Ahead of COP31, the latest Lancet Countdown report finds that the health impacts of climate change are accelerating, with heat-related deaths, drought and other climate-related risks increasing faster than a decade ago, even as clean energy investments and climate action begin to deliver health benefits.
A decade after the Paris Agreement entered into force, the 2026 Lancet Countdown on Health and Climate Change reports that many climate-related health harms are growing faster than the global response. The report, produced by an international collaboration of researchers and institutions led by University College London and developed in strategic collaboration with WHO, tracks global trends across 54 indicators linking climate change and health.
According to the report, annual average heat-related deaths increased by nearly 36% in the years following the Paris Agreement compared with the previous decade. In 2023 alone, heat was linked to a record 710 000 deaths globally, with more than 70% of that burden attributable to human-caused climate change. The report also highlights worsening drought conditions, increasing exposure to hydrological extremes, and substantial economic losses linked to heat exposure.
At the same time, the report points to important progress. Global investment in clean energy reached a record US$ 2.1 trillion in 2025, while many countries that have lowered fossil fuel-related air pollution are estimated to be protecting thousands of people from premature deaths each year. The report also notes advances in climate-resilient health systems, including increased adoption of national health adaptation plans and climate-informed early warning systems.
“Climate change is already harming health in every region of the world, and the evidence shows that many of these impacts are accelerating,” said Dr Diarmid Campbell-Lendrum, Head, Climate change, Air Quality and Energy and Health Unit. “At the same time, this report demonstrates that climate action is a health intervention. Cleaner energy, stronger health systems and early warning systems are saving lives today. As countries prepare for COP31, placing health at the centre of climate policies can help protect communities, strengthen resilience and deliver immediate benefits for people’s health and well-being.”
The report’s authors call for climate change to be formally recognized and addressed as a global health emergency, and for health considerations to be integrated across climate mitigation, adaptation and financing decisions. Priorities include accelerating reductions in greenhouse gas emissions, increasing support for adaptation, and expanding investments that strengthen health system resilience.
WHO is responding to climate-related health risks through a range of existing functions, including surveillance, climate-informed early warning systems, health adaptation planning, technical guidance and emergency response operations. WHO acts as Secretariat for the Alliance for Transformative Action on Climate and Health (ATACH), the only network of health ministries and partners working together to develop climate-resilient, low-carbon and sustainable health systems at the country level.
WHO’s emergency architecture is designed to respond to acute and protracted events with serious health consequences and it is taking steps to use existing instruments to respond to climate emergencies in line with the recommendations in the report. Since September, it is responding to the expected health impacts of the ongoing El Niño event through a graded emergency response and a Global Incident Management Team (IMT), mobilizing expertise, health intelligence and support to countries most at risk.
Under the International Health Regulations (2005) (IHR), a public health emergency of international concern (PHEIC) is defined as an extraordinary event which is determined to constitute a public health risk to other States through the international spread of disease and to potentially require a coordinated international response. Public health events that meet the criteria of a PHEIC may include those driven by climate change.
The 2026 report brings together the work of 146 researchers from more than 100 institutions across over 30 countries.
WHO is a strategic collaborator of the Lancet Countdown and provides technical leadership on climate change and health.
