Record Sea Surface Temperature Jump in 2023–2024: Implications for the transient climate response to emissions and a possibly upcoming warming hiatus

Climate Coffee, 23rd April 2026

Over the past months, global sea surface temperatures (SSTs) have quietly done something quite important: they have returned to levels below those before the pronounced jump observed in 2023/24 (https://climatereanalyzer.org/clim/sst_daily/?dm_id=world2).
Earlier this year, we published a study in Nature magazine https://www.nature.com/articles/s41586-025-08674-z showing that abrupt SST jumps of this magnitude can arise solely from internal climate variability, as climate models can simulate such events without invoking an external shock or a permanent system shift. A key feature of these simulated jumps is that they are transient - temperatures typically relax back to pre-jump levels about two years later.
What is striking is that the real-world evolution has closely followed this pattern. Observed SSTs have now also returned to pre-jump levels, roughly two months later than the model range suggested. Given the small number of simulations with such high jumps (8 models), the range for the return remains uncertain, and a 2-month delay is well within uncertainty. The return of SSTs below pre-jump levels thus adds confidence to the interpretation that the 2023/24 jump may have been driven by internal variability rather than a fundamental reorganisation of the climate system. However, until we have observations over the next few years, we still cannot exclude a fundamental system shift.
At the same time, the relatively late recovery may point toward a climate system that responds more strongly to forcing than many models currently suggest - in other words, a potentially higher equilibrium climate sensitivity (ECS) and stronger underlying warming.
This interpretation aligns with another recent study of ours by Linus Vogt (https://esd.copernicus.org/articles/16/1453/2025), which shows that many climate models simulate too little Antarctic sea ice compared to observations. Because Antarctic sea ice strongly affects how much heat the Southern Ocean absorbs, this bias can lead to an underestimation of ECS.

Taken together, these results highlight an important nuance: short-term climate variability can produce large, temporary excursions, but the climate system's background sensitivity still matters enormously for long-term warming. Understanding both - and not confusing one for the other - is crucial for interpreting recent extremes and for improving future projections. At the same time, recent events are a reminder of how little we still understand about the climate system, and how important it is to keep questioning, testing, and refining our models as new observations emerge.

Publication: Terhaar, J., Burger, F.A., Vogt, L. et al. Record sea surface temperature jump in 2023–2024 unlikely but not unexpected. Nature 639, 942–946 (2025). https://doi.org/10.1038/s41586-025-08674-z

Recording: https://youtu.be/b6nWGqHkZ1Y

Sign up for more events