A new global assessment of climate and health has concluded that the risks to people’s health are growing faster than the response designed to limit them. The work, led by an international research collaboration based at University College London, tracks 54 indicators connecting a warming climate with health, energy, food, work and the resilience of health services.
Its central finding is not that every measure is moving in the same direction. Investment in cleaner energy has expanded, and practical protections are being adopted in more places. But the assessment says those gains have not yet kept pace with the escalating harms associated with extreme heat, drought, heavy rainfall and other climate-related pressures.
Heat remains a defining health risk
The assessment estimates that annual average heat-related deaths rose by nearly 36 per cent in the decade after the Paris Agreement took effect, compared with the preceding decade. For 2023, it links heat to a record 710,000 deaths worldwide and estimates that more than 70 per cent of that burden was associated with human-caused climate change.
These are population-level estimates rather than a count of death certificates carrying a single cause. Heat often worsens existing heart, lung, kidney and other conditions, while the effect of a hot period can depend on housing, local services, age, work and access to cooling. That does not make the warning less significant. It means the figures should be understood as an estimate of a broad health burden, not as a precise account of every individual death.
The report also identifies worsening drought conditions and greater exposure to hydrological extremes. These hazards can affect health directly, but they can also disrupt food supplies, water systems, livelihoods and the ability of clinics and hospitals to operate. Reduced capacity to work safely in high temperatures adds an economic consequence that can itself make communities less able to prepare for later shocks.
Signs of progress, but not enough to offset the damage
The assessment does not present the picture as uniformly bleak. Global investment in clean energy reached a record US$2.1 trillion in 2025. In countries where fossil-fuel air pollution has fallen, cleaner air is estimated to be protecting thousands of people from premature death each year.
There has also been progress in efforts to make health systems more resilient. National health adaptation plans and climate-informed early-warning systems are becoming more common. Such measures can help authorities identify risks, communicate with the public and prepare services before a heatwave, flood or other event puts people at greater risk. Their presence, however, does not guarantee that every community has the staff, funding, equipment or local infrastructure needed to respond.
The assessment argues that climate action should be judged partly by its immediate health effects, not only by long-term emissions targets. Cutting pollution can improve the air people breathe now, while better preparedness can reduce harm when hazards occur. The challenge is that these benefits need to be delivered at a scale and speed that match the risks already emerging.
A call for health to sit at the centre of climate policy
The researchers call for climate change to be formally recognised and addressed as a global health emergency, with health considered in decisions on emissions reduction, adaptation and finance. That is a recommendation, not an announcement that a new emergency status has been declared. It does not by itself create a new international legal mechanism or guarantee additional funding.
What it does underline is the connection between climate policy and everyday public health. Decisions about energy, transport, buildings, food systems and emergency planning can shape exposure to heat and pollution, as well as the ability of health services to cope when conditions worsen. For a report that records both growing harms and practical gains, the message is clear: cleaner energy, stronger public-health systems and earlier warnings are already valuable, but they will need to expand much more quickly to protect people in every region.
