Global Warming (GW) is a recognised fact, the implications of which have far reaching impacts on almost all aspects of existence of life on Earth. The impacts of GW to humans will be felt socially, economically and environmentally. The aim of this research was to understand the probable effects GW will have on maize production in South Africa. This was done by taking climatic data for Vereeniging (situated in a maize growing region) and analysing it to determine climatic trends. These trends were used alongside the critical values1 used to determine NRHA2 for field crop production. The difference between the winter rainfall values (critical and actual) was found to be 238mm (390mm – 152mm) and summer to be 66.4mm, therefore, the summer rainfall period for Vereeniging was found to be more sensitive to change than the winter rainfall period. This has the implication of affecting the sowing and growing period for maize. The sowing period may shift from October (in the summer sowing season) to early March or April (in the winter sowing season). The average was calculated for the maximum temperature and minimum temperature in order to get an average temperature for the summer and winter months (the same as for rainfall discussed earlier) for Vereeniging. The average temperatures of 13.4°C and 20.1°C for winter and summer respectively are close to the critical values3 for maximum NRHA. This indicates that maize is susceptible to marginal changes. It was also concluded that maize is more susceptible to marginal changes in temperature than for rainfall. The results of this paper show only marginal changes in the variables and that the production of field crops is sensitive to such changes. This susceptibility to changes will result in numerous impacts caused by Global Warming. / Professor. J. T. Harmse