September was the hottest on record globally, the EU's climate service has revealed, putting the world on course for 2020 being the warmest ever year.
The Copernicus Climate Change Service (C3S) said on Wednesday that every month this year had ranked within the top four warmest of the month in question, while September had broken records overall.
It was 0.05°C warmer last month than September 2019 — the last record holder — and was 0.08°C warmer than the same period in 2016.
September 2020 also saw the second lowest Arctic sea ice extent ever recorded, both for daily and monthly averages.
It comes after a period of unusually high temperatures off the coast of northern Siberia, in the Middle East, parts of South America and Australia — while Europe experienced its own heatwave, too.
The continent was around 0.2°C above the warmest September recorded in 2018, while much of the region, and in particular the south east, saw above average temperatures.
However, C3S noted, similar magnitudes have been recorded over the last 20 years and are no longer considered unusual.
These latest temperature checks mean the planet is now on par with 2016, the current hottest year on record, and, dependent on weather events closing out the year, 2020 could surpass it.
Siberia has had a particularly warm year. In May, temperatures were up to 10°C higher than average, while June was more than 5°C higher than the 1981-2010 average across the whole of Arctic Siberia.
The climate agency said it is now watching out for La Niña, a cold-weather event, and the levels of Arctic ice cover this autumn, which are expected to influence whether 2020 breaks the world's all-time annual temperature record.
Carlo Buontempo, Director of Copernicus Climate Change Service at ECMWF, said weather conditions this year served as further proof that more comprehensive monitoring was necessary.
He said: "In 2020, there was an unusually rapid decline in Arctic sea ice extent during June and July, in the same region where above average temperatures were recorded, preconditioning the sea ice minimum to be particularly low this year.
"The combination of record temperatures and low Arctic sea ice in 2020 highlight the importance of improved and more comprehensive monitoring in a region warming faster than anywhere else in the world."