The sharp increase in the frequency, intensity and duration of extreme heat events over the past 50 years is set to create significant risks to agrifood systems and ecosystems in the future, according to a new report from the Food and Agriculture Organization (FAO) of the United Nations and the World Meteorological Organization (WMO).
The joint FAO-WMO report describes the physical science of extreme heat, the vulnerabilities observed and the projected impacts on agriculture. It also offers adaptation strategies, case studies and policy recommendations.
“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.
WMO secretary-general Celeste Saulo added, “Extreme heat is increasingly defining the conditions under which agrifood systems operate. More than simply an isolated climatic hazard, it 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.”
Impact on environment, ecosystems and people
The report found that for the most common livestock species, stress begins at above 25°C, which can be lower for animals such as chickens and pigs, which cannot cool themselves by sweating.
Fish can suffer cardiac failure as they struggle to maintain elevated respiration rates in waters where extreme heat events drive dissolved oxygen levels lower. In 2025, more than 90% of the global ocean experienced at least one marine heat wave, according to WMO’s State of the Global Climate 2025 report.
For most major agricultural crops, yield declines begin to occur above 30°C – lower for some crops, such as potatoes and barley. Evidence in the report underlines a strong correlation between heat waves and wildfires, with longer and more intense fire seasons.
Extreme heat also poses a danger to agricultural laborers, and the number of days when it is too hot to work could 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.
The report says that it is not just the direct impacts that pose a danger, but also the role of extreme heat as a risk multiplier for water stress, flash droughts and wildfires, or fostering the spread of pests and diseases.
The report covers such effects, including the less-understood consequences of a rapid rise in temperature, such as flash drought.
Report recommendations
The report points to the need for innovation and the implementation of adaptive measures such as selective breeding and crop choices adjusted to the new climate reality, adjusted planting windows and altered management practices that can shelter crops and agricultural activities from the impacts of extreme heat.
Early warning systems are a particularly important tool to help farmers respond to extreme heat.
Access to financial services – cash transfers, insurance and payment schemes, shock-responsive social protection schemes and other forms – underpins all categories of adaptation options.
In related news, a study has identified the atmospheric trigger behind flash droughts in Puerto Rico