New paper on Global Water Vapor puts climate modelers in a bind

Wow! You can bet they spent many sleepless nights trying to torture a overall, AGW confirming, positive trend. My spider-senses tell me they were unable to… because the overall trend is negative? Damn spider-senses, are usually wrong.
Anyway, alarmists should let out a big “sigh of relief”. This certainly indicates we are not going to cook in are own juices… soon. GK

The graph presented in the post is the global average Total Precipitable Water vapour timeseries from 1988 to 2009.
The change of total precipitable water vapour (PW) column tell us little about the water vapour impact on the greenhouse effect or outgoing longwave radiation because changes in the upper atmosphere have a much greater effect than changes near the surface.
Computer simulations using HARTCODE, a line-by-line radiative code, show that a 20% reduction of water vapour in a layer at 300 to 400 mbar pressure level (about 8 to 9 km altitude) has 30 times the effect on outgoing longwave radiation (OLR) as the same absolute change of water vapour near the surface.
Specifically, a reduction of 0.14 mm PW in a layer 307 to 423 mbar (equal to 20% reduction) would cause a 0.80 W/m2 increase in OLR, while the same 0.14 mm PW reduction in an atmosphere layer near the surface at 1013 to 848 mbar (equal to 0.964% reduction) would cause a 0.026 W/m2 increase in OLR. A water vapour amount change in the upper layer has 0.80/.026 = 30 times the effect as the same change in the surface layer. The vertical location of the water vapour change is very important to the greenhouse effect. This effect is shown graphically here;
http://www.friendsofscience.org/assets/documents/FOS%20Essay/H2O_OLR.jpg
The NVAP Data and Information is given here;
http://eosweb.larc.nasa.gov/PRODOCS/nvap/table_nvap.html
The NVAP readme file shows that the precipitable water vapour information is available in 5 layers:
L1: 850-1000mb
L2: 700-850mb
L3: 500-700mb
L4: 300-500mb
L5: 200-300mb
With warming, the water vapour reduction in the L4 and L5 layers largely offset the increase in the lower layers.
A graph of water vapour at 400 mbar in the tropics from NOAA versus CO2 is here:
http://www.friendsofscience.org/assets/documents/FOS%20Essay/SH400TropicsVsCO2.jpg
In the topics, the specific humidity best fit line has declined by 0.11 g/kg, or 13%, from 1960 to 2011.
Further info at;
http://www.friendsofscience.org/assets/documents/FOS%20Essay/Climate_Change_Science.html#Water_vapour

“””””……SteveSadlov says:
July 18, 2012 at 11:56 am
Water vapor behaves differently at different pressures. Water vapor at or near the ground is a very different thing from water vapor at 30K feet. Other phases of water are further different. Most clouds probably present a negative feedback. I’m even starting to doubt that solid state high clouds are a positive feedback. A remaining area to investigate is precip. Everything we thought we knew about H20 is probably wrong……”””””
Why would that be so ? Water vapor (aka gas) consists of independent H2O molecules, each as free as a lark. Depending on how close they may be to each other or to other molecular species, and also depending on their mean velocity, which generally depend on pressure and Temperature respectively, they will spend part of their time involved in collisions, with other free molecules, and part of their time in free flight between such collisions.
In any case, while in free flight, the H2O molecule can encounter a solar radiation photon; perhaps one with a suitable wavelength to excite some molecular excited state in the H2O molecule, thereby absorbing that solar energy, which as a result will never reach the surface, including the deep ocean, as a solar spectrum photon; thus resulting in a surface cooling effect.
This effect clearly is operational at the individual molecular level, in the case of this H2O vapor, so I don’t see how there can be any significant altitude or other effect, apart from the abundance of such molecules; it still has to be a negative feedback cooling effect (in the sense that MORE H2O vapor molecules, leads to LESS solar radiation energy reaching earth’s surface to be stored in the ocean or rocks.
Also the loss of such solar radiant energy to the surface, must result in a subsequent reduction in the emission of LWIR radiant energy from the surface, which can participate in the so-called “greenhouse” effect capture by other H2O molecules, or even by the much less abundant CO2 molecules. I’m not seeing any positive feedback build up in earth absorbed energy, as a result of this increase in H2O vapor; regardless of the altitude of such molecules.

It turns out that the Journal of Geophysical Research: Atmospheres recently published a paper on the “recent changes in tropospheric water vapor over the Arctic” (HTML version not behind a paywall: http://www.agu.org/journals/jd/jd1210/2011JD017421/index.shtml). Their conclusions:
“statistically significant trends in precipitable water over the Arctic as assessed over the period 1979–2010 are mostly positive. … [The results are] consistent with a changing Arctic environment with a warmer atmosphere that can carry more water vapor, higher north Atlantic sea surface temperatures and reduced sea ice extent
They are also consistent with reduced sea ice from increase solar insolation/particulate deposition as the cause of a warmer atmosphere that can carry more water vapor and higher north Atlantic sea surface temperatures.
From the paper,
We have no clear explanation for this decadal-scale {around year 2000} shift from negative to positive relative humidity anomalies.
The cause is accelerated ice melt after 2000.

uknowispeaksense says:
July 18, 2012 at 6:07 am
[snip – multiple site policy violations ~mod]
which ones?
REPLY: Check the site policy here and then take your choice. -REP

Speaking of T-storms this report is interesting: http://www.damninteresting.com/rider-on-the-storm/

…. Under normal circumstances one would expect about three and a half minutes of free-fall to reach the breathable altitude of 10,000 feet. The circumstances, however, were not normal…. Bill’s brutalized body had spent around forty minutes bobbing around the area of atmosphere which mountaineers refer to unfondly as the Death Zone….
No human before or since Bill Rankin is known to have parachuted through a cumulonimbus tower and lived to tell about it.

Garrett says:
July 18, 2012 at 10:18 am
…..I can just about comprehend people’s disbelief that humans are causing GW, I cannot get my head around why so many still think that the Earth is not warming at all.
The problem here is that many people, apparently you included, can’t get their head around what ‘The Earth’s climate is warming / has warmed, actually means’.
Does it mean this second, minute, hour, day, week, year,decade, century, millenia?
As Gail points out, it depends on what timescale you select, and you should ponder the following.
At all times, the Earth’s climate has both warmed from one or more points in the past and has cooled from one or more points in the past, with only 2 exceptions when the climate is the warmest its ever been and when the climate is the coldest its ever been.
So, the following two statements are always equally true.
The Earth’s climate has warmed up to the present.
The Earth’s climate has cooled up to the present.

Some of us were saying, the Magic Gas story is a lie from first to last, maybe when Anthony did Al Gore’s experiment online for himself, he saw too: there is no magic gas. It’s all a lie, and was from the beginning. It’s crime is what it is. Straight up ‘I fear no law enforcement on earth’ crime, by government employees gaming the system using other government employees – like Al Gore – as cover from law enforcement.

“Catastroligists”, “Calamatologist” and Joe Bastardi’s “climate-clowns”, some subsitutes for the bland-sounding “alarmist.”