Grape vines and climate change

Vines moving northwards and upwards, but are monocrop vines sustainable?

The increase in extreme weather caused by climate change is directly affecting the wine growing process, the grapes themselves, the composition of the wine and as a result, the taste. Some prestigious vineyards are now suffering as they struggle to continue to produce their prized wines.

·       Environmental shifts are leading to early budding, which increases the risk of spring frost damage.

·       Summer heatwaves make the grapes hibernate instead of ripening evenly.

·       Harvests are starting earlier year upon year, which causes the chemical composition of the grapes to become unbalanced to the point where their aromatics and complexities are significantly reduced.

Prolonged droughts, desertification and widespread wildfires that happen as a result have been impacting winemakers the world over. In addition to severe biodiversity loss, drought-provoked wildfires alter the taste a of the wine (“smoke taint”), where volatile compounds in the smoke are absorbed by the grapes, producing an unpleasant taste.

Bordeaux is currently experiencing a major change in its wine production.  Merlot, for which the region is famed (up to 60% of its vineyards producing this variety), is on the verge of extinction as a result of the warming climate and the harvest season that has been shifting earlier and earlier since the 1980’s. Winemakers there are faced with no choice but to experiment with different grapes from hotter regions.

Long-established wine growing practices are being challenged. Adapting to climate change often means new planting positions for vineyards, for example on north-facing slopes, although that might not be enough to protect vines from damage. Irrigation, formerly considered necessary only on poorer sites, has become essential.

Old vines can also play a vital role in the long-term resilience of the wine industry, because they have often never been irrigated, resulting in very deep rooting and therefore much better drought tolerance. They also tend to have much healthier mycorrhizal networks supporting the roots, leading to better tolerance of frost, flooding and disease pressure too. Often old vines are untrelissed  bush vines with thick trunks, having never been in chemical agriculture, with healthier soils beneath and all these factors can increase resilience.

The physical locations of vineyards are also moving north and upwards in altitude – hence the increasing trend of French winemakers buying land in the south of England. In hilly regions like Catalonia, some winemakers are moving vineyards further up hillsides to try and stay in the same climate zone, but that will only work for so long until there is no more hill.

The Arctic is warming four times faster then the rest of the world, and there Sweden is the leading Scandinavian nation pushing the boundaries of what is possible in viticulture. The past two decades have seen a boom in production, mainly using the hardy Solaris grape, used for white wines. As well as the warming climate, an important factor is the increased availability of early ripening varieties. The climate also lends itself to producing “ice wines” – a type of speciality dessert wine in which the grapes are harvested when frozen on the vine and pressed in their frozen state.

Chardonnay grapes

New ways of growing grapes are being adopted, but there are many questions. Should leaves be left on to provide shade for the grapes, increasing the disease risk, or should they be removed? If so, is it better to remove them earlier, to allow the grapes to adapt to sun exposure, or leave it as late as possible? Should the inter-row strips be left to grow freely, for increased biodiversity and to keep the soil cooler?

A recent study also shows that under “middle of the road” climate change predictions, a large part of Eastern and South-eastern England is likely to become suitable for growing Chardonnay grapes for still wine like those made in the Chablis region of Burgundy (they are already being planted for sparkling wines, which don’t require such a degree of ripeness, along with Pinot Noir and Pinot Meunier). In our own tests of vine leaf quality, Chardonnay also came out top for the taste and quality of the cooked leaves – a true dual-purpose crop!

Bolivian tree/grape agroforestry system (credit: Oliva Oller)

Vineyards have not always been monocrop systems. In ancient Rome, grapevines were trained on trees (e.g. Poplars) and associated with arable crops and livestock, and more recent Mediterranean systems used mulberry trees with grape vines. As a matter of fact, species of the genus Vitis are of course climbers that naturally grow on trees. Maybe it’s time for wine growers to revisit these more sustainable systems.

Growing with trees gives many ecosystem benefits and increases resilience and sustainability, though at potential costs of lower and more expensive production – though most diverse agroforestry vineyards are small scale with the vines grown for family use. In traditional Bolivian systems, grapes are trellised up trees which are high pruned yearly to maintain the vines at a height convenient for harvesting, and to control shade. It’s a system we are using in Devon for other climbers like hardy kiwi vines (Actinidia arguta).

Biss, A. J., & Ellis, R. H. (2022). Weather potential for high-quality still wine from Chardonnay viticulture in different regions of the UK with climate change. OENO One, 56(4), 201–220. https://doi.org/10.20870/oeno-one.2022.56.4.5458

Cockburn, H. (2022). A nice glass of Arctic wine? How the climate crisis is pushing vineyards north. The Independent, 1/9/22. https://www.independent.co.uk/climate-change/news/arctic-wine-sweden-norway-spain-drought-heatwave-b2157792.html

Crawford, M. (2022). Comparative test of edible grape variety leaves. Agroforestry News Vol 30 No 4.

Currin, T. (2022). Old vines dig deep in the heatwave. https://www.jancisrobinson.com/articles/old-vines-dig-deep-heatwave

Oliva Oller, P., Notaro, M., Langer, E. et al. (2022). Structure and management of traditional agroforestry vineyards in the high valleys of southern Bolivia. Agroforestry Systems 96, 375–386. https://doi.org/10.1007/s10457-021-00725-4