The September temperature data was described as "unprecedented," and researchers are puzzled as to why extreme temperatures are so high.

Now, researchers predict that 2023 will be the warmest year on record since observations began, leading us to a global temperature regime not seen in about 120,000 years. So why are the extremes higher than expected?

For climatologists, the September temperature data elicited a range of superlatives: "stunning," "unprecedented," "mind-boggling," "nerve-wracking."

Take a look at the data they are reacting to, and you will understand why.

September 2023 was not just a record-breaking September; it obliterated the previous record for the warmest September in history. It was half a degree warmer than the previous warmest September in 2020.

If this doesn't sound like much, remember that it is the average global temperature compiled from satellite data and monitoring stations covering the entire globe.

It was nearly a degree warmer than the recent September average.

And compared to pre-industrial times, before greenhouse gases began to warm the atmosphere, it is now 1.75 degrees warmer.

Another reason experts are expressing astonishment is that extremes continue to occur. June, July, and August were also exceptionally warm.

Researchers from the EU's Copernicus Climate Change Service, who prepared this latest analysis, now predict that 2023 will be the warmest year on record, leading us to a global temperature regime not seen in about 120,000 years.

The significant deviation from previous average temperatures in the context of an already warming world has led some to speculate that climate change is accelerating.

However, there is currently no clear evidence that this is happening.

On the chart above, major sources of global temperature data (colored lines) are compared to the average of all climate change models used to predict the scale of global warming expected as greenhouse gas emissions increase (shaded area represents model uncertainty).

Despite recent extreme events, average global temperatures are rising in line with what climate scientists have been predicting for decades.

But what baffles researchers is why the extremes we are witnessing in some parts of the world are much higher than many expected.

El Niño, a cyclical weather phenomenon in the Pacific Ocean, undoubtedly contributes to the current global temperature, as it introduces a pulse of warmth into the global climate system, making 2023 warmer and contributing to extreme weather events.

Anomalously high ocean temperatures off the west coast of South America, as observed in these satellite data, are one of its distinctive features.

But they suspect something more significant is happening.

The Atlantic Ocean has also been significantly warmer than usual. It is not linked to the Pacific El Niño system.

Nevertheless, this warmth contributes to the intensification of heatwaves in Europe this summer and an increase in extreme precipitation events, similar to what was observed in New York last week.

No one knows for sure why, but various climate consequences are possible, such as the melting of ice sheets, affecting ocean currents and allowing the ocean to absorb more heat.

The record loss of Antarctic sea ice this year may be both a symptom and a cause of the current temperature anomaly.