A new paper in *Communications Earth & Environment* combines modern crop maps, herbarium records and archaeological sites to map rice’s temperature envelope. The authors find domesticated Asian rice has rarely prospered where mean annual temperature tops 28 °C or where warm‑season peaks exceed 33 °C. These limits have held steady throughout 9,000 years of domestication. Across the continent, this envelope aligns with satellite‑derived paddy maps.

Rice feeds more than a billion Asians, yet breeding and irrigation have only masked heat stress rather than broadened the crop’s thermal niche. Historical data show the species expanded geographically without shifting its core temperature window, and recent shifts in China moved fields northward into cooler zones while intensifying irrigation in the hottest areas. Smallholder economies depend on these marginal lands.

Projections for the end of the century suggest the land area surpassing rice’s thermal ceiling could grow ten to thirty times across India, China, Vietnam and the Philippines. Such expansion threatens staple production for over 1 billion people, forcing farmers to abandon marginal fields or adopt heat‑tolerant varieties that remain unavailable. Immediate policy focus must address this looming mismatch between climate and crop suitability. Adaptation strategies must be scaled quickly.