WHO reports 100 countries join climate health alliance as inaction claims half a million lives annually

The global health community is confront­ing an escalating crisis as climate change drives unprecedented health impacts, with two landmark reports revealing both the devastating toll of inaction and emerg­ing international efforts to build resilient health systems.

The 2025 Lancet Countdown on Health and Climate Change, produced in collabo­ration with the World Health Organiza­tion, documents that 12 of 20 key health threat indicators have reached record lev­els, whilst simultaneously the Alliance for Transformative Action on Climate and Health has expanded to encompass 100 countries committed to climate-responsive healthcare infrastructure.

Heat-related mortality surges 23% since 1990s
The mortality burden from rising tem­peratures has intensified dramatically, with heat-related deaths averaging 546,000 an­nually, representing a 23% increase since the 1990s. Population-level exposure to dangerous heat conditions has expanded substantially, with the average person experiencing 16 days of climate change-attributable extreme heat in 2024. Vulner­able populations face disproportionate risks, with infants and older adults enduring over 20 heatwave days per person – a fourfold in­crease over two decades.

“The climate crisis is a health crisis. Ev­ery fraction of a degree of warming costs lives and livelihoods,” said Dr Jeremy Far­rar, Assistant Director General for Health Promotion and Disease Prevention and Care at the World Health Organization. “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.” Economic and food security impacts compound health burden.

The physiological consequences of cli­mate change extend beyond direct thermal stress. Droughts and heatwaves contributed to 124 million additional people facing moderate or severe food insecurity in 2023, whilst heat exposure eliminated 640 billion potential labour hours in 2024, generating productivity losses equivalent to US$ 1.09 trillion. The economic burden of heat-re­lated mortality amongst older adults alone reached US$ 261 billion.

Fossil fuel subsidies exceed climate finance by threefold margin
Financial allocation patterns reveal a stark disconnect between stated climate com­mitments and governmental spending priorities. Governments allocated US$ 956 billion to net fossil fuel subsidies in 2023 – more than triple the annual fund­ing pledged to support climate-vulnerable countries. Fifteen nations spent more subsidising fossil fuels than their entire national health budgets, highlighting the structural barriers to health-protective cli­mate policy.

Health systems demonstrate climate leadership capacity
Despite these challenges, emerging data in­dicate significant capacity for health sector climate action. Health related greenhouse gas emissions decreased 16% globally be­tween 2021 and 2022 whilst maintaining care quality improvements. WHO data re­veal that 58% of Member States have com­pleted health Vulnerability and Adaptation assessments, with 60% having finalised Health National Adaptation Plans.

Urban health systems are advancing risk preparedness, with 834 of 858 report­ing cities having completed or planned climate risk assessments. The transition towards renewable energy infrastructure has generated measurable co-benefits, with an estimated 160,000 premature deaths avoided annually between 2010 and 2022 from reduced coal-derived out­door air pollution alone.

Alliance expansion reflects growing political commitment
The Alliance for Transformative Action on Climate and Health has rapidly ex­panded since its 2022 establishment to support delivery of the COP26 Health Commitments on Climate Resilient and Low Carbon Health Systems. The addi­tion of Cook Islands, Malaysia and Tuvalu between July and October 2025 brought membership to 100 countries and over 95 partner organisations.

Small island developing states face par­ticular vulnerabilities, with Tuvalu – the smallest WHO Member State – having championed climate and health initiatives for decades. As a rapidly growing economy, Malaysia is building resilience and sustain­ability across multiple sectors, including healthcare infrastructure.

“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,” said Dr Marina Romanello, Executive Director of the Lancet Countdown at University College London.

The renewable energy sector achieved record generation of 12% of global elec­tricity in 2024, creating 16 million jobs worldwide. Medical education has ex­panded to incorporate climate and health competencies, with two-thirds of medi­cal students receiving relevant training in 2024. These developments provide an evidence base for accelerated health-centered climate action ahead of COP30 from 10-21 November in Belém, Brazil.