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about Gavin Schmidt

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

A CERES of fortunate events…

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The CERES estimates of the top-of-atmosphere radiative fluxes are available from 2001 to the present. That is long enough to see that there has been a noticeable trend in the Earth’s Energy Imbalance (EEI), mostly driven by a reduction in the solar radiation reflected by the planet, while the outgoing long wave radiation does not appear to contribute much. But what can be causing this?

A paper last year (Goode et al., 2021) also reported on a two decade estimate of Earthshine measurements which appear to confirm a small decrease in albedo (and decrease in reflected short wave (SW) radiation). While the two measurements are subtly different due to the distinct geometries, they do show sufficient coherence to give us some confidence that they are real.

Comparison of CERES SWup trends (blue) with inferred changes in Earthshine (black).

Similarly, Loeb et al. (2021) show that the trends in the EEI derived from CERES match what you get from the changes in ocean heat content.

Satellite-derived trends in EEI compared to estimates from changes in ocean heat (updated by Schmidt et al, 2023).

A few people have started to interpret the dominance of the SW trends to imply that the overall trends in climate are not (despite copious evidence) being driven by the rise in greenhouse gases (for instance, the rather poorly argued and seemingly un-copyedited Dübal and Vahrenholt (2021)) but these simplistic interpretations are seriously confused.

We can explore the issues and pitfalls of this using the ‘simple model’ of the greenhouse effect we explored back in 2007. At that time, we said:

You should think of these kinds of exercises as simple flim-flam detectors – if someone tries to convince you that they can do a simple calculation and prove everyone else wrong, think about what the same calculation would be in this more straightforward system and see whether the idea holds up. If it does, it might work in the real world (no guarantee though) – but if it doesn’t, then it’s most probably garbage.

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References

  1. P.R. Goode, E. Pallé, A. Shoumko, S. Shoumko, P. Montañes‐Rodriguez, and S.E. Koonin, "Earth's Albedo 1998–2017 as Measured From Earthshine", Geophysical Research Letters, vol. 48, 2021. http://dx.doi.org/10.1029/2021GL094888
  2. N.G. Loeb, G.C. Johnson, T.J. Thorsen, J.M. Lyman, F.G. Rose, and S. Kato, "Satellite and Ocean Data Reveal Marked Increase in Earth’s Heating Rate", Geophysical Research Letters, vol. 48, 2021. http://dx.doi.org/10.1029/2021GL093047
  3. H. Dübal, and F. Vahrenholt, "Radiative Energy Flux Variation from 2001–2020", Atmosphere, vol. 12, pp. 1297, 2021. http://dx.doi.org/10.3390/atmos12101297

Climate impacts of the #IRA

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With the signing of the Inflation Reduction Act (IRA) on Tuesday Aug 16, the most significant climate legislation in US federal history (so far) became law.

Despite the odd name (and greatly overused TLA), the IRA contains a huge number of elements, totalling roughly $350 billion of investment, in climate solutions over the next ten years. This is an historic effort though it falls short of the broader ‘Green New Deal‘ goals that were proposed in 2019, and doesn’t include all of the elements that were in the proposed 2021 reconcilliation package (the American Jobs Plan in “Build Back Better“) that ultimately floundered.

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The CO2 problem in six easy steps (2022 Update)

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One of our most-read old posts is the step-by-step explanation for why increasing CO2 is a significant problem (The CO2 problem in 6 easy steps). However, that was written in 2007 – 15 years ago! While the basic steps and concepts have not changed, there’s 15 years of more data, updates in some of the details and concepts, and (it turns out) better graphics to accompany the text. And so, here is a mildly updated and referenced version that should be a little more useful.

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River Ice break-up trends 2022

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As in previous years, the spring break-up of river ice on the Tanana River at Nenana and the Yukon River at Dawson City in Canada (new! h/t Ed Wiebe), is a great opportunity to highlight phenology that indicates that the planet is in fact reacting to the ongoing global warming. As we’ve done in previous years, the Nenana dates can be plotted and show a clear trend towards earlier break-ups (by about 8 days/century over the whole record, or 13 days/century since 1975).

Nenana Ice Classic break up dates since 1917.

2022 was on trend, and in 2014, I noted that May 3rd was the most likely date given the trends until then.

Dawson City in the Yukon is about 250 miles east of Nenana which is close enough for the seasonal anomalies in climate to be quite highly correlated. So one might expect that the break-up dates would be similarly correlated… and indeed they are:

Break up dates at Nenana and Dawson City

The ice at Dawson breaks up on average 3.8 days later than the ice at Nenana (5.1 days this year), but the correlation between the two series is an impressive 0.82. There have been 15 times the ice went out within 24 hours of each other and in 1963 they broke up less than 3 minutes apart! The trends are likewise very similar 7.7±3.8 days/century for Nenana, compared to 6.5±3.1 days/century since 1917. This pretty much puts paid to the occasional claim of the urban heat island in Fairbanks affecting the water and causing the trend.

[Update: I misunderstood the Yukon river break up website, and erroneously stated that the break-up was on May 2nd. It was not. I’ll update this again when it has. Apologies.]

[Update II: The Yukon river ice broke up on May 7, and I’ve updated the graph and text.]

Digital Twinge

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A couple of weeks ago the EU announced that they were funding a project called DestinE (Destination Earth) to build ‘digital twins’ of the Earth System to support policy making and rapid reaction to weather and climate events.

While the term ‘digitial twin’ has a long history in the engineering world, it’s only recently been applied to Earth System Modeling, and is intended (I surmise, as does Bryan Lawrence) to denote something more than the modeling of either weather or climate that we’ve been doing for years. But what exactly? And is it an achievable goal or just a rebranding effort of things that are happening anyway?

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The modern demarcation problem

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Defining (and enforcing) a clear line between information and mis-information is impossible, but that doesn’t mean misinformation doesn’t exist or that there is nothing to be done to combat it.

I found myself caught in an ‘interesting’ set of exchanges on twitter a few weeks ago (I won’t link to it to spare you the tedium, but you could probably find it if you look hard enough). The nominal issue was whether deplatforming known bull******s was useful at stemming the spread of misinformation (specifically with respect to discussions around COVID). There is evidence that this does in fact work to some extent, but the twitter thread quickly turned to the question of who decides what is misinformation in the first place, and then descended into a free-for-all where just the very mention that misinformation existed or that the scientific method provided a ratchet to detect it, was met with knee-jerk references to the Nazi’s and the inquisition. So far, so usual, right?

While the specific thread was not particularly edifying, and I’ll grant that my tweets were not perfectly pitched for the specific audience, this is a very modern example of the classic Demarcation Problem (Stanford Encyclopedia of Philosophy) in the philosophy of science.

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Issues and Errors in a new Scafetta paper

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Earlier this week, a new paper appeared in GRL by Nicola Scafetta (Scafetta, 2022) which purported to conclude that the CMIP6 models with medium or high climate sensitivity (higher than 3ºC) were not consistent with recent historical temperature changes. Since there have been a number of papers already on this topic, notably Tokarska et al (2020), which did not come to such a conclusion, it is worthwhile to investigate where Scafetta’s result comes from. Unfortunately, it appears to emerge from a mis-appreciation of what is in the CMIP6 archive, an inappropriate statistical test, and a total neglect of observational uncertainty and internal variability.

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References

  1. N. Scafetta, "Advanced Testing of Low, Medium, and High ECS CMIP6 GCM Simulations Versus ERA5‐T2m", Geophysical Research Letters, vol. 49, 2022. http://dx.doi.org/10.1029/2022GL097716
  2. K.B. Tokarska, M.B. Stolpe, S. Sippel, E.M. Fischer, C.J. Smith, F. Lehner, and R. Knutti, "Past warming trend constrains future warming in CMIP6 models", Science Advances, vol. 6, 2020. http://dx.doi.org/10.1126/sciadv.aaz9549

The Future of Climate Modeling?

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There was an interesting workshop last week focused on the Future of Climate Modelling. It was run by the World Climate Research Program (WCRP) Core Project on Earth System Modelling and Observations (ESMO) which is part of a bewildering alphabet soup of various advisory committees that exist for mostly unclear historical reasons. This one actually does something useful – namely it helps organize the CMIP activities that many modeling groups contribute to (which inform the assessment reports like IPCC and various national Climate Assessments). They had a wide variety of people and perspectives to discuss the changing landscape of climate modeling and what people want from these models. You won’t agree with everything, but it was informative.

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Another dot on the graphs (Part II)

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We have now updated the model-observations comparison page for the 2021 SAT and MSU TMT datasets. Mostly this is just ‘another dot on the graphs’ but we have made a couple of updates of note. First, we have updated the observational products to their latest versions (i.e. HadCRUT5, NOAA-STAR 4.1 etc.), though we are still using NOAA’s GlobalTemp v5 – the Interim version will be available later this year. Secondly, we have added a comparison of the observations to the new CMIP6 model ensemble.

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