Extreme Heat Threatens Global Food Systems, Endangering Livelihoods of Over a Billion People – UN Report Warns

Extreme heat is pushing global food and farming systems to the brink, threatening the livelihoods of over a billion people as rising temperatures and more frequent heatwaves redefine how food is produced worldwide, a new UN report warns.

The joint report by the Food and Agriculture Organization (FAO) and the World Meteorological Organization (WMO) finds that extreme heat is already causing half a trillion work hours to be lost each year, with impacts set to intensify as temperatures rise.

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

Across farming systems, the impacts are already visible. For many major crops, yields begin to decline above 30°C (86°F), leading to weakened plant structures and reduced productivity. Livestock experience stress at even lower temperatures, particularly pigs and poultry, which cannot cool themselves efficiently, resulting in reduced growth, lower dairy yields and, in severe cases, organ failure.

In oceans, rising temperatures are lowering oxygen levels, putting fish under strain – with 91 per cent of the global ocean experiencing at least one marine heatwave in 2024.

Wheat and maize, which has seen a 10% decrease in some areas, is projected to decline further as temperatures rise to more than 1.5C above preindustrial levels.

Farmers could find it impossible to work safely for as many as 250 days of the year – more than two-thirds of the time – in already hot regions including much of India and south Asia, tropical sub-Saharan Africa and swathes of Central and South America.

Livestock are already experiencing an increase in mortality rates, as heat stress begins for common species at about 25C. Extreme heat reduces yields from dairy cows and cuts the fat and protein content of milk. Pigs and chickens are unable to sweat and, as temperatures rise, face digestive tract breakdowns, organ failure and cardiovascular shock.

Yields begin to decline at temperatures above 30C for most agricultural crops, with damage including weakened cell walls and the production of toxins.