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Gavin Schmidt is a climate modeler, working for NASA and with Columbia University.

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

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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Oh My, Oh Miocene!

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A recent paper suggested that ‘climate sensitivity’ derived from a new paleo-CO2 record is around 7.2ºC (for equilibrium climate sensitivity ECS) and ~13.9ºC (Earth System Sensitivity – ESS) for a doubling of CO2. Some press has suggested that this means that “Earth’s Temperature Could Increase by 25 Degrees” (F). Huge if true! Fortunately these numbers should not be taken at face value, but we need to dig into the subtleties to see why.

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New journal: Nature 2023?

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[Last update Dec 6, 2024] There were a number of media reports today [May 11, 2024] related to Yuan et al. (2024), for instance, New Scientist, The Guardian etc. However, this is really just the beginning of what is likely to be a bit of a cottage industry in the next few months relating to possible causes/influences on the extreme temperatures seen in 2023. So to help people keep track, we’ll maintain a list here to focus discussions. Additionally, we’ll extract out the key results (such as the reported radiative forcing) as a guide to how this will all eventually get reconciled.

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References

  1. T. Yuan, H. Song, L. Oreopoulos, R. Wood, H. Bian, K. Breen, M. Chin, H. Yu, D. Barahona, K. Meyer, and S. Platnick, "Abrupt reduction in shipping emission as an inadvertent geoengineering termination shock produces substantial radiative warming", Communications Earth & Environment, vol. 5, 2024. http://dx.doi.org/10.1038/s43247-024-01442-3