Assessing the impact of weather variables on the quality ratings of nine wine indexes across four French wine regions: Bordeaux, Burgundy, Rhône and Loire

Details

Supervisors

Iania, Leonardo

Faculty

Louvain School of Management

Degree label

Master [120] : ingénieur de gestion, à finalité spécialisée

Abstract

This research aims to analyse the relationships between climatic conditions and the quality of wines produced in France's most prestigious viticultural regions. Specifically, this study examines wine vintages from 1970 to 2019 across nine Appellation d'Origine Contrôlée (AOC) indices from four French wine regions: Bordeaux (St. Julien/Pauillac/St. Estephe, Pomerol, St. Emilion, Sauternes/Barsac), Burgundy (Côte de Nuits, Côte de Beaune, Burgundy White), Rhône (Côte Rôtie/Hermitage) and Loire (White). This study seeks both to investigate the different impacts of weather variables on the quality of French wines and to explore the similarities and differences among wine regions in aspects such as colour and grape variety. To fulfil this purpose, the research uses four types of regression models (linear, quadratic, semi-log linear and semi-log quadratic) for each of the nine AOC indexes, using quality ratings data from Robert Parker Wine Advocate and weather data from the National Oceanic and Atmospheric Administration National Centers for Environmental Information (NOAA NCEI). The explanatory variables in the regression models include mean temperature, temperature difference measures, precipitation, number of freezing days, the North Atlantic Oscillation (NAO) index and a trend component for non-weather-related improvements. The main findings of this research show that weather variables significantly impact French wine quality. Mean temperature, precipitation and the number of frost days show a significant presence in explaining the wine quality. In contrast, temperature differences and the North Atlantic Oscillation Index show a more limited impact. On a regional level, Bordeaux and Rhône share certain similarities: a strong sensitivity to frost and precipitation extremes, with an explanatory power based solely on weather variables. On the contrary, Burgundy and Loire include the trend variable, yet the explanatory level of this variable remains limited. White wines, particularly those from Loire and Burgundy, show less sensitivity to extreme weather conditions than red wines. These results highlight the crucial role of climate conditions on French Viticulture. It is therefore pivotal to have a better understanding of both the influence of these climate factors and the future impacts that climate change will have on these wine-growing regions, enabling winemakers to learn, pivot and adapt.