Abstract
Improvements in the ability to model El Niño and other large-scale interannual climate variations have allowed for the development of seasonal climate forecasts, predicting rainfall and temperature anomalies for many places around the world. These forecasts have allowed developing countries to predict shortfalls in grain yields, with benefits for food security. Several countries communicate the forecasts to subsistence farmers, which could allow them to mitigate the effects of drought on their harvests by adapting their cropping decisions accordingly. However, it has not been demonstrated that subsistence farmers benefit from having access to the forecasts. Here we present evidence of subsistence farmers using the forecasts over multiple years to make different decisions and significantly improving their harvests when they do so. In a controlled study, farmers in Zimbabwe who reported adapting their farming methods to seasonal climate forecasts significantly improved their harvests over baseline amounts. Moreover, farmers who had attended a brief workshop and learned more about the forecasts were significantly more likely to use the forecasts than were farmers who learned of the forecasts through nonparticipatory channels.