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Climate change a threat to Sherry’s flor yeast, study says

Warming temperatures are threatening the future survival of Sherry wines such as Fino and Manzanilla, according to a recently published study by a research team from the Universidad Politécnica de Madrid (UPM),

These styles are produced via biological ageing, which involves the formation of a veil of flor yeast on top of the barrel during maturation. Such flor is responsible for the development of these wines’ unique flavours and texture and is therefore generally understood to be an integral part of their terroir expression. ‘We have dual terroir,’ said Barbadillo vineyard manager Catina Aveledo, ‘the vineyard terroir and the bodega terroir, which is about the air (temperature, humidity and circulation) so maybe “aeroir”. Both are important for Sherry. The latter, vitally important for Manzanilla.’

The study points out that traditional ‘cathedral’ Sherry wineries are ‘good examples of nearly zero-emission buildings (NZEB)’, as their design provides the necessary levels of humidity and temperature for the flor to develop and thrive without the need for energy intensive cooling systems.

‘Jerez’s cathedral warehouses were built over 100 years ago and since then they’ve worked perfectly,’ César Porras Amores, who was involved in the study, told Decanter. ‘We know that climate change is a reality and the temperature in the world is increasing,’ he continued, ‘and for that reason we have simulated the indoor conditions in a futuristic scenario… to understand how the winery will behave in that scenario.’

According to the research paper, temperatures in the region will rise by an average of 2.3°C by 2050, and up to an astonishing 4°C in the summer of hot years. Some cathedrals would struggle to absorb such a shift, meaning that they might fail to provide the necessary conditions for the production of biologically aged Sherries. ‘If the climate change estimates presented in our research are confirmed in the future, [wine] companies will have difficulties retaining the comfort temperature inside the warehouse [such as] high natural ventilation.’

Fermín Hidalgo, owner of leading Sanlúcar de Barrameda-based Bodegas Hidalgo La Gitana, highlighted how the yeast required to ferment and mature Manzanilla wines is particularly sensitive to heat. ‘Climate change will affect biological ageing in many wineries. However, all of our wineries are built in the best possible way… one of our wineries is the tallest cathedral-style winery in the Sherry area, 14.5 metres high.’

Alongside height, Hidalgo argued that proximity to the sea offers a further mitigating element. ‘All of our wineries are located in the low part of Sanlúcar, less than 500 metres from the sea. Therefore, so far, we have not needed to implement anything in our wineries.’

He admitted however that some bodegas, particularly those with lower ceilings, surrounded by buildings, or far from bodies of water will indeed suffer the effects of the warming climate.

‘The temperature in those wineries will increase. A way to try to reduce that increase in temperature may be by installing watering systems in the soil at wineries. However, the watering systems will not reduce 100% the increase in temperatures.’

The team of researchers at UPM is now working on the development of a new NZEB building specifically designed to absorb the forecasted temperature rise by employing new ‘intelligent’ construction materials, esparto blinds – which stimulate ventilation while minimising sun radiation – and innovative heating, ventilation and air conditioning systems.

‘We would like to have results as soon as possible as the wine sector is asking for them,’ said Porras. ‘We want to take it easy, but I think in probably one year, or something like that, from now we will provide the wine industry with new solutions in terms of construction materials that can help build cathedral warehouses suitable for the future climate.’

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