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about Gavin Schmidt

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

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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Another dot on the graph

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So last week was the annual release of the temperature records from NASA, NOAA and Berkeley Earth. The Copernicus ERA5 data was released a few days ago, and the HadCRUT data will follow soon. Unlike in years past, there is no longer any serious discrepancy between the records – which use multiple approaches for the ocean temperatures, the homogenization of the weather stations records, and interpolation.

Depending on the product, 2021 was either the 5th, 6th or 7th warmest year, but in all cases, it is part of the string of warm years (since 2015) that have all been more than 1ºC warmer than the late 19th C.

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“Don’t Look Up”

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The highlight of the movie season for climate science has clearly been the release on Dec 24th 2021 of “Don’t Look Up”. While nominally about a different kind of disaster – the discovery of a comet heading to Earth on a collision course – the skewering of our current science-policy dysfunction transcends the specifics and makes a powerful metaphor for climate change, and even the ongoing COVID-19 pandemic.

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Making predictions with the CMIP6 ensemble

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The CMIP6 multi-model ensemble is a unique resource with input from scientists and modeling groups from around the world. [CMIP stands for the Coupled Model Intercomparison Project, and it is now in its 6th Phase]. But as we’ve discussed before (#NotAllModels) there are some specific issues that require users to be cautious in making predictions. Fortunately, there are useful ‘best practices’ that can help avoid the worst pitfalls.

A new paper by McCrystall et al that has just appeared in Nature Communications illustrates these issues clearly by having some excellent analyses of the changes in Arctic precipitation regimes at different global warming levels, and examining the sensitivity of their metrics to both local and Arctic warming, but unfortunately relying on the CMIP6 multi-model mean for their headline statements and press release.

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References

  1. M.R. McCrystall, J. Stroeve, M. Serreze, B.C. Forbes, and J.A. Screen, "New climate models reveal faster and larger increases in Arctic precipitation than previously projected", Nature Communications, vol. 12, 2021. http://dx.doi.org/10.1038/s41467-021-27031-y

Net Zero/Not Zero

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At the COP26 gathering last week much of the discussion related to “Net-Zero” goals. This concept derives from important physical science results highlighted in the Special Report on 1.5ºC and more thoroughly in the last IPCC report that future warming is tied to future emissions, and that warming will effectively cease only once anthropogenic CO2 emissions are balanced by anthropogenic CO2 removals. But some activists have (rightly) pointed out that large-scale CO2 removals are as yet untested, and so reliance on them to any significant extent to balance out emissions is akin not really committing to net zero at all. Their point is that “net-zero” is not zero and hence will serve as a smokescreen for insufficient climate action. To help sort this out some background might be helpful.

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Forced responses: Nov 2021

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A bi-monthly open thread related to climate solutions. This month will start off with COP-26 and many targets and plans and mechanisms will be proposed and discussed. Look out for the updated impacts of the evolving NDCs such as this one from Climate Resource, suggesting that the world could be on track for just a little less than 2ºC warming (relative to the pre-industrial) (if everyone does what they pledge and we are lucky with respect to climate sensitivity). Please be respectful and constructive.