World endures ‘decade of deadly heat’ as 2024 caps hottest years on record

The world has endured a “decade of deadly heat”, with 2024 capping 10 years of unprecedented temperatures, the UN has said.

Delivering his annual new year message, the UN secretary general, António Guterres, said the 10 hottest years on record had happened in the past decade, including 2024.

The UN’s climate and weather agency, the World Meteorological Organisation (WMO), will publish official temperature figures for the year in January. The organisation said the past year was set to be the warmest on record, capping a decade of unprecedented heat fuelled by human activities and driving increasing weather extremes, while greenhouse gas levels continued to reach new highs, locking in more heat for the future.

Guterres said: “I can officially report that we have just endured a decade of deadly heat. The top 10 hottest years on record have happened in the last 10 years, including 2024.

“This is climate breakdown, in real time. We must exit this road to ruin and we have no time to lose. In 2025, countries must put the world on a safer path by dramatically slashing emissions and supporting the transition to a renewable future. It is essential, and it is possible.”

The WMO secretary general, Celeste Saulo, said every degree of warming mattered and led to increased climate extremes, with temperatures “only part of the picture”.

“This year we saw record-breaking rainfall and flooding events and terrible loss of life in so many countries, causing heartbreak to communities on every continent,” she said.

“Tropical cyclones caused a terrible human and economic toll, most recently in the French overseas department of Mayotte in the Indian Ocean. Intense heat scorched dozens of countries, with temperatures topping 50C on a number of occasions. Wildfires wreaked devastation.”

The WMO pointed to a new report that found climate change intensified 26 of the 29 extreme weather events studied by World Weather Attribution (WWA) in 2024, which killed at least 3,700 people and displaced millions.

Climate change added 41 days of dangerous heat in 2024, according to the report from WWA, a network of scientists who examine the role of global warming in extreme weather events, and research and reporting organisation Climate Central.

The WMO said that as global temperatures increased and extreme heat events worsened, there was a growing need for countries and international organisations to work together to tackle severe heat risks.