Climate health toll accelerates ahead of COP31, Lancet report calls for urgent action

The report tracks 54 indicators connecting climate change and health, drawing on an international research collaboration led by University College London.

Climate change is taking a growing toll on people's health, with the 2026 Lancet Countdown report warning ahead of COP31 that many harms are accelerating faster than the global response. Rising heat deaths, worsening drought and greater exposure to water-related extremes show how changing conditions are affecting lives and livelihoods worldwide. The findings come a decade after the Paris Agreement entered into force, as governments face calls to put health at the centre of climate decisions.

The report tracks 54 indicators connecting climate change and health, drawing on an international research collaboration led by University College London. Developed in strategic collaboration with the World Health Organization, it examines the damage caused by climate change and the health benefits emerging from action to address it. The press release describes contributions from 146 researchers at more than 100 institutions across over 30 countries.

Clean energy investment, lower air pollution and stronger health services are delivering benefits that can protect communities today. The scale and speed of those gains remain insufficient to match the growing health burden described in the report. Its authors want climate change formally recognised and addressed as a global health emergency, with health shaping decisions on emissions, adaptation and financing.

Heat deaths and drought reveal the growing burden

Annual average heat-related deaths increased by nearly 36% in the years following the Paris Agreement compared with the previous decade, according to the report. Heat was linked to a record 710,000 deaths worldwide in 2023, with more than 70% of that burden attributed to human-caused climate change. Those figures show how strongly rising temperatures are already affecting survival, adding urgency to efforts to reduce emissions and protect people from dangerous heat.

Worsening drought conditions and increasing exposure to hydrological extremes are adding to the risks facing communities. The report records substantial economic losses linked to heat exposure, placing the consequences beyond illness and deaths alone. Its findings support calls for faster greenhouse gas reductions, greater support for adaptation and expanded investment in health services that can withstand climate pressures.

Cleaner energy and stronger health systems deliver gains

Global clean energy investment reached a record US$2.1 trillion in 2025, reflecting growing spending on changes that can benefit health. Countries that have reduced air pollution from fossil fuels are estimated to be preventing thousands of premature deaths each year. National health adaptation plans and climate-informed early warning systems are becoming more widely adopted, helping countries prepare for climate-related threats.

Dr Diarmid Campbell-Lendrum, who heads WHO's Climate Change, Air Quality and Energy and Health Unit, described climate action as a health intervention with immediate benefits. He pointed to cleaner energy, stronger health systems and early warnings as measures already saving lives in communities facing climate risks. His message ahead of COP31 was that putting health at the centre of climate policies can protect people, strengthen resilience and improve well-being.

WHO builds preparedness and responds to climate emergencies

WHO's work includes surveillance, climate-informed early warnings, health adaptation planning, technical guidance and emergency response operations. It provides technical leadership on climate change and health and serves as a strategic collaborator of the Lancet Countdown. WHO also acts as Secretariat for the Alliance for Transformative Action on Climate and Health, described in the release as the only network bringing health ministries and partners together to develop climate-resilient, low-carbon and sustainable health systems at country level.

The organisation's emergency arrangements cover acute and prolonged events with serious health consequences, and it is taking steps to use existing instruments to respond to climate emergencies in line with the report's recommendations. Since September, WHO has been responding to the expected health effects of the ongoing El Niño event through a graded emergency response and a Global Incident Management Team. That response brings together expertise, health intelligence and support for countries facing the greatest risks.

The call to recognise a global health emergency sits alongside an existing legal framework under the International Health Regulations (2005). A public health emergency of international concern is an extraordinary event posing a risk to other states through the international spread of disease and potentially requiring a coordinated international response. Climate-driven public health events can meet those criteria, making the framework relevant to some emergencies arising from a changing climate.