WINETECH Technical Yearbook 2020

The integration of multiple view points for adaptation/ mitigation strategies in the context of warmer and drier future (PART 5)

The overall novelty in the study is anchored in the integration of multiple viewpoints to assess the grapevine’s response to climate: from climate data analysis to remote sensing combined with a detailed view on the response of the grapevine in growth, ripening and wine style, all in the context of climate change. The study showed seasonal variability to be driving the grapevine’s response, this is concerning with seasonal extreme events predicted to increase. Spatial and temporal data sources need to be integrated to create new spatial and temporal layers of higher resolution, which would aid more insightful within-season decision making and adaptive strategies for a warmer (or cooler) future. The completion of Dr Southey’s PhD thesis laid a good foundation to integrate different data sources, climate information, as well as remote sensing layers specific to the application and value of climatic indices and chill unit models in the wine sector. The results highlighted that the conventional indices are not always sufficient to highlight the sensitive seasonal differences happening in the context of increased seasonal variability as the indices are based on daily temperatures that average out the changes happening at hourly resolutions. The study highlighted the need for new indices that quantify the observed hours at specific temperature thresholds. Considering climate change, the lapse rate

throughout the day is shifting and not always quantified in heat and chill models. There is a need for improved accessibility to hourly temperature data to drive adaptation strategies. It was also highlighted to include other variables like relative humidity and wind into the modelling of grapevine physiological responses based on indices. The study highlighted the need for access to climate data, with a high temporal resolution to best monitor and quantify the changing environment to ensure effective and timeous adaptation strategies that will allow for continued economic sustainability. THE WAY FORWARD: INTEGRATION OF MULTIPLE DATA SOURCES Increased seasonal variability has put pres- sure on the need for an accessible and reliable central climate database. This was also highlighted as a priority from the 2018 survey outcomes when interviewing farmers, researchers and consultants. The accessibility of climate and terrain information has been prioritised by Wine- tech as a research topic. The research outcomes and TerraClim aligns with an industry need for an interactive tool to access terrain and climate information to aid long- and short-term decision making at field level. The results from this study can be viewed by way of an online spatial decision support system (www.terraclim.co.za) to farm and field level (figure 1).

SEPTEMBER 2020

TARA SOUTHEY: Centre for Geographical Analysis, Department of Geography and Environmental Studies, Stellenbosch University, Stellenbosch KEYWORDS: Climate, terrain, GIS, innovation, TerraClim

African wine industry. The study confirmed the hypothesis that grapevines will respond to climate change and continue to do so in the expression of phenology, growth and ripening, as the grapevine’s performance is affected by the constant environmental parameters despite the differences on vineyard and site level. The plant-based analysis and aspects of the grapevine most affected by climate, as isolated from this study can be used to build models with reference to climate change.

The final part of the series deals with the transition of fundamental research into the domain of the decision maker, through web applications to aid long- and short-term decision making in the context of climate change. HIGHLIGHTS FROM PREVIOUS PAPERS IN THE FIVE-PART SERIES The last four articles in the series have highlighted the reality of climate change and the possible impacts on the South

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