A heat advisory sign is shown along US highway 190 during a heat wave in Death Valley National Park in Death Valley, California, on July 16, 2023. AFP

Last month smashed the previous November heat record, pushing 2023's global average temperature to 1.46˚C warmer than pre-industrial levels, the EU's Copernicus Climate Change Service said.

There had been warnings this year could take the title of hottest year from 2016 — particularly after records toppled in September and October — but this marks the first time it has been confirmed.

November also contained two days that were 2˚C warmer than pre-industrial levels. Not one such day had ever before been recorded.

Samantha Burgess, deputy head of the Copernicus service, said that 2023 has "now had six record-breaking months and two record-breaking seasons."

"The extraordinary global November temperatures, including two days warmer than 2C above pre-industrial (levels), mean that 2023 is the warmest year in recorded history," she said. Scientists say data from ice cores, tree rings and the like suggests this year could be the warmest in more than 100,000 years.

'Temperature will keep rising'

Meanwhile, 2023 has seen a series of devastating extreme weather events linked to climate change, even as the world's carbon emissions continue to rise.

According to Copernicus, whose records go back to 1940, the first 11 months of this year have been 0.13C hotter than in 2016, the previous warmest year.

Global temperatures in the second half of this year are believed to have been partly propelled by the El Nino weather pattern, which has caused fewer "anomalies" so far in 2023 than in 2015-2016, the Copernicus service said.

September to November, the three months marking autumn in the northern hemisphere, were the hottest ever "by a large margin," according to Copernicus.

November alone was 1.75˚C warmer than pre-industrial levels — and marked a significant 0.85˚C increase over 1991-2020, Copernicus said.

Such numbers could suggest that world is coming uncomfortably close to warming 1.5 degrees Celsius since pre-industrial times, which is a key threshold in the Paris climate agreement.

However to actually breach the Paris limit, global temperatures would need to stay above 1.5C over decades.

"As long as greenhouse gas concentrations keep rising we can't expect different outcomes," Copernicus head Carlo Buontempo said.

"The temperature will keep rising and so will the impacts of heatwaves and droughts," he added.

Also on Wednesday, researchers warned of 26 Earth "tipping points" such as melting ice sheets, that have the potential to unleash a domino effect of irreversible catastrophes across the planet.