Modelling the relationship between climate, winegrape price and winegrape quality in Australia

An essential pre-requisite to exploration of the potential impacts of climate change on wine quality is to establish a robust relationship between winegrape quality and climate. Here, Australian wine industry regional scale climate and winegrape quality information were evaluated. A model that describes the climate sensitivity of quality measures for premium winegrape varieties grown in Australia is presented. The relationship between winegrape quality and climate varies for the different varieties examined: with some varieties, a linear reduction in quality in response to a warmer climate is exhibited, while a quadratic relationship of quality change with increasing temperature is exhibited by some other varieties. For varieties displaying a more linear relationship, the relative sensitivities to changes in growing season temperature can be calculated. For example, Cabernet Franc and Pinot Noir are the varieties displaying the greatest sensitivity to temperature changes in Australian winegrowing regions, while Semillon, Chardonnay and Shiraz are less responsive. For varieties displaying a quadratic relationship of quality to temperature, the optimum growing temperature can be calculated. The optimum mean January temperature (°C) for growing of Cabernet Sauvignon in Australia is 18.5°C; for Shiraz, 19.1°C; Verdelho, 20.7°C; and Ruby Cabernet, 21.5°C. Our study reveals the sensitivity of winegrape quality to climate, and should help to quantitatively inform the Australian wine industry of its potential exposure to projected climatic changes.