Climate Change Is Outpacing Health Action as Heat Deaths Hit Record Highs, Lancet Countdown Warns

Climate change should be formally declared a global health emergency, according to the authors of the 2026 Report of the Lancet Countdown on Health and Climate Change, published in The Lancet ahead of the 31st UN Conference of the Parties. The tenth annual indicator report, led by University College London and produced in collaboration with the World Health Organization, draws on the work of 146 multidisciplinary researchers from more than 100 institutions across more than 30 countries. It tracks 54 indicators of the health impacts of climate change and the health effects of climate action, and its central conclusion is stark: many of the health harms of climate change grew faster in the decade since the Paris Agreement entered into force, from 2016 to 2025, than in the previous decade from 2006 to 2015, as climate action fails to keep pace with the escalating harm.

The most striking finding concerns heat. Heat was linked to an average of 540,800 estimated deaths per year between 2016 and 2023, of which 68 percent, or 369,900 deaths, were attributed to human-caused climate change, up from 55 percent, or 219,100 deaths per year, in 2006 to 2015. In 2023 alone, the hottest year in that period, heat was linked to a record 710,000 estimated deaths, exceeding deaths from malaria or HIV, with 71.5 percent of them driven by climate change. Altogether, the report estimates that climate change caused almost 3 million heat deaths between 2016 and 2023. The report’s authors say the rate of increase in many climate-related health threats is accelerating, and that heat deaths linked to climate change have reached a record high.

The economic toll of heat is also mounting. Heat reduced people’s capacity to work productively in 2025, costing the global economy an estimated US$1.07 trillion in potential income, equivalent to 0.91 percent of global economic output, and marking the third consecutive year that losses topped US$1 trillion. South-East Asia and Africa were hit hardest, with losses equivalent to 3.9 percent and 3.2 percent of GDP respectively, compared with 0.2 percent in Europe and 1.5 percent in the Americas. The agriculture and construction sectors, both dominated by outdoor and physically demanding jobs, absorbed the biggest share of the losses, at 38 percent and 29 percent respectively, because heat directly impairs labour productivity and puts workers’ health at risk. In Africa, where agriculture accounts for 71 percent of heat-related potential income losses, the impact is particularly pronounced.

Water extremes are worsening alongside the heat. More than half the world’s land, 51.8 percent, was hit by extreme drought for at least a month in 2025, the second-worst year on record after 2023, and since 2016 the area affected by drought has grown more than 700 percent faster than it did in 2006 to 2015. A new satellite-based analysis identifies growing extremes in water storage: since 2003, 43 percent of the world’s land has seen a long-term drop in water storage, becoming drier, while a separate 37 percent has seen a long-term rise, becoming wetter. Together these hydrological extremes affect more than 80 percent of the world’s land and threaten crops, food supplies and sanitation. Very extreme rainfall is also becoming more common, reaching almost 17.2 percent of global land each year in 2016 to 2025, up from 14.8 percent the previous decade, increasing the risk of floods, landslides and waterborne disease.

Yet the report is not a catalogue of unrelieved bad news. Since the Paris Agreement, cleaner energy, more resilient health systems, more health-protecting legislation and growing scientific evidence have delivered real health benefits to local communities. Global investment in clean energy grew 7.2 percent in 2025 to a record US$2.1 trillion, 82 percent more than the US$1.16 trillion invested in fossil fuels, and such investment has helped renewable electricity grow from 5.5 percent of total generation in 2016 to 13.5 percent in 2023. Cleaner air has prevented an estimated 323,000 deaths a year in at least 77 countries where air pollution from fossil fuels has fallen since 2016. The report’s authors stress, however, that these gains are still too slow, too insufficient and too inconsistent to offset the growing risks.

Health systems are taking early action. A quarter of WHO member states, 56 of 194, now have a national plan for adapting health services to climate change, up from just 14 in 2015, and 47 have separately completed a vulnerability assessment to underpin such plans. Almost half of WHO member states declared having a health surveillance system that incorporates climate information, and more than half of respondents, 75 of 145, declared having at least one climate-informed health early warning system. Importantly, the report finds that health early warning systems are slowing down the increase in deaths from extreme weather events in the places that have them. Legal momentum is building as well: national laws referencing both climate change and health have risen roughly 50-fold since 2000, most of that growth since 2016. Funding for climate-related health research has also increased, up 655 percent between 2016 and 2024, from US$42 million to US$316 million, though almost all of it, 84 percent, still goes to researchers in the world’s wealthiest countries, leaving evidence gaps where the risks are often greatest.

Progress on the transition away from fossil fuels continues to fall short, and the report documents how production plans are increasingly misaligned with the Paris Agreement’s 1.5°C goal. The world’s 100 largest oil and gas companies are now planning to produce 150 percent more fossil fuels by 2040 than is compatible with keeping warming to 1.5°C, up from 138 percent in the previous year’s assessment. Fossil fuels still supply more than 80 percent of the world’s energy, and climate-heating emissions reached a record high in 2024. Despite gains in some countries, fossil-fuel air pollution still kills an estimated 2.73 million people a year worldwide. Production plans persist despite rising fossil fuel costs straining public finances: global net fossil fuel subsidies reached record levels in 2022 to 2024, net subsidies have doubled since 2016, with a cumulative US$6.20 trillion allocated since the Paris Agreement, and ten countries spent more on fossil fuel subsidies in 2024 than on their health systems.

The report also details how lobbying and disinformation by fossil fuel interests and their political allies continue to weaken support for climate action, and finds that national governments, international organisations and the private sector are now less engaged with health and climate change, reversing previous progress. Adaptation funding is falling far short of what is needed. The health adaptation needs quantified so far by developing countries, as classified by the UNFCCC, put the minimum cost at US$3.3 billion a year, based on data from only 48 of the 79 countries that have completed these estimates. Yet only around a third of this declared need, US$1.1 billion, was committed in 2024. Finance and human resourcing are identified as the top barriers to implementing Health National Adaptation Plans, and shrinking foreign aid budgets, including cuts to Overseas Development Assistance, risk widening the gap and placing the heaviest burden on the most vulnerable countries.

Against this backdrop, the report’s authors are calling for climate change to be formally recognised and addressed as a global health emergency, for a new WHO instrument to enable a coordinated global response, and for governments to put health at the centre of every climate decision, from emissions targets to climate funding priorities. Their priorities include urgent, fair cuts to greenhouse gas emissions, sustained investment in science, and climate finance for health delivered as grants rather than loans, so that countries can adapt without taking on more debt. Professor Marina Romanello, Executive Director of the Lancet Countdown at University College London, said the findings are unambiguous: the health harms of climate change are growing faster than the world’s response, and in many cases even accelerating, while real progress in clean energy, health system readiness and health-protective regulation is too slow and too small and is not reaching those who need it most. Helen Clark, former Prime Minister of New Zealand and Chair of the Board of the Lancet Countdown, said the report is a stark warning that climate change is a health emergency, and that what is missing is not evidence but the political will to act on it.

Professor Anthony Costello, Co-Chair of the Lancet Countdown, noted that ten years ago the group proposed that responding to climate change could offer the greatest health opportunity of the 21st century through adaptation and rapid progress in phasing down fossil fuels and other emission sources. A decade on, he said, there is proof that health-centred climate action works, with cleaner air, more resilient healthcare and warning systems protecting health and saving lives globally, but the pace and scale of emissions reduction remains entirely out of step with the pace and scale of the harm. The report was published ahead of COP31 and introduces four new indicators this year, covering the availability of water in land, healthcare sector greenhouse gas footprint assessments, climate-related health research funding, and legislative engagement with health and climate change, along with an updated media engagement indicator and a new attribution of estimated heat-related deaths to human-caused climate change. The report was supported by Wellcome, which provides core financial support to the Lancet Countdown, and its full author list and declarations of interest are provided in the paper.

Subject of Research: Health impacts of climate change and the health effects of climate action tracked by the 2026 Lancet Countdown report

Article Title: The Lancet: Experts call for climate change to be declared a global health emergency, as many health impacts outpace climate action

Article References: The Lancet: Experts call for climate change to be declared a global health emergency, as many health impacts outpace climate action. Original publication (Bibliographic details unavailable.)

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Keywords: Lancet Countdown, climate change, global health emergency, heat deaths, drought, Paris Agreement, fossil fuels, clean energy investment, health adaptation, WHO, COP31, air pollution