Carbon Brief’s latest quarterly climate update puts the odds that 2027 will be the warmest year on record at 96%, with a median global temperature of about 1.74 degrees Celsius above pre-industrial levels. Climate scientist Zeke Hausfather wrote the Nov. 3 analysis, which also finds a 98% chance that at least one of 2026 or 2027 sets a new record. The driver is an El Niño whose effect on global temperature arrives with a delay of roughly three months.
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The same update treats 2026 as a near-tie. Its best estimate for this year is about 1.52 degrees, level with the 2024 record, so a record for 2026 is close to a coin flip at 67% across six datasets while the case for 2027 is far stronger.
The 96% figure and the 1.74-degree median for 2027
In Hausfather’s Carbon Brief analysis, published on Nov. 3 and updated on Nov. 4, the 2027 median is about 1.74 degrees with a 90% range of 1.54 to 1.95 degrees; the summary section rounds it to 1.7. The 96% record probability follows from that distribution: nearly all of the plausible outcomes sit above the 2024 value of 1.52 degrees, so only a small tail falls below it. Carbon Brief also gives the 2026 and 2027 outcomes together: a 98% chance that at least one of the two years breaks the record, which reflects how little separates 2026 from 2024 and how far above both the 2027 median sits.
The method averages six datasets, GISTEMP, NOAAGlobalTemp, HadCRUT5, Berkeley Earth, ERA5 and JRA-3Q, and combines year-to-date observations with El Niño forecasts in a statistical model.
2026 as a statistical tie with 2024
For this year, the 90% range is 1.50 to 1.55 degrees, and Carbon Brief gives a 93% chance that 2026 exceeds 1.5 degrees, which would make it the second year to do so after 2024. The record odds vary sharply by dataset: Berkeley Earth 97%, NASA’s GISTEMP 82%, HadCRUT5 72% on data through August, JRA-3Q 48%, NOAA 34% and ERA5 18%. The spread explains why Carbon Brief calls the year a tie rather than a record.
January through September was the second-warmest such period at about 1.45 degrees, behind only 2024. August was the warmest August in all six datasets, roughly 0.12 degrees above the previous record. September came in second behind 2023 at about 1.62 degrees, and the Copernicus Climate Change Service’s September bulletin agrees with the ranking, putting it at 1.63 degrees above pre-industrial and 0.11 degrees cooler than September 2023. Copernicus adds that the 12 months through September averaged 1.50 degrees.
An El Niño that has already broken records
Hausfather’s analysis reports that the daily Niño3.4 record was broken in September and has been exceeded every day since. Carbon Brief examined 656 forecasts from 14 dynamical models; on average they show a peak near 4 degrees in December, more than 1 degree above the prior record. Because global temperatures trail the tropical Pacific by about three months, the largest effect lands in 2027 rather than this winter.
The U.S. Climate Prediction Center sees the same event from the observational side. Its Oct. 8 ENSO discussion left the El Niño Advisory standing and reported Niño-3.4 at plus 2.1 degrees, and put the odds of a strong-to-very-strong event lasting into January-March 2027 above 83%. The center set its next update for Nov. 12.
The picture has shifted over the year. Carbon Brief’s April update put 2026 at 1.47 degrees, most likely the second-warmest year, with only a 19% chance of beating 2024, and said a super El Niño would make a 2027 record likely.
Ways the 96% call could miss
Hausfather cautions that the forecast lies beyond the range of events the statistical model was trained on. If this El Niño’s warming effect is no larger than that of the strongest past events, the odds of a record year would be closer to 50%. In plain terms, the 96% depends on the extra-strong El Niño translating into extra-strong warming.
The year also brought regional extremes. Western Europe had its hottest summer on record, Spain’s September beat the 1987 record by 0.7 degrees, and about 22% of the Earth’s surface had its warmest July to September. Earth’s energy imbalance rose from about 0.53 watts per square meter in 2000-2010 to about 1.25 in 2016-2026, a 2.4-fold increase. Arctic sea ice tied for the 10th lowest September minimum, and the Antarctic winter maximum was the third lowest on record.
The test comes in the months ahead. The December peak of the El Niño and the datasets’ monthly updates through 2027 will show whether the model’s extrapolation holds. Two numbers will move first: the Nov. 12 Climate Prediction Center update, which can raise or lower the odds of a historic-strength El Niño, and the October and November readings from the six datasets, which decide whether 2026 itself edges past the 1.52-degree mark set in 2024.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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