Identification of the best viticultural areas by spatial optimisation. Application in New Zealand South Island in the context of climate change

Abstract

The global winegrowing sector is under pressure due to the effects of global climate change. This is particularly true for New Zealand, where the wine industry is limited to a few regions. This study focuses on the South Island of New Zealand. It uses the Multi-objective Optimisation for Agrosystems (MOA) model to (i) investigate how potential exposure to climate risks and phenological stages will evolve under climate change, (ii) assess the suitability of current vineyards for viticulture in the future, and (iii) investigate potential emerging areas favourable for viticulture. The results show that a significant shift in the phenological stages of veraison and ripeness can be expected in the future due to the warming of the South Island of New Zealand. The projected phenological stages advancement is around one week in the near term for both Shared-Socioeconomic Pathways studied (SSP2-4.5 and SSP5-8.5) and is more than three weeks and one month in long-term for SSP2–4.5 and SSP5-8.5 respectively. A regional to local increase in frost risk (Canterbury, Otago, and Southland) and a slight increase in disease risk (especially on the coast) are also projected in the future, while the South Island of New Zealand is not expected to be affected by heatwaves. The results show that Marlborough, New Zealand's most important winegrowing region, will continue to be one of the best areas for viticulture in the 21st century. On the other hand, new winegrowing opportunities are expected to emerge inland and southwards. Overall, this study contributes to the understanding of the impact of climate change on the New Zealand wine industry and emphasises the need to adapt to changing climate conditions. It also provides insights into the future suitability of vineyards and identifies potential expansion areas for the New Zealand viticulture sector.