Extreme heat threatens livelihoods, health of over a billion people

• A joint report by the Food and Agriculture Organisation of the United Nations (FAO) and the World Meteorological Organisation (WMO) finds that extreme heat events currently threaten the livelihoods and health of over a billion people.

• Extreme heat refers to situations where daytime and nighttime temperatures rise above their usual ranges for a protracted period, leading to physiological stress and direct physical damages to food crops, livestock, fish, trees and human beings.

• The frequency, intensity and duration of extreme heat events have risen sharply over the past half century, and the risks to agrifood systems and ecosystems are set to soar in the future.

• Extreme heat is already causing half a trillion work hours to be lost each year, with impacts set to intensify as temperatures rise.

• Agricultural workers and agrifood systems are on the frontlines, absorbing the greatest impacts from extreme heat.

A risk multiplier

• 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.

• Across farming systems, the impacts are already visible. For many major crops, yields begin to decline above 30°C, leading to weakened plant structures and reduced productivity. 

• For the most common livestock species, stress begins at above 25°C, and a bit lower for chickens and pigs, which are unable to cool themselves by sweating. 

• Above that threshold, animals begin to suffer, initially seeking shade, drinking more water, eating and moving less, while if exposure persists, they begin to suffer from digestive tract breakdowns, organ failure and cardiovascular shock. 

• Even when not lethal, extreme heat reduces dairy yields as well as fat and protein content — which worsens the carbon footprint of animal-sourced foods. 

• 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 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. Forests are also affected, as extreme heat disrupts photosynthesis and increases the risk of wildfires.

• Extreme heat also amplifies other climate risks. It can trigger droughts, worsen water scarcity, increase wildfire risks and accelerate the spread of pests and diseases – creating what the report describes as “compound effects” that ripple across entire ecosystems.

• In some regions, these impacts are already severe.

• A 2025 heat event in Kyrgyzstan, for example, saw temperatures rise around 10°C above normal, contributing to a 25 per cent decline in cereal harvests, while also triggering locust swarms and reducing irrigation capacity.

• Elsewhere, prolonged heat and drought conditions in Brazil in 2023 and 2024 cut soybean yields by as much as 20 per cent, while a major heatwave across North America in 2021 led to significant losses in fruit crops and a sharp spike in forest fires.

• The human toll is equally stark. In parts of South Asia, sub-Saharan Africa and Latin America, the number of days too hot to work could rise to 250 per year — putting millions of agricultural workers at risk and undermining food production.

Call to action

• The report points to the need for innovation and the implementation of adaptative measures such as selective breeding and crop choices adjusted to the new climate reality, adjusting planting windows and altering management practices that can shelter crops and agricultural activities from the impacts of extreme heat. 

• Early warning systems are a particularly important tool in aiding farmers in their efforts to 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. 

• Technical solutions are necessary but by themselves will be insufficient without addressing pervasive socio-economic barriers in low and middle-income countries, including limited access to information, education, awareness and training.

(The author is a trainer for Civil Services aspirants.)