The 2026 Lancet Countdown on Health and Climate Change, released earlier this week, finds that climate-related health harms are growing faster than the response intended to contain them. Ten years after the Paris Agreement entered into force, renewable energy, health adaptation and public awareness have delivered benefits. Nevertheless, greenhouse gas emissions continue to reach record levels, and numerous health threats have accelerated. Drawing on 54 indicators, the authors call for climate change to be formally recognised and addressed as a global health emergency.
Action since 2016 has reduced projected end-of-century warming, but expected temperatures remain dangerously high. The report considers an overshoot of 1.5°C probably unavoidable. Its central argument is that protecting health requires simultaneous investment in adaptation and rapid emissions reductions: adaptation alone will become increasingly costly and insufficient as warming intensifies.
Heat, extreme weather and infectious diseases
Heat-related mortality provides particularly striking evidence. During 2016–2023, heat was associated with an estimated average of approximately 540,800 deaths annually, including 369,940 attributable to human-caused climate change. In 2023, estimated heat-related deaths reached 710,000, with 71.5% attributed to climate change. These are modelled estimates rather than directly counted deaths. Countries with low human development had the highest proportion of climate-attributable heat deaths, illustrating disproportionate harm to populations least responsible for warming.
Extreme weather is also threatening food security, infrastructure and sanitation. Extreme drought affected 51.8% of global land for at least one month in 2025. The drought-affected area grew 704% faster during 2016–2025 than during the preceding decade. This describes an acceleration in the rate of increase, rather than a 704% expansion in total affected land. Very extreme precipitation affected 17.2% of global land annually during 2016–2025, increasing risks associated with floods and landslides.
Changing temperatures and rainfall are altering infectious disease risks. Environmental suitability for dengue transmission has increased, while an estimated record 1.72 billion people lived within 100 kilometres of coastal waters environmentally suitable for Vibrio transmission in 2025. Suitability for malaria and West Nile virus transmission is shifting geographically, increasing in some locations and declining in others. These indicators describe environmental conditions favourable to transmission, rather than directly counting additional infections.
Economic losses reinforce health inequalities
Heat also damages the economic conditions supporting health. In 2025, exposure resulted in an estimated 573 billion potential working hours lost and US$1.07 trillion in potential income losses. Estimated losses were equivalent to 5% of GDP in low-human-development countries and 3.7% in medium-human-development countries, compared with 0.5% in very-high-human-development countries.
These disparities reinforce existing inequalities. The authors argue that countries contributing most to climate change should provide meaningful support to those most affected and least responsible. They also warn that environmental, health and economic pressures can interact, creating system-wide risks substantially greater than separately calculated impacts suggest.
Adaptation remains inadequate
Most countries had not reported completing key health adaptation assessments or developing national plans. By 2025, 75.8% of WHO member states had not reported completing a climate vulnerability and adaptation assessment since 2020, while 71.1% had not reported developing a Health National Adaptation Plan. These reporting gaps do not establish that countries had undertaken no preparation.
Insufficient finance and staffing were identified as major barriers. Only 48 developing countries disclosed quantified health adaptation funding needs, and international climate finance covered less than one-third of these limited requirements. Falling development assistance threatens to widen the gap.
There are encouraging developments. Fifty-six countries reported having health adaptation plans, compared with 14 in 2015, and climate-informed health early warning systems were available in 75 countries. However, warnings protect health only when connected to practical responses, accessible services and measures that vulnerable populations can realistically implement.
Fossil fuel dependence continues to undermine health
Fossil fuels still supply 80.7% of global energy. Although modern renewables increased their share of electricity generation from 5.5% in 2016 to 13.5% in 2023, rising demand pushed energy-related greenhouse gas emissions to a record high in 2024.
The transition remains highly unequal. Modern renewables supplied 14.6% of electricity in very-high-human-development countries but only 2.9% in low-human-development countries. Meanwhile, polluting biomass provided 87.9% of household energy in low-human-development countries.
Air pollution creates an enormous preventable health burden. The report estimates that fossil fuel-derived outdoor air pollution caused an average of 2.78 million avoidable deaths annually since 2016. Household solid fuel use caused an estimated two million deaths in 2023. International consumption patterns also transfer pollution-related harm to poorer countries.
Governments allocated US$6.20 trillion in net fossil fuel subsidies during 2016–2024. Ten countries spent more on these subsidies than on their health systems in 2024. Meanwhile, major oil and gas companies’ production plans increasingly exceed levels compatible with limiting warming to 1.5°C.
Evidence that climate action improves health
The report documents substantial benefits from existing interventions. Countries reducing fossil fuel-related air pollution collectively avoided an estimated 323,000 deaths annually. Cleaner household energy prevented an estimated 400,000 deaths in 2023 compared with 2016.
Clean energy employment increased, reaching almost twice direct fossil fuel employment, while clean energy investment exceeded fossil fuel investment by 82% in 2025. These findings demonstrate opportunities to improve health, livelihoods and energy security together.
However, the transition must avoid transferring harms elsewhere. The authors emphasise responsible mineral extraction, sustainable resource use, safe disposal and equitable access to affordable energy. They recommend health sector involvement in designing policies that maximise benefits and minimise unintended consequences.
Political barriers and priorities for action
The authors identify fossil fuel lobbying and disinformation as important obstacles. They describe messaging that promotes delay by exaggerating transition costs, presenting fossil fuels as indispensable and overstating unproven technological solutions. Social media and artificial intelligence can amplify these narratives. The report also records declining engagement with health and climate change among governments, international organisations and corporations.
The authors propose six priorities: strengthen emergency recognition and response; align international governance around climate and health; accelerate equitable emissions reductions; make mortality and wellbeing central measures of climate policy; establish shared climate–health data infrastructure; and expand grant-based or highly concessional finance.
Specific recommendations include stronger early warning systems, sustainable cooling, worker protections, climate education for health professionals and healthcare decarbonisation. The report presents these as coordinated measures to protect populations now while limiting future harm. Its central conclusion is that effective solutions already exist, but implementation requires political commitment, adequate resources and action proportionate to the escalating health threats.
Here is a summary infographic that accompaned the report: