Bordeaux University

I had a wonderful opportunity touring the Bordeaux University today where I learned about the European climate model and climate research program. In the Bordeaux region, a long term phenological observation have been kept by many châteaux, including some harvest data records. However, due to the changes in ownership and poor record keeping, multiple phenological events are not readily available for the region as a whole. As a result of that, the University of Bordeaux started recording the phenology, composition, and overall vintage ratings from 10 to 15 of the top châteaux in the region. Overall, the phenology of grapevines in Bordeaux has shown 3 to 4 weeks of earlier harvesting in the growing season. This effect has been very noticeable in the Merlot and Cabernet Sauvignon varieties, indicated by a higher sugar content.

The data above was shared with me by the climate scientist at Bordeaux University. From the table, one can see that Cabernet Sauvignon is grown in regions that span from intermediate to hot climates with growing seasons that range from roughly 16.5-19.5oC. For cooler climate varieties such as Pinot Noir, they are typically grown in regions that span from cool to lower intermediate climates with growing seasons that range from roughly 14.0-16.0oC. From the general bounds that cool to hot climate suitability places on high quality wine production, it is clear that the impacts of climate change are not likely to be uniform across all varieties and regions, but are more likely to be related to climatic thresholds whereby any continued warming would push a region outside the ability to produce quality wine with existing varieties. For example, if a region has an average growing season average temperature of 15oC and the climate warms by 1oC, then that region is climatically more conducive to ripening some varieties, while potentially less for others. If the magnitude of the warming is 2oC or larger, then a region may potentially shift into another climate maturity type (e.g., from intermediate to warm). if a region is a hot climate maturity type and warms beyond what is considered viable, then grape growing becomes challenging and maybe even impossible.