Climate Change Worsening Global Health Emergency, New Report Warns

Ten years after the adoption of the Paris Agreement, a new report led by University College London in collaboration with the World Health Organization (WHO) indicates that detrimental health indicators linked to climate change are not only increasing but accelerating.

The report, which includes findings from 146 researchers across more than 100 institutions in over 30 countries, found that heat exposure was associated with an average of over 540,000 estimated deaths annually between 2016 and 2023. The researchers attribute 68% of these fatalities to climate change.

"These numbers point to a clear emergency," said Marina Romanello, professor at University College London and executive director of The Lancet Countdown. "The rate of increase in many climate-related health threats is accelerating, while heat deaths linked to climate change have reached a record-high, and the economic toll is battering vulnerable sectors and communities the hardest."

The period from 2016 to 2023 saw the 11 hottest years on record. In 2023 alone, heat was linked to an estimated 710,000 deaths, with over 71% attributable to climate change, a figure exceeding the loss of life from malaria or HIV. Over the entire 2016-2023 period, nearly 3 million deaths could be connected to climate change.

Economically, heat is also taking a significant toll. The report estimates that the world lost over a trillion dollars in potential income in 2025 due to reduced productivity, marking the third consecutive year such losses have exceeded the trillion-dollar mark.

An expanding shoreline is seen at drought-shrunken Grant Lake, October 26, 2022 near Lee Vining, California.

"The threats to people's health and people's survival have reached unprecedented levels, with many of these threats and impacts even accelerating in the last decade with respect to the previous one," Romanello stated.

Furthermore, the pace of land affected by extreme drought has accelerated by approximately 700% between 2016 and 2025 compared to the decade preceding the Paris Agreement. In 2025, over half of the world's land experienced extreme drought for at least a month. Conversely, the report also found an increase in extreme rainfall events, with the share of land hit by very extreme rainfall rising from 14.8% between 2006-2015 to 17.2% from 2016-2025.

"The risks become even more profound when you consider how different hazards interact and compound. At the same time, drought is spreading, and the world is swinging to water extremes, some drying out, while others are flooding. This isn't a gradual worsening; it's a step change that must be recognized as the global health emergency it is," Romanello said.

Women use fans as they walk in a street in Toulouse, southwestern France, on August 23, 2023, during a heat wave in France.

On a more positive note, global investment in clean energy grew by over 7% in 2025, reaching a record $2.1 trillion. This figure is 82% more than investments in fossil fuel energy sources. The report noted that new investment helped renewables increase their share of global electricity generation from 5.5% in 2016 to 13.5% in 2023. Cleaner air, as a result, is estimated to have prevented about 323,000 deaths annually in numerous countries, although these gains were offset by increases elsewhere globally.

Despite this growth in renewables, fossil fuels still accounted for over 80% of the global energy supply, with the resulting air pollution responsible for approximately 2.7 million deaths worldwide each year, according to the report.

The authors recommend that climate change be treated as a "global health emergency." They propose six priorities for a health-centered response, including urging the WHO and United Nations to utilize existing resources and suggesting the WHO formally recognize climate change as a health emergency to coordinate a global response. They also advocate for making health and well-being core objectives in all climate actions.

The researchers call for countries and global institutions to prioritize climate and health, demanding swift and equitable cuts in greenhouse gas emissions. Recommendations also include establishing a shared pool of climate and health data and increasing grants and low-interest loans from wealthier nations to support these efforts.

"We have not really managed to tackle climate change 10 years after the Paris Agreement, and we're seeing these escalating health harms that have made climate change now a very severe, very grave global health emergency that requires an urgent emergency response to be adequately addressed," Romanello concluded.