cool, moderate, warm and hot.
Styles vary greatly from one climate to another. Wines from colder climates tend to have a higher acidity and lighter body. Aroma-wise, these wines usually display a fresh fruit character; citrus, apple and pear fruit for whites, crunchy red fruit for reds.
On the other hand, wines from warmer regions often present a lower acidity, fuller body and higher alcohol content. The fruit aromas are much riper in warm regions. Stone and tropical fruit for white wines, black and jammy fruit for reds. Please note that the above are broad generalisations. It’s always possible to find exceptions to these rules!
Climates based on continentality
Continentality levels, in conjunction with temperature, define another climatic classification, complementary to the one above:
- Continental climate
- Maritime climate
- Low continentality
- Longer ripening season, seasons are less well defined
- Rainfall normally spread out throughout the year
- Examples: Rías Baixas (Spain), Bordeaux (moderate maritime); Pays Nantais in Loire (cool maritime)
- Mediterranean climate
- Low continentality
- Warm or hot climate overall
- Summers are dry and hot
- Rainfall concentrated more in winter
- Plenty of warmth and sunlight, resulting in full-bodied and riper wines
- Examples: Central and south Italy, Greece, coastal California, Chile, South Africa
Conclusion
As you might have noticed by the length of this post, the natural factors affecting wine are numerous and complexly intertwined. Several variables exist to influence the environmental conditions of an area, which in turn affect the style and character of the wine produced.
I will end this article revealing a secret. There is an easy (and exciting) way to learn all these concepts: travel! Visit your favorite wine regions. Explore their landscapes and observe the climatic conditions. And, of course, don’t forget to book some wine tastings at local wineries along the way. You will soon become an expert… both in wines and geography!
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