The Bordeaux wines are better when they are produced in years that have wet winters followed by hot, dry summers. Climate Change makes these weather patterns more frequent, which could explain, in part, why Bordeaux wines are improving.

To better understand the relationship between the weather and wine quality, Andrew Wood from the University of Oxford and his colleagues analyzed the records of temperatures, rainfall, and critics’ reviews of Bordeaux wines (mostly reds) from 1950 to 2020.

The focus was on Bordeaux because the vineyards there are irrigated exclusively by rain. Wine critics also provide ratings for the wines of smaller localities in the region to determine if it has been a good year.

The highest-rated wine is generally produced during years of wet winters when the vines are dormant and hot, humid summers when the grapes ripen.

Wood says that high rainfall during winter can produce better grapes. “If the plant’s reserves of water are filled in winter, they can draw from this in spring and grow vigorously,” he says. He says it may also reduce soil salinity so that grapes contain less salt.

Wood says that drier summer conditions may be better because they concentrate sugars and aromatics in the grapes as they ripen. He says that warm temperatures help to develop these flavor components because they increase photosynthesis.

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Researchers found that Bordeaux wine ratings have increased in general since 1950. Wood says that this may be due to the technological advancements in winemaking and efforts to match consumers’ preferences, as well as climate changes in France, which has increased the frequency and intensity of hot, dry summers and wet winters.

Wood says that Bordeaux wines will continue to improve with climate change and as these weather patterns become commonplace. However, there will be a point where it is too hot and dried for grapes to thrive. Wood says “we , can’t know from this analysis when the failure point will occur.”

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He says that vineyards will also be increasingly affected by extreme weather events such as wildfires and floods. These could destroy entire harvests.

Wood, who conducted the study, believes that other vineyards in the world that grow similar grape varietals, like Cabernet Sauvignon and Merlot, should also benefit.

He says that winemakers can use these findings to improve their wines. For example, they could irrigate the soil in winter and trim the foliage of vines to reduce the shading of grapes. They could also increase drainage or erect rain covers in the event of a wet, humid summer.