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Unforced Variations: Jan 2025

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This month’s open thread on climate topics. Please remember to be substantive, respectful and vaguely on topic.

Note that we’ll have an update to the various observational datasets after Jan 10th, and hopefully an update to all the model-observation comparisons the week following (depending on other things not getting in the way).

Happy New Year to you all! (Our 20th!).

Nature 2023: Part II

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This is a follow-on post to the previous summary of interesting work related to the temperatures in 2023/2024. I’ll have another post with a quick summary of the AGU session on the topic that we are running on Tuesday Dec 10th, hopefully in the next couple of weeks.

6 Dec 2024: Goessling et al (2024)

This is perhaps the most interesting of the papers so far that look holistically at the last couple of years of anomalies. The principle result is a tying together the planetary albedo and the temperature changes. People have been connecting these changes in vague (somewhat hand-wavy ways) for a couple of years, but this is the first paper to do so quantitatively.

Fig 1B from Goessling et al (2024) giving an attribution of the 2023 anomaly from the pre-industrial.

The authors use the CERES data and some aspects of the ERA5 reanalysis (which is not ideal for these purposes because of issues we discussed last month) to partition the changes by latitude, and to distinguish impacts from the solar cycle anomaly (~0.03 K), ENSO (~0.07K) and the albedo (~0.22K) (see figure above).

What they can’t do using this methodology is partition the albedo changes across cloud feedbacks, aerosol effects, surface reflectivity, volcanic activity etc., and even less, partition that into the impacts of marine shipping emission reductions, Chinese aerosol emissions, aerosol-cloud interactions etc. So, in terms of what the ultimate cause(s) are, more work is still needed.

Watch this space…

References

  1. H.F. Goessling, T. Rackow, and T. Jung, "Recent global temperature surge intensified by record-low planetary albedo", Science, vol. 387, pp. 68-73, 2025. http://dx.doi.org/10.1126/science.adq7280

Unforced Variations: Dec 2024

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This month’s open thread on *climate* topics. Obviously, last month’s events lent themselves to broader discussions, but this month (and going forward), we remind you that comments have to be climate-related.

Note too that there are plenty of dying websites where you can troll to your heart’s content and post tedious partisan talking points, but here they will be unceremoniously deleted. Similarly, self-indulgent and repetitive comments to make the point that everyone is an deluded idiot except you, will also be binned.

Be substantive, be relevant, be concise, and most of all, be nice.

Cold extremes do in fact decrease under global warming

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The title of this post might seem like a truism, but for about a decade some people have claimed the opposite, and many people have spent much time and effort trying to understand why. Much of that effort was wasted.

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