Detectable use of ENSO information on crop production in Southern Africa

Authors: COUGHLAN DE PEREZ, ERIN - Tufts University; ANDERSON, WESTON - University Of Maryland; Han, Eunjin; MASUKWEDZA, INNOCENT - University Of Sussex; MPHONYANE, NTLELE - National University Of Lesotho

Submitted to: Climate Services
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/14/2024
Publication Date: 8/29/2024
Citation: Coughlan De Perez, E., Anderson, W., Han, E., Masukwedza, I., Mphonyane, N. 2024. Detectable use of ENSO information on crop production in Southern Africa. Climate Services. 36. https://doi.org/10.1016/j.cliser.2024.100514.
DOI: https://doi.org/10.1016/j.cliser.2024.100514

Interpretive Summary: For over 100 years, people have known that El Niño brings less rain to Southern Africa. Farmers in the region now receive seasonal rainfall forecasts operationally. While there are many ideas about how farmers could use these forecasts, it is unclear if they are actually used or benefit farmers much. This study examined subnational farming data in Southern Africa to see if farmers adjust their practices in response to El Niño warnings. The study found that farmers in Lesotho and parts of South Africa planted less corn and sorghum (i.e., reduced cropping areas) when the season started dry and El Niño was happening. This did not happen when the dry start coincided with La Niña (El Niño's opposite). Also, in these areas, droughts during El Niño years led to worse yields than droughts without El Niño. The results imply that El Niño warnings might discourage farmers, leading them to plant less, invest less in farming, or find other ways to make money. However, the study could not find evidence that even more accurate forecasts would further improve yields. This information helps policymakers design programs that guide farmers to better prepare for the changing climate, particularly in South Africa and other developing countries.

Technical Abstract: People have known that El Niño events are associated with low rainfall in Southern Africa for a century and seasonal rainfall forecasts have been developed into agricultural advisories for farmers in the region. While there is abundant theory as to how farmers might (or should) use seasonal rainfall on their farms, little is known about whether this information has been widely used or has had widespread benefit. In this study, we used subnational data on cropping area and yield to see if we could detect any macro-level patterns in agricultural choices or outcomes that are related to knowledge of the El Niño Southern Oscillation or seasonal forecast information in Southern Africa. We found that in Lesotho and parts of South Africa, planted areas of maize and sorghum were reduced when there was a dry start to the season and an El Niño event was apparent at the time of planting, while it was not reduced when there was a dry start to the season and a La Niña event was apparent at the time of planting. Similarly, we found that in both Lesotho and most provinces of South Africa, drought years associated with El Niño had worse yields than those not associated with El Niño (controlling for rainfall). This association could indicate that people are discouraged during El Niño years by the potential for drought, and they might be reducing cropping areas, reducing agricultural investments, or turning to other income-generating activities rather than farming. We were unable to detect a relationship between the accuracy of seasonal rainfall forecasts and yields in Lesotho or any province in South Africa. Therefore, we are unable to observe any additional yield response to more accurate seasonal forecast information.