Global Findings Suggest Millions of Lives Lost Annually Due to Inaction on Climate Change

October 28, 2025

by Lancet

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New global findings in the 9th annual indicator report of The Lancet Countdown on Health and Climate Change reveal that the continued overreliance on fossil fuels and failure to adapt to climate change is being paid in people's lives, health, and livelihoods, with 12 of 20 indicators tracking health threats reaching unprecedented levels.

The report says failure to curb the warming effects of climate change has seen the rate of heat-related deaths surge 23% since the 1990s, to 546,000 a year. In 2024 alone, air pollution from wildfire smoke was linked to a record 154,000 deaths, while the global average transmission potential of dengue has risen by up to 49% since the 1950s.

Authors say 2.5 million deaths every year are attributable to the air pollution that comes from continued burning of fossil fuels. This is also straining national budgets—as fossil fuel prices soared, governments collectively spent 956 billion US dollars on net fossil fuel subsidies in 2023. Meanwhile, oil and gas giants keep expanding their production plans—to a scale three times greater than a livable planet can support.

While some governments backtrack on climate commitments, the report also exposes the life-saving impact of action already underway. An estimated 160,000 lives are being saved annually from the shift away from coal and the resultant cleaner air, while renewable energy generation reached record-highs.

The report reveals the emerging leadership of local governments, communities, organizations and the health sector, and calls for 'all hands on deck' to accelerate progress.

As health threats from climate change reach unprecedented levels and political backsliding on climate action threatens to stall progress, the 2025 Report of The Lancet Countdown on Health and Climate Change issues a fresh clarion call for 'all hands on deck' to accelerate and intensify efforts to simultaneously reduce greenhouse gas emissions (GHG) and adapt to climate change.

'This year's health stocktake paints a bleak and undeniable picture of the devastating health harms reaching all corners of the world—with record-breaking threats to health from heat, extreme weather events, and wildfire smoke killing millions. The destruction to lives and livelihoods will continue to escalate until we end our fossil fuel addiction and dramatically up our game to adapt,' warned Dr. Marina Romanello, Executive Director of The Lancet Countdown at University College London.

She added, 'We already have the solutions at hand to avoid a climate catastrophe—and communities and local governments around the world are proving that progress is possible. From clean energy growth to city adaptation, action is underway and delivering real health benefits—but we must keep up the momentum.

'Rapidly phasing out fossil fuels remains the most powerful lever to slow climate change and protect lives. At the same time, shifting to healthier, climate-friendly diets and more sustainable agricultural systems would massively cut pollution, greenhouse gases and deforestation, potentially saving over ten million lives a year.'

The 9th Lancet Countdown annual indicator report, led by University College London, and produced in collaboration with the World Health Organization (WHO), represents the work of 128 leading experts from 71 academic institutions and UN agencies globally.

Published in The Lancet ahead of the 30th UN Conference of the Parties (COP), the report provides the most comprehensive assessment to date of the connections between climate change and health, including new metrics which record deaths from extreme heat and wildfire smoke, the coverage of urban blue spaces (rivers, lakes, and coastlines), health adaptation funding and individual engagement with health and climate change.

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The year 2024 was the hottest on record, with catastrophic consequences for the health, lives, and livelihoods of people across the globe, says the report. Worldwide, the average person was exposed to a record extra 16 health-threatening hot days owing directly to climate change, with the most vulnerable (those aged under 1 year and over 65 years) experiencing, on average, an all-time high of 20 heat wave days—a 389% and 304% increase, respectively, from the 1986–2005 yearly average.

In parallel, a new indicator in this year's report reveals that heat-related mortality per 100,000 increased by 23% since the 1990s, with total heat-related deaths reaching an average of 546,000 annually between 2012 and 2021.

Hotter and drier conditions have also fueled conditions for wildfires, with fine particle pollution (PM 2.5) from wildfire smoke resulting in a record 154,000 deaths in 2024 (up 36% from the 2003–2012 yearly average), while droughts and heat waves increased the number of people experiencing moderate or severe food insecurity by 123 million in 2023, compared to the annual average between 1981 and 2010.

Added to this, delays in the adoption of clean, climate-friendly energy means over 2 billion people still use polluting and unreliable fuels in their homes.

Across 65 countries with low access to clean energy, air pollution from the household use of dirty fuels resulted in 2.3 million avoidable deaths in 2022, including some of the 2.52 million deaths still attributable to ambient air pollution from the burning of fossil fuels globally.

Unsustainable food systems are also fueling climate change, and high-carbon, unhealthy diets contributed to 11.8 million diet-related deaths in 2022, which could largely be avoided by transitioning to healthier, climate-friendly food systems.

More broadly, the report highlights that climate change is increasingly destroying livelihoods, straining the economy, and burdening health budgets. Heat exposure resulted in a record 639 billion potential hours of lost labor productivity in 2024, with income losses equivalent to a staggering US$ 1.09 trillion (almost 1% of global GDP). At the same time, the cost of heat-related deaths in those over age 65 reached an all-time high of US$ 261 billion.

In response to soaring fossil fuel prices, and with outdated energy grids overly reliant on them, governments around the world poured US$ 956 billion into net fossil fuel subsidies in 2023 to keep energy locally affordable—increasing fiscal pressures and dwarfing the $300 billion a year committed to support the most climate-vulnerable countries made at COP29.

Concerningly, 15 out of 87 countries responsible for 93% of global CO2 emissions spent more on net fossil fuel subsidies than their national health budgets in 2023.

As Dr. Romanello explained, 'The increased affordability and accessibility of clean renewable energy presents an opportunity to increase local energy generation, reduce the health harms of fossil fuels, and support the redirection of fossil fuel subsidies towards promoting a healthier future.'

Also publishing today is the 2025 Latin America Report of The Lancet Countdown, which also identifies an alarming intensification and confluence of climate hazards. Professor Stella Hartinger, Director of The Lancet Countdown Latin America and global report author, said, 'Around the world we are seeing these multiple health impacts compound each other to trigger a cascade of harms that undermine the very social and economic foundations that support people's health and well-being.

'After nine years of global monitoring, it's clear that these health harms are the price we are paying for the consistent failure of global leaders to deliver the action needed to combat climate change and protect health—a price paid most severely by vulnerable countries that have contributed the least to the crisis.'

Authors say delays in adaptation are exacerbating the health harms of climate change. 'Scarce financial support for adaptation remains a key barrier, and data in this report shows it is still grossly insufficient to cover the financial needs disclosed by countries,' said Dr. Romanello.

'A political shift towards reduced foreign aid support from some of the world's wealthiest countries, further restricts financial support for climate change action, leaving all populations increasingly unprotected.'

Added to these growing harms, the report says political backsliding on climate and health action threatens to condemn millions to a future of disease, disasters, and early death. And yet, emboldened by growing profits and a fractured political consensus on climate commitments, the world's 100 largest fossil fuel giants have increased their projected production (as of March 2025), which would lead to their GHG emissions surpassing levels compatible with 1.5°C almost three times over by 2040, pushing the possibilities of health protecting adaptation efforts out of reach.

Private banks are supporting this deadly fossil fuel expansion, with the top 40 lenders to the fossil fuel sector collectively investing in a five-year high of US$ 611 billion in 2024 (up 29% from 2023). This exceeded their green sector lending by 15%, further hindering the zero-emission energy transition, threatening public health and jeopardizing national economies on which people's livelihoods depend.

While energy-related emissions break new record-highs, over 128 million hectares of forest were destroyed in 2023 (up 24% since 2022), diminishing the world's natural capacity to mitigate climate change.

'The stark reality is that one of the greatest threats to human prosperity comes from leaders and companies who are rolling back on climate commitments, delaying action, and doubling down on fossil fuel production—meanwhile each unit of greenhouse gases emitted drives up the costs and challenges of adaptation,' said Professor Nadia Ameli, Lancet Countdown Working Group 4 Co-Chair.

'If we remain locked into fossil fuel dependence, health systems, cooling infrastructure, and disaster response capacities will soon be overwhelmed—putting the health and lives of the world's 8 billion people further at risk.'

Countries facing the worst consequences consistently track as the most politically engaged in climate change and health, yet they are being left behind in the clean energy transition. Deeply unequal access to technology and clean energy is leaving the most vulnerable communities reliant on dirty, harmful fuels.

Just 3.5% of electricity comes from clean renewables in low-income countries compared with 13.3% in wealthy countries, while 88% of households in poorer countries still rely on polluting biomass to cook and heat their homes.

While some national governments roll back on climate commitments, the report outlines that local governments, individuals, civil society, and the health sector are leading the way in shaping a healthier future, signaling what could be the start of transformative climate action.

A growing number of cities (834 of 858 reporting in 2024) have completed or intend to complete climate change risk assessments, according to the CDP (the world's largest voluntary reporting system on climate change progress). The health sector itself has shown impressive climate leadership, with health-related GHG emissions falling 16% globally between 2021 and 2022, and almost two-thirds of medical students around the world received climate and health education in 2024, building capacity for further progress.

According to the report, the global momentum for climate change action is already delivering associated health and economic benefits. An increased shift away from coal, particularly in wealthy countries, prevented an estimated 160,000 premature deaths yearly between 2010 and 2022, due to fine particulate (PM2.5) air pollution from burning fossil fuels.

The share of electricity generated by modern renewables reached a record-high 12% in 2022, with the clean energy transition generating healthier, more sustainable jobs. Globally, over 16 million people worked directly or indirectly in renewables in 2023 (up 18.3% from 2022).

As Professor Tafadzwa Mahbhaudi, Director of The Lancet Countdown Africa explained, 'Climate change action remains one of the greatest health opportunities of the 21st century, also driving development, spurring innovation, creating jobs, and reducing energy poverty. Realizing the myriad benefits of a health-centered response requires unlocking so-far untapped opportunities to mitigate climate change and build resilience to the impacts already being felt.'

As Professor Anthony Costello, Co-Chair of The Lancet Countdown warned, 'As a rising number of world leaders threaten to reverse the little progress to date, urgent efforts are needed at every level and in every sector to both deliver and demand accelerated action that will yield immediate health benefits.

'As some governments uphold an unsustainable, unhealthy and ultimately unlivable status quo, people around the world are paying the ultimate price. We have to build on the momentum we have seen from local action: Delivering health-protective, equitable, and just transition requires all hands on deck.'

More information: The 2025 report of the Lancet Countdown on health and climate change, The Lancet (2025). DOI: 10.1016/S0140-6736(25)01919-1

Journal information: The Lancet

Provided by Lancet