W00t, its the Big Fight, or at least its the spat du jour. Does anyone outside the little blogospheric circle care? My guess is no. As I said over at Timmy’s recently, my personal “does-the-outside-world-give-a-shit-o-meter” (as applied to the latest septic nonsense to hit the blogospheric fan) is “has anyone tried to push it into any of the major GW type articles on wikipedia”? By that test, the latest stuff from Lewis scores zero. Even Schwartz managed better.
But (whilst Romm wouldn’t be my choice as the prime upholder of Truth and Light) the latest to-and-fro provides an interesting way to tell who is lying to you. To no-one’s great surprise, the answer is… available at the end of this post. Its all out in the open, and verifiable to everyone (the one unverifiable aspect is who has changed their postings since they were first written. I’ve taken snapshots of how things are now).
* Joe Romm demonstrates himself to be an angry know-nothing in his attack on Matt Ridley’s WSJ essay – Ridley responds – Ridley at WUWT [cite], complaining about…
* Error-Riddled Matt Ridley Piece Lowballs Climate Change, Discredits Wall Street Journal. World Faces 10°F Warming – Romm at TP [cite], complaining about…
* Matt Ridley: Cooling Down the Fears of Climate Change – Ridley’s piece [cite] puffing Lewis’s piece about sensitivity.
For the moment, we care not whether Lewis’s original is correct or not (I still think its wrong, but have done no real analysis, that you’ll have to wait for. I’m still hoping someone competent might do it – hint, hint). I think Romm’s headline assertion that Ridley has “Discredit[ed the] Wall Street Journal” is dubious, on the grounds that it had no reputation to lose on the subject of Climate Change. But on…
Part the first
He [Romm] quotes a scientist as saying
it is very clear water vapor … is an amplifying effect. It is a very strong warmer for the climate.
I agree. My piece states:
water vapor itself is a greenhouse gas.
So there is no confusion there. At least not on my part.
But this is indeed confused by Ridley, in an important way. The WV feedback is important, and Ridley can’t be unaware of that. By confusing this with the doubted-by-no-one statement that WV is a GHG, Ridley is throwing up squid ink. Though I’m dubious he really understands this stuff at all – there is a fair chance that some of his errors are simply caused by his own lack of competence.
Part the second
However, I do discuss the possibility that clouds, formed from water vapor, either amplify or damp warming – and nobody at this stage knows which. This is the point that my physicist informant was making: the consequence of increased temperatures and water vapor in the atmosphere may be changes in clouds that have a cooling effect. You will find few who disagree with this. As the IPCC AR4 said:
Cloud feedbacks remain the largest source of uncertainty.
Joe Romm disagrees with this consensus, saying
The net radiative feedback due to all cloud types is likely positive.
He gives no backing for this dogmatic conclusion.
Romm, correctly, points out that his “The net radiative feedback due to all cloud types is likely positive” is taken from the AR5 draft, and says so (at least it currently says so. Whether it originally did, I can’t say. However Ridley really can’t fulminate about “no backing” and “dogmatic”, because it really is sourced).
What AR5 says (at least in part) is:
Therefore, there is very high confidence that the net feedbacks are strongly positive and the black body response of the climate to a forcing will therefore be amplified. Cloud feedbacks continue to be the largest uncertainty… New approaches to diagnosing cloud feedback in GCMs have clarified robust cloud responses, while continuing to implicate low cloud cover as the most important source of intermodel spread in simulated cloud feedbacks. The net radiative feedback due to all cloud types is likely positive, although a negative feedback (damping global climate changes) is still possible.
The AR4 was less certain:
22.214.171.124.4 Conclusion on cloud feedbacks. Despite some advances in the understanding of the physical processes that control the cloud response to climate change and in the evaluation of some components of cloud feedbacks in current models, it is not yet possible to assess which of the model estimates of cloud feedback is the most reliable. However, progress has been made in the identification of the cloud types, the dynamical regimes and the regions of the globe responsible for the large spread of cloud feedback estimates among current models. This is likely to foster more specific observational analyses and model evaluations that will improve future assessments of climate change cloud feedbacks.
So it appears to me that:
(1) AR5 has strengthened the assessment of cloud forcing, which is now thought to be likely (which is weak, but its there) to be positive,
(2) AR4 and AR5 both say cloud feedbacks remain the largest source of uncertainty. Ridley is right to quote this, but wrong to imply that this is the last word the IPCC has to say on the subject,
(3) Ridley is wrong to say that by asserting (1) Romm is denying (2) – the two are entirely compatible. Obviously: they’re in the same IPCC paragraph,
(4) Ridley is wrong to say that Romm’s assertion is dogmatic, or not backed. Its a quote from the draft, and its fully backed up.
(5) Ridley is wrong to state, of the cloud feedback, that “nobody at this stage knows which… You will find few who disagree with this”. That would have been defensible from the AR4, but not now.
I think its most likely that Ridley is incompetent – if he knows what he is actually saying, then he knows he is wrong on all these counts, and he knows that anyone competent will be able to see that. Of course, he may just be playing to the gallery.
If you want more, in a bit I didn’t bother look at Ridley tries to drag in Schlesinger onto his side. Alas, Schlesinger will have none of it, and Romm quotes a letter from Schlesinger: Matt Ridley mentions the findings of my Climate Research Group’s paper… In his article, Mr. Ridley is just plain wrong about future global warming…