Climatic drift in Herault: evolution of heat balances (threshold of 10 °C) from 1980 to 2010

Abstract

The temperatures have a major role on the behavior of the vineyards because they directly influence the phenology of the vineyards as well as the characteristics of the grapes, such as the rate of potential sugar. They are a key element of the differentiation of the wine-making-countries soils. Measured thermal data translated into balance sheets at the threshold of 10°C stored in a large climatological data covering a Mediterranean region (Herault administrative department, southern France) by the Climatological Association of the Hérault (ACH). GIS tools (Geographical Information systems) with geostatistics allow us to obtain surface data and to establish maps of agroclimatic indications from point measurements of climate data. We use regression-kriging which combines a regression of the thermal climate variables with environmental co-variates (software: R, Saga, Grass Gis. Explanatory variables: height, slope, aspect, MRVBF and distance from the sea) ) and kriging of the regression residues. The spatial analysis of the heat balance between 1980 and 2010 uses data from 30 to 45 stations. The results show that the evolution of heat balances is continuous on the last 3 decades with the emergence of a new class of thermal variant as well as real opportunities for viticulture development on terroirs nearby the limits of the territory (at more than 300 meters in height). The vitivinicultural identity and its quality are then constantly evolving and the continuation of the climatic drift will demand new adaptations (vines, cultural practices, agricultural diversification).