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Boundary Layer Clouds: Another Instance of IPCC Authors Reviewing Their Own Work
As we’ve discussed before (and is well known), clouds are the greatest source of uncertainty in climate sensitivity. Low-level (“boundary layer”) tropical clouds have been shown to be the largest source of inter-model difference among Global Climate Models (GCMs). Clouds have been known to be problematic for GCMs since at least the Charney Report in 1979. Given the importance of the topic for GCMs, one would have thought that AR4 would have devoted at least a chapter to the single of issue of clouds, with perhaps one-third of that chapter devoted to the apparently thorny issue of boundary layer tropical clouds.
This is what an engineering study would do – identify the most critical areas of uncertainty and closely examine all the issues related to the critical uncertainty. Unfortunately, that’s not how IPCC does things. Instead, clouds are treated in one subsection of chapter 8 and boundary layer clouds in one paragraph.
Interestingly, the language in IPCC AR4 is (using the terminology of climate science) “remarkably similar” to Bony et al (J Clim 2006) url , with the differences as interesting as the similarities. It seems to me that each language change from Bony to IPCC had the effect of papering over or softening the appearance of problems or contradictions, rather than clearly drawing the issues to the attention of the public. (Note – Bony was a lead author of the chapter – another instance of IPCC authors reviewing their own work.)
Read the entire Climate Audit post: ‘Boundary Layer Clouds: IPCC Bowdlerizes Bony’
CRN comment: Reviewer Richard Allen made sensible scientific comments only to see them rejected by the lead authors.