The Lancet Countdown 2025 Report is out: here is CSH’s take on it
The Lancet Countdown on Health and Climate Change is an international research collaboration monitoring the evolving impacts of climate change on health and tracking the benefits of climate action. In its 10th annual report, the 2025 Lancet Countdown reveals the latest evidence on how the health of people worldwide is deeply interlinked with our planet’s climate health.
Delays in climate action are costing lives, but health leadership offers a lifeline
Climate change is no longer a distant risk; it is a public health emergency unfolding now. The 2025 Lancet Countdown on Health and Climate Change delivers a stark warning: delays in climate action are claiming millions of preventable lives and destabilising health systems globally. But it also offers hope. Countries, cities, and communities that are taking decisive action are already seeing measurable health and economic benefits.
Our Founder and CEO, Rachel Stancliffe, emphasised that the 2025 Lancet Countdown Report highlights the urgent need to accelerate health-led climate action, calling for stronger investment in adaptation, the rapid phase-out of fossil fuels, and bold policies that put human health and wellbeing at the centre of climate decision-making.
“We have the data, the evidence and the tools. What we need now is courage and collaboration. Healthcare professionals can lead the change towards systems that protect both people and the planet”
Rachel Stancliffe, Founder and CEO, the Centre for Sustainable Healthcare
The human cost of inaction
Across 13 of 20 health impact indicators, the situation has worsened, the highest levels since the Lancet Countdown began tracking the health dimensions of climate change.
Heat exposure has intensified: Adults over 65 experienced 304% more heatwave days in 2024 than in 1986–2005, and infants 389% more.
Heat-related mortality now averages 546,000 deaths annually, a 63% rise since the 1990s.
Heat and physical activity: People were exposed to an average 1,609 hours in 2024 where outdoor activity carried moderate or greater heat stress risk, 36% higher than the 1990s baseline.
Rising night-time temperatures have increased sleep loss by 9% globally, undermining physical and mental health.
Mental health risks are worsening: social sentiment during extreme weather events declined by 132%, indicating heightened stress, anxiety, and reduced wellbeing.
The indirect effects of climate change are equally grave. Extreme weather, floods, and droughts are driving food insecurity and undermining livelihoods. The number of undernourished people has been steadily rising since 2014.
Diet-related deaths reached 11.8 million in 2022, including 1.9 million deaths from excessive red meat and dairy consumption, deaths that are largely preventable through healthier, more climate-friendly diets.
Infectious disease risks are escalating: dengue transmission potential has increased by 48.5%, malaria risks have expanded in highland regions, and tick-borne disease areas now cover an additional 364 million people.
These health burdens are no longer isolated environmental issues, they are reshaping the very foundations of public health, deepening inequities, and stretching healthcare systems to their limits.
Glimmers of progress
Amid these alarming trends, the Lancet Countdown also points to encouraging developments that show the life-saving power of climate action:
Air pollution progress: Deaths from fossil fuel-derived outdoor air pollution have fallen by 5.8% since 2010, avoiding 160,000 deaths annually, largely driven by coal phase-out policies in high-income countries.
City-level resilience:97% of surveyed cities have completed or are developing climate risk assessments, reflecting a growing commitment to local adaptation.
Healthcare leadership: Health system emissions fell by 16% between 2021 and 2022, showing that decarbonisation within healthcare is both possible and impactful.
Growing scientific engagement: Research on health and climate change is accelerating rapidly, over 6,000 peer-reviewed articles were published in 2024, a tenfold increase since 2010. Studies on climate impacts with attributable links to human-caused climate change have also surged, exceeding 4,500 studies globally.
Education momentum:66% of public health institutions and 72% of medical schools now provide climate-health education, equipping the next generation of practitioners to respond effectively to this crisis.
“As some countries and companies rollback on climate commitments, local and grassroots leadership is building momentum for a healthier future.”
Lancet Countdown 2025 report
This progress demonstrates that climate action, even when limited, delivers measurable and immediate health gains. As climate-driven events increase, urgent investment in robust, equitable healthcare systems is essential to meet the growing demand.
Healthcare at the forefront of climate action
The 2025 report sets out a clear, evidence-based roadmap for health professionals and systems worldwide. It calls for urgent acceleration in five priority areas:
Develop and implement evidence-based adaptation plans to strengthen health system resilience and adaptive capacity.
Educate and train the health workforce to prepare and respond to the growing health effects of climate change.
Reduce healthcare emissions through optimised resource use, elimination of waste, and rapid transition to renewable energy.
Establish rigorous monitoring and evaluation to assess interventions and course-correct based on evidence.
Raise awareness among patients and the public to promote behaviours that improve both climate outcomes and personal health.
These actions are no longer optional, they are essential to safeguard global health security.
The NHS: leading the way, but urgent acceleration is needed
The UK’s National Health Service remains the world’s first health system to commit to net zero, a landmark achievement, but the Lancet Countdown 2025 underscores that the pace of change must now increase.
Climate pressures on care delivery are mounting: Heatwaves, flooding, and infrastructure stress are increasingly disrupting hospitals, supply chains, and workforce wellbeing.
Adaptation planning must be embedded across all NHS Trusts, ensuring that services remain resilient to future climate shocks.
Education and engagement remain vital: every healthcare professional must understand the health impacts of climate change and integrate sustainability into their practice.
Green investment and system innovation are critical to ensuring that decarbonisation enhances, rather than compromises, patient care.
The NHS has shown the world that health-led climate action is possible. But with health impacts worsening globally, the time for incremental progress has passed — bold, systemic transformation is now required.
CSH in action: translating evidence into transformation
At the Centre for Sustainable Healthcare, we’re turning evidence into action, supporting healthcare systems to put sustainability at the heart of care delivery. Through our education programmes, community initiatives, and partnerships across the NHS, we help healthcare professionals translate climate ambition into measurable impact.
When sustainability is embedded in everyday practice, healthcare not only reduces emissions but also improves outcomes, builds resilience, and strengthens the wellbeing of patients, staff, and communities.
Sustainable healthcare education
Our Education Programme offers a wide range of professional training and educational courses to equip healthcare teams with the knowledge, confidence and practical tools to embed sustainable approaches in their practice; including making changes at an individual or team level, introducing sustainability to quality improvement processes, undertaking carbon footprint calculations, and take a leadership role on meeting Net Zero targets.
Our Green Health Routes initiative offers a practical, health-positive approach to climate adaptation by connecting communities with local green spaces. This programme, which encourages outdoor activity in parks, woodlands, and meadows, is supported by healthcare practitioners and includes ‘green prescriptions’ that foster both physical and mental wellbeing.
We support NHS Trusts and healthcare organisations in the UK and internationally to embed sustainability into quality improvement and service design through our Sustainability in Quality Improvement (SusQI) framework. SusQI provides a holistic approach to healthcare improvement, viewing every change through a lens of sustainable value. To help teams apply this in practice, CSH offers strategic guidance, project support, training courses, and open-access SusQI resources.
The 2025 Lancet Countdown makes the health consequences of inaction undeniable, but it also highlights the transformative potential of climate action led by the health sector. Every measure to reduce emissions, adapt systems, or empower communities is a step towards saving lives.
At the Centre for Sustainable Healthcare, we stand with the Lancet Countdown in calling for urgent, coordinated action to protect health in a changing climate. We champion health-centred, evidence-based solutions that reduce emissions, strengthen resilience, and promote equity across healthcare systems. Together, we can create a future where sustainability is integral to care, safeguarding the wellbeing of people and the planet for generations to come.
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