Extreme Rainfall: A Major Threat to Rice Production in China

Extreme climate events pose a significant risk to global food production. While extreme heat has been extensively studied, extreme rainfall often remains overlooked in historical analyses and future projections, leaving its impacts and mechanisms poorly understood. This study investigated the magnitude and mechanisms of extreme rainfall impacts on rice yield in China, utilizing long-term nationwide observations and multi-level rainfall manipulation experiments.

Our findings reveal that rice yield reductions due to extreme rainfall have been comparable to those caused by extreme heat over the past two decades, reaching 7.6 ﾱ 0.9% (one standard error) based on nationwide observations and 8.1 ﾱ 1.1% based on a crop model incorporating the mechanisms revealed through manipulative experiments.

Extreme rainfall primarily reduces rice yield by limiting nitrogen availability for tillering, leading to a lower number of effective panicles per area. Additionally, extreme rainfall exerts physical disturbance on pollination, reducing the number of filled grains per panicle.

Considering these mechanisms, we project an additional ~8% yield reduction due to extreme rainfall under a warmer climate by the end of the century. These findings demonstrate the critical need to account for extreme rainfall in food security assessments. Ignoring its impact could lead to inaccurate predictions and inadequate strategies for mitigating the risks to global food production.