Impact on Australian Viticulture from Greenhouse Induced Temperature Change

In Australia, projected shifts in annual average temperature between present day and the year 2030 will be in the order of 0.3 to 1.7°C in many of the viticulture areas. By 2070 the projected increase in annual average temperature in viticultural areas is 0.8 to 5.2°C (Figure 1) (Most major grape growing regions are found within the black ovals). The estimates take into account uncertainties associated with the range of future global warming (the greenhouse gas emissions scenarios (IPCC 2000)) and the range of regional climate model responses (IPCC 2001). For this wine industry impact assessment we were interested in projected changes to average regional climate for all Australian wine-growing regions. Using GIS techniques, gridded climate data was extracted, for each wine region, from a range of climate maps. This climate data was then compared to various assigned or inherent estimators of regional grape quality. Our analysis indicated that temperature increases will impact on grape production and grape quality within a region. Increasing temperature will have a negative impact on grape quality, given the grapes of a particular variety will ripen in the present day climate. Yield (tonnes/hectare) generally increased with temperature. From the yield (tonnes/hectare) and price ($/tonne) relationships, the income ($/ha) was derived, which was also related to temperature. Using derived temperature sensitivity relationships, the impact of climate change was explored. Climate change projections were used to produce 'cost' impact models. Depending on the emissions scenario used in the model, and the grape growing region itself, by 2030 a cost of 0-25% to grape quality could be expected Viticulture-suitability maps in projected climates are shown and in general there is a southward shift of suitability. (Figure Presented).