Climate change and its effect on grape cultivation

Modern viniculture currently has two major threats: changing attitudes by generations towards wine consumption, and changing vineyards in response to climate change. The latter is properly part of viticulture, and I will look at it here.

This topic was something that was long addressed by Dr Richard Smart, who died recently (Richard Smart: the man who changed wine):

Smart addressed the impact of climate change on wine regions, suggesting that some areas might become too hot for certain grape varieties, necessitating adjustments in vineyard management and variety selection. He consulted to vineyards to help them adapt by taking measures such as finding suitable new grape varieties for their regions.

He was absolutely right; and this is now of particular concern in Europe: Why Europe is the world's fastest warming continent. Two recent research publications by Elizabeth M. Wolkovich have been more specific, at a global scale. The grapevine characteristics included in her scientific analyses are shown in the first figure.

The more detailed of her two articles looks at Uneven impacts of climate change around the world and across the annual cycle of winegrapes (PLOS Climate 539):

    Anthropogenic [human affected] climate change has uneven impacts across the globe and throughout the year. Such unevenness poses a major challenge for human adaptation, especially for agricultural and other managed systems.
     Here, we use recent phenological models with a dataset of mean phenology for over 500 cultivars (varieties) to estimate climatic changes in growing regions across the globe for a major perennial crop that has been highly affected by climate change: winegrapes.
     We examine a suite of grower-relevant metrics, including temperatures during budburst, throughout the growing season and temperatures and precipitation surrounding harvest. We find that climate change has impacted all regions, especially for heat metrics across the full growing season (GDD [see the below graph], maximum temperature and days above 35°C). By far the largest shifts, however, are in European regions, where the number of hot days (>35°C) and maximum growing season temperatures are several standard deviations higher than before significant anthropogenic climate change.
     Climate change impacts have thus been highly uneven across the world’s winegrowing regions and the impacts are variable across the growing season.

The other paper is a review article: The problem of terroir in the anthropocene (Harvard Data Science Review, 7-2). She is particularly concerned about the way in which climate change effects the characteristics that we usually associate with wine terroir. Note also that the Anthropocene is a term used to refer to the period of time during which humanity has become a planetary force of change:

     Climate is integral to the concept of terroir. With anthropogenic climate change, the terroir of the world's winegrowing regions is changing, and will continue to change for decades or centuries.
     Here I show how variety phenology — the timing of major growth and reproductive events including budburst, flowering, veraison, and harvest — is a critical component of terroir and one that is becoming increasingly mismatched due to climate change.
     The clearest signal of this shift comes from the earlier harvests of wine grapes over the last several decades with harvests 2–3 weeks earlier in France and other regions. These earlier harvests have reshaped the climatic profile under which berries ripen, leading to wines with higher alcohol and shifted phenolic and aromatic attributes.
     But these shifts also hint at a major way to adapt viticulture to climate change — through matching variety phenology to the current and future climates of established winegrowing regions. Here I show how variety phenology — the timing of major growth and reproductive events including budburst, flowering, veraison, and harvest — is a critical component of terroir and one that is becoming increasingly mismatched due to climate change. I outline how growers and researchers alike can leverage current and new data to help develop a framework to shift varieties with climate change.

So, the purpose of these two articles is to point a practical way forward, which we would be best advised to heed. What cultivar we grow where (and thus we value the subsequent wine) will need to be re-evaluated, sooner rather than later.