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Report warns of 'dangerous feedback loop' where climate driven production shortfalls fuel expansion of damaging practices
Extreme heat is "increasingly defining" the conditions under which the world's agrifood systems operate, according to a new UN report, which argues on-farm resilience and adaptation measures are urgently required to maintain food security.
The study from the UNs Food and Agriculture Organisation (FAO) and the World Meteorological Organisation (WMO) stresses that extreme heat already threatens the livelihoods and health of over a billion people and causes half a trillion work hours to be lost each year.
Titled "Extreme heat and agriculture", the joint report explores how sustained high temperatures impact agricultural systems and can interact with rain, solar radiation, humidity, wind, and drought to trigger devastating impacts.
"Extreme heat" refers to occasions where day and night time temperatures rise above their usual ranges for a protracted period, causing physiological stress and direct physical damages to food crops, livestock, fish, trees, and people. According to the report, its intensity roughly doubles at 2C of global warming, and quadruples at 3C relative to a 1.5C increase in average global temperatures.
As such, the study warns yields of crops like maize and wheat have already declined by 7.5 and six per cent for every 1C of warming and are projected to fall by up to an additional 10 per cent for every 1C of warming in the future.
It adds that under high-emission scenarios, nearly half the world's cattle could be exposed to dangerous heat by 2100, with annual losses nearing $40bn. These impacts could be reduced by almost two-thirds under a low-emission scenario that limits future temperature increases.
The report also highlights how the number of days each year when it is too hot to work may rise to 250 in parts of South Asia, tropical Sub-Saharan Africa, and parts of Central and South America.
The study adds how marine heatwaves have already caused repeated mass mortality events and are forcing fish stocks to migrate in search of cooler water, while fruit and nut trees and natural forests are less productive and at growing risk of more frequent and intense wildfires.
Together, such losses create what the FAO and WMO describe as a "dangerous feedback loop", where shortfalls in farm production lead to agricultural expansion to compensate - thereby increasing greenhouse gas emissions that will fuel further climate change.
With global mean temperatures on the cusp of exceeding the 1.5C warming limit outlined in the Paris Agreement, the report warns the "fingerprints of extreme heat" on agriculture are already visible and argues there is an urgent need for adaptation and mitigation measures worldwide.
"As the frequency and intensity of extreme heat events continue to increase with climate change, building systemic resilience through adaptation and dedicated risk reduction is imperative," the report states. "The path forward requires a shift from reactive crisis management to proactive risk reduction, beginning with the empowerment of agricultural producers by giving them access to essential information and tools."
In addition to ambitious and multilateral efforts to cut emissions, the report sets out the pressing need for innovation and the implementation of adaptative measures such as selective breeding and crop choices that could help farmers respond to the "new climate reality".
Moreover, calls for adjustments to planting windows, alterations to management practices that can shelter crops and agricultural activities from the impacts of extreme heat, and the wider use of early warning systems as part of new adaptation strategies for farmers.
The FAO and WMO added that improved access to financial services - such as cash transfers, insurance and payment schemes, and shock-responsive social protection schemes - are required to underpin adaptation efforts.
"Extreme heat is increasingly defining the conditions under which agrifood systems operate," said WMO Secretary-General Celeste Saulo, who stressed that it acts "as a compounding risk factor that magnifies existing weaknesses across agricultural systems".
In one stark example, the report cites how in the spring of 2025 part of Kyrgyzstan endured a period of temperatures that were 10C higher than usual, leading to a thermal shock for fruit and wheat crops, a locust outbreak, heightened evaporation that reduced irrigation capacity, and eventually a 25 per cent decline in cereal harvests.
The report adds that rising average global temperatures and more frequent and intense extreme heat events also narrow the "thermal safety margin" species rely on for biological processes that support photosynthesis, cellular regeneration, and reproduction.
For the most common livestock species, stress and suffering generally begins at above 25C - though this threshold is slightly lower for chickens and pigs, which are unable to cool themselves by sweating. For most major agricultural crops, yield declines begin to occur above 30C, according to the study.
"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 Qu Dongyu, director-general of the FAO.
Higher temperatures are coming and farmers, food companies, and policymakers will have to respond. Proven techniques and technologies exist that can enhance climate resilience, while shifts in diets are also likely to be required. But changes will have to come fast if the world is to avert a climate-induced food security crisis that will only compound the geopolitical challenges already stalking the globe.
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