RealClimate is “Climate science from climate scientists”
But sometimes it feels as if  Gavin Schmidt, a genuine climate modeller, isn't reasoning logically.

Today's exchange summary:

Gavin argues that a big shift in climate can’t occur because we would need methane emissions orders of magnitude larger than recently recorded.

I answer that Dr Natalia Shakhova and Dr. Igor Semiletov think that will happen because the methane reservoir is so large, the water column is so shallow and the permafrost seal is weakening.

Gavin says: If this reservoir existed and was so poised to release methane as you speculate, then it would have done something during warmer conditions early in the Holocene, or in the last interglacial. There is no evidence that it did so.

Me: Recent warming may be exceeding earlier Holocene warming. The earlier warming occurred over thousands of years. When greenhouse gasses rise in mere decades, slow moving processes which remove them can be overwhelmed.

Gavin replies: The rate of warming has nothing to do with the arguments put forward – [by Shakhova and Semiletov] they are all based on absolute temperature thresholds, so the dismissal of orbitally driven causes is not appropriate.

[Here Gavin avoided a rebut to my response on the grounds that what I said wasn’t what Shakhova  and Semiletov said.]

Please note, I am not arguing for Arctic changes to be ignored - they are large, serious and likely to increase - but this does not mean that anything goes. I see no basis for Dr. Shakhova and Dr. Semiletov's argument that 'runaway warming is at most a hundred years away' - the statement is basically meaningless. If they mean a real transition to Venusian conditions, that is ridiculous, but if they only mean to imply that there are some amplifying feedbacks, then there is no argument (except on the terminology) - but the issue is whether they will be large or small. - gavin]

[bold mine, blue is my commentary]

What’s the name for that propaganda technique where you interpret your opponent’s claim as meaning one of two possible extremes, neither of which is plausible? They didn't fail to distinguish runaway Arctic warming from Runaway Greenhouse Effect (which involves the climate forcing of water vapor). On the other hand they said far more than "there are some amplifying feedbacks".

Rephrasing the issue as just terminology, as there is no argument but the issue of whether they will be large or small, sounds like reframing something critical for human survival as if it were a minor difference.

Gavin Schmidt may be highly skilled, but I feel as if he's discounting with language instead of presenting reasoned arguments.

Here's the full article with comments section. Mine are comments 15, 32 and 37.

How do you see it? Am I misunderstanding?

Tags: RealClimate comments

Views: 36

Replies to This Discussion

Grinning Cat informs me, privately, that

The technique of interpreting a statement only in light of two possibilities is the “false dilemma” or “bifurcation fallacy”:
http://www.logicalfallacies.info/presumption/false-dilemma/
https://en.wikipedia.org/wiki/False_dilemma


The fallacy of the excluded middle from the Wikipedia article sounds like the best fit for Gavin Schmidt's last reply, to me.

image source


Thanks, Grinning Cat.

You're right, the "excluded middle" fallacy makes more specific sense here. Thanks!

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