Extreme heat threatens livelihoods, health and labour productivity for over a billion people around the world, warns the latest report from the World Meteorological Organization (WMO). Agricultural workers and the food production systems that they manage are on the frontlines.

The increased intensity and duration of climate change-related heat waves, driven largely by the indiscriminate burning of fossil fuels, poses a direct risk to crop and livestock production,  fisheries – and the health of workers who must work long hours outdoors during extreme heat to manage those systems, warned the report, published on Earth Day, observed  every April 22.

“This work highlights how extreme heat is a major risk multiplier, exerting mounting pressure on crops, livestock, fisheries and forests, and on the communities and economies that depend upon them,” said FAO Director-General QU Dongyu.

The report titled “Extreme heat and agriculture,” prepared in collaboration with Food and Agriculture Organization (FAO), assessed risks as well as adaptation options.

Among the latter, early warning systems can help farmers prepare for extreme heat, the report stresses. It also urges countries to look at options such as selective breeding of crops to prioritize more drought- and heat-resistant plants, and make those more widely accessible to farmers.

“Extreme heat is increasingly defining the conditions under which agrifood systems operate,” said WMO Secretary-General Celeste Saulo.

Risks to the agrifood systems set to soar

The frequency, intensity and duration of extreme heat events have risen sharply over the past half century, WMO said, leading to soaring risks.

“More than simply an isolated climatic hazard, it [heat] acts as a compounding risk factor that magnifies existing weaknesses across agricultural systems. Early warnings and climate services like seasonal outlooks are vital to help us adapt to the new reality,” WMO’s Saulo said.

Apart from its direct impacts, extreme heat when combined with droughts, wildfires, water stress, and pests has an escalating impact on production, the report cautioned.

Wide-ranging impacts – crops, fishes, livestock and humans

The impact of extreme heat on humans has received more attention in recent years – but the way in which heatwaves have also  affecting crop and fish production and therefore prices, has received less attention.

The extent of the impact of extreme heat is different relative to the context of when and where they occur.

For livestock, heat stress begins when the temperatures exceed 25°C. The threshold is even lower for chickens and pigs, as they are unable to cool themselves by sweating.

In 2025, more than 90% of the ocean’s global expanses experienced at least one marine heatwave, according to the WMO’s State of the Global Climate 2025 report. When heat rises in water bodies, it leads to a reduction in the presence of dissolved oxygen, making the fish struggle to maintain their respiration rates. As a result, they can suffer from cardiac failure, and production declines.

For most major agricultural crops, yield declines begin to occur above 30°C; but it is lower for some crops such as potatoes and barley. Evidence also points to a strong correlation between heat waves and wildfires, with longer and more intense fire seasons.

Agricultural labourers are hardest hit due to extreme heat as the number of days each year when it is simply too hot. The number of extreme heat days may soon rise to 250 per year in much of South Asia, tropical Sub-Saharan Africa and parts of Central and South America, according to the report.

Also read: ILO: Excessive Heat Linked to Climate Change Affects 70% of Workers

Key insights for policymakers

Along with more selective development of climate-resistant plant and animal species, the report highlighted the need for adjustments in planting windows and altered water management practices,  so that crops and agricultural activities can be sheltered from the impacts of extreme heat.

The report also urges countries to improve access to financial services like cash transfers, insurance and payment schemes, and other climate shock-resilient social protection schemes for agrifood workers.  Innovative insurance schemes are currently being tested in developing countries like India, but their effectiveness is yet to be proven.

“Protecting the future of agriculture and ensuring global food security will require not only building on-farm resilience but also exercising international solidarity and collective political will for risk sharing, and a decisive transition away from a high-emissions future,” the report says.

Image Credits: WMO, Extreme heat and agriculture report.