Two different methodologies are linked to determine the effects of climate change on the Western Cape farm sector in South Africa. First, it uses a general circulation model to model climate change. Second, a sectoral mathematical programming model is used to determine these effects on key variables of the farm economy. Results indicate that less water will be available to agriculture. This will have a negative overall impact, with both producer and consumer welfare decreasing. Total employment in the farm sector will also decrease as producers switch to extensive farming. The total decline in welfare falls disproportionately on the poor.