Hundreds of thousands of people were forced to flee climate disasters last year, the United Nations said on Wednesday, highlighting the urgent need for early warning systems covering the entire planet.

Poorer countries are severely affected by cyclones, droughts, wildfires and other disasters, according to the State of the Global Climate annual report by the World Meteorological Organization (WMO), the UN's weather and climate agency.

The WMO said the record number of people fleeing climate disasters was based on figures from the International Displacement Monitoring Centre (IDMC), which has been collecting data on the subject since 2008.

In Mozambique, around 100,000 people were displaced by Cyclone Chido.

But wealthy countries were also hit, with the WMO pointing to the floods in the Spanish city of Valencia, which killed 224 people, and the devastating fires in Canada and the United States which forced more than 300,000 people to flee their homes in search of safety.

"In response, WMO and the global community are intensifying efforts to strengthen early warning systems and climate services," said the agency's chief Celeste Saulo.

The WMO wants everyone in the world covered by such systems by the end of 2027.

Besides underlining the massive economic and social upheavals from extreme weather, the State of the Global Climate report said climate change indicators had once again reached record levels.

"The clear signs of human-induced climate change reached new heights in 2024, with some of the consequences being irreversible over hundreds if not thousands of years," the WMO said.

The 2015 Paris climate accords aimed to limit global warming to well below two degrees Celsius above pre-industrial levels - and to 1.5 degrees Celsius if possible.

The report said 2024 was the warmest year in the 175-year observational record, and the first calendar year over the 1.5 degrees Celsius threshold, with the global mean near-surface temperature 1.55 degrees Celsius above the 1850-1900 average, according to an analysis compiling the six major international datasets. (AFP)