Households hit by very hot weather can struggle to maintain food supplies in a matter of days rather than months, according to a study today [21 August] from Oxford researcher Carolin Kroeger, who reveals for the first time that food security can be rapidly impacted by heat.

The specialist in climate inequality, a researcher in Oxford’s Department of Social Policy and Intervention (DSPI), is author of the ground-breaking study, which is published in Nature Human Behaviour. She explains, ‘Usually, research focuses on a country level and the fact that heat damages crops, which can lead to food insecurity in months. But this research, at the household level, shows heat can lead to food insecurity in a matter of days.’

Food insecurity affects more than two billion people internationally and rising temperatures are expected to increase that number because of the long-term impact on crops and harvests. But today’s research shows much more rapid short-term effects because of heat-related income losses at the individual level.

DSPI’s Professor Aaron Reeves explains, ‘This paper greatly advances our understanding of the impacts of extreme heat on the lives of people subjected to it and will provoke important discussions about how to protect people in the climate emergency. Such research could not be more timely as the world experienced its hottest month on record in July.’

When it gets too hot to work, people lose income, which means households may struggle to afford to buy food. This is experienced more in countries with vulnerable and informal work patterns – especially agriculture.

The study used over half a million household observations from 150 countries and suggests that, if a country with the population of India experienced a particularly hot week, an additional eight million people could experience moderate-to-severe food insecurity.