Every major global climate record was broken last year, the World Meteorological Organization (WMO) said on Tuesday, with its chief voicing particular concern about ocean heat and shrinking sea ice.

The UN weather agency said in its annual State of the Global Climate report that average temperatures hit the highest level in 174 years of record-keeping by a clear margin, reaching 1.45 degrees Celsius above pre-industrial levels.

Ocean temperatures also reached the warmest in 65 years of data with over 90% of the seas having experienced heatwave conditions during the year, the WMO said, harming food systems.

“The WMO community is sounding the Red Alert to the world,” said WMO Secretary-General Celeste Saulo, who took over the job in January.

“What we witnessed in 2023, especially with the unprecedented ocean warmth, glacier retreat and Antarctic sea ice loss, is cause for particular concern.”

Climate change, driven by the burning of fossil fuels, coupled with the emergence of the natural El Nino climate pattern pushed the world into record territory in 2023. Scientists have warned that 2024 could be even worse, with El Nino fuelling temperatures in the first few months of the year.

Tuesday’s report showed a big plunge in Antarctic sea ice, with the peak level measured at 1 million km2 below the previous record - an area roughly equivalent to the size of Egypt.

That trend, combined with ocean warming which causes water to expand, has contributed to a more than doubling of the rate of sea-level rise over the past decade compared with the 1993-2002 period, it said.

Ocean heat was concentrated in the North Atlantic with temperatures an average 3 degrees Celsius above average in late 2023, the report said. Warmer ocean temperatures affect delicate marine ecosystems and many fish species have fled north from this area seeking cooler temperatures.

Saulo, a meteorologist from Argentina who has promised to strengthen global warning systems for climate disasters, said she hoped the report would raise awareness of the “vital need to scale up the urgency and ambition of climate action”.