Underestimated rice yield risks from extreme cold in China

Despite global warming, intensifying extreme cold anomalies present a significant paradox for global food security. While heat-related risks are well-documented, the impact of extreme cold on crop yields remains a critical yet understudied vulnerability in climate change assessments. Here, we leverage a comprehensive national observation dataset comprising 4,193 geo-referenced extreme cold days across 218 sites (1991–2012) to quantify rice (Oryza sativa L.) yield responses in China. Our results reveal a counterintuitive doubling in the frequency of extreme cold days over the past two decades, characterized by a significant intensification in the lower percentiles (0–25th, P ≤ 0.007). These anomalies caused a 5.0 ± 0.3% (one standard error for interannual variability) reduction in national rice yields, mainly attributed to high cold sensitivity during vegetative and reproductive growth stages. Using an emergent-constraint approach to CMIP6 projections, we demonstrate that future cold-related yield risks are substantially underestimated. Under continued warming, we projected an additional 3.0 ± 0.9% yield loss by the end of the century, a magnitude three times larger than unconstrained estimates. These findings provide a transferable benchmark for assessing cold-vulnerable rice ecosystems globally and underscore the necessity of integrating cold extremes into adaptation strategies to ensure global food security. Increased occurrences of extreme cold days during the vegetative and reproductive growth stages contribute to national rice yield reductions in China over the past two decades, and these yield risks is projected to persist in the future, as indicated by observations and emergent-constraint analyses of climate model simulations.