Dr Roy Spencer, has weighted in on Dessler et al 2008. Water-vapor climate feedback inferred from climate fluctuations, 2003-2008,

Whereas Dessler closes his paper firmly in the climate liberal camp.

[23] The existence of a strong and positive water-vapor feedback means that projected business-as-usual greenhouse gas emissions over the next century are virtually guaranteed to produce warming of several degrees Celsius. The only way that will not happen is if a strong, negative, and currently unknown feedback is discovered somewhere
in our climate system.

Climate conservative Spencer continues where he left off:

The Rest of the Story: Shortwave Feedback

The other half of the feedback story which Dessler et al did not address is the reflected solar component. This feedback is mostly controlled by changes in low cloud cover with warming. The IPCC admits that feedbacks associated with low clouds are the most uncertain of all feedbacks, with positive or negative feedback possible…although most, if not all, IPCC models currently have positive SW feedbacks.

But I found from the CERES data a strongly negative SW feedback during 2002-2007. When added to the LW feedback, this resulted in a total (SW+LW) feedback that is strongly negative.

Is my work published? No…at least not yet…although I have tried. Apparently it disagrees too much with the IPCC party line to be readily acceptable. My finding of negative SW feedback of around 5 W m-2 K-1 from real radiation budget data (the CERES instrument on Aqua) is apparently inadmissible as evidence.

In contrast, Dessler et al.’s finding of positive LW feedback inferred indirectly from the AIRS instrument, even though it is only 1.3 W m-2 K-1 (3.3 Planck response minus their reported 2.0 for the LW feedback parameter) is not only admissible, but the reviewers even let the authors call it “strongly positive” feedback. Sheesh.

The last calculations regarding the Planck response seem to suggest that the null value — no feedback response — should be 0.7. Is this right? This would impact on the determination of the significance of the result considerably.

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