Economic impact of climate change on milk production: a case study of selected areas in the Free State

[摘要] Dairy cows are sensitive to increasing temperature and humidity, which affects their feed intake, and causes a direct as well as an indirect impact on milk production. This study aimed at computing the economic impact of climate change-induced heat stress on milk production in the Free State, South Africa. The semi-arid regions of Free State �?Bloemfontein, Bothaville and Bethlehem �?were selected as representative regions, based on availability of climate data. In this current study, a model developed by - St-Pierre, Cobanov and Schnitkey (2003) was adopted in order to estimate the milk production losses for all representative study areas.The baseline (1950�?999) and mid-century (2040�?070) climate data as well as Temperature Humidity Index thresholds (THIthershold), 70 and 65, were used. Taking present time prices, it was found that with a THIthreshold of 70 for Bloemfontein, Bothaville and Bethlehem, a loss of 17 cents, 16 cents and 2 cents, respectively, per cow each day, on average was incurred. Thus, taking the average number of cows in the Free State (Lacto data, 2015) as an example, a farmer would lose about ZAR8 687.00 in a year, on average. While, for a THIthreshold of 65, milk production loss showed an increase amounting to 60, 50 and 17 cents per cow/day, on average, for Bloemfontein, Bothaville and Bethlehem, respectively. For the mid-century 2050s data with a THIthreshold of 70, and no mitigation strategies being employed by farmers, milk production loss doubled for all the three study areas.To understand dairy farmers' perceptions on climate change-induced heat stressed, a semi-structured questionnaire was used for Bloemfontein as a sample region. Farmers responded that increasing temperature and variability of rainfall as comprising one of the reasons for their lower milk production. However, this awareness is not consistent with the fact that almost all interviewed farmers employ no measures to adapt to the increased heat, nor do they use any measures to mitigate heat stress.Using a model applied by St-Pierre, Cobanov and Schnitkey (2003), this paper computed milk production loss when farmers employ moderate heat abatement strategies (wetting and forced ventilation) for the mid-century climate data (2040�?070). It was found that production loss per cow reduced by more than 50 % and consequently lowered revenue losses for farmers. It is recommended that exhaustive analysis of the economic impacts of climate change-induced heat stress on milk production should be done, as it is an important sector in alleviating household food insecurity in South Africa.

[发布机构] University of the Free State