September didn’t just break the global temperature record; it obliterated the record by an unprecedented margin.
Data from Copernicus, run by the EU, shows the Earth’s average surface air temperature was 16.38 degrees Celsius last month — 0.5C above the previous warmest September in 2020.
It was not only a record for September but also the all-time warmest compared to average for any month, landing 1.75C above the 1850–1900 pre-industrial reference period.
“The unprecedented temperatures for the time of year observed in September — following a record summer — have broken records by an extraordinary amount,” according to Samantha Burgess, deputy director of the Copernicus Climate Change Service.
September follows a record hot June, July and August, and has lifted the year-to-date 2023 temperature 0.05C above the current warmest calendar year of 2016.
“This extreme month has pushed 2023 into the dubious honour of first place — on track to be the warmest year and around 1.4C above pre-industrial average temperatures,” Ms Burgess said.
Other climate datasets showed a similar figure for September, leaving climatologists gob-smacked.
Ocean temperatures and ice also at record levels
The average sea surface temperature for September was also the highest on record at 20.92C and the second highest across all months, behind August 2023.
This year’s global ocean heat is perhaps even more significant than the high air temperatures, with six months out of nine in 2023 breaking a record.
The warm oceans have coincided with record low sea-ice forming around Antarctica, staying at record low levels in September for the fifth consecutive month.
Ice coverage around Antarctica grows through the austral winter and typically peaks in September, but was 9 per cent below average last month, easily the lowest annual maximum extent on record.
Climate change the main driver of 2023 records
Historical data shows than even though El Niño has developed the trend this year is well outside the typical warming seen during Pacific warm phases.
“In particular, the Septembers of other recent years with developing El Niño events, such as 1997 and 2015, have not been especially warm.” was stated in the Copernicus monthly summary
The culprit of the prolonged records is therefore climate change as the earth corrects the climate change trajectory following three years of suppressed warming during a triple La Niña when heat is stored below the ocean surface.
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