Understanding what causes weather-related stresses that lead to crop
failures is a critical step towards stabilizing global food production.
While there are many sources of weather-related stresses, the 30-60 day
Madden-Julian Oscillation (MJO) is the dominant source of subseasonal
climate variability in the tropics, making it a potential – but as of
yet unexplored – source of crop failures. Here crop models and
observational yield statistics are used to assess whether the MJO
affects maize yields. We find that the influence of the MJO is
widespread, affecting crop yields throughout the tropics. In dry, hot
environments the MJO can lead to crop failures by reducing
precipitation, decreasing soil moisture, and increasing extreme heat,
while in wetter, cooler environments - where water stress is less common
- MJO-forced decreases in rainfall bring increases in solar radiation
that benefits crop yields. These results provide a pathway to develop
actionable early warnings using subseasonal forecasts.