The first of several global climate analyses for the month of September is now in, and the warmth it documents is simply astonishing.
As Zeke Hausfather of Berkeley Earth put it on Twitter: "This month was, in my professional opinion as a climate scientist – absolutely gobsmackingly bananas."
During September, the average air temperature at the surface was 0.5 degrees C (1.674 degrees F) above the 1991-2020 average for the month, according to the European Copernicus Climate Change Service. That's the biggest jump in temperature over the long-term average ever seen for any month in the Copernicus dataset, which goes back to 1940.
The month was about 1.75 degrees C (3.15 F) above the 1850-1900 preindustrial average temperature for September. That's significant because most nations of the world have committed to trying to hold global heating to below 1.5 degrees C in an attempt to minimize even worse climate change impacts than we've seen so far.
The record-smashing September we've just experienced follows on from a record-warm August and July. The latter also happened to be the warmest month ever seen in records that extend back to the 1880s.
For the year so far — January through September — the global mean temperature is 1.40 degrees C above the preindustrial average. That means we're inching ever closer to exceeding that 1.5 degrees threshold.
Humankind's emissions of greenhouse gases have been driving long-term warming of the planet. On top of that trend, a strengthening El Niño — which may be evolving into what is known as a "super El Niño" — is releasing huge amounts of heat from the ocean into the atmosphere, helping to drive up global temperatures.
Years with strong El Niños tend to break temperature records. It is already clear that 2023 almost certainly will go down as the warmest year on record. And next year could prove to be even warmer.