Observed climatic trends in South African wine regions and potential implications for viticulture

Global warming is scientifically and widely accepted (IPCC). Climate change is a reality and its impacts are increasingly felt in South Africa. Using the longest data series from weather stations located in different South African wine regions and districts of South Africa, the Winkler index for viticulture can be calculated and a descriptive statistical analysis (moving averages, decade averages and linear trends) performed. This provides preliminary results with respect to climatic variation in South African vineyards over the past 40 years.
Analysis of the Winkler index showed that some regions reached the upper level of their group while others changed to warmer groups during the study period. Significant climatic trends, similar across the different wine regions of South Africa, were observed. The first signs of warming were visible in the maximum winter temperatures during the late 1960’s and 1970’s. The significant breakpoint occurs in the mid 1980’s with an increasing acceleration since 2000. This is similar to trends found in literature. These trends hold implications for potential changes in cultivar distribution, adaptation of viticultural and oenological practices and may have already contributed to the development of new wine regions in South Africa.