Vulnerability to high temperature shapes global warming impacts on rice yield.

Abstract

Complex and spatially varying warming impacts on rice yield hinder climate change impact assessments on food security. To address this issue, we compiled a global dataset of field-warming experiments (<i>n</i> = 214) and analyzed stage-specific crop responses to temperature variations. Results show that exposures to high (30° to 35°C) and extreme high (>35°C) temperatures are the dominant drivers of warming-induced rice yield losses, primarily through harvest index reductions. One additional exposure day above 30°C during the reproductive stage reduces rice yields by 1.1 to 1.8%. In contrast, current global gridded crop models underestimate this sensitivity, simulating only 0.1 to 1.3% yield loss per exposure day. After adjusting the model biases, we estimate that global rice yield losses decrease by 8.1% under 1°C of global warming, approximately twice the unadjusted estimates, with South and Southeast Asia being the most vulnerable regions. Our results highlight the critical role of high-temperature exposure in shaping warming impacts on rice yield.