False Sense of Certainty

Bruce Hall observes that climate forecasters probably need to adjust their confidence intervals.  For example:

  • NOAA predicted a the beginning of this season that there was an 85% chance of an above-normal season.  In fact, the hurricane season was well below average.  I haven’t done the math, but my guess is that if their forecast showed 85% probability of above normal, the year probably came in in the bottom 1% of its expected distributions
  • The UK Met Office predicted that there was a 60% probability that world temperatures in 2007 would be the highest in the last 100+ years, ie higher than temperatures in 1998.  In fact, it looks like 2007 will be among the coolest years in decades, and will come in as much as a half degree C below 1998, a huge difference.  Again, I have not run the numbers, but it is safe to say that this outcome would probably have been in the bottom 1% of the original forecast distribution.

If all your forecasts are coming out in the bottom 1% of the forecast range, then it is safe to assume that one is not forecasting very well.  Which reminds me of Michael Mann, who said with famous confidence that there was a 95-99% probability that 1998 was the hottest year in the last 1000, which is an absurd claim.  (Mann now denies having said this, but he is actually on film saying it, about 25 seconds into the linked clip).

6 thoughts on “False Sense of Certainty”

  1. I suppose somebody needs to go back and look at these predictions in an organized way.

    I do believe that these warmers are using probabilities they have pulled out of their asses as a way of hedging themselves.

  2. Here is NOAA’s summary paragraph dated August 9th:

    “NOAA is predicting a very high likelihood (85% chance) of an above-normal 2007 Atlantic hurricane season, a 10% chance of a near-normal season, and only a 5% chance of a below-normal season, according to a consensus of scientists at the National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center, National Hurricane Center, Hurricane Research Division, and Hydrometeorological Prediction Center.”

    So this wasn’t just a pre-hurricane season forecast, but one that was made 70 days or over 1/3 of the way into the season. It does not give me a great deal of confidence that our climate scientist can tell us what global temperatures are going to be next year much less in the next 10 or 20 years. Those of you who are observant will notice that NOAA used the phrase “consensus of scientists”. Haven’t we heard that somewhere before? Just askin.

  3. With respect to the claim that 2007 will be cooler, do you know where I can track down this year’s “global” temperature to date?


  4. Thanks Joe, I had poked around junkscience before but had somehow never come across that particular page – it’s a nice collection.

  5. Have you seen this release from the NOAA…


    An excerpt…
    “Including 2007, seven of the eight warmest years on record have occurred since 2001 and the 10 warmest years have all occurred since 1997. The global average surface temperature has risen between 0.6°C and 0.7°C since the start of the twentieth century, and the rate of increase since 1976 has been approximately three times faster than the century-scale trend.”

    Seems like they’re trying real hard to hide the fact the temps have been flat or down since 1998….


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