Extreme heat is no longer an episodic weather event but fast becoming a defining force shaping the future of global agriculture. A new joint report by the Food and Agriculture Organization and the World Meteorological Organization, released around Earth Day, underscores how rising temperatures are steadily eroding the foundations of food production systems across continents.
Titled ‘Extreme Heat and Agriculture,’ the report describes extreme heat as a ‘risk multiplier’, one that amplifies existing vulnerabilities rather than acting in isolation. Today, it threatens the livelihoods of an estimated 1.23 billion people, particularly those dependent on agriculture. Crops, livestock, fisheries and forests are all under stress, but it is agricultural workers who are exposed daily to harsh outdoor conditions, standing on the frontline of this crisis. The impacts are already visible and measurable. Most staple crops begin to experience yield declines when temperatures rise above 30 degree Celsius. Livestock are even more sensitive, with heat stress setting in at around 25 degree C and lower for poultry and pigs. In oceans, the situation is equally alarming because in 2025, over 90 per cent of global waters experienced at least one marine heatwave, disrupting ecosystems as oxygen levels dropped. The report highlighted that such changes are no longer isolated anomalies but part of a widening trend.
For human labour, the implications are severe. In regions such as South Asia, tropical sub-Saharan Africa, and parts of Central and South America, the number of days unsuitable for outdoor work could rise to nearly 250 per year under high-emission scenarios. Researchers noted that this will translate into lost working hours, reduced productivity and widening inequality while agricultural workers are estimated to be 35 times more likely to die from heat exposure than those in other sectors, while 470 billion labour hours were lost globally in 2021 alone due to extreme heat. The report explained that the vulnerability of agriculture stems from biological limits. Every crop, animal and aquatic species operates within a narrow thermal safety margin, typically between 25 degree C and 35 degree C during critical growth stages. Once these thresholds are crossed, the consequences can be immediate: stunted crops, declining milk yields, fish mortality and ecosystem disruption.
Risks intensify further when heat interacts with other climate factors. The report stressed that compound events, particularly the combination of heat and drought, are among the most damaging. “High temperatures accelerate soil moisture loss, trigger flash droughts and increase wildfire risks, creating feedback loops that amplify heat,” it stated.
Recent global events illustrate this pattern. In Brazil, prolonged heatwaves during 2023–2024 pushed temperatures more than 5 degree C above normal, leading to a near 10 per cent drop in soybean production while also triggering wildfires and floods. In Morocco, successive heatwaves combined with drought caused cereal yields to collapse by 43 per cent. In southern Chile, marine heatwaves wiped out over 40,000 tonnes of farmed salmon, while in Portugal, extreme heat contributed to the 2017 wildfire season that burned 540,000 hectare and claimed 116 lives.
India presents a particularly stark example. Rice, which accounts for nearly 70 per cent of caloric intake in the country, remains highly vulnerable to temperature shifts. The 2022 heatwave among the most intense recorded, saw temperature rise up to 10.8 degree C above normal, alongside rainfall deficits reaching 99 per cent in some regions. The report pointed out that wheat yields fell by up to 34 per cent, vegetable yields dropped by as much as 50 per cent, and dairy production declined by 15 per cent due to heat stress.
The Indo-Gangetic plains are projected to face even greater risks. The report suggested that labour capacity during the growing season could fall below 40 per cent by the end of the century under high-emission scenarios. At the same time, wet-bulb temperatures may exceed safe limits for human survival in certain areas. Globally, the outlook remains concerning. For every 1 degree C rise in temperature, yields of crops such as maize and wheat are projected to decline by 4 per cent to 10 per cent.