Climate variability and maize yield in South Africa: results from GME and MELE methods

This paper investigates the impact of climate variability on maize yield in the Limpopo Basin of South Africa using the Generalized Maximum Entropy (GME) estimator and Maximum Entropy Leuven Estimator (MELE). Maize constitutes about 70 percent of grain production and covers about 60 percent of the cropping area in South Africa. It is a summer crop, mostly grown in semiarid regions of the country, and is highly susceptible to changes in precipitation and temperature. The two models directly estimate a yield function for maize with the two relevant climate variables, that is, temperature and precipitation, together with the other traditional inputs (labor, seed, fertilizer, and irrigation). The study finds that the MELE fits the available data better than the GME. Similarly, increased precipitation, increased temperature, and irrigation have a positive impact on yield. Furthermore, results from the MELE show that:

the impact of precipitation on maize yield is stronger than that of temperature, meaning that the impact of climate variability on maize yield could be negative if the change increases temperature but reduces precipitation at the same rate and simultaneously
the results from MELE point to the fact that a percentage reduction in mean precipitation could have greater negative impact on maize yield vis-à-vis the gain from an equal percentage increase in mean temperature due to climate change
there is enough evidence that shows that the mean temperature has increased. On the other hand, mean rainfall is expected to decrease and its variance to increase in South Africa
increase in temperature would impact negatively on maize yield and consequently pose a serious threat to food security within South Africa, which would also have an impact on the countries within the entire Southern African region that obtain about half of their maize from South Africa
the impact of irrigation and mean precipitation on yield is positive, with precipitation having the overall highest impact on yield indicating that irrigation may partially mitigate the impact of decreased precipitation on yield, all other things being equal.