Method
Daily Maximum Temperature in January
Physiological and growth processes reach their optimum in the region of 28-30°C air temperature and decline rapidly above 35°C. At 40-45°C these processes come to a halt and damage (e.g. bleaching, sunburn) can occur in exposed tissues.
The mean monthly day-time maximum temperature (Tmax) in mid-summer (January) was calculated from daily temperature data. More detail is provided in the section Background: Climate Change Modelling.
The modelling for the intermediate future (2050s) was conducted using five different CMIP3 GCMs (Schulze, 2011).
Maps
Map Information
In the following maps, Tmax January (°C) is presented under historical climatic conditions, and as the projected change from the historical climatic conditions to the intermediate future climatic conditions (2050s).
With projected climate change in the intermediate future it is particularly the east and north-east that display the highest increases at > 2.5°C. The western interior and Klein Karoo show increases of 2.2-2.5°C, and the southern areas show increases < 2.2°C.
The projected increase in Tmax in mid-summer will particularly impact those parts of the region e.g. northern Berg River valley, Wolseley-Tulbagh and Klein Karoo, that are already hot and also have high projected increases in Tmax in mid-summer. Impacts on fruit will be wide-ranging, including increases in sunburn, poor red colour development, and increased irrigation water demand resulting from high evapotranspiration rates.