Nearly 150 researchers across 30 countries have called for climate change to be declared a "global health emergency," backed by the annual Lancet Countdown on Health and Climate Change — the field's most comprehensive tracking instrument. The numbers are stark: more than half a million heat deaths in 2023 alone, nearly 3 million since 2016, and $1.07 trillion in lost potential income last year from heat exposure. This is not a forecast. It is an invoice. The acceleration is the story, not the trend. Climate change's share of heat-related deaths rose from 55% in the pre-Paris decade to 68% since 2016. The yearly increase in climate-driven heat deaths more than doubled. Drought-affected land area grew 700% faster than in the prior decade. Satellite data show 80% of the world's land surface shifting toward hydrological extremes — either drying out (43%) or getting wetter (37%). Heat waves and droughts pushed 128 million more people into food insecurity in 2024 compared with the 1981-2010 baseline. Marina Romanello, executive director of the Lancet Countdown at University College London, called it "a step change," not a gradual worsening. The economic damage concentrates where it does the most structural harm. Heat wiped out 573 billion potential working hours in 2025, with farmworkers absorbing the worst. Africa and South-East Asia lost up to 5% of GDP to heat-related productivity collapse, compared with 0.5% in wealthier economies. This is a regressive tax imposed by physics: the countries least responsible for emissions bear costs ten times larger as a share of their economies. Governments, meanwhile, are subsidizing the source of the problem at record levels. Net fossil fuel subsidies doubled since 2016 to $6.2 trillion. Ten countries now spend more on fossil fuel subsidies than on their entire health systems. Energy-related emissions hit a record in 2024. The world's 100 largest oil and gas companies are on track to produce 150% more oil and gas by 2040 than is compatible with the 1.5°C target — up from 138% a year ago. Romanello compared new fossil fuel investment to "investing in Blockbuster when you have Netflix." There are signs of progress, but they are outpaced by the damage. Renewable energy growth helped reduce deaths from fossil fuel air pollution in half of 140 countries assessed, preventing an estimated 323,000 deaths annually. Fifty-six countries now have national health adaptation plans for climate impacts, up from 14 in 2015. But fossil fuels still supply over 80% of global energy, and the structural inertia is enormous. The researchers want a new WHO instrument — something beyond the existing PHEIC mechanism used for COVID-19 and mpox — designed for sustained, cross-sector coordination rather than acute outbreak response. Developing countries estimate they need $3.3 billion annually for health system adaptation, likely an undercount. Only about a third was committed in 2024. Foreign aid cuts led by the US and followed by Germany are widening the gap further. The core problem is a misalignment between who pays and who decides. The health costs of climate change are borne disproportionately by low-income populations and economies, while the subsidies sustaining fossil fuel production flow through wealthy-country treasuries and multinational energy firms. As former New Zealand Prime Minister Helen Clark put it: "What's missing is not evidence, but the political will to act on it." The Lancet data suggest the evidence surplus and the action deficit are both growing at accelerating rates.
