People in India experienced more than 2,600 hours annually during which heat posed a moderate or higher risk of heat stress during moderate outdoor physical activity, according to the 10th indicator report of the Lancet Countdown on Health and Climate Change. The report also estimated that high night-time temperatures caused people in India to lose an average of 64 hours of sleep annually between 2021 and 2025.
Released ahead of the 31st United Nations Climate Change Conference (COP31), the report found that the health impacts of climate change accelerated during the decade following the entry into force of the Paris Agreement in 2016, while global climate action failed to keep pace with the growing risks.
The report, led by University College London (UCL) in collaboration with the World Health Organization (WHO), calls for climate change to be formally recognised as a global health emergency. It recommends placing health considerations at the centre of decisions on emissions reduction, climate adaptation and climate finance.
India’s annual exposure to potentially harmful heat conditions was more than 200 hours higher than the average recorded in the 1990s. The estimated annual loss of sleep due to high night-time temperatures was approximately three hours greater than the annual average during 1986–2005.
Heat-Related Deaths and Extreme Weather Risks Increase
The report found that the global annual average of heat-related deaths increased by nearly 36% in the decade following the Paris Agreement. Human-caused climate change was responsible for more than 70% of the estimated 710,000 heat-related deaths recorded worldwide in 2023, the hottest year in the period examined.
Between 2016 and 2023, heat was associated with an estimated average of 540,800 deaths annually worldwide. Of these, approximately 369,900 deaths per year, or 68%, were attributed to climate change. This represented an increase from 55%, or 219,100 deaths annually, during 2006–2015.
In 2023 alone, an estimated 71.5% of heat-related deaths were linked to climate change. Overall, the report estimated that climate change contributed to nearly three million heat-related deaths between 2016 and 2023.
The findings also highlighted the growing threat of droughts and extreme rainfall. Nearly 52% of the world’s land experienced at least one month of extreme drought in 2025, marking the second-highest level on record.
According to the report, the area affected by drought has expanded more than 700% faster since 2016 than during the preceding decade. Meanwhile, very extreme rainfall affected an average of 17.2% of global land annually between 2016 and 2025, compared with 14.8% during the previous decade. These changes increase the risks of flooding, landslides and waterborne diseases.
The report also cited satellite-based analysis indicating that since 2003, approximately 80% of the world’s land has experienced significant shifts in groundwater storage patterns, with implications for food security, sanitation and access to water.
Paris Agreement Goals Remain Under Pressure
The Paris Agreement, which entered into force in 2016, established the goal of limiting global warming to well below 2°C above pre-industrial levels while pursuing efforts to limit the increase to 1.5°C.
However, an assessment by the United Nations indicated that current policies could result in global warming of approximately 2.8°C by the end of this century, with temperatures continuing to rise thereafter.
Professor Marina Romanello, executive director of the Lancet Countdown at UCL, said the health consequences of climate change were increasing faster than the global response.
The report acknowledged improvements in healthcare systems, cleaner energy, scientific research and climate-related legislation since 2016. However, it warned that these developments remain insufficient and inconsistent to counter the growing health risks.
The findings have particular relevance for India, where recurring heatwaves threaten outdoor workers, older people, children and individuals with existing health conditions. Extreme heat can cause dehydration, heat exhaustion and potentially fatal heatstroke, while aggravating cardiovascular and respiratory illnesses.
The authors warned that the benefits of cleaner energy and improved preparedness are being undermined by continued fossil fuel expansion and inadequate investment in climate adaptation.
Clean Energy Investment Offers Opportunities
Despite the worsening risks, the report identified progress in the transition towards cleaner energy. Global investment in clean energy reached a record $2.1 trillion in 2025, nearly twice the amount invested in fossil fuels.
The report estimated that cleaner air had helped prevent approximately 323,000 deaths annually across at least 77 countries where air pollution from fossil fuels had declined since 2016.
However, fossil fuels continue to account for more than 80% of global energy supply. The report also warned that the world’s 100 largest oil and gas companies remained on course to exceed production levels compatible with the 1.5°C warming target by 150% in 2040, up from an estimated 138% in the previous year’s assessment.
The findings underscore the need to accelerate the transition to cleaner energy while strengthening public health protection against rising temperatures and extreme weather.
Report Calls for Health-Centred Climate Action
The 10th indicator report represents the work of 146 multidisciplinary researchers from more than 100 institutions across over 30 countries. It tracks 54 indicators covering the health impacts of climate change and the consequences of climate action.
Four new indicators introduced this year examine land water availability, greenhouse gas emissions assessments in the healthcare sector, funding for climate-related health research, and legislative engagement with health and climate change.
The authors called for a coordinated international response, including a new WHO instrument to address climate-related health risks, faster and fairer reductions in greenhouse gas emissions, sustained investment in scientific research and increased funding for health adaptation.
They also urged governments to provide climate finance through grants rather than loans, enabling vulnerable countries to strengthen their healthcare systems without accumulating additional debt.
The report concluded that protecting public health must become a central objective of climate policy, as rising heat-related deaths, worsening droughts and extreme rainfall increasingly threaten communities, food systems and water security worldwide.
