Gavin Schmidt’s TED talk

I know Rachel’s already posted about Gavin’s TED talk, but it’s worth posting again. I thought I might also highlight the slides from another talk that Gavin gave at the Royal Society. You can also listen to the talk.

What’s interesting about Gavin’s Royal Society talk, is that it’s about using Global Circulation Models (Global Climate Models – GCMs) to model our past climate, in particular the mid-Holocene, the Last Glacial Maximum (LGM), and the last Millenium. It also probably has one of the best quotes on this topic that I’ve encountered

If we had observations of the future, we obviously would trust them more than models, but unfortunately …… observations of the future are not available at this time. (Knutson & Tuleya – 2005).

I don’t want to say too much about this as it’s not something I’m that familiar with, but as I understand it these are the same models that are being used to understand how different emissions pathways (RCPs) will influence our future climate. This type of modelling therefore seems useful as it’s another way of testing the models. You can also use it as another estimate of climate sensitivity, although I’m unclear as to whether or not this can be regarded as an independent estimate. It does, however, seem to give ECS estimates that are consistent with other methods – as shown in the figure below, which I’ve taken from Gavin’s talk slides.
Anyway, that’s all I was going to say. I’m sure there are some regular commenters who understand the significance of the paleo-model comparisons better than I do. The main point of this post was simply a chance to highlight Gavin’s excellent TED talk, which you can view below.

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24 Responses to Gavin Schmidt’s TED talk

  1. John Mashey says:

    1) Indeed, that was an excellent talk, although I may be biased by having helped design supercomputers for NASA, NCAR, GFDL etc and talk to their researchers, quite stimulating.

    2) The “observations of the future unavailable” quote is fairly famous as such go.

    3) However, one slight error (well, an in-joke, really, that I think the audience didn’t quite get) was about Fortran, where he mentioned “newfangled things like C”
    Fortran is ~60 years old, C is ~40, still an eternity in computing 🙂
    But, while the system software for those supercomputers was in C, most of the cycles were used running big Fortran codes …

  2. John,
    Yes, I noticed the C comment and really enjoyed it. I still use Fortran 77 🙂 In fact, any any basic modelling I’ve done for blog posts has almost exclusively been done in Fortran 77.

  3. John Mashey says:

    Ahh, f77 … almost as old as C, none of this newfangled stuff like f90.
    (Of course, speaking from a compiler code optimization view, one can often generate better code for Fortran than the equivalent C, enough to matter for long-running computational codes.)

    Actually, any computer language that actually gets a serious installed base tends to last a long time, as per Languages, Levels, Libraries, and Longevity in ACM Queue … where I note that that Vernor Vinge’s sci-fi idea of a UNIX C timer routine being used in a starship 5,000 years from now …is unfortunately not so outlandish, given:
    “The word for all this is ‘mature programming environment.’”

  4. BBD says:

    S-ff is still ~3C for 2xCO2 then…

    It’s almost as though this might be approximately correct.

  5. BBD says:

    And that’s enough of that filthy programming talk. This is a decent, family blog.

  6. And here was me about to point out that I’m in the process of migrating to a new more modern version of the code that I normally use – now written in Fortran 90, rather than Fortran 77 – and the new code is MPI, not simply OpenMP 🙂

  7. BBD says:

    FILTH! Computers are the Devil’s work!


  8. Rachel M says:

    I’m glad you’ve posted this because it’s a really good talk and your blog gets much more traffic than mine. Everyone should watch it. Gavin has another youtube video that I also thought was great and worth highlighting:

  9. BBD says:

    Interesting clip, Rachel; thanks.

    I particularly noted the sentiment that if scientists do not speak, the “dark space” in public discourse is colonised by vociferous agenda-pushers.

  10. jsam says:

    Despite BBD’s imprecations, I started on WATFIV and did some digital-analog computing – nothing cranks diffy-qs like an analog computer. And bootstrapping a PDP-8 from paper tape… Computer porn finished…

  11. .. or starting an Elliot 803 by setting the bits of the first instruction manually from the control board and pushing a bar to get that instruction executed.

  12. BBD says:

    I used to be a very technical boy (William Gibson fans might get the reference) but not these days. Neophilia has its limits, I have discovered. The medium is not the message.

  13. uknowispeaksense says:

    Reblogged this on uknowispeaksense.

  14. John Mashey says:

    Ignoring the Luddite-speak, I strongly recommend William J. Kaufman & Larry L. Smarr, Supercomputing and the Transformation of Science, a 1993 book, but beautiful and still quite relevant. You can get it for not much more than shipping cost.
    Larry is a serious guy in this turf, yet aother physicist who saw the light and got into computing 🙂 Among other things, he ran NCSA back when the Mosaic web browser was done, but he bought lots of SGI gear, which was nice.

  15. BBD says:


    I jest.

  16. Eli Rabett says:

    You gotta read Rabett Run, had that quote back in 2006 and several times since.

    This one is particularly enjoyable given recent posts here.


  17. Eli,
    I do read Rabett Run, I just haven’t worked my way through the whole back catalog 🙂

  18. The paleo climate runs provide an independent validation of the climate models and thus of their estimates of climate sensitivity. That is why the CMIP, Coupled Models Intercomparison Project, was this time complemented with PMIP, Paleo Models Intercomparison Project. For details there is a nice, but more technical talk by Gavin Schmidt (again) on this to the Royal Society, for which we only have audio and the slides.

  19. Victor,
    Thanks. That’s a clearer description of the merits of the PMIP project (the acronym to which I had not appreciated until you mention it). I think, however, that the links you’ve provided are the same as those in the post. Good enough to post twice though 🙂

  20. 🙂 Reading too fast. Sorry.

    One of the think Schmidt emphasises in his Royal Society talk is that while the modellers work on performing well for AGW, they are normally not interested in paleo climate. Thus the dangers of the models being tuned to perform well as much smaller. That also makes the paleo comparisons important. And naturally that the more cases you have, the more difficult it becomes to tune for any special one.(That is also way the validation includes a lot more that just the curve of the global mean temperature for the last 150 years.)

  21. toby52 says:

    Physicists and computer scientists have not seen eye-to-eye since Isaac Newton and Gottfried Leibnitz fell out over calculus, one of the great scientific brawls.
    Part of Leibnitz’s bio on Wiki:
    He became one of the most prolific inventors in the field of mechanical calculators. While working on adding automatic multiplication and division to Pascal’s calculator, he was the first to describe a pinwheel calculator in 1685 and invented the Leibniz wheel, used in the arithmometer, the first mass-produced mechanical calculator. He also refined the binary number system, which is at the foundation of virtually all digital computers.

  22. Eli Rabett says:

    Setting the switches on a PDP 8 to boot up and play star wars. . .Does anyone remember FORTH? Eli was rather fond of the tiny thing for controlling experiments esp when you only had zero memory.

  23. BBD says:

    Since we wax nostalgic, I remember as a boy, perhaps aged seven, or eight, talking to my maternal great-grandmother, then in her 90s, one sunny afternoon. A jet flew overhead, and GGM said ‘I remember when there were no aeroplanes, then the first ones. And no cars’. And I thought, I wonder what I’ll see? Men on Mars?

    But no. The rise of the machines and an intertube front seat on the PMIP’d ride into the future. Stranger than fiction.

  24. Pingback: The Climate Change Debate Thread - Page 4085

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