Colouring Doubt’s Flag


Judith Curry is keen to frame doubt in the form of an italian flag. Specifically with reference to this statement from IPCC WG1 Summary for Policy Makers:

Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.

Curry’s flag interpretation of this statement is that we could colour the flag 5% white (uncommitted belief), 67% green (anthropogenic forcing), 28% red (natural variability). A minor quibble: the opposite of “due to increase in anthropogenic GHG” is not “natural variability” as that excludes other anthropogenic activies such as sulphate emissions and secondary effects like ozone increases due to Montreal protocol. Anyway, her flag would look like this (if she drew it):

Does that seem right, can we be almost certain that there is only 5% wiggle room for doubt? Also, if I say that 70% of the variation is anthropogenic that doesn’t mean the rest (or almost all the rest) is natural, it just means I don’t know. I interpret the IPCC statement as meaning that there are a wide range of supportable beliefs about the anthropogenic cause of 20th century warming, but 95% (ish) of those will have more than 50% of the flag coloured green. Amongst the population of possible flags is this one:

Note that this flag already represents quite an extreme position with respect to the IPCC statement, because whilst it’s compatible with the IPCC statement, only 5% of the flags have a smaller green area than this. Here’s a more median position:

How can we represent the range of beliefs that are compatible with the IPCC statement. Like this?

4 Responses to “Colouring Doubt’s Flag”

  1. mike Says:

    Rather than dreaming up versions of the Italian flag for the IPCC report, wouldn’t it be better to try and align our colours with the “science” portion of Climate Science–with its limited known-knowns, partially-knowns, known-unknowns, and unknown-unknowns (I believe Secretary Rumsfeld is a pioneer in this field). Also, instead of offering self-satisfied digs at Dr. Curry’s blog on your own obscure blog, wouldn’t it better advance the cause of science to post your musings to Dr. Curry’s blog so that the “big boys” can have a shot at them.

    But maybe it’s better this way

  2. drj11 Says:

    Neither her blog nor mine appear to further the cause of science. That’s best done in the peer-reviewed literature.

    As for my self-satisfied digs, that’s precisely what _this_ blog is for. So I can be smug and arrogant.

    Anway, I assume Judith Curry’s blog does pingbacks.

  3. mike Says:

    Hey! That’s a great reply! Not quite on board with the peer review business, at least until we have a credible review of the peers and their reviews. But altogether I very much enjoyed your response and your unapologetic view of matters. I’ll drop by from time to time,if you don’t mind.

  4. Philosopher Says:

    [totally irrelevant to the discussion of how to represent uncertainty. deleted]

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