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James Hansen 1, Michael Crichton and Pat Michaels 0

 May 15, 2007

A good post by Realclimate sets the record straight on “Jim Hansen’s now famous congressional testimony given in the hot summer of 1988.”

Who tried to smear Hansen by shamelessly misreporting his testimony? Pat Michaels and Michael Crichton.

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This entry was posted by Joe on Tuesday, May 15th, 2007 at 7:18 pm and is filed under Politics, Science. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

3 Responses to “James Hansen 1, Michael Crichton and Pat Michaels 0”

  1. Jim Manzi says:
    May 17, 2007 at 5:12 pm

    Actually the subtleties are quite important. This is the key summary that Gavin provides in the post you have linked to:

    “But can we say that this proves the model is correct? Not quite. Look at the difference between Scenario B and C. Despite the large difference in forcings in the later years, the long term trend over that same period is similar. The implication is that over a short period, the weather noise can mask significant differences in the forced component.”

    In Hansen’s peer-reviewed 2006 NAS article that reviewed the accuracy of these projections (his own), he said that 17 years is too brief a period to permit precise assessment of climate sensitivity. Gavin actually references this in his post.

    What both of these climate modelers have said boils down to the fact that the period since the prediction is still too short to permit falsification or non-falsification of the forecast.

  2. Joe says:
    May 17, 2007 at 5:21 pm

    But you left out this:

    The bottom line? Scenario B is pretty close and certainly well within the error estimates of the real world changes. And if you factor in the 5 to 10% overestimate of the forcings in a simple way, Scenario B would be right in the middle of the observed trends. It is certainly close enough to provide confidence that the model is capable of matching the global mean temperature rise!
    … [The paragraph you cite.]
    Hansen stated that this comparison was not sufficient for a ‘precise assessment’ of the model simulations and he is of course correct. However, that does not imply that no assessment can be made, or that stated errors in the projections (themselves erroneous) of 100 to 400% can’t be challenged. My assessment is that the model results were as consistent with the real world over this period as could possibly be expected and are therefore a useful demonstration of the model’s consistency with the real world. Thus when asked whether any climate model forecasts ahead of time have proven accurate, this comes as close as you get.

  3. Jim Manzi says:
    June 9, 2007 at 3:45 pm

    Joe:

    The first paragraph in summary says that the model matched the historical temperature rise. Which is true, but to see the problem, consider that if you had terminated the measurement period in 2000 instead of 2005, you would have found a 600% error. By what a priori logic is 17 years the right period and 12 years the wrong period for measurement?

    This fallacy (in reverse) is the basis for the,as Gavin correcly notes, erroneous assertions that Hansen was “off by 300%”.

    The second paragraph that you cite makes this point, in what is really a logical repreat of the first paragraph, stated as the model is ‘consistent’ with obversations. As per above, true. But consistent at year 17, though not at year 12 and in a forecast for which (as of the 17 year point) the forecast temperature increase is greater for a lower-emissions scenario than a higher-emissions scenario is the not the same as passing a real falsification test.

    As Hansen indicates, within 10 years the scenario predictions should diverge enough to provide a real test.

    Please note that there is a very long RC thread on ths topic.

    Thanks,
    Jim