CLIMATE change should be declared a “global health emergency” to drive a coordinated response from governments, after heat-related deaths reached three million worldwide between 2016 and 2023, according to a report published by The Lancet on Wednesday.
The 10th edition of the British medical journal’s annual climate and health assessment found that 68% of those deaths were directly attributable to human-caused climate change, highlighting the growing threat of rising temperatures to public health.
The report, compiled by 146 researchers from 30 countries ahead of the COP31 climate summit in November, estimated that heat-related deaths hit a record 710,000 in 2023, with more than 70% linked to human-induced climate change.
Marina Romanello, executive director of the Lancet Countdown research project on health and climate change, said three million heat-related deaths had been recorded globally in the eight years since the 2015 Paris Agreement.
“That’s roughly equivalent to the entire population of Wales being wiped out in the space of eight years due to heat,” she told a news conference.
Romanello called for a global health emergency declaration to ensure governments adopt an integrated, long-term response rather than repeatedly reacting to individual crises.
She said such an approach should build resilience and strengthen countries’ capacity to prevent and manage future emergencies.
The Paris Agreement, a legally binding international treaty, aims to limit global warming to well below 2 degrees Celsius above pre-industrial levels while pursuing efforts to keep the increase to 1.5 degrees Celsius.
Professor Ollie Jay of the University of Sydney said researchers assessed the contribution of human-caused warming by comparing recorded heat-related deaths with the number estimated to have occurred without climate change.
He said climate change had intensified both the frequency and severity of extreme heat events. In 2025, an extreme drought affected more than half of the world’s land surface for at least one month, the report noted.
The economic toll is also mounting. Researchers estimated that reduced worker productivity caused by rising temperatures cost the global economy more than US$1 trillion a year over the past three years.
South-east Asia and Africa were among the hardest-hit regions, losing an estimated 3.9% and 3.2% of their gross domestic product respectively, compared with 0.2% in Europe and 1.5% in the Americas.
The report also highlighted progress in climate adaptation and clean energy investment. Since 2016, 56 of the World Health Organization’s 194 member states have adapted their health and early-warning systems to anticipate extreme events.
Investment in clean energy reached US$2.1 trillion in 2025, twice the amount invested in fossil fuels. However, fossil fuels still account for about 80% of global energy supply and contribute to air pollution that causes an estimated 2.73 million deaths annually.
The report said at least 323,000 deaths had been avoided across 77 or more countries since 2016 as fossil-fuel-related air pollution declined.
Funding for climate-related health research increased sevenfold to US$316 million in 2024, but 84% went to researchers in wealthy countries, despite poorer nations facing some of the greatest climate-related health risks.
Romanello said researchers’ work had also been complicated by the disappearance of some data sources, particularly in the United States, including information on fossil fuel subsidies that US authorities had not made public.
She added that geopolitical instability over the past two years had pushed climate change and its health consequences into the background, warning that continued inaction was worsening the situation. - October 28, 2026
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