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Lindzen agrees with a strong WV feedback -- who disagrees?
In his most recent paper (2010), "Can thin cirrus clouds in the tropics provide a solution to the Faint Young Sun paradox?", Richard Lindzen notes the following
"Recent studies suggest that the strong positive water vapor feedback implied by the invariance of relative humidity may be within reasonable agreement with satellite observations [Dessler et al., 2008], even though the vertical profile of relative humidity is not strictly conserved."
By Dessler 2008, he's referring to:
http://geotest.tamu.edu/userfiles/216/Dessler2008b...
Which studied satellite trends in humidity over the period 2003-2008. They find a strong positive feedback consistent with a constant RH, as predicted by models.
Soden 2005 studied 22 years worth of satellite humidity, and also found roughly constant RH:
http://www.gfy.ku.dk/~kaas/Bornoecourse/Material/s...
On the other hand, we have Paltridge 2009 which uses the NCEP reanalysis and finds not only a decreasing RH, but a decreasing q, and thus, a negative WV feedback.
http://www.springerlink.com/content/m2054qq6126802...
But, as mentioned in the study, the NCEP reanalysis has known problems with model bias, and radiosondes have issues with instrumentation changes and poor ocean coverage.
Now that Lindzen is on board with a strong WV feedback, are any scientists left? Is anyone skeptical of Lindzen's position?
I can get the full papers through my school. I'll look around to see if I can find an online copy.
I could provide a screenshot of the page with the quote if you'd like. I don't think I can legally post the whole paper, though.
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Dana,
To me, the quote on its own sounds like Lindzen is acknowledging the evidence for a strong WV feedback. But, just to give you more context, the paper does not discuss the water vapor feedback at any great length, but through the majority of it, Lindzen's model assumes an invariant RH. When discussing whether this assumption is reasonable, Lindzen cites Dessler08.
Bravo,
I don't doubt that Lindzen believes in net negative feedbacks. The WV feedback is but one of many feedbacks, and he's sure that clouds will more than compensate for it. But I think Lindzen confuses short-term feedbacks (scale of decades to millennia), which must be net positive to explain things like D-O events and transitions to and from glacial periods, with feedbacks that act on much longer scales, which must be negative to explain why the Earth didn't become an ice-cube.
5 Answers
- Dana1981Lv 71 decade agoFavorite Answer
Well it sounds a bit like Rondanelli and Lindzen are stating Dessler's results without necessarily concurring with them. I'd have to read more of the paper to get a sense as to what they're arguing in terms of the water vapor feedback, and unfortunately the paper doesn't seem to be available for free anywhere yet.
http://scholar.google.com/scholar?cluster=66609108...
But as for the question at hand, I'm not sure about Roy Spencer's opinion on the subject. He certainly thinks clouds will be a major negative feedback, but I don't know about water vapor. He probably agrees it's positive.
http://www.drroyspencer.com/2010/04/the-great-glob...
*edit* ah see that's why I wanted to read the paper. If Lindzen is using Dessler as a reference for assuming RH will remain relatively constant, then certainly he thinks it's a positive feedback.
- bravozuluLv 71 decade ago
I am quite sure you are mistaken about that. Positive feedback theory is negated by dim Earth. He stated as much in this lecture at 25 minutes and thirty seconds into it.
http://vmsstreamer1.fnal.gov/VMS_Site_03/Lectures/...
If he actually stated that, it is taken out of context. The water vapor positive feedback is not consistent with the faint earth paradox. The cirrus clouds are negative feedback. That is consistent. The fact that he doesn't agree with the logic on positive feedback means that he doesn't buy the argument. He might have acknowledged that the increasing WV would be consistent. That is not the same thing.
another example
"Now, along comes Richard Lindzen to argue that negative feedbacks, that is feedbacks that tend to keep the earth's temperature constant, are more plausible than positive feedbacks.
The notion that the earth's climate is dominated by positive feedbacks is intuitively implausible, and the history of the earth's climate offers some guidance on this matter. About 2.5 billion years ago, the sun was 20%-30% less bright than now (compare this with the 2% perturbation that a doubling of CO2 would produce), and yet the evidence is that the oceans were unfrozen at the time, and that temperatures might not have been very different from today's. Carl Sagan in the 1970s referred to this as the "Early Faint Sun Paradox."
"
- Ottawa MikeLv 61 decade ago
Is that paper you mention by Lindzen available anywhere in full? Where did you get that quote? All I can find is the abstract.
- 1 decade ago
This is one of the few journals my university isn't;t subscribed too. Grrr. I would need to read it before commenting, as all the papers ive read of Lindzens in the past have been rather , well, poor would be a polite term.
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- Anonymous4 years ago
I believe the assumption of that fact. What approximately if a shark assaults someones off the coast of Australia and has their legs for lunch? Now that individual is not any greater beneficial in actual experience, yet possibly he turns into greater beneficial in spirit and character. Oh, I merely began off pessimistic yet grew to become that around. damn't. "unfavourable little Tink Tink"! Haha.