Study calls for global health emergency as climate deaths near 3 million

The Lancet Countdown on Health and Climate Change, published ahead of next month's UN climate summit in Turkiye, tracks 54 indicators covering heat, air quality, infectious disease, energy systems and economic losses. It is the first time the authors have quantified heat-related deaths directly due to human-caused climate change.

The report estimates more than half a million heat-related deaths occurred annually between 2016 and 2023, with 68% caused by climate change. In 2023 alone, heat was linked to a record 710,000 deaths, with more than 70% attributable to human-caused warming, researchers found.

Separate peer-reviewed studies cited in the report found that severe heat killed more than 50,000 people across Europe during the 2025 Northern Hemisphere summer, with about two-thirds of those deaths attributed to climate change.

Developing countries had the highest proportion of heat-related deaths, which the authors said "reflected the disproportionate adverse impacts of climate change on those least responsible for it".

"Even here in Australia, we know people do die from heatwaves, people do die from bushfire smoke exposure and things like that," said Professor Paul Beggs, a climate health expert at Macquarie University and study co-author. "So I think it doesn't matter where you live; climate change is already having an impact on health, and that's only going to increase."

The report notes significant progress on renewable energy, with clean energy investment reaching a record in 2025 and nearly double that of fossil fuels. It estimates cleaner air from switching energy sources prevented 323,000 deaths a year in at least 77 countries since 2016. However, fossil fuels still supply more than 80% of global energy, pushing emissions to record highs in 2024.

The authors cited "lobbying and disinformation by fossil fuel interests and political allies" as obstructing the transition to clean energy, and singled out the US for promoting fossil fuel expansion and withdrawing from the Paris Agreement.

"A severe El Nino threatens to compound the impacts of climate change and trigger unprecedented climate-related humanitarian crises globally," the report states. "Climate change has become a global health emergency. Addressing it requires urgent course correction."

Professor Marina Romanello, executive director of the Lancet Countdown, said: "A decade after the Paris Agreement, our findings are unambiguous: the health harms of climate change are growing faster than the world's response to them, and in many cases even accelerating."

"Real progress has been made in clean energy, health system readiness, and health-protective regulation, all of which are already delivering health benefits to local communities. However, progress has been too slow, too small, and isn't reaching those who need it most."

Professor Beggs said Australia, as president of COP31, had an opportunity to prioritise human health over fossil fuels. "We're really hoping for big things in terms of progress on mitigating climate change, and that means reducing fossil fuel emissions," he said.