The World Meteorological Organisation (WMO) also warned that the average temperature for the year is up some 1.4 degrees Celsius from pre-industrial times.

The WMO Secretary-General, Petteri Taalas, said the onset earlier this year of El Nino, the weather phenomenon marked by heating in the Pacific Ocean, could tip the average temperature next year over the 1.5-degrees Celsius target cap set in Paris.

“It's practically sure that during the coming four years, we will hit this 1.5, at least on a temporary basis,” he said in an interview. “And in the next decade, we are more or less going to be there on a permanent basis.”

WMO issued the findings at the UN's annual climate conference, this year being held in the oil-rich United Arab Emirates city of Dubai. The UN agency said the benchmark of the Paris Accord goal will be whether the 1.5-degree increase is sustained over a 30-year span and not just a single year.

“Clarity on breaching the Paris agreement guard rails will be crucial,” said Richard Betts of Britain's Met Office. “Without an agreement on what actually will count as exceeding 1.5 degrees Celsius, we risk distraction and confusion at precisely the time when action to avoid the worst effects of climate change becomes even more urgent,” he added.

WMO's Taalas said that whatever the case, the world appears on course to blow well past that figure anyway. 

“We are heading towards 2.5 to 3 degrees warming and that would mean that we would see massively more negative impacts of climate change,” Taalas said, pointing to glacier loss and sea level rise over “the coming thousands of years.”

The nine years from 2015 to 2023 were the warmest on record, WMO said. Its findings for this year run through October, but it says the last two months are not likely to be enough to keep 2023 from being a record-hot year.