Climate-linked heat deaths have climbed steeply in the decade since the Paris Agreement, according to the tenth Lancet Countdown report on health and climate change, which was published on Wednesday. The study found that annual average heat-related deaths rose by nearly 36 per cent after the accord was introduced, and that a growing share of them can be traced to human-caused warming. India is among the countries with the highest heatwave exposure for the most vulnerable age groups.
What the Lancet Countdown Report Found
The 2026 edition draws on the work of 146 researchers at more than 100 institutions in over 30 countries, according to ABC News, and tracks 54 indicators of how climate change affects health. Heat was linked to an average of about 540,800 deaths a year between 2016 and 2023, the latest year for which data are available. Researchers attributed 68 per cent of those deaths to climate change.
The year 2023 stood out as the worst on record. Heat was linked to an estimated 710,000 deaths, a figure that exceeds annual deaths from malaria or HIV, and 71.5 per cent of them were driven by climate change, according to the findings reported by the Press Trust of India. Across the eight years from 2016 to 2023, climate change is estimated to have caused almost 3 million heat deaths. The authors said it was the first time the Countdown had directly quantified heat deaths caused by human-induced warming.
Marina Romanello, executive director of the Lancet Countdown and a professor at University College London, said the findings were unambiguous. In her assessment, the health harms of climate change are growing faster than the world’s response, and in many cases are accelerating.
Why Climate-Linked Heat Deaths Matter for India
The report’s findings carry particular weight for India. Press Trust of India reported that India ranked among the top countries for heatwave exposure for both infants and older adults, alongside China, the United States and Russia. Globally, 2025 was the second highest year on record for heatwave exposure among these groups. Older adults experienced 10.8 billion person-days of heatwaves and infants 1.1 billion, compared with the record highs of 15.3 billion and 2.3 billion in 2024.
Last year’s edition had already flagged the scale of the risk. It found that people in India experienced an average of 19.8 heatwave days in 2024, of which about 6.5 would not have been expected without climate change, and that heat exposure cost India an estimated 247 billion potential labour hours. Agriculture accounted for 66 per cent of those losses and construction for 20 per cent, as reported by The Tribune.
Drought, Lost Work and Wider Harms
Heat is only one strand of the picture. The report found that drought affected more than half of the world’s land for at least a month in 2025, and that the pace at which land is hit by extreme drought has accelerated by about 700 per cent between 2016 and 2025 compared with the previous decade, according to ABC News. Globally, heat exposure caused the loss of 573 billion potential work hours in 2025, equivalent to US$1.07 trillion in lost income, with low and middle-income countries bearing the heaviest burden.
The authors also warned that a severe El Niño could compound these impacts and trigger unprecedented humanitarian crises. They said fossil fuels still supply about 80 per cent of global energy, and that lobbying and disinformation by fossil fuel interests were obstructing the transition to cleaner sources.
Signs of Progress and the Call to Act
The report is not without encouraging findings. Renewable energy growth had vastly exceeded expectations, and clean energy had helped prevent an estimated 400,000 deaths in 2023 compared with 2016 through improved air quality. Policy progress has also helped reduce projected warming by 2100 from as much as 3.5 degrees Celsius to 2.6 degrees. Even so, the authors judged global action to be grossly insufficient.
Their central recommendation is that climate change be formally recognised as a global health emergency. They also want a new instrument from the World Health Organization to enable a coordinated global response, and for governments to place health at the centre of every climate decision, from emissions targets to climate funding. Climate finance for health, they said, should be delivered as grants rather than loans so that countries can adapt without taking on more debt.
Timing Ahead of COP31
The report was released ahead of the COP31 climate conference in Turkiye, where governments are expected to face pressure to translate commitments into implementation. For India, where heat already strains workers, children and the elderly, the Lancet Countdown report offers a measured but sobering reminder that the gap between pledges and protection is still wide.
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