Experts Urge Global Health Emergency Declaration Over Climate Change
Climate-related health harms are accelerating faster than global action, with heat linked to a record 710,000 deaths in 2023, a major international assessment warns.
Climate change should be formally declared a global health emergency, experts have urged, warning that rising temperatures, extreme weather and worsening environmental conditions are causing escalating damage to human health while governments struggle to respond at the necessary pace.
The call follows the latest findings of the Lancet Countdown on Health and Climate Change, an international assessment led by University College London in collaboration with the World Health Organization (WHO). More than 140 experts from over 30 countries contributed to the research, which examines the links between climate change, public health, energy systems and government action.
The report finds that health-related impacts of climate change have intensified during the decade since the 2015 Paris Agreement, with annual average heat-related deaths rising by nearly 36% globally compared with the preceding decade.
In 2023 alone, heat was associated with a record 710,000 deaths, with researchers estimating that more than 70% of the toll was attributable to human-caused climate change. The findings underline the growing public health consequences of global warming and the urgent need to integrate health considerations into climate policies.
Published ahead of the upcoming United Nations climate summit, COP31, the assessment calls for health protection to become a central objective of climate decision-making, from reducing greenhouse gas emissions to directing investment towards vulnerable communities and resilient healthcare systems.
Heat and Extreme Weather Intensify Health Risks
Rising temperatures are increasing the frequency and severity of dangerous heat exposure, placing additional pressure on human health and healthcare services. Prolonged heat can contribute to cardiovascular and respiratory complications, kidney problems, dehydration and heatstroke, with older people, outdoor workers, children and individuals with existing health conditions facing particular risks.
The growing burden of heat-related mortality reflects the interaction between rising temperatures, population exposure and vulnerability. Urban areas can experience additional heat stress because buildings, roads and other artificial surfaces absorb and retain heat, while communities without adequate shade, cooling or reliable electricity have fewer ways to protect themselves.
Climate change is also affecting health through droughts, floods, changing infectious disease patterns and disruptions to food and water supplies. These impacts can compound existing inequalities, particularly in regions where healthcare access, sanitation infrastructure and social protection systems are limited.
The assessment tracks 54 indicators covering a wide range of these relationships. Its monitoring framework includes heat exposure, air quality, climate suitability for infectious disease transmission, extreme weather events, health adaptation, research funding, legislation and climate-related economic losses.
Together, these indicators provide a broad picture of how climate change is affecting health systems and communities while measuring whether governments are responding effectively.
Drought and Changing Water Conditions Threaten Communities
The report identifies growing disruption to the global water cycle as another major concern. Extreme drought affected nearly 52% of the world’s land for at least one month during 2025, representing the second-highest level recorded.
Drought can undermine agricultural production, reduce water availability and increase the risk of food insecurity. Prolonged shortages can also compromise sanitation and hygiene, increasing health risks in communities that depend on vulnerable water supplies.
Using satellite-based analysis, researchers found that 80% of the world’s land had experienced significant shifts in patterns of groundwater storage, including increasingly dry and wet conditions, since 2003.
These changes can have far-reaching consequences. Declining groundwater availability can threaten drinking water supplies and agricultural livelihoods, while excessive groundwater fluctuations and related flooding can damage infrastructure and complicate water management.
Such pressures can intensify existing public health problems, particularly where communities lack adequate sanitation facilities, reliable water infrastructure or resources to adapt to changing climatic conditions.
Clean Energy Delivers Measurable Health Benefits
Despite the deteriorating health outlook, the report identifies important progress in the transition towards cleaner energy. Global investment in clean energy reached a record level in 2025, nearly doubling investment in fossil fuels.
The researchers also found that improvements in air quality had helped prevent an estimated 323,000 deaths annually across at least 77 countries where air pollution from fossil fuels had declined since 2016.
The findings demonstrate that climate mitigation can deliver immediate public health benefits, rather than simply reducing risks expected decades into the future. Replacing polluting energy sources with cleaner alternatives can lower emissions while reducing exposure to harmful air pollutants.
Investments in renewable electricity, energy efficiency and cleaner transport can therefore provide multiple benefits, including fewer pollution-related illnesses, reduced healthcare costs and improved quality of life.
However, the transition remains incomplete. Fossil fuels continue to supply more than 80% of global energy, generating the greenhouse gas emissions responsible for continued warming.
Fossil Fuel Expansion Raises Concerns
The report warns that planned oil and gas production remains inconsistent with the goal of limiting global warming to 1.5°C above pre-industrial levels.
The world’s 100 largest oil and gas companies are projected to exceed production levels compatible with the 1.5°C pathway by approximately 150% in 2040, according to the assessment. This represents an increase from the previous year’s estimate of 138%.
The findings highlight a significant contradiction between climate commitments and continued investment in fossil fuel extraction. Expanding production risks locking economies into emissions-intensive infrastructure and increasing the difficulty of meeting international climate targets.
The United Nations has also warned that the world is likely to exceed the 1.5°C threshold. Such an overshoot would increase the likelihood of more intense extreme weather events and heighten the risk of triggering potentially irreversible changes in Earth’s climate systems.
For public health, continued warming could mean greater heat exposure, worsening food and water insecurity, and growing pressure on healthcare services.
Health Must Become Central to Climate Policy
The researchers are calling for governments to place health at the centre of climate decisions, including emissions reduction, energy planning, adaptation measures and public investment.
Progress has been made in clean energy deployment, health-system preparedness and regulations designed to protect public health. However, the report concludes that these advances remain insufficient and are not reaching the communities most in need of protection.
Strengthening early-warning systems, improving healthcare preparedness for extreme heat, expanding access to clean energy and investing in climate-resilient infrastructure could help reduce the growing burden of climate-related illness and mortality.
A formal global health emergency declaration could help elevate the issue on the international agenda and strengthen coordination between climate, health and development institutions. Its effectiveness, however, would depend on translating heightened recognition into sustained financing, enforceable policies and practical action.
The report’s central message is that climate change is no longer only an environmental or economic challenge. It is an escalating public health crisis whose consequences are already measurable. Without faster emissions reductions and stronger protection for vulnerable populations, the health costs of a warming world are likely to continue rising.