When somebody hits you with that new 'IPCC is 95% certain' talking point on global warming, show them this

95% is a figure provided by the politically naive to the numerically ignorant – just like the rest of the IPCC report, that is…

Why are you using Hadcrut 3? I know it’s probably more accurate and I presume it proves your point better than Hadcrut 4. But the warmists will be onto it in a flash.

Let’s not forget that these IPCC models are considered to be the antithesis of the “physics-based notion that sound science equals reductionist, high control, high precision science.” That quote was supporter Briane Wynne in a 1994 book.
When you read my sources they pretty consistently say that the ‘science’ involved at the IPCC is actually sociology. Which many of us do not believe deserves the label.

The only “evidence” the IPCC has are their models which allegedly show only natural + anthropogenic forcing can explain the latter 1957-2008 warming.
http://www.ipcc.ch/publications_and_data/ar4/syr/en/fig/figurespm-4-l.png
Of course, they conveniently leave out of the models ocean oscillations, global brightening, accumulated solar energy anomaly [the “sunspot time integral”], etc. which can more than explain the 1957-2008 warming.
http://hockeyschtick.blogspot.com/2013/08/natural-climate-change-has-been-hiding.html

@ Bob, lol.

Just wondering, why was CRUT3 used? Aren’t they on 4 or 5 by now?

Reblogged this on Power To The People and commented:
The weather was more extreme in 1913. https://notalotofpeopleknowthat.wordpress.com/2013/01/20/how-extreme-was-us-weather-in-2012/
The Climate models being used by the IPCC to justify “skyrocketing” fuel costs to “save the earth” have no relationship with reality and harm the poor the most who cannot afford to pay for the high fuel costs. High fuel costs = more poor people = more children dying. http://wattsupwiththat.com/2013/03/15/james-hansens-policies-are-shafting-the-poor/
“When the climate models do not agree with the reality”, Vahrenholt thundered, “then reality is not what’s false!” http://notrickszone.com/2013/08/15/vahrenholt-thrashes-leading-ipcc-former-ncar-scientist-in-hamburg-debate-the-wound-of-climate-science/

The actual quote should be:
“The IPCC is now 95% certain the Climate Model Ensembles are crap do not reflect reality.”
IPCC GRAPH of Models vs global temperature.

Right, and they were 95% certain that in the 1970s that we were heading for an ice age, or in the ’80s they were 95% certain that we were headed for much of the world being under water by now. Their own words:
“If present trends continue, the world will be about eleven degrees colder by the year 2000.” -Kenneth Watt, Earth Day 1970
“Entire nations could be wiped off the face of the Earth by rising sea levels if the global warming trend is not reversed by the year 2000.” -Noel Brown, ex UNEP Director, 1989
“[in twenty years {2008}] the West Side Highway [and thus much of Manhattan] will be under water.” -James Hansen, 1988, NASA
“[Inaction will cause]… by the turn of the century [2000], an ecological catastrophe which will witness devastation as complete, as irreversible as any nuclear holocaust.” -Mustafa Tolba, 1982, ex Executive Director of the UN Environment Program
Enough with the never ending predictions of doom!

You were too kind Anthony Lubos did a much more scientific dissection on it
http://motls.blogspot.com.au/2013/08/95-percent-confidence-in-hep-vs-ipcc.html
There is going to start being a chasm opening up between climate science and science itself if they keep doing this. I hope they really rethink this whole idea before any release and have the intelligence to leave the confidence levels alone.

100% of climate models do not work.
Now that is a consensus and a certainty anyone can live with.

I would guess they are 95% sure of human influence since the ’50s and some number less than that (maybe 90% sure?) for warming before the 50’s. The difference probably owes to less reliable data.

I agree with Bill.

You know, I watched that Carlin piece a few nights back. I like Carlin, his social commentary is generally quite good and even when it is wrong, it is funny. This one started out with ignorance and just got worse and it never got funny. Rather ironic for someone who was generally so perceptive.

We can show the all we want but it won’t stop them because of the money flow that rewards them for their BS. Eureferendum just reported about one of the EU money sources aimed to protest (and ban) shale gas exploration in the EU.
Read Energy, the new Battle of Britain
http://www.eureferendum.com/blogview.aspx?blogno=84268

@Ian –
CNN also repeated the lies this morning (as I noted in an earlier post on another thread). No question about it, the MSM are political campaigners, not news reporters. Only Fox seems to have not taken this low road, but even they could do a lot more than occasionally having Marc Morano on Cavuto.
@dp, Richard M –
How easy it is to blow holes in AGW with the simplest of observations. Good work.

95%… so there are at least AR6 96%, AR7 97%, AR8 98%, AR9 99% and AR10 100% for UN bureaucrats although they may not stop there… AR12 102%?

dbstealey says:
August 20, 2013 at 3:53 pm
richardscourtney,
Was this the chart you asked about?
And here is another chart based on Phil Jones data.
—————————
Using the Phil Jones data one could make a WUWT escalator. I’m sure it would be a nice addition on the right side of the site. 🙂

Rob, Milodon,
To give ourselves too much credit is to claim we know more than we do. That is Comtism (of Auguste Comte). Comte pushed this thinking and called it “positivism”, inspiring Hegel and Marx. It’s an exaggerated sense of knowing without humility, a resisting, a suppression of the discomfort of our vast not-knowing. The not-knowing that is basic to science. This error that triggered the imbalance and arrogance of the European “Enlightenment” and led to mass deaths of the twentieth and soon the twenty-first century. Taken up by fascists and pro-agressives, today it fuels every idealistic world movement, continuing to be incredibly dangerous, still gaining in strength. Quack environmentalism is but one way to express of positivism’s motivation. If it was just pseudo-environmentalism we could probably knock it down, but it’s much more integrated into society than that.
Positivism means that science and philosophy are literally a thing of the past, that there more important things at hand. It’s why there’s so little traction with proper science.

dbstealey’s chart from Phil Jones could be (ab)used thus:
The identical increases in temperature are natural BUT, they are on top of a steadily increasing man-made, catastrophic-if-it-continues, have to go back to the dark ages, man-made-CO2-induced global warming.
If the chart goes much higher perhaps it will prop up the sky and stop it falling.
should be assumed

95% confidence is worthless. Once out of twenty times, you will ‘prove’ green jelly beans cause acne (xkcd). Can we get back to 5-sigma science, please?

FThoma says:
August 20, 2013 at 8:58 pm
///////////////////
I do not recall his article, but it sounds implausible to me.
During the war (just as in peace time) shipping is confined to narrow lanes. Ships do not cross even 1% of the oceans. So if there was spillage from ships (one presumes predominantly due to being attacked), on a global basis, not much of the ocean surface would be covered with oil.
Heck even the large spillages these last 40 or so years Torrey Canyon (about 120,000 tonnes) Exon Valdes (about 100,000 tonnes), Braer (about 85,000 tonnes), Sea Empress (about 75,000 tonnes) etc, had no impact on a global basis even if the spill covered hundreds of square miles. Those ships were carrying so much oil that they would have been the equivalent to a loss of hundreds of wartime convoys.
Since I did not read the article, I do not know whether he looked into the effect of those ships, and whilst I do not like joining isse with an article that I have not seen, my gut tells me it is rather implausible.

Now I want to see a number from the IPCC telling me the cause[s] of the temperature standstill with 95% certainty. Can they do this? If temps start to fall can they admit that co2 is NOT the main driver of climate?
Now see this graph showing 2 distinct warming periods.
There has been a 0.8C rise in global surface temperature since around 1880. Now take out the rise up to 1950 and what do you have left? Now take out the natural component since 1950 and what do you have left?
Now see this question from the BBC and the reply from Dr. Phil Jones at the Climate Research Unit.

BBC Q&A: Professor Phil Jones
13 February 2010
[Q] A – Do you agree that according to the global temperature record used by the IPCC, the rates of global warming from 1860-1880, 1910-1940 and 1975-1998 were identical?
[A] …..So, in answer to the question, the warming rates for all 4 periods are similar and not statistically significantly different from each other….
http://news.bbc.co.uk/2/hi/8511670.stm

The IPCC are a bunch of climate clowns.

The proposition leaked is this one:
“It is extremely likely that human influence on climate caused more than half of the observed increase in global average surface temperature from 1951-2010”
note: In the IPCC vocabulary “extremely likely” means to have a 95% chance.
Now, according to GISTEMP the Global Land-Ocean Temperature Index has increased by 0.73°C in the half century between 1951 and 2010. However, there is a marked endpoint effect here, because 2010 was unusually warm (the next 2 years being about 0.1°C cooler). Therefore it is a bit more correct to calculate trend during this period, which turns out to be 0.111°C/decade, that is, 0.56°C for the entire period.
With this, we are ready to transform the statement above to another, logically equivalent one.
“There is a one in twenty chance that according to observations human influence on climate caused no more than 0.28°C increase in global average surface temperature from 1951-2010”
Please note that “human influence on climate”, beyond GHG emissions includes land use changes, a sharp decrease in sulphate emissions (a.k.a. “global brightening” due to clean air acts all over the developed world) and increasing black carbon (soot) production (mainly from ill maintained diesel engines and incomplete biomass burning) as well. All these influences tend to increase surface temperature, so the part due to GHGs can’t be more than 0.15°C. In the same period CO₂ content of the atmosphere increased by 33% of a doubling. Which means climate sensitivity to CO₂ doubling is less than 0.5°C. And that implies strong negative feedbacks, absolutely inconsistent with any computational climate model the IPCC relies on.
Even if all anthropogenic temperature increase is attributed to GHGs, observed sensitivity is still no more than 1°C, which rejects any positive feedback whatsoever.
Now, in a sane world conceptual models inconsistent with observations would be dropped immediately. Are they?
The only way out is to suppose an extremely long equilibration time (e-folding at ~ 1 century), that is, high effective heat capacity of the climate system. In that case the slow warming rate observed becomes consistent with a ~3°C equilibrium climate sensitivity. However, this escape route comes at a price. Effective heat capacity so high as to be able to make observations consistent with strong positive feedbacks (needed to raise long term climate sensitivity sufficiently) is inconsistent with both observations (ARGO measurements of Ocean Heat Content) and computational climate models. On top of that a long lag time would severely limit warming rate due to GHGs on multi decadal scales, which is not alarming enough, even if one chooses to deny both observations and theory.

Does Global warming increase welfare?, if so, Ky is doing very well. 25% on it here.

“Drafts seen by Reuters of the study by the U.N. panel of experts, due to be published next month, say it is at least 95 percent likely that human activities – chiefly the burning of fossil fuels – are the main cause of warming since the 1950s.”
Shouldn’t that read:
“…it is at least 95 percent likely that human activities – chiefly placing weather stations near asphalt and cooling vents within urban heat islands, and massaging past temperatures to make them cooler – are the main cause(s) of “warming” since the 1950s.”
Re: massaging – see many of my earlier posts, or go to NWS BWI (or other stations) and add up any month’s means 1981-2010, divide by 30, and see that it somehow comes out higher than the 30 year climatic “normals”. Funny how that happens.

The experts are 95% convinced that their expertise is worth paying for. Quelle surprise.

Keitho says:
August 21, 2013 at 6:29 am
TomRude says:
August 20, 2013 at 8:50 pm (Edit)
95%… so there are at least AR6 96%, AR7 97%, AR8 98%, AR9 99% and AR10 100% for UN bureaucrats although they may not stop there… AR12 102%?
————————————————————————————–
We could get Spinal Tap to play some theme music for the IPCC and we could turn up the volume all the way to 11
___________________________________________________
Thanks Keitho for giving me the opening for, once again, posting absolutely the greatest single thing that Global Warming has produced to date: Spinal Tap and Every Bassist in the Known Universe at Live Earth.
http://youtu.be/iN42uzNFVmQ

Either an idiot did the statistical analysis or a P.O.S. pawn of the political make money on global warming bandwagon who calls him/herself a scientist (prostitute) did the work. What a ship of fools.

Here’s another such scientific “consensus” that sounds wonderfully similar: The Inquisition’s “panel of experts” was 100 percent certain, based on Ptolemy’s models and righteous thinking, that the earth occupied the center of the universe, whereas Galileo, a seventeenth century ‘denier’, supported the Copernican view of a heliocentric system based on actual observation.

3. How is the IPCC 95% certain one side is caused by man and the other is not?

It would be from tallying the relative contibutions of various forcings, wouldn’t it?
(Now checking the leaked draft report)

The guidance note defines attribution as ‘the process of evaluating the relative contributions of multiple causal factors to a change or event with an assignment of statistical confidence’.

Ch 10: Attribution
Which includes observed natural (eg, solar, volcanic) and anthropogenic (eg, GHG, aerosol) drivers.
Delving further into question 3 – AR5 attaches no particular confidence to pre-1950 attribution (data is sparser for that period), but posits a combination of solar and GHG forcing (both positive). Solar forcing has been insignificant for the post-1950s period, which may be partly why they attach high confidence to anthropogenic causes since then.
Both AR4 and AR5 (leaked draft) concur on anthropogenic forcing being the main driver the since the mid-20th century.
AR4 SPM – “Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”
AR5 SPM – “It is extremely likely that human activities have caused more than half of the observed increase in global average surface temperature since the 1950s.”
Very little has changed between drafts, except that confidence is a bit higher for the claim.

Richard,
Attribution studies apply observed forcings and physics to modeling and compare to observed responses (like temperature). There is no empirical basis for the supernatural powers of witches. I am a little unclear of some of your argumentation. If you are saying that models fail to take into account unknown unknowns, then yes, obviously. But invoking such is uncomfortably similar to mystical arguments. We don’t know what causes gravity, but we make sufficiently useful models of it to navigate spacecraft to asteroids and planets in the solar system. Our understandings of things is always limited but that does not make them useless. As far as i can make out, IPCC has determined that that of all the known knowns, the dominant cause of global warming since 1950 is anthropogenic GHGs. Put another way, they are saying that it is extremely likely that anthropogenic GHGs have caused >50% of the warming since the mid-20th century. That doesn’t seem overly-confident on the surface. That still leaves nearly half of the warming to potentially have been caused by natural forces. It isn’t the sun, it isn’t volcanic activity, and long-term ocean atmosphere fluctuations (like the AMO) appear to lag global temperature rises, indicating that either those systems are responding to global temperature, or that the effects are local. In this light, the IPCC claim doesn’t seem so extreme. They are not saying, for example, that 95% of the warming since 1950 is anthropogenic in origin, only more than half.

Smoking Frog says: August 22, 2013 at 5:44 am
“That’s unfair to Ptolemy and to those who used his model. It was actually useful! Would you say that the climate models are actually useful? What’s this “righteous thinking”? Are you suggesting that Ptolemy was a Christian? That’s not likely. He died in 168 AD.”
You’re missing the point. No I’m not saying Ptolemy was a Christian, nor am I saying his models weren’t useful for the purposes of describing what they thought were seeing. I’m saying that the “consensus” view of the universe at the time, based entirely upon Ptolemy’s ungainly models and religious attitudes, was wrong. Hence the “righteous thinking”. The Roman Church at the time insisted that this view of a geo-centric universe was not only right, but that it was blasphemous even to argue the opposite. The Inquisition enforced acceptance of this “consensus” view while flying in the face of clear observable evidence presented by the likes of Copernicus and Galileo that it wasn’t.
THAT is the point.
Not much has changed since the time of Galileo because these attitudes are clearly still prevalent.

Richard,

It is also true that “There is no empirical basis for AGW.”

The absorptive properties of greenhouse gases have been long inventoried. Upwelling radiance in the spectral bands pertinent to CO2 have been observed to darken over time from satellites. Your opinion is at odds with even the skeptical climate scientists and popular bloggers, like Roy spencer, Roger Pileke senior, and Anthony Watts, who to their credit eschew the notion that increased GHGs in the atmosphere will have no effect on global temperatures. Surely you’re not one of those Sky Dragon Slayers?
The capacity for CO2 and other GHGs to absorb long-wave radiation is not an assumption, it is a well-verified fact, and the absorptive properties for various gases at thousands of spectral wavelengths have been observed and calculated through spectroscopy since at least the 1960s and the information stored in databases, like the HITRAN database. This is a fundamental, empirically derived component of modeling for attribution studies, which include line-by-line calculations for the gases in the atmosphere.
Not all processes in attribution modeling are empirically derived, but to claim that there is no empirical basis is flat out wrong.

Another pea-watch alert: They are now saying “since the 1950s, not “since 1950.” I.e., it’s now since 1960

I don’t see why IPCC should not update their figures in line with better understanding, but let’s quote the Summary for Policy Makers.
AR4 SPM – “Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”
AR5 SPM – “It is extremely likely that human activities have caused more than half of the observed increase in global average surface temperature since the 1950s.”
Mid-20th century is equivalent to 1950s, isn’t it?

There is NO empirical basis for AGW: none, zilch, nada. And you cite none.

The evidence that the contribution to increased CO2 in the atmosphere is primarily from fossil fuels is incontrovertible from many lines of emiprically measured evidencde (isotopic ratios, fossil fuel inventories etc).
The empirical evidence that increasing the amount of CO2 in a column of air has been known since the 1860s.
Radiance changes anticipated from occlusion of upwelling infrared radiation in the spectral bands associated with CO2 have been empirically measured by satellites.
The globe has warmed.
None of these are derived from climate models. They are some of empirical bases for the well-known understanding that increased GHGs should cause some warming.

And this is the importance of the missing tropospheric Hot Spot which is predicted by AGW as it is emulated by climate models.

Enhanced tropical tropospheric warming is not a signature of greenhouse warming. It is the expected effect from warming of the atmosphere by any source (solar, volcanic etc). It is a function of atmospheric heat ransfer, not greewnhouse gases. Lack of observed enhanced heating in this zone says nothing about AGW.

There will not be any empirical evidence for AGW unless and until there is observation of a climate behaviour which is definitively known to be an effect of AGW.

.
Lowered temperature of the lower stratosphere is a signature of greenhouse warming and has been observed by satellites.
Same goes for global winters warming faster than summers over the long-term.
Same goes for reduction of the diurnal range over the long-term (observed over the period from the mid-20th century).
These effects are not anticipated to be evident on shorter time scales. These are long-term climate predictions which become evident with enough data.
These are not anticipated signatures of warming from non-GHG sources.
All these are empirically based observations.
I will be happy to provide reference material.
Attribution is not based on assumptions.

Why are people not using the BEST data for the graphs? That is the most comprehensive analysis. Or if we are going to use the likely inferior HadCRUT, why not use the most recent version? [Of course, it’s only a detail because these are all similar.]

Keitho:
>> It has become apparent from the empirically derived data that the previously used climate models underestimate the damping effects that nature has on the rate and sign of climate change.
What study are you referring to?
The oceans dampen the rate (but not the final value reached) and that dampening is believed now to be a little greater I think, but the sign of any dampening (regardless of the source), by definition, is always negative in some sense (eg, to the forcings).
Factoring in all improvements in our understanding, the predicted direction of future (equilibrium and multi-decade) global surface temperatures is to a significantly higher level than our current levels. That is clearly reflected in each IPCC report so far. The predictions of this have not changed that much.
>> increasing levels of atmospheric CO2, which it is thought to be caused by man burning fossil fuels
Can’t argue there. The history is clear: very stable rates for millions of years and then a surge in the last century that took it to levels not believed to have existed on earth in millions of years.
>> the actual outcome does not indicate anything to be concerned about thanks to the effect of these poorly understood damping factors.
That’s not what the data says. That’s what you believe perhaps. Despite the uncertainties, it is becoming more and more certain (but not perfectly so, never) that if we don’t slow down significantly our fossil fuel burning, future generations of our descendants will have to deal with an environment humans and most of the species we depend upon have never seen. Further, it will imply significant changes to many major existing metro centers.
We will need to have major breakthroughs in farming, disease fighting, water conservation, and many other areas (like carbon sequestering) if we hope to avoid mass deaths. Or we can mitigate this by more quickly moving to the energy sources that future generations will eventually rely on since fossil fuels will be significantly more so depleted for them at our current rates of consumption.

Sorry, RACookPE1978, I think my version is more accurate.
You can’t make energy cheaper as supply runs out while demand remains high. That is basic economics.
You are aware that fossil fuels don’t grow on trees right? They aren’t renewable. Meanwhile the sun keeps shining its colossal amount of energy upon us daily without end in sight.
So you advocate pushing harm onto future generations and ignore taking action that can make their loss of fossil fuel a little easier to take.
“Thanks, great gramps. Now I know why I love you so much. Thanks.”

I said >> Have you ever closed the oven door or the house door or increased any insulation on anything and observed a rise in temperature
To make it clear, I am talking about a house in Winter.. generally any case where the temp on the outside is cooler than the temp on the inside (note the reference: outer space is cold, planet’s surface is warm).

See, in the past (several times) the CO2 has regularly been far above today’s mere 400 ppm. And temperatures ALWAYS increased AFTER CO2 rose.

Is that a typo (asking the question genuinely)? It is well-known that CO2 changes follow temperature changes during the quaternary ice ages – the famous lag that many people point out here. You appear to be arguing that CO2 fluctuations cause temperature changes – which is correct – but seems at odds with your general thrust.
[True. Typo. Mod]

This Hot Spot is induced by warming from greenhouse gases and NOT by warming from any other source. This is shown by Figure 9.1 and the associated text of the most recent IPCC Scientific Report (AR4) and its associated text which can be seen and read here http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9s9-2-2.html

Panel a) shows the amount of solar forcing over the previous century. You can see the enhanced tropospheric warming in that panel quite clearly. The reason it is not as pronounced as the CO2 panel is that the forcing is much weaker. But the enhanced heating is there.
I’m afraid you have been misinformed by popular misinterpretations. You can also see the opposite effect (enhanced cooling of the tropical troposphere) in panel e), which shows overall cooling from aerosols.
The most marked spatial difference between the panels is the pattern of stratospheric cooling with tropospheric warming.associated with GHG changes. None of the other panels has this pattern (whether warming or cooling). The cooling of the stratosphere is unique to GHG warming, not from other sources. That is the signature of GHG warming, for which there is plenty of reference in the literature. There is none that posits enhanced tropical tropospheric warming is a unique signature of GHG warming.
It’s a furfy, Richard.

The basis of the issue is that models produce an enhanced warming in the tropical troposphere when there is warming at the surface. This is true enough. Whether the warming is from greenhouse gases, El Nino’s, or solar forcing, trends aloft are enhanced. For instance, the GISS model equilibrium runs with 2xCO2 or a 2% increase in solar forcing both show a maximum around 20N to 20S around 300mb (10 km):

(images at source)
http://www.realclimate.org/index.php/archives/2007/12/tropical-troposphere-trends/
The two panels for solar and GHG heating in the graphs there show what happens when the amount of forcing is roughly equivalent. The hotspot appears in both, and also in the solar panel in the IPCC graphs. The tropospheric enhancement is not as pronounced for non-GHG forcings in the IPCC charts, because they were estimated to have been small or cooling over the period 1890 to 1999. But you can see the enhanced changes in the tropoical troposphere for forcings that were non-negligible.

Richard,
the IPCC does not describe the cause of the hotspot. It does not refer to it at all. If you look at the solar panel a), it is pretty clear that warming at the surface produces an enhanced warming in the tropical troposphere. It is not as pronounced as the panels for GHGs, simply because the forcing is weaker. But unless one is colour blind, the enhanced warming is difinitely there.
Did you examine the two graphs at my link, where roughly equal amounts of forcing for solar and CO2 are side by side, and the hotspot enhanced warming in the tropical troposphere is equally pronounced? These are results from ModelE, the same model used for the graphs in the IPCC charts, but this time giving solar and CO2 equivalent forcing values.
But perhap you would give more credence to a WUWT post on the subject.

Based on theoretical considerations and simulations with General Circulation Models (GCMs), it is expected that any warming at the surface will be amplified in the upper troposphere. The reason for this is quite simple.
More warming at the surface means more evaporation and more convection. Higher in the troposphere the (extra) water vapour condenses and heat is released. Calculations with GCMs show that the lower troposphere warms about 1.2 times faster than the surface. For the tropics, where most of the moist is, the amplification is larger, about 1.4.
This change in thermal structure of the troposphere is known as the lapse rate feedback. It is a negative feedback, i.e. attenuating the surface temperature response due to whatever cause, since the additional condensation heat in the upper air results in more radiative heat loss.

http://wattsupwiththat.com/2013/07/16/about-that-missing-hot-spot/
The enhanced warming in the hotspot is not a result of increased GHGs. It is a result of the change in moist adibiatic lapse rate when the surface warms.
Richard, can you explain why the physics that makes the enhanced tropical tropospheric warming a unique property of GHG warming? What’s the mechanism? The mechanism described in the literature has nothing to do with GHGs, (other than discussing GHG as a dominant forcing).
Other comments from well-known, qualified scientist skeptics.
Judith Curry:

Here is why I don’t think the tropical tropospheric temperature trends is a good litmus test for AGW. The physics underlying the amplified tropical tropospheric warming in the models is the decreasing slope of the saturated adiabat as temperatures warm. Deep convection throughout the tropics will therefore result in saturated adiabat having a dominant influence on the vertical temperature profile, and hence result in the upper tropical troposphere warming faster than the surface. In climate models, it is the convective parameterization that determines this vertical transport of heat.

Richard Lindzen:

The moist-adiabatic lapse rate (or saturated-adiabatic lapse rate) is the rate of decrease of temperature with height along a moist adiabat. …
The response is characterized by the so-called hot spot (i.e., the response in the tropical upper troposphere is from 2–3 times larger than the surface response). The models are likely correct in this respect since the hot spot is simply a consequence of the fact that tropical temperatures approximately follow the moist adiabat. This is essentially a consequence of the dominant role of moist convection in the tropics.

And from other scientists quaified on the matter;
Carl Mears:

Because the MALR decreases with temperature, this means the any temperature increase at the surface becomes even larger high in the troposphere. This causes the so called hot spot, a region high in the troposphere that shows more warming (or cooling) than the surface. Note that at this point, I haven’t said a thing about greenhouse gases. In fact, this effect has nothing to do with the source of the warming, as long as it arises near the surface. Surface warming due to any cause would show a tropospheric hotspot in the absence of other changes to the heating and cooling of the atmosphere. Never the less, the tropospheric hotspot is often presented as some sort of lynchpin of global warming theory. It is not. It is just a feature of a close-to-unstable moist atmosphere.

Isaac Held:

The change in CO2 itself has very little to do with this moist adiabatic response; you get essentially the same temperature response if you just just prescribe and then warm the surface temperature [in a model]

Chris Colose:

Tropospheric warming in the tropics is a signature of greenhouse warming, but it is more accurate to say that it is not a unique signature (i.e., you get this “hotspot” with all types of forcings). The ‘hotspot’ arises due to the moist adiabat.
Stephen Sherwood:

The regulation of lapse rate changes by atmospheric convection is expected to work exactly the same way whether global temperature changes are natural or forced (say, by greenhouse gases from fossil fuel burning).

This blogger gets it right;

A great deal of the confusion surrounding the issue of temperature trends in the upper troposphere comes from the mistaken belief that the presence or lack of amplification of surface warming in the upper troposphere has some bearing on the attribution of global warming to man-made causes.
It does not.
Attribution of anthropogenic origins of the current climatic changes can be tested from many different directions. On of the most clear examples for those with some familiarity with the Earth’s atmosphere is the issue of stratospheric cooling. If the sun were to suddenly increase its output by 2%, we would rightfully expect the atmosphere as well as the surface to warm up in response. This can be examined, for instance, by looking at the response in a GCM like GISS ModelE:

This furfy is a slightly more complicated version of the canard that had traction for a couple of years that 1934 was the warmest year in the global record. Even today you can see the odd comment to that effect. But 1934 was the warmest year (at the time) in the US, not the global record.
Now, different data sets show either the enhanced warming or they do not (Spencer, Pielke and other skepticfs allude to this in various peer-reviewed papers). The matter is still controversial. but the notion that the hotspot is a unique signature of GHG warming is just wrong. The hotpsot is a function of the moist adibiat in response to warming (from any source) at the surface. It is not a unique function oy GHG warming.
But I am curious to know if you have lit on any actual physical mechanism that would explain the hotspot as a feature unique to GHG warming. Do you have a peer-reviewed or creditable cite that explains the physics which isolates this effect to GHGs? I can’t imagine what it might be.
(Eventually we may get back to talking about attribution)

Richard,
also in my posts was quotes from climate scientists, including skeptic scientists Judith Curry and Richard Lindzen, explaining that the hotspot is a consequence of changes in the moist adibiatic lapse rate from warming at the surface by any cause, and specifically not caused by GHG increases. I also linked to a post from this very site explaining that the enhanced warming of the troposphere is a result of surface warming from any cause.
If you disagree with the WUWT post, with Judith Curry, Richard Lindzen and the other scientists I cited, could you please explain what mechanism is responsible for the effect that can only be achieved by greenhouse warming? What are the physics?

Richard, we are agreed that the cause of the hotspot is a consequence of changes in the moist adibiatic lapse rate from warming at the surface. We aslo agree that different sources of warming will not have the same pattern of atmospheric warming/cooling. You appear to be saying that an enhanced hotspot is a unique signature of greenhouse warming.
You said:

The AGW hypothesis as exemplified by climate models predicts that temperature at ~10 km altitude in the tropics will rise by between 2X and 3X the rate of temperature rise at the surface. So, a region of elevated temperature (i.e. the Hot Spot) will occur at altitude.

The IPCC graph you cite is modeling for various sources of temperature change from 1890 to 1990. The magnitude for each of them is different, hence the magnitude of enhancement in the hotspot area will be different – but should be about twice the effect at the surface. Let’s look more closely at the panels:
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9s9-2-2.html
a) Solar
Surface warming is 0.0 – 0.2 C/century
Hotspot warming is 0.2 – 0.4 C/century
The hotspot has warmed twice as much as the surface. Agreed?
d) Ozone
Surface warming is 0.0 – 0.2 C/century
Hotspot warming is 0.1 – 0.3 C/century (the effect is very localised in the centre and to the right of the hotspot)
e) Aerosol
Surface cooling is 0.0 – 0.4 C/century
Hotspot cooling is 0.4 – 0.6 C/century
The values are colour coded in 0.2C increments, which make it difficult to get absolute values, but for each of the modeled forcings that cause temperature changes in the tropics at the surface (volcanoes being the exception – there is virtually no change in surface temps over the long term), there is an enhanced change in the temperature in the hotspot region aloft The reason this signal is more apparent in the well-mixed GHG panel is that the temperature change at the surface is larger and more persistent than the others.
As I said before, there is controversy over whether or not the hotspot is apparent in observed data.
If it turned out that there was no enhancement of warming in the tropical troposphere, this would indicate a flaw in understanding of heat transport in the atmosphere. It wouldn’t suggest that there has been no global warming over the last century or so (we have better records for that). And it wouldn’t indicate that greenhouse gases do not warm the planet. Spencer, Lindzen and Christy (along with Pielke Sr and Jr and Anthony Watts) agree that a doubling of CO2 should cause some warming at the surface.
And, as Spencer, Christy, Lindzen and others have published in the literature, the data is not certain, and they express caution about leaping to conclusions without more study. That seems like sound advice to me.

I think the science is imperfect and that concern amongst the research communies is genuine. I don’t buy into conspiracy theories.

Indeed. And there is considerable doubt as to its real existence accordingly.

Richard Lindzen expects the hotspot to be a real feature of moist adibiatic convection, and blames the data for us not having observed it. This is the general opinion of expert researchers. A minority of these doubt its existence. A good number think that the models may exaggerate the moist adibiatic lapse rate change. Roy Spencer posits that no hotspot would mean a lower climate sensitivity.
Depending where you go in the public blogosphere, there is considerable doubt (outright disbelief) of its existence and sometimes selected papers are cited accordingly, while commentators wishing to urge that there is no signficant discrepancy with models highlight studies that indicate the hotspot is there. Most non-expert commentators pick a side, and a number of experts seem to do so as well (on both sides). I am skeptical of absolutist positions.
There have been hundreds of papers on tropospheric temperatures. Below is a short list of some of them.
http://agwobserver.wordpress.com/2009/12/24/papers-on-tropospheric-temperatures/
http://agwobserver.wordpress.com/2009/09/06/papers-on-tropical-troposphere-hotspot/
(most of the papers in the second link have been moved to the first)