In brief
A consortium of 146 researchers released a report noting that climate‑driven health hazards have surged faster in the decade following the Paris Agreement, with a record 710,000 heat‑related deaths in 2023. The study argues that climate change is responsible for roughly two thirds of those deaths and that unresolved risks to public health merit emergency status. While clean‑energy investment hit a record $2.1 trillion in 2025, fossil fuels still provide over 80 % of global electricity and are linked to millions of annual deaths.
Scientists from 71 institutions, led by University College London and the World Health Organization, released the Lancet Countdown 2026 report on Monday, calling for climate change to be declared a global health emergency. The report, which was announced in Sydney, warns that climate‑related health risks have accelerated since the Paris Agreement, with a record 710,000 deaths worldwide attributed to heat in 2023.
The analysis of 146 researchers found that the average number of heat‑related deaths per year from 2016 to 2023 was 540,800, and that about 68 percent of those deaths were linked to human‑caused climate change. In the hottest year of the period, 2023, more than 70 percent of heat deaths were attributed to climate change, according to the report’s lead authors at University College London.
Beyond mortality, the study estimates that heat exposure will cost the global economy 573 billion potential work hours lost in 2025 and 1.07 trillion U.S. dollars in lost income. These figures illustrate the economic burden of climate‑driven health hazards, even as public funds claim a record $2.1 trillion in clean‑energy investment during 2025.
Energy Mix and Health Impact
Despite record investments, the report notes that fossil fuels supply more than 80 percent of world electricity. Pollution created by these fuels is associated with an estimated 2.73 million deaths annually, a figure that remains a crucial driver of global health risk under climate change.
The University of Sydney, which contributed seven researchers to the project, emphasized that the health risks associated with climate change are growing faster than in the decade prior to the Paris Agreement. The global‑health community has therefore urged the International Health Regulations to be amended to recognize climate change as an emergency that crosses national borders and public‑health systems.
Experts also highlighted that the pandemic of heat‑related sickness has multiplied in severity over the last decade, calling for immediate capacity building and preventive measures at the global level. The group behind the Lancet Countdown has called for a coordinated strategy that links climate mitigation with public‑health preparedness.
What remains uncertain, the study notes, is the precise proportion of mortality and economic loss that can be directly tied to climate change as opposed to other environmental factors, and how those proportions will evolve under different emission scenarios. The authors caution that while the percentages cited are their best estimates, they are based on current data sets which may be incomplete or affected by regional reporting disparities. The full report therefore recommends establishing a monitoring framework that will refine these estimates as new health‑impact data become available.
