Altitude has become a key talking point in wine over the past few years. The phrase 'high-altitude vineyards' is increasingly being used on wine labels as a selling point. Some may regard this as a cynical marketing ploy by winemakers wanting to stand out from the crowd of wine bottles, but we're not interested in gossip, we want the facts! If altitude can be used to differentiate and explain variations between wines, what effect have altitude on wine, and what difference does it make?

What is high-altitude wine?

Firstly what constitutes high-altitude? Only one association, the European Centre for Research, Environmental Sustainability and Advancement of Mountain Viticulture (CERVIM) has had a go at defining the term, setting its use for vineyards that are a minimum of 500 metres above sea level. In Europe, 500 metres would seem reasonably high, while in Argentina, 500 metres is considered quite low. Practically all the vineyards in the Mendoza region of Argentina are planted between 600 and 1,100 metres above sea level - so already there is a grey area on what qualifies as high-altitude.

What effect does altitude have in the vineyard?

The effect of altitude on the vine and vineyard varies with other factors such as latitude and the landscape. It is generally the case that average diurnal temperatures (the difference between night and day-time temperatures) fall as the altitude increases. This effect has opened up potential vineyard areas which were previously considered too hot for viticulture, in warmer regions of Spain, Greece or South Africa for example. However, height and climate are not the only factors to be considered when searching for the perfect location to plant a vineyard. The closer to the equator you get, the warmer the average annual temperature is to start with; and humidity levels, aspect, and rain protection are almost equal in importance.

Mountains can affect vineyards planted close to them; while the Vosges Mountains protect Alsace from westerly rain-bearing winds, making it one of 'France's driest regions; the Andes creates a rain shadow over vineyards in Argentina necessitating irrigation – not something needed in Alsace. Mountains in Chile and California channel fog, mist and clouds over vineyards that benefit from their cooling influence. In short 'it's a culmination of factors alongside altitude that makes quality wine production viable.

Why does high-altitude wine cost more?

The cost of providing resources to farm vineyards at high altitude is also a key factor to consider and will most definitely affect the price of the final bottle. While snowmelt provides water for a natural irrigation system in months without rainfall Irrigating vines is often not permitted in many protected quality vineyard areas across the world), there is a cost to farming close to the snow-line. Vineyards on steep hills cannot be cultivated by machine. All picking, pruning, and protecting of the precious grapes has to be done by hand and labour is an expensive resource. Vineyards in extremely high altitude areas such as Elqui in Chile (2,000 metres above sea level) also tend to be isolated, so labour is hard to come by as well, recruiting from further away adds further to the overall production expense.

The advantage of farming vineyards at altitude do offset these extra costs. Sunlight is an essential requirement for growing most plants, if you can increase the luminosity of the sunlight and the number of sunshine hours that a plant, such as a grapevine gets, the more it flourishes and the fruit will more fully ripen. Well-ripened grapes mean intense flavours in the wine. At altitude, with less atmosphere, the intensity, or UV properties, of the sun is increased. Also, the diurnal temperature range is increased as the thinner atmosphere at altitude cools quicker once the sun is setting. These wide diurnal temperature ranges heavily influence the quality of the wines produced.

What is the advantage of altitude to winemakers?

The main advantage is that vineyards on slopes at high altitude get more solar radiation, while also benefitting from cool temperatures, particularly at night, this slows down the grapes ripening process, which in turn increases the production of flavour compounds in the skin. At the same time that these flavour compounds are developing the sugars are ripening, this tends to happen slowly as well, the result is that the grapes are often harvested with fully-ripe flavours before the sugar levels have risen to levels that would make the wine very alcoholic – say 14%-15% ABV. These more elegant wines with complex flavours also have a more pronounced and attractive acidity, which beautifully carries the flavours around the mouth. These raised acidity levels tend to be created in grapes that ripen in cooler temperatures – such as those found at altitude.

Vineyards at high altitudes that are steep and exposed also tend to be quite windy places. Wind, providing 'it's not too strong, is often a desirable vineyard factor, particularly in hot or coastal vineyards as firstly it inhibits disease in the grapes by cooling the vines down and removing moisture in the air; secondly it also thickens the skin of the grapes, or can make the grapes smaller and more concentrated. Thick grape skins result in deep colouration and high tannin in red wine, as well as darker, richer fruit flavours.

Why is wine labelled as high-altitude?

Vineyards in the mountains of Western Cape of South Africa or in Andalucía in Spain will rightly advertise the fact that their wines are grown at high altitude as they expect the enlightened consumers to know it equates to intensified flavours in the wine while not being overbearingly alcoholic with jammy fruit. Altitude has also opened up wine production in parts of the world never thought possible such a Bolivia and the Himalayas in China. With both qualitative and viability advantages associated with high-altitude grape farming, we can certainly expect to see more of it in the future.

So to recap, high-altitude wines are made from grapes grown at least 500 metres above sea level. At high-altitudes, vines get more sun during the day and cool winds at night, this intensifies the flavour of the final wine. These wines are costly to produce and therefore come at a premium, but in our opinion at least, the complex flavours and attractive acidity make them worth it.