Here is a sobering thought; if the industrialized world continues to produce greenhouse gases at its current rate, the United Nations predicts that there will be an increase in the global mean temperature of about 3.2˚C between now and the end of this century. This is a similar increase to the change that resulted in the most recent ice age.
Wine, which is among the most sensitive agricultural products, demonstrates how climate change is transforming traditions and practices, many of which are centuries old. Around the globe, producers have contemplated and experimented with adaptations, not only to hotter summers, but also to warmer winters, droughts and the sort of unexpected, sometimes violent events such as spring frosts, forest fires, and flooding, to name a few, that are a result of climate change.
Original archives compiled from 664 years of harvest dates and weather conditions from Beaune (pronounced: [bon]) in the Burgundy region of France, is the longest known homogeneous series of grape harvest dates available. These records indicate that temperatures have climbed enough that harvests now begin an average of 13 days earlier than they did prior to 1988.
Grape growers have been noting significant changes in weather patterns since the 1990s. Places such as England, that were traditionally unsuited for producing fine wine, have been given the opportunity to become part of the global wine world, transforming local economies in the process.
In areas like Burgundy, Barolo, Champagne and the Mosel and Rhine Valley, where great vintages were once rare, warmer growing seasons have made it much easier to produce exceptional wines on a consistent basis. This good fortune has increased both land values and wine prices giving grape growers and winemakers fame and fortune. The character of these wines has evolved in part as a result of climate change.
If the growing season becomes too hot, the grapes will advance through their life cycle too quickly. As a result tannins and anthocyanins, the compounds responsible for giving grape skins their color, won’t develop properly. Subdued acid and increased alcohol levels are also possible and often undesirable.
Variations between daytime and nighttime temperatures are in jeopardy as well. In warmer growing regions, that difference can be crucial to achieving freshness and encouraging certain flavour and aroma development.
Intense heat or too much direct sunlight can lead to dried fruit notes or create dull wines. Fruit that’s left too long on the vine can be damaged from sunburn or may simply shrivel.
Wine growers in northern Italy have already experienced more regular occurrences of sun-damaged crops.
The summer of 2019 in Southern Australia was the hottest since keeping national records began in 1910, and it ushered in an 8% loss of white wine varieties, with Chardonnay dropping 12% to its lowest yield in the past five years. Growers in Priorat, Spain reported devastating vine damage, scorched leaves and desiccated grapes when temperatures shot up to a record 42˚C.
Freezes during the winter or extreme frost in the spring may become less frequent in the years ahead but they have the potential of being much more severe. A decrease in regular winter frosts may also encourage the spread of pests and insect-borne diseases that would normally die off during cold seasons.
The amount of moisture is pivotal. Too much rain approaching or during harvest can lead to watery grapes and a weak vintage. Similar to mild winters, damp, soggy and humid conditions make the vines susceptible to a variety of pests, fungi, mildew and disease.
Rising sea levels, which according to NASA are expected to surge by about 66 centimetres by the beginning of the next century will have the capability of altering or destroying coastlines. Severe floods are also possible and could destroy many vineyards in Portugal, New Zealand and California.
Drought can be another challenge for grape growers. Even though vines may be more tolerant to water deficiency than other crops, the resulting stress can even be desirable, spurring root growth. However, too much stress can hinder photosynthesis, delay or inhibit bud ripening, lower winter hardiness or cause the vine to stop producing altogether. In these situations the soil could be eroded away by wind.
While irrigation can be beneficial, it is not always possible. The recent 3 year drought in South Africa resulted in a decline in vineyard area, improper berry set, hindered vine growth overall and produced the smallest yield since 2005.
The fast moving effects of climate change are forcing the wine industry to take decisive steps to counter or adapt to the changing climate. For example, some growers are pursuing higher altitude locations, which provide shorter periods of intense heat or are better at sustaining day-night temperature swings.
A group of Chilean winemakers, who recently cultivated Patagonia, are advancing into wild territory where nothing is guaranteed. Their hope is that the patchwork of microclimates and terroirs will provide future reprieve from some of nature’s elements, even if it means risk in the short term.
In order to minimize the effects of the intense sunlight, producers are rethinking canopy management, pruning techniques, developing cover crops and extensive shading methods, increasing vineyard biodiversity and finding ways to reuse water.
New World wine producers are experimenting with different grape varieties. In South Africa, growers are testing more drought-resistant varieties. In Australia, vintners are now growing Italian grapes like Fiano, Vermentino and Nero d’Avola varietals that can thrive in a warmer environment. In California, new varieties are being introduced to the Napa Valley.
In Old World regions as well, where many grapes and blends have been historically prescribed by law, the idea of moving to different vines is gaining momentum. For example, in Bordeaux the Union of Bordeaux AOC and Bordeaux Supérieur winemakers have unanimously approved a list of seven “varieties of interest for adapting to climate change”, those being Arinarnoa, Castets, Marselan, Touriga Nacional, Alvarinho, Liliorila and Petit Manseng.
Implementation of each of these solutions requires a great deal of time, research and testing. Unfortunately, the methods being devised now may not work in the future as the climate continues to change.
In the short term, it may appear that there is currently better wine from regions we know and new wine from previously uncharted areas, but the reality is we are going to experience ever-worsening and unpredictable viticultural challenges in the near future.