The world’s slow response to climate change is already claiming millions of lives every year. According to the Lancet Countdown on Health and Climate Change 2025, produced with the World Health Organization, the health impacts of a heating planet have reached record levels, as overreliance on fossil fuels continues and adaptation lags behind community needs.
Twelve out of twenty key indicators tracking health threats have reached their highest levels ever, showing not only that lives are being lost, but that health systems and economies are being destabilized.
Rising Heat-Related Deaths: Over Half a Million Lost Each Year
Heat is now one of the biggest killers associated with the climate crisis. The rate of heat-related mortality has risen 23% since the 1990s, now causing an average 546,000 deaths per year globally. Dangerous heat exposure reached 16 days per person in 2024—far more than expected in a stable climate—while vulnerable groups like infants and older adults faced over twenty days each, quadrupling since the early 2000s.
Each fraction of a degree increase in global temperature is costing lives, revealing a dire need for adaptive measures in health care and urban planning.
Wildfire, Drought, and Food Insecurity: A Growing Challenge
Extreme events related to climate change, including droughts and heatwaves, forced an estimated 124 million people into moderate or severe food insecurity in 2023. Crop failures, water scarcity, and supply chain disruptions threaten nutrition, particularly in the world’s poorest regions. With rural populations, children, and the elderly at greatest risk, international bodies are calling for urgent agricultural reforms and safety nets to protect those most exposed.
Economic Impacts: Trillions in Lost Productivity
Heat exposure has enormous economic costs. In 2024, approximately 640 billion potential labor hours were lost globally, amounting to $1.09 trillion in lost productivity. The specific costs of heat-related deaths among older adults reached $261 billion.
These figures reflect both workplace disruptions and deeper inequalities, as low-income countries suffer most from changing weather patterns and failed adaptation.
Fossil Fuel Subsidies Far Exceed Climate Finance
Governments spent an astonishing $956 billion on fossil fuel subsidies in 2023—three times more than what was pledged for climate-vulnerable nations. Shockingly, fifteen countries allocated more money to fossil fuel support than to their entire health budgets, revealing a misalignment between climate ambitions and actual spending.
As leading health authorities urge the world to prioritize clean energy and zero-carbon solutions, fossil subsidies remain a major obstacle.
The Case for Rapid, Health-Centered Climate Action
While many governments have delayed climate commitments, communities, cities, and the health sector are proving that tangible progress is possible. Health-promoting climate action is the most powerful driver for a safer, more resilient future. Notably, from 2010 to 2022, reduced coal-derived air pollution prevented 160,000 premature deaths annually, while renewable energy generation hit new records, accounting for 12% of global electricity and creating 16 million jobs.
In 2024, two-thirds of medical students were trained in climate and health, providing the expertise needed to adapt care systems and protect vulnerable populations. Cities worldwide are now leading the way, with nearly all reporting cities having completed or planning climate risk assessments. The energy transition is delivering cleaner air, healthier workplaces, inward investment, and measurable economic gains.
The Health Sector Shows Climate Leadership: Cutting Emissions, Raising Standards
Hospitals and health systems are at the frontline of climate adaptation. Between 2021 and 2022, health-related GHG emissions fell 16% globally, even as quality of care improved. This is a promising sign that adaptation can reduce emissions, save costs, and enhance patient outcomes.
More countries are assessing climate risk and completing adaptation plans. 58% of WHO member states have completed health vulnerability assessments. Additionally, 60% have national health adaptation plans. They are positioning themselves to withstand ongoing climate shocks.
COP30 Belém: Placing Health at the Center of Climate Negotiations
The Lancet Countdown’s findings serve as a clarion call. They urge for placing health at the core of climate policy, looking ahead to COP30 in Brazil. WHO is set to launch a COP30 Special Report on Climate Change and Health. The aim is to shape policy so that protecting lives becomes the primary motivation for climate progress. Global leaders are urged to deliver the Belém Action Plan—landmark steps to protect health and promote sustainable, equitable development.
Evidence-Based Momentum: Solutions Exist, But Action Must Accelerate
Experts highlight that communities and local governments are already proving climate action delivers real health and economic benefits. Clean energy, nature-based solutions, and resilient crops are transforming cities and rural regions alike. Shifts to healthy, climate-friendly diets and sustainable agriculture could cut pollution. They could also reduce greenhouse gas emissions. These measures could potentially save over 10 million lives every single year.
Lancet Countdown’s ninth annual report draws on nearly a decade of tracking climate-health links. It brings together more than 300 researchers, WHO, UN agencies, and policy leaders, emphasizing that the world’s greatest health opportunity lies in rapid climate action, not delay.
