When the Bordeaux dries up

More than half of the world's wine-growing regions could become unusable if average temperatures rise by more than 2 degrees Celsius. This includes areas in Spain, Portugal and southern California. In the worst-case scenario, as much as up to 70 per cent could no longer provide articles for the wine supply, writes a team of experts in "Nature Reviews Earth & Environment". However, the experts also see reason for hope: up to a quarter of existing wine-growing regions could become more productive due to climate change and new areas could be added - for example in southern England.

The fact that viticulture - like all branches of agriculture - changes with the climate is not a new realisation. However, the experts from Bordeaux, Palermo and Burgundy have now compiled all the key factors that could affect the carefully cultivated grapes on a heated planet. They have also included in their analysis the fact that the world's winegrowers are not completely unprepared for the effects of climate change, but are taking various measures to counteract the decline of their vines.

The most obvious stress factors are heat and drought; the hardest hit are the regions where many hours of sunshine have so far been a flagship for their vines. Zinfandel from Southern California is therefore highly unlikely to have a future - and will either be replaced by drought-resistant varieties or even by wines that previously grew in completely different regions. Higher temperatures also shift the growth cycle of the plants forwards so that the grapes ripen earlier when it is warmer. On average, winegrowers now harvest their vines two to three weeks earlier in the year than 40 years ago.

More alcohol, less acidity

As a result, the grapes have a different composition of ingredients at harvest - and you can taste it. Instead of fruity-fresh flavours, they are dominated by overripe or cooked fruit, writes the team of authors. In addition, wines from grapes that have grown in higher temperatures contain more alcohol and less acidity. This in turn increases the risk of microorganisms contaminating the (potentially) expensive wine.

Wine growers could do a lot to be able to bottle high-quality wines in the future: breed other varieties that are more likely to thrive under the new conditions; delay the time of ripening through cross-breeding or genetic modification; or manage their vineyards differently. New growing areas in more northerly climes could offer opportunities, provided they do not have to make way for the production of non-alcoholic foods.

However, the research team fears that all these endeavours will not help if wine lovers do not join in: After all, the geographical origin of a wine often vouches for quality; a bottle of Bordeaux may usually cost more than Württemberg Trollinger. According to the team of authors, the decline of the beverage will therefore mainly depend on whether sommeliers favour new grape varieties and the northward migration of growing regions.

Spectrum of science

We are partners of Spektrum der Wissenschaft and want to make well-founded information more accessible to you. Follow Spektrum der Wissenschaft if you like the articles.