September did not break the record for the month set in 2023 and was only marginally cooler than the same period last year, said the EU's global warming monitor.

"The global temperature context remains much the same, with persistently high land and sea surface temperatures reflecting the continuing influence of greenhouse gas accumulation in the atmosphere," said Samantha Burgess, strategic lead for climate at Copernicus.

September was 1.47C above the 1850-1900 average used to define the pre-industrial period before human activity began significantly influencing the climate.

Such incremental rises may appear small. But scientists say every fraction of a degree of extra warming further destabilises the planet, raising the risk of extreme weather and triggering destructive climate tipping points.

Global temperatures have been pushed steadily higher by humanity's emissions of greenhouse gases, primarily from fossil fuels burned on a massive scale since the industrial revolution.

Scientists expect that 2025 will be the third-hottest year after 2024 and 2023, with recent months tracking just behind the records set during this extraordinary stretch.

Nations face this reality as they gather in Brazil next month for the UN climate negotiations held every year to address the collective response to global warming.

Major economies are not cutting emissions fast enough to avoid the worst impacts of climate change, and many are still approving new oil, coal and gas projects.

Copernicus uses billions of measurements from satellites, ships, aircraft and weather stations to aid its climate calculations.

Its records go back to 1940, but other sources of climate data -- such as ice cores, tree rings and coral skeletons -- allow scientists to expand their conclusions using evidence from much further in the past.

Scientists say the current period is likely the warmest the Earth has been for the last 125,000 years.