For almost half of humanity, Rice is much more than just a food: it constitutes the basis of the daily diet. Half of human beings get 20% of their calories from this cereal and more than a billion people depend on its cultivation for their livelihood. An immense number of people thus rely on a single plant.
The good news is that rice benefits from centuries of adaptations. The bad news is that these adaptations have a limit and we are reaching it.
A study published in the journal Communications Earth & Environment crossed 9,000 years of archaeological data with modern agricultural observations and climate projections. Worrying conclusion: Asian rice has never thrived where the average annual temperature exceeds 28°C nor where the peaks of the hot season exceed 33°C. Thresholds that have remained stable throughout its history but are now threatened.
The thermometer that rice cannot pass
A team of researchers from the University of Florida has traced the expansion of rice across 803 archaeological sites in Asia. Verdict: in nearly nine millennia, humanity has succeeded in cultivating rice in colder climates – particularly during the brutal cooling that occurred around 4,200 years ago, which favored the emergence of resistant varieties allowing its spread to Korea and Japan — but he never knew how to adapt to extreme heat.
As lead researcher Nicolas Gauthier explains, At extremely high temperatures, “you reach a point where the plant physically stops functioning.” Unlike cold, which can be circumvented by adjusting growth rates, Excessive heat simply paralyzes the biological mechanism of the plant.
And the coming heat wave is of a completely different magnitude. The study warns that in the next 50 years, global warming will progress 5,000 times faster that any variation in temperature to which rice has had to adapt throughout its entire evolutionary history.
By 2070, almost the entire southern growing area — from India to Malaysia — will display an average annual temperature above 28°C. Projections estimate that areas exceeding these thresholds could be multiplied by ten to thirty in the main Asian producing countries by the end of the century.
Un problème inégalement réparti
India, today the world’s leading producer of rice with nearly 150 million tonnes per year, faces a real risk. But paradoxically, those who depend most on rice for their livelihood will also be those who have the least access to new genetically adapted varieties that science might develop. The hardest-hit regions in the south – Indonesia, Malaysia and Bangladesh – are not those dominating global agricultural innovation.
Science offers a few avenues: genetic improvement, adaptation of sowing schedules and moving crops to higher latitudes.
But Nicolas Gauthier is categorical: even if a large-scale famine can be avoided, the transition will be brutal and unequal. Rice cultivation could disappear from Southeast Asia and move elsewhere, without solving the problem of those who can no longer cultivate it.
Rice has survived ice ages, droughts and the collapse of great civilizations. This time, it is the speed of change that is the problem. Climate changes work in cascade: what affects one crop today can disrupt entire supply chains tomorrow, raise prices and destabilize populations that we never talk about in the newspapers.
Every tenth of a degree not avoided today is a debt that someone will pay tomorrow, probably with an empty plate.
Référence de l’article :
Gauthier , N. , Alam , O. , Purugganan , MD et al. Projected warming will exceed the long-term thermal limits of rice cultivation. Commun Earth Environ 7, 84 (2026).
