Here’s an interesting paper that breaks with consensus. The only problem is that it is being ignored for the most part by the mainstream climate community, even going so far as to having a debate over the paper’s source of data (NCEP reanalysis of radiosonde data) and declaring the data to be too “iffy”. You can read all about that debate at Climate Audit called “
A peek behind the curtain“. It is a firsthand account of the attempt at publishing from one of the authors, Garth Paltridge. Here is how he characterized the debate at a conference:
Those ‘against’ (among them a number of people from GISS) simply said that the radiosonde data were too ‘iffy’ to report the trends publicly in a political climate where there are horrible people who might make sinful use of them. Those ‘for’ simply said that scientific reportage shouldn’t be constrained by the politically correct.
Since most of the objections seemed to be coming from GISS, who has a surface data set that one could also describe as “iffy”, I find their argument rather humorous.
What is really interesting though is this graph presented in comments at CA by Ken Gregory:
Ken writes:
“The relevant discussion of the water vapour effect from the IPCC Fourth Assessment Report (Chapter 8 page 632):
The radiative effect of absorption by water vapour is roughly proportional to the logarithm of its concentration, so it is the fractional change in water vapour concentration, not the absolute change, that governs its strength as a feedback mechanism. Calculations with GCMs suggest that water vapour remains at an approximately constant fraction of its saturated value (close to unchanged relative humidity (RH)) under global-scale warming (see Section 8.6.3.1). Under such a response, for uniform warming, the largest fractional change in water vapour, and thus the largest contribution to the feedback, occurs in the upper troposphere.
This means that changes in specific humidity in the upper troposphere (300 – 700 mb) may be very significant even though the amount of water vapour there is low due to the cold temperatures.
If relative humidity remains constant, CO2 induced warming would cause increasing specific humidity and a strong positive feedback. But if relative humidity is actually falling (due to water vapour being displaced by CO2 as per Miskolczi) then water vapour may cause a negative feedback. The specific humidity has declined dramatically in 2008 at ALL levels in the troposphere.
I do not know the accuracy of the NCEP reanalysis data on upper tropospheric humidity, but the direct measurement of humidity by weather balloons seems preferable to the very indirect determination from satellite data.”
I agree. Here is more on the paper and it’s conclusions. – Anthony
New Paper Suggests Long-Term Water Vapour Feedback is Negative
(1) Environmental Biology Group, RSBS, Australian National University, GPO Box 475, Canberra, ACT, 2601, Australia
(2) Johns Hopkins University, Baltimore, MD, USA
(3) Centre for Australian Weather and Climate Research, Hobart, TAS, Australia
The Abstract states:
The National Centers for Environmental Prediction (NCEP) reanalysis data on tropospheric humidity are examined for the period 1973 to 2007. It is accepted that radiosonde-derived humidity data must be treated with great caution, particularly at altitudes above the 500 hPa pressure level. With that caveat, the face-value 35-year trend in zonal-average annual-average specific humidity q is significantly negative at all altitudes above 850 hPa (roughly the top of the convective boundary layer) in the tropics and southern midlatitudes and at altitudes above 600 hPa in the northern midlatitudes. It is significantly positive below 850 hPa in all three zones, as might be expected in a mixed layer with rising temperatures over a moist surface. The results are qualitatively consistent with trends in NCEP atmospheric temperatures (which must also be treated with great caution) that show an increase in the stability of the convective boundary layer as the global temperature has risen over the period. The upper-level negative trends in q are inconsistent with climate-model calculations and are largely (but not completely) inconsistent with satellite data. Water vapor feedback in climate models is positive mainly because of their roughly constant relative humidity (i.e., increasing q) in the mid-to-upper troposphere as the planet warms. Negative trends in q as found in the NCEP data would imply that long-term water vapor feedback is negative—that it would reduce rather than amplify the response of the climate system to external forcing such as that from increasing atmospheric CO2. In this context, it is important to establish what (if any) aspects of the observed trends survive detailed examination of the impact of past changes of radiosonde instrumentation and protocol within the various international networks.
The paper concludes:
It is of course possible that the observed humidity trends from the NCEP data are simply the result of problems with the instrumentation and operation of the global radiosonde network from which the data are derived. The potential for such problems needs to be examined in detail in an effort rather similar to the effort now devoted to abstracting real surface temperature trends from the face-value data from individual stations of the international meteorological networks. As recommended by Elliot and Gaffen (1991) in their original study of the US radiosonde network, there needs to be a detailed examination of how radiosonde instrumentation, operating procedures, and recording practices of all nations have changed over the years and of how these changes may have impacted on the humidity data.
In the meantime, it is important that the trends of water vapor shown by the NCEP data for the middle and upper troposphere should not be “written off” simply on the basis that they are not supported by climate models—or indeed on the basis that they are not supported by the few relevant satellite measurements. There are still many problems associated with satellite retrieval of the humidity information pertaining to a particular level of the atmosphere—particularly in the upper troposphere. Basically, this is because an individual radiometric measurement is a complicated function not only of temperature and humidity (and perhaps of cloud cover because “cloud clearing” algorithms are not perfect), but is also a function of the vertical distribution of those variables over considerable depths of atmosphere. It is difficult to assign a trend in such measurements to an individual cause.
Since balloon data is the only alternative source of information on the past behavior of the middle and upper tropospheric humidity and since that behavior is the dominant control on water vapor feedback, it is important that as much information as possible be retrieved from within the “noise” of the potential errors.
Like this:
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Well there you go. The entire argument for CO2 induced warming is out with the bath water. CO2 needs the water vapor feedback to induce the “catastrophic” warming visioned by Hansen et al. CO2 on it own can not cause the warming more than it has to date due to its logarithmic nature.
“The specific humidity has declined dramatically in 2008 at ALL levels in the troposphere.”
Are we sure? Isn’t that what the data debate is about?
This supports what Pelkie and Spencer have said for a while now.
It has warmed, so even with the same amount of water vapor, RH will go down. The change [a couple of per cent] looks reasonable for ~1 degree warming.
Don’t worry, Michael Mann, et al., will valiantly ride in to the rescue of AGW hypocrisy with their “peer reviewed” data invention mechanism known as RegEM to make sure they can couple their hockey stick derived from tree-rings in North America to redefine what we know about humidity in the atmosphere.
Mark
Can someone provide an explanation in simple terms why this is so? And how rough is “roughly”? Is the correlation R2 = 0.9 or 0.3?
Also, as I understand it, the data from radiosondes are even more tangled and questionable than the surface temperature record. How does this make them more preferable than satellite data? Maybe neither are adequate for the purpose they are being used.
Just trying to understand this.
Jim Arndt (08:49:52) :
Well there you go. The entire argument for CO2 induced warming is out with the bath water.
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I read a similar comment at CA. Went along the lines of “No positive feedback, game over for AGW”. To this longtime scientist, but relative newbie to the quantitative and pseudoquantitive aspects of AGW theory, I always thought that “water vapor positive feedback” was likely to be a convenient invention. Is there a single paper in the history of the evolution of AGW theory where it became clear, quantitatively, that CO2 couldn’t do it alone, and where an accomplice had to be invented ?? Anyone ??
I’m sure that there are many others, besides me, who would be interested in this, so thanks in advance.
One wonders how much publicity this paper would have gotten if the “iffy” data resulted in positive feedback.
Bit off topic, about the protest on Monday at Capitol Hill.
We observed the protest live and recall clearly that the protestors were anti-gas. They were against the coal powered plant being converted to gas and even shouted down one elderly politician when she said the plant could be converted to gas quickly.
Well, it looks like more dirty tricks as history is being rewritten:
http://www.time.com/time/health/article/0,8599,1882700,00.html
QUOTE:
As it turned out, the action may have been almost too successful. On Feb. 26, just a few days before the protest, Speaker of the House Nancy Pelosi and Senate majority leader Harry Reid called for the 103-year-old plant to switch from coal to cleaner-burning natural gas, a move long pushed for by environmentalists but blocked by representatives from coal-heavy states. Protesters claimed an early victory. “Getting the plant to switch shows the power of popular pressure,” said Steven Biel, the director of Greenpeace’s global-warming campaign.
Calling the surface data “iffy” is too generous by far.
Criminal is closer to the adjective that I would use.
It would certainly be more interesting to see the same graph but in term of Absolute Humidity. I can’t believe they measured the relative humidity only. Are they playing the same game as that of the Climate Change Cheerleaders by only showing graphs with negative slopes? Showing that the Absolute humidity has gone up would not undermine the real cause of global warming.
The present graph only shows that the air at those different levels can in fact pick up more water.
Leif Svalgaard (09:02:44) :
It has warmed, so even with the same amount of water vapor, RH will go down. The change [a couple of per cent] looks reasonable for ~1 degree warming.
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That it has warmed in the last 100 years has never been contested. The cause of that warming is the core of the debate.
If water vapor does not increase, then RH will go down as temperature increases. Again, basic science. Also completely missing the point.
ALL, and I do mean ALL of the models predict that RH will remain constant as temperatures rise, which is the source of the positive feedback that turns the very modest temperature increases due to CO2 alone into the catastrophic predictions that justify massive govt take overs of the economy.
Leif Svalgaard (09:02:44) :
It has warmed, so even with the same amount of water vapor, RH will go down. The change [a couple of per cent] looks reasonable for ~1 degree warming.
True, but the author claims that climate models tend to keep RH constant which means absolute humidity must increase. It’s this increase in absolute humidity that drives the positive feedback. If you believe the NCEP data (and the author is very cautious about that), the increase in absolute humidity that is at the heart of global warming theory is absent or much lower than predicted. It has warmed, but maybe not as a result of the process described in the climate models.
But I thought the science was settled. Silly me.
Gary (09:23:12) :
Also, as I understand it, the data from radiosondes are even more tangled and questionable than the surface temperature record. How does this make them more preferable than satellite data? Maybe neither are adequate for the purpose they are being used.
I believe the distinction is that the satellites can only infer this data through indirect measurements whereas the radiosondes, with all their apparent warts, are performing direct measurements. Don’t quote me on this, however.
Mark
“One wonders how much publicity this paper would have gotten if the “iffy” data resulted in positive feedback.”
Ross, if this analysis resulted in positive feedback, and water vapour was established as the catalyst for CO2 to create catastrophic warming, then I suppose that Hansen, Mann et al would be wanting a ban on humanity’s production and use of evil Dihydrogen Monoxide as well as CO2. Kettles would be banned and anything else that causes water to evaporate into vapour…
Tropospheric…but over which continent?, over Australia?, then it is weather…
This article remembers me of an ancient observational practice of the Incas: They used to observe the pleiads, if they were blurry to the sight, there was water up there and rain would come.
DB2 (08:52:13) :
” “The specific humidity has declined dramatically in 2008 at ALL levels in the troposphere.”
Are we sure? Isn’t that what the data debate is about?”
I am sure that the NCEP reanalysis data shows the specific humidity has declined in 2008 at all levels in the troposphere.
What debate? The issue is that there should be a debate about this, but the mainstream jounals avoid it.
philincalifornia (09:24:51) :
” Is there a single paper in the history of the evolution of AGW theory where it became clear, quantitatively, that CO2 couldn’t do it alone, and where an accomplice had to be invented ?? Anyone ??”
There is a vast volume of physical research on the actual heat trapping capasity of CO2. The best description I’ve seen is by Lubos Motl, a terrific physicist who perhaps is discounted by some because they assume his views on AWG are just part of his strongly held right wing beliefs.
Lubos, like many people are convinced that CO2 can, and has warmed the climate, but the feeedbacks needed for serious warming appear to be lacking. If only CO2 is considered, we’ve already seen 2/3 of the warming we will ever induce anthropogenically.
http://motls.blogspot.com/2007/06/realclimate-saturated-confusion.html
Leif, buddy, noboby is dispiting that is hasn’t warmed. The data here clearly tells me that humidity has not increased with increasing CO2 and temp, like the almighty models say it should be doing. *THAT* is what we’re saying…
Ray (09:55:39) :
“It would certainly be more interesting to see the same graph but in term of Absolute Humidity. I can’t believe they measured the relative humidity only.”
In the interest of full disclosure, here is an Excel spreadsheet with the NOAA data. Scoll down to row 72 to see a series of graphs of specific humidity.
http://members.shaw.ca/sch25/Ken/Optical%20Depth%20Data.xls
The fact that there is even a question about water vapor feedback shows how shaky the science behind alarmism is. Water vapor feedback is a pillar supporting the AGW structure.
If the warming is constrained by negative water vapor feedback, sounding this alarm is akin to yelling fire in a crowded theater where the fire is nicely contained inside a fire box.
The journals and MSM will not respond to this because “climate change” is about advocacy now and no longer about science.
“Any further debate will only distract us and delay needed action on CO2 reduction.”
For some perspective on the numbers in the above RH chart above versus the global warming models, from 1948 to 2003, GISS Model E simulations has built-in:
– a decline in RH of 0.45% at 760MB,
– a decline in RH of 0.26% at 630MB,
– a decline in RH of 0.76% at 470MB,
– an increase in RH of 0.18% at 337MB, and,
– an increase in RH of 0.74% at 180MB.
So, the data above is showing a decline in RH of 4.0% to 8.0% depending on height while the models have very small changes in RH built-in/assumed at these levels (with a very slight decline in the overall weighted average of RH as temperatures increase).
http://data.giss.nasa.gov/work/modelEt/lat_height/work/tmp.3_E3Af8aeM20_1_0112_1948_2003_1951_1980_-L3AaeoM20D_lin/mean.txt
So, the chart and data above is very inconsistent with the models and with global warming theory so it is no wonder they don’t want the data shown (and why they don’t believe the numbers in the first place).
Gary (09:23:12) :
“The radiative effect of absorption by water vapour is roughly proportional to the logarithm of its concentration, so it is the fractional change in water vapour concentration, not the absolute change, that governs its strength as a feedback mechanism.”
Can someone provide an explanation in simple terms why this is so? And how rough is “roughly”? Is the correlation R2 = 0.9 or 0.3?”
The way I think of it myself is to assume that there are a finite number of photons available to be absorbed by a finite number GH gas molecules. Thus, if in the first X meters of travel 75% of the photons are absorbed, then in the second X metres 0.75*(1-0.75) will be absorbed and so on and so forth.
Water differs from other GH gasses (like CO2) in that it varies dramatically by altitude, hence the “roughly” part.
Cheers, 🙂