Grapevines are intuitive plants. They respond to the temperature around them to take cues for when to begin their cycle and start the process of producing grapes.
One of the greatest challenges of climate change is that the climate is not only getting warmer, but the weather is getting weirder, confusing the natural cycle of grapevines.
Losing the chill of winter
Milder winters have been causing grapevines to start their annual cycle earlier than before — prompted by warmer weather than usual. ‘March has become an increasingly hot month — it is not rare to go to the vineyard dressed in shorts and a T-shirt to finish pruning and binding today,’ says Domaine Guillemot-Michel’s winemaker, Gautier Roussille, about his family’s estate in Burgundy. ‘As a consequence, budbreak happens in early April, but April frosts are still pretty common.’
Early budbreak is a problem, because spring often sees unsettled weather (even beyond climate change) and frost can pose a deadly risk to the delicate buds. The phenomenon known as ‘global weirding’ also means that late frosts are increasingly common – and hazardous – for grape growers today.
‘We had two large frosts in 2019 and 2021 which caused around 50% loss of our annual production,’ adds Gautier. ‘This is worse than what my parents-in-law got in 30 vintages! Losing yield like in 2019 and 2021 has the financial consequence we dread, but even when we are not hit badly by frost, we incur additional cost and labour to fight it.’
As a biodynamic producer, Gautier and his team use herbal teas to reinforce the vines’ natural defences, and the earlier budbreak means they have had to apply these teas by hand approximately ten times in recent years. Sending out a workforce of four people for ten days is an exponential cost. The earlier budbreak also makes the grape vines more vulnerable to mould (particularly mildew and downy mildew), requiring even more work and greater costs.
The risks of a shorter growing season
Once growers have cleared the vulnerable period of spring, summer would – in theory – be a safer time in the vineyard as the grapes begin to grow and take on their colour during relatively stable conditions. In certain parts of the world, however, a stable summer is no longer a safe bet. The earlier budbreak becoming so typical in many regions around the world is matched with accelerated ripening, shortening the average growing season.
A shorter growing season, measured from budbreak to harvest, means winemakers need to be attuned to what is happening in the vineyard – and ready to pick at the drop of a hat. The risk of leaving grapes hanging on the vine just a couple of days longer than desired can easily lead to over-ripeness and concentration in warmer wine regions – with sugar ripeness and alcohol quickly accelerating. As a result of this shorter growing season and warmer temperatures, harvest dates have been brought significantly forward in many regions around the world.
Heating up in the Rhone Valley
In the Rhône Valley these changes have been notable, and producers saw record-breaking heat in the summer of 2022, with a 50-day period in which daily temperatures peaked above 32°C. ‘We started harvesting on 11th August, something unprecedented,’ says Caroline Frey, winemaker at Paul Jaboulet Aîné. Not only is harvest being brought forward by over a month in some cases, but the warmer summers also make the ripening window much narrower — meaning everything ripens at once.
‘What is clear is that maturity arrives earlier in warm years,’ adds Caroline about their vineyards of syrah, ‘and we see maturity differences between different plots reduced. We need to harvest faster and that requires larger teams.’ Logistically, harvest is much more demanding and intensive with the shorter, and earlier, ripening window from the warming climate.
Unpredictable Burgundy
To the contrary in Burgundy, just 300 miles away from the Rhône, the ripening window has expanded… also bringing its own problems and additional costs: ‘Harvests tend to start earlier, but in fact there is a larger period in which we might be harvesting now — we can start to pick as early as late August and finish as late as end of October,’ explains Gautier. ‘This means it is more difficult to secure pickers as there is no way they will block two full months for you in advance, not knowing when picking will occur.’
What does it mean for winemakers?
As grapevines respond to our increasingly erratic and hard-to-predict climate, their growing cycles are becoming less consistent, and winemakers and growers are having to work much harder in the vineyard and remain more attentive than ever. Producers worldwide are having to intensify their focus on pruning and canopy management to control budbreak and ripeness. While in the cellar, more gentle extractions are required to mitigate typically thicker skins caused by warmer conditions, and greater awareness is needed for increasing alcohol levels in the face of climate change.
Although the impacts are overwhelmingly challenging, is anyone winning in the face of climate change? Marginal climates, such as England and Canada, are indeed becoming less marginal with greater ripeness than ever before. That could be considered a win, but then again, if the devastating and repeated forest fires of Canada are anything to go by, even the ‘positive’ side of climate change is coming at a high cost.
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