99% chance that 2023 will breach 1.5°C avg temp threshold: Study

It is “virtually certain” that the average temperature through 2023 will be at least 1.5°C above the pre-industrial average – making it, by far, the warmest year since measurements began – according to latest data from a leading non-profit focused on land temperature data analysis.

The forecast, which says there’s a 99% chance of 2023 being the warmest year on record, represented a large change from the forecast at the beginning of the year, when only 14% chance of record temperatures in 2023 was estimated, California-based Berkeley Earth said in its November 2023 temperature update.

The report left it to an “extraordinary event” like an asteroid hitting the Earth or a supervolcanic eruption to cool December enough to avoid the new record.

“The surprising warmth over recent months and the strong El Nino, raised our estimates for the final 2023 annual average. We now consider there to be a 99% chance that 2023 has an annual-average temperature anomaly more than 1.5°C above the 1850-1900 average. Prior to the start of 2023, the likelihood of a 1.5 °C annual average this year was estimated at ~1%,” the update published on December 19 said.

In a similar prediction just days before, the US’s National Oceanic and Atmospheric Administration said that November’s record temperatures, coming on the back of record temperatures since June, now seals 2023 to be the warmest year ever, with greater than 99% chance of it breaking all past annual temperature records.

To be sure, a monthly or even yearly breach of 1.5°C — a key threshold under the Paris Agreement beyond which multiple tipping points could be triggered leading to cascading effects for the climate system — does not automatically mean that the goal has been exceeded. But this year’s breach serves to emphasise that time is running out to meet this target by bringing down emissions.

“Unless sharp reductions in man-made greenhouse gas emissions occur soon, the long-term average is likely to pass 1.5°C during the 2030s,” the Berkeley Earth statement said.

The past six months in a row — June, July, August, September, October, and November — have all set new records for monthly average temperature in 2023, and mostly by large margins.

“At 1.77 ± 0.12 °C (3.18 ± 0.22 °F) above the 1850 to 1900 average, November 2023 was by far the warmest November and the 2nd largest anomaly on record (behind September 2023),” Berkeley Earth said in a series of posts on X, formerly Twitter.

“The September to November season was a scorcher, with the three largest global temperature anomalies on record. 19% of the Earth’s surface – including 32% of the land – saw a three month average that set a new local record high,” Robert Rhode, lead scientist at Berkeley Earth, said on X.

The El Nino that set in early this year may have an even larger warming effect on global mean temperatures in the next year.

Usually, the second year of an El Nino is warmer than the first.