An increase in peak temperatures could be more damaging to crop yields than rising average temperatures, new research suggests.

The study by Stanford University researcher David Lobell, looked at the relationship between crop yields and changing meterological conditions, such as higher temperatures, in Africa. Rather than rely on crop-simulation models, the research, published in Nature Climate Change, used a data set of more than 20,000 historical maize trials in Africa, combined with daily weather data, that showed a nonlinear relationship between warming and yields.

The results showed that a relatively small increase from 31˚ C to 32˚ C could cause twice the amount of damage to crops with as much as 40% of yields lost, even when drought is out of the equation. Under drought conditions the damage is more severe, with yields decreasing by 1.7% every day that temperatures are higher than 30˚ C.

Roughly 65% of present maize-growing areas in Africa would experience yield losses for 1 °C of warming under optimal rain-fed management, with 100% of areas harmed by warming under drought conditions.

The results indicate that data generated by international networks of crop experimenters represent a potential boon to research aimed at quantifying climate impacts and prioritizing adaptation responses, especially in regions such as Africa that are typically thought to be data-poor.