By Joke Kujenya
FAILURE TO act on climate change is now claiming millions of lives every year, according to the 2025 Lancet Countdown on Health and Climate Change released in collaboration with the World Health Organization (WHO).
The report warns that the world’s overreliance on fossil fuels and slow adaptation to rising global temperatures are already causing widespread harm to human health, weakening economies, and overwhelming health systems.
The 2025 edition of the report finds that 12 of 20 key health indicators linked to climate threats have reached record highs.
The findings underscore the scale of global inaction and the urgent need to make health protection the central focus of climate policy.
“The climate crisis is a health crisis. Every fraction of a degree of warming costs lives and livelihoods,” said Dr Jeremy Farrar, WHO Assistant Director-General for Health Promotion, Disease Prevention and Care.
“This report, produced with WHO as a strategic partner, makes clear that climate inaction is killing people now in all countries.
However, climate action is also the greatest health opportunity of our time. Cleaner air, healthier diets, and resilient health systems can save millions of lives now and protect current and future generations.”
The report paints a stark picture of global vulnerability, from rising heat-related deaths to mounting economic strain. It also highlights examples of progress, showing how rapid, health-centred climate action can save lives and drive sustainable growth.
Among its key findings, the 2025 Lancet Countdown report reveals that heat-related deaths have risen by 23% since the 1990s, reaching an annual average of 546,000 deaths.
It says the average person experienced 16 days of dangerous heat in 2024 that would not have occurred without human-induced climate change. Infants and older adults bore the brunt, facing more than 20 days of heatwave exposure per person, a fourfold increase over the past two decades.
The data further link extreme weather events to food insecurity. Droughts and heatwaves in 2023 pushed an additional 124 million people into moderate or severe food insecurity, worsening global hunger and malnutrition.
WHO officials note that such conditions increase the risk of disease outbreaks, displacement, and mortality, particularly in vulnerable communities.
On the economic front, the report finds that global heat exposure in 2024 led to the loss of 640 billion potential labour hours, with productivity losses valued at US$1.09 trillion.
Heat-related deaths among older adults carried costs of approximately US$261 billion, underscoring the severe financial toll of rising temperatures.
The report also exposes a striking imbalance in government spending. In 2023, nations collectively provided US$956 billion in net fossil fuel subsidies, more than triple the amount pledged to help climate-vulnerable countries adapt and respond to climate change.
Fifteen countries spent more on subsidising fossil fuels than on their entire national health budgets.
Dr Marina Romanello, Executive Director of the Lancet Countdown at University College London, emphasised that solutions already exist.
“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,” she said.
She added that rapidly phasing out fossil fuels in favour of renewable energy and efficiency remains the most powerful way to slow global warming and protect human health.
“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,” Dr Romanello stated.
The report also outlines the positive impacts of current climate actions. Between 2010 and 2022, reductions in coal-derived air pollution helped prevent an estimated 160,000 premature deaths annually.
Renewable energy sources accounted for a record 12% of global electricity generation, supporting 16 million jobs worldwide. In 2024, two-thirds of medical students received training in climate and health, indicating growing recognition of climate impacts within the health sector.
Despite the overall warning tone, the Lancet Countdown notes significant progress by cities, local authorities, and the health sector. Nearly all reporting cities — 834 out of 858 — have completed or are in the process of completing climate risk assessments.
These actions are laying the foundation for more resilient urban environments and public health systems.
Health systems themselves have made strides.
Also, data provided by WHO show that global health-related greenhouse gas emissions dropped by 16% between 2021 and 2022, even as care quality improved.
Moreover, 58% of WHO-Member States have completed a health vulnerability and adaptation assessment, while 60% have finalised a Health National Adaptation Plan.
These measures are helping governments prepare for the increasing health risks of a warming planet.
The report also frames these developments as a call to further integrate health into the core of global climate action.
With the 2025 United Nations Climate Change Conference (COP30) scheduled to take place in Belém, Brazil, the findings are expected to inform the next stage of negotiations and commitments.
According to WHO, the forthcoming COP30 Special Report on Climate Change and Health will build on the Lancet Countdown’s findings, highlighting key policies and investments needed to protect global health and deliver on the Belém Action Plan — the anticipated outcome of COP30.
As such, the report is expected to advocate for coordinated strategies that address both mitigation and adaptation through a health-centred lens.
Also, according to the report, the Lancet Countdown on Health and Climate Change operates in partnership with Wellcome, which continues to provide core financial support.
The initiative is led by University College London in collaboration with WHO and 71 academic and United Nations institutions worldwide.
Now in its ninth year, it offers the most comprehensive annual assessment of how climate change impacts health and what can be gained through swift, coordinated action.
Meanwhile, key global findings in the Lancet 2025 report, shows:
▪️Heat-related mortality: Up by 23% since the 1990s, averaging 546,000 deaths annually.
▪️Heat exposure: Average person faced 16 dangerous heat days in 2024, not possible without climate change. Infants and older adults each endured 20+ heatwave days per person, four times more than two decades ago.
▪️Food insecurity: 124 million additional people faced moderate or severe food shortages in 2023 due to droughts and heatwaves.
▪️Labour productivity: 640 billion potential labour hours lost in 2024; economic losses reached US$1.09 trillion.
▪️Economic losses from elderly heat deaths: Valued at US$261 billion.
▪️Fossil fuel subsidies: US$956 billion in 2023—triple the global annual pledge to help climate-vulnerable nations. Fifteen countries spent more on fossil fuel subsidies than their total national health budgets.
▪️Air pollution gains: 160,000 premature deaths avoided annually (2010–2022) through reduced coal-based air pollution.
▪️Renewable energy: Supplied 12% of global electricity in 2024, supporting 16 million jobs worldwide.
▪️Medical education: Two-thirds of medical students trained in climate and health.
▪️Health sector emissions: Fell 16% globally (2021–2022).
▪️Adaptation readiness: 58% of WHO Member States completed health vulnerability assessments; 60% finalised Health National Adaptation Plans.
▪️Cities’ climate assessments: 834 of 858 reporting cities have completed or are finalising risk assessments.
In summation, these figures depict the growing human, economic, and environmental costs of climate inaction, while highlighting that decisive climate action delivers measurable health and economic benefits, the 2025 Lancet report reveals.
