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Post by steve on Oct 19, 2010 11:41:02 GMT
It has been noted that long-term trends in mid and upper tropospheric specific humidity are downwards for one dataset (NCEP/NCAR). Such a trend would be indicative of a negative feedback to warming. It has, however, been argued that this analysis includes datasets that were not designed to be precise enough to observe long term trends. For example, radiosonde measurements are notoriously problematic due to lack of knowledge about instrument change, difficulty in taking accurate observations and so forth. Remember that radiosondes were mainly done for weather forecasting, not climate. More recent analyses that have been better designed to look for long term trends have found positive trends in water vapour. The following paper analyses 5 analyses including the NCEP/NCAR one. Furthermore, the NCEP/NCAR analysis that shows a long-term down trend in humidity, has also been found to show a short term *positive* feedback - ie. increased humidity with increased surface temperature and decreased humidity following surface cooling. The suggestion is that since the newer analyses show positive feedbacks and since the older analysis shows positive feedbacks on short term (if not long term) changes in temperature, that it is likely that the long term negative feedback in the older dataset is indeed spurious. Trends in tropospheric humidity from reanalysis systems. Dessler and Davis, Journal of Geophysical Research 2010 geotest.tamu.edu/userfiles/216/Dessler10.pdfInteresting to see what Roy Spencer's comment is. |
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Post by nautonnier on Oct 19, 2010 11:54:26 GMT
It has been noted that long-term trends in mid and upper tropospheric specific humidity are downwards for one dataset (NCEP/NCAR). Such a trend would be indicative of a negative feedback to warming. It has, however, been argued that this analysis includes datasets that were not designed to be precise enough to observe long term trends. For example, radiosonde measurements are notoriously problematic due to lack of knowledge about instrument change, difficulty in taking accurate observations and so forth. Remember that radiosondes were mainly done for weather forecasting, not climate. More recent analyses that have been better designed to look for long term trends have found positive trends in water vapour. The following paper analyses 5 analyses including the NCEP/NCAR one. Furthermore, the NCEP/NCAR analysis that shows a long-term down trend in humidity, has also been found to show a short term *positive* feedback - ie. increased humidity with increased surface temperature and decreased humidity following surface cooling. The suggestion is that since the newer analyses show positive feedbacks and since the older analysis shows positive feedbacks on short term (if not long term) changes in temperature, that it is likely that the long term negative feedback in the older dataset is indeed spurious. Trends in tropospheric humidity from reanalysis systems. Dessler and Davis, Journal of Geophysical Research 2010 geotest.tamu.edu/userfiles/216/Dessler10.pdfInteresting to see what Roy Spencer's comment is. Interesting that you gleefully jump on: "Furthermore, the NCEP/NCAR analysis that shows a long-term down trend in humidity, has also been found to show a short term *positive* feedback - ie. increased humidity with increased surface temperature and decreased humidity following surface cooling."When you have been lecturing anyone that cares to listen that short term doesn't mean long term. Indeed this quote would appear to bear you out. But from this can we take it Steve that any evidence that agrees with your hypothesis is correct and if it disagrees it should be discarded? More sensible comment on the cite you gave is of course _water vapor_ feedback can be positive. Water vapor is after all the most plentiful and effective 'green house gases'. However, when water vapor turns to clouds (you have noticed clouds Steve?) then the feedback becomes negative ask any sunbather. When the water droplets or ice crystals coalesce and precipitate out - then the surface gets colder - another negative feedback. The hydrologic cycle is powerful and provides both positive AND negative feedback. We do not need over paid supposedly highly qualified climate 'scientists' to tell us that. |
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Post by hunterson on Oct 19, 2010 12:34:25 GMT
It has been noted that long-term trends in mid and upper tropospheric specific humidity are downwards for one dataset (NCEP/NCAR). Such a trend would be indicative of a negative feedback to warming. It has, however, been argued that this analysis includes datasets that were not designed to be precise enough to observe long term trends. For example, radiosonde measurements are notoriously problematic due to lack of knowledge about instrument change, difficulty in taking accurate observations and so forth. Remember that radiosondes were mainly done for weather forecasting, not climate. More recent analyses that have been better designed to look for long term trends have found positive trends in water vapour. The following paper analyses 5 analyses including the NCEP/NCAR one. Furthermore, the NCEP/NCAR analysis that shows a long-term down trend in humidity, has also been found to show a short term *positive* feedback - ie. increased humidity with increased surface temperature and decreased humidity following surface cooling. The suggestion is that since the newer analyses show positive feedbacks and since the older analysis shows positive feedbacks on short term (if not long term) changes in temperature, that it is likely that the long term negative feedback in the older dataset is indeed spurious. Trends in tropospheric humidity from reanalysis systems. Dessler and Davis, Journal of Geophysical Research 2010 geotest.tamu.edu/userfiles/216/Dessler10.pdfInteresting to see what Roy Spencer's comment is. My take on Dr. D is that he is desperately hoping to find some evidence that he can point to as *proof* of global climate disruption that will not fall apart upon review. The humidity of the upper troposphere is perfect for his uses: it is subtle, has no direct impact on anything, is very hard to measure and is the tip of the tail of the dog. He hopes to use this tiny tip to wag the tail to wag the dog, in effect. Dr. D- an extremely political scientist in a field filled with politically active scientists, is simply hoping to close the deal. BTW, usually a positive feedback is doing something. I think if you will read this closely, all he is claiming to find is an artifact of global climate disruption, and not something that is going to contribute very much to his desperately desired apocalypse. But Dr. D is nothing if not consistent. |
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Post by steve on Oct 19, 2010 13:35:31 GMT
nautonnier, Yes of course it doesn't - I'm glad you've been listening  . Which is why I'm interested in Spencer's response. What is slightly different to Spencer's findings is that the long and short term effects are the same variable over roughly the same order of time (one or two decades as compared with a few years is arguably not much different when compared with the timescales of atmospheric processes) suggesting that they are inconsistent with each either - at least one or other of them is wrong. At the very least it puts the original analyses under question, but also appears to do more than that. |
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Post by magellan on Oct 19, 2010 16:34:46 GMT
Settle this discussion by counting the number of sentences that contain the word "cloud". Dessler does not address clouds, why is that? It should be obvious; Dessler thinks CO2 drives climate and assumes like GCM modelers that positive feedback dominates.
Nor does he address the little problem of no warming in the "analysis" period where all relevant data is available.
The Dessler paper is more AGW diarrhea just like his previous one which mentioned cloud one time in the entire article, yet he was allowed to conclude that a several degree increase in global temperature is "virtually guaranteed".
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Post by steve on Oct 19, 2010 17:50:55 GMT
Magellan,
Clarify?
From the previous Dessler paper you quote-mined:
Yes, it's a pointed statement but in line with the paper's findings. Cloud feedbacks are not going to cancel out water vapour feedbacks. You can find that out from people other than Dessler.
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Post by lenardob on Oct 19, 2010 18:09:26 GMT
are not clouds pretty much the largest WATER VAPOR negative feedback there is?
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Post by matt on Oct 19, 2010 18:18:42 GMT
are not clouds pretty much the largest WATER VAPOR negative feedback there is? No. Clouds consist of water droplets or ice crystals. |
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Post by icefisher on Oct 19, 2010 18:24:51 GMT
It has been noted that long-term trends in mid and upper tropospheric specific humidity are downwards for one dataset (NCEP/NCAR). Such a trend would be indicative of a negative feedback to warming. It has, however, been argued that this analysis includes datasets that were not designed to be precise enough to observe long term trends. For example, radiosonde measurements are notoriously problematic due to lack of knowledge about instrument change, difficulty in taking accurate observations and so forth. Remember that radiosondes were mainly done for weather forecasting, not climate. More recent analyses that have been better designed to look for long term trends have found positive trends in water vapour. The following paper analyses 5 analyses including the NCEP/NCAR one. Furthermore, the NCEP/NCAR analysis that shows a long-term down trend in humidity, has also been found to show a short term *positive* feedback - ie. increased humidity with increased surface temperature and decreased humidity following surface cooling. The suggestion is that since the newer analyses show positive feedbacks and since the older analysis shows positive feedbacks on short term (if not long term) changes in temperature, that it is likely that the long term negative feedback in the older dataset is indeed spurious. Trends in tropospheric humidity from reanalysis systems. Dessler and Davis, Journal of Geophysical Research 2010 geotest.tamu.edu/userfiles/216/Dessler10.pdfInteresting to see what Roy Spencer's comment is. Well the first thing Spencer would say is people should be cautioned about taking this as a complete analysis. Its the old tale of combining half an analysis with half a wit. He also would caution against assuming causation of warming by the increase in humidity. I kind of have seen it as a no brainer that humidity increases when it gets warmer. One can study that phenomena on one's kitchen range though that does not rule out other phenomena overwhelming it when you are talking 10ths of a degree. Freeman Dyson has the right perspective on that: Saying climate scientists are making the mistake the atmosphere is an orderly clean and neat and simple physical process when it fact it is disorderly, dirty, messy and complex physical process. I call understanding that as "street smarts" science and Dyson gets it as he has actual experience with success/failure of complex stuff. Climate science is a science with no history of success/failure and by its own definition of itself won't have any for about 100 years. (evidenced by its reaction to its last decade of failure) |
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Post by northsphinx on Oct 19, 2010 18:25:12 GMT
are not clouds pretty much the largest WATER VAPOR negative feedback there is? No. Clouds consist of water droplets or ice crystals. that is not water vapor...... |
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Post by magellan on Oct 19, 2010 18:41:33 GMT
Magellan, Clarify? From the previous Dessler paper you quote-mined: Yes, it's a pointed statement but in line with the paper's findings. Cloud feedbacks are not going to cancel out water vapour feedbacks. You can find that out from people other than Dessler. Cloud feedbacks are not going to cancel out water vapour feedbacks.
You say so, therefore it is? What do you think Spencer's work is about? Sheesh. You claim to understand Spencer's research, but if you did, you wouldn't make such statements. There is no evidence to support Dessler's unwarranted claim there will be several degrees of increase in warming. Objective people would note that Dessler carefully omits opposition research in his index. It is nothing new what Dessler is claiming; it is the same untested "amplification" mechanism that doesn't exist in the real world, that is the the bottom line. If Dessler were even close to being right he should have been required to include the same type of detailed experiment that Spencer has done which based on observations indicates negative feedback moderates earth's climate. Instead, the pal reviewers (pro AGW biased) let these people get away with making all sorts of ludicrous conclusions and claims. RPS (who you said has "senior moments") dissects Dessler's unsubstantiated claims quite well here pielkeclimatesci.wordpress.com/2010/01/07/reply-to-andrew-dresslers-guest-post-on-water-vapor-feedback/ Following that is Spencer's (once again) evidence based science that does not support Dessler or the latest Schmidt et al charade. |
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Post by steve on Oct 19, 2010 21:42:00 GMT
magellan,
I was interested in hearing what you meant by this:
The following is just incoherent.
It's not "the same untested amplification". It is a study of observations - just like Spencer's. Spencer's was a study of radiative changes with temperatures. This is a study of water vapour changes with temperatures.
RPS does not dissect the claims at all. He, like you, makes inferences to clouds (irrelevant to the particular study I've linked to) and points to one or two regional studies where the results apparently differ.
I note he also has another of his moments when he says:
when he'd forgotton that he'd only just written in the lines above that the net forcings are the difference between now and pre-industrial times. Since the earth has warmed about 1 degree since preindustrial times, some of this net forcing has been cancelled by roughly 3 Watts of extra radiation due to the warming.
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Post by matt on Oct 19, 2010 23:08:36 GMT
However, when water vapor turns to clouds (you have noticed clouds Steve?) then the feedback becomes negative ask any sunbather. When the water droplets or ice crystals coalesce and precipitate out - then the surface gets colder - another negative feedback. The hydrologic cycle is powerful and provides both positive AND negative feedback. We do not need over paid supposedly highly qualified climate 'scientists' to tell us that. Your comment was negative but all the feedbacks aren't. Clouds also warm the planet by blocking IR. |
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Post by magellan on Oct 19, 2010 23:21:38 GMT
magellan, I was interested in hearing what you meant by this: The following is just incoherent. It's not "the same untested amplification". It is a study of observations - just like Spencer's. Spencer's was a study of radiative changes with temperatures. This is a study of water vapour changes with temperatures. RPS does not dissect the claims at all. He, like you, makes inferences to clouds (irrelevant to the particular study I've linked to) and points to one or two regional studies where the results apparently differ. I note he also has another of his moments when he says: when he'd forgotton that he'd only just written in the lines above that the net forcings are the difference between now and pre-industrial times. Since the earth has warmed about 1 degree since preindustrial times, some of this net forcing has been cancelled by roughly 3 Watts of extra radiation due to the warming. There is zero evidence that increasing CO2 causes an amplification of surface temperature via water vapor as claimed by Warmologists. Instead of waving arms, start producing the evidence steve Milesworthy. Dessler has not produced one iota of evidence to support his statements. Zero. Neither has Hansen, Schmidt or the rest of the Team. (0.6 to 0.85) falls under the observed value from the work of Hansen. That isn't happening either. You are witnessing negative feedback occurring right before your eyes; take off the blinders. What part of this don't you understand?  |
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Post by nautonnier on Oct 19, 2010 23:32:35 GMT
are not clouds pretty much the largest WATER VAPOR negative feedback there is? Steve lives in Devon - they never see clouds  |
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. Which is why I'm interested in Spencer's response.
