Rice yields in tropical/subtropical Asia exhibit large but opposing sensitivities to minimum and maximum temperatures

TLDR

Data from farmer‑managed fields have not been used previously to disentangle the impacts of daily minimum and maximum temperatures and solar radiation on rice yields in tropical/subtropical Asia, highlighting the need to consider diurnal temperature variation when assessing climate change effects on irrigated rice in Asia. We used a multiple‑regression model on data from 227 intensively managed irrigated rice farms across six major rice‑producing countries, incorporating farm‑specific weather variables, controlling for unobserved farm‑ and site‑specific factors, and including farm‑ and site‑specific economic variables to obtain precise estimates. Temperature and radiation significantly affect rice yield during vegetative and ripening stages; higher minimum temperatures reduce yield while higher maximum temperatures increase it, with radiation effects varying by growth phase, implying that recent temperature and radiation trends would have accelerated yields in high‑yield seasons but slowed them in low‑yield seasons, leading to a net negative impact from moderate warming in coming decades and potentially more negative effects as maximum temperatures rise further.

Abstract

Data from farmer-managed fields have not been used previously to disentangle the impacts of daily minimum and maximum temperatures and solar radiation on rice yields in tropical/subtropical Asia. We used a multiple regression model to analyze data from 227 intensively managed irrigated rice farms in six important rice-producing countries. The farm-level detail, observed over multiple growing seasons, enabled us to construct farm-specific weather variables, control for unobserved factors that either were unique to each farm but did not vary over time or were common to all farms at a given site but varied by season and year, and obtain more precise estimates by including farm- and site-specific economic variables. Temperature and radiation had statistically significant impacts during both the vegetative and ripening phases of the rice plant. Higher minimum temperature reduced yield, whereas higher maximum temperature raised it; radiation impact varied by growth phase. Combined, these effects imply that yield at most sites would have grown more rapidly during the high-yielding season but less rapidly during the low-yielding season if observed temperature and radiation trends at the end of the 20th century had not occurred, with temperature trends being more influential. Looking ahead, they imply a net negative impact on yield from moderate warming in coming decades. Beyond that, the impact would likely become more negative, because prior research indicates that the impact of maximum temperature becomes negative at higher levels. Diurnal temperature variation must be considered when investigating the impacts of climate change on irrigated rice in Asia.