Rising temperatures pose a significant threat to human health and, consequently, to work productivity, especially for informal manual laborers. Migrant laborers from eastern Indian states like Bihar, Jharkhand, West Bengal, and Odisha come to Delhi for manual work in Gurugram, facing challenges in maintaining their income. These labourers are mostly small and marginal farmers in their home states, seeking to supplement their income during the lean season by working in big cities to support their agricultural activities.
“Severe heat puts our bodies out of gear,” said Jagganath, a labourer and contractor from eastern Odisha, who was contracted to clean the sewage system in a high-income locality of Gurugram before the rainy season. “What five of us could finish in a week now takes us 12 days because the extreme heat is affecting our work schedule. We generally work during the early hours, but fewer working hours are impacting our income, which we need to support our farming back in the village,” he explained while resting under a Neem tree in the lane.
What Jagganath highlighted is the increasing heat stress that is silently undermining their income and health. He points out that he has not contributed to the rise in global temperatures, unlike affluent localities or wealthy countries.
A new study by the UK-based nonprofit Energy and Climate Intelligence Unit (ECIU) has shed light on the loss of working hours on farms due to heat stress. Workers in the study's countries are losing an average of 50 days a year to heat stress, and the hours lost are increasing by 4-5 hours each year due to climate change. Alarmingly, India ranks highest in the number of work hours lost to heat.
Heat stress to India’s farm sector
Indian farm workers lose nearly 81 working days a year due to heat stress. This figure has increased by 52% since 1990, highlighting the significant threat that heat stress poses to food security.
The study Heat Stress & UK Food Imports reports that each Indian worker lost 648 hours in 2024, reflecting a 52% increase since 1990. Assuming a working day consists of eight hours, this loss amounts to a total of 81 days. The study aimed to examine the effects of heat stress on countries that supply food to the UK and assess their vulnerabilities to the UK's food security.
The report indicates that El Niño cycles can exacerbate these impacts, increasing risks for food crops in India. In 2025, extreme weather events occurred on 331 out of 334 days from January to November, according to an analysis by a Delhi think tank. These events, including heatwaves, heavy rainfall, floods, landslides, and extreme cold, resulted in at least 4,419 fatalities and significant crop losses.
The study highlighted a specific instance of heat stress in 2023 that resulted in crop losses, particularly in tomatoes, affecting labor and food availability. In 2023, extreme rainfall in some regions of India caused the price of tomatoes to surge by 400% due to crop damage from flooding. Simultaneously, extreme heat and humidity—made 30 times more likely by climate change—along with record monsoon rains adversely impacted rice crops, leading to domestic food shortages and restrictions on exports.
Global heat stress and dipping income
In 2025, the UK is set to import £7.4 billion worth of food from 15 countries, representing 11% of the nation’s total food imports by value. Key products include essential items such as rice, sugar, lentils, nuts, fish, and soy for animal feed, as well as various fruits and vegetables like grapes, onions, oranges, and peas. Additionally, the imports encompass coffee, chocolate, wine, and tequila.
The countries involved in this trade include Brazil, Peru, Colombia, Ecuador, Mexico, and Argentina from Latin America; South Africa, Kenya, Egypt, Ghana, and Côte d’Ivoire from Africa; and India, Vietnam, Indonesia, and Papua New Guinea from Asia. Notably, these countries score below 50 on the Notre Dame Global Adaptation Initiative (ND-GAIN) Climate Vulnerability Index, indicating significant climate risks and limited capacity for adaptation. Rising temperatures are already exerting pressure on agricultural labor forces in these regions, impacting their ability to meet global food demands.
Heat stress poses a growing global concern. According to the International Labour Organisation (ILO), by 2030, heat stress could reduce global working hours by 2.2%, costing an estimated $2.4 trillion in GDP—a significant increase from $280 billion in 1995. As of 2024, around 71% of the global workforce faces excessive heat exposure, with the risk even higher in Asia (74.7%), the Arab states (83.6%), and Africa (92.9%). Outdoor workers, in particular, suffer from extreme heat conditions, lacking access to cooling methods and adequate shade.
Recent years have witnessed unprecedented climate conditions, with 2025 marking the third hottest year on record, following 2023 and 2024. Global average temperatures continue to rise, breaking heat records annually. The anticipated strong El Niño effect in 2026 could exacerbate climate change impacts, potentially making 2027 the hottest year yet.
Heat stress is becoming a silent pandemic that disproportionately affects older adults and individuals in less affluent regions lacking air conditioning. Its impact restricts everyday activities, such as walking and light household tasks, and these limitations have sharply increased over the past 75 years, particularly since 1995. As climate change intensifies, addressing these challenges becomes increasingly urgent.
