Relationship between CO2 and Global Warming

[Andre]

The vote of the majority may say more about the convincing power of the ideas than provide an good understanding of the reality. But what do we think?

 

[CobblyWorlds]

If CO2 is not the cause of the recently observed warming then what is?

 

[Andre]

If CO2 is not the cause of the recently observed warming then what is?

Century-millenium scale oceanic oscillations?
Decadal atmospheric oscillations?
Interacting oscillations all in warm phase currently?
Solar activity, influencing cosmogenic condensing nucei?
land albedo changes due to changed land use?
Oceanic albedo changes (algae) due to anthropogenic disturbing of the food chains?
Airliner water vapour emission in the stratosphere?
Soot, haze?

I found http://segovia.mit.edu/publications/2002/sretoc.pdf interesting.

 

[CobblyWorlds]

Century-millenium scale oceanic oscillations? - Far, Far, Far, to slow to account for the current warming.

Decadal atmospheric oscillations? - Why not apparent in the past? You'd need to tie it in with the next one* to make a workable hypothesis.

Interacting oscillations all in warm phase currently?* - Good one! EXTREMELY difficult to disprove. But by the same token extremely difficult to prove. Occams Razor >> We have a mechanism that will increase net global energy balance - CO2 forcing. So I'll be sticking with that until this alternate is proven.

Solar activity, influencing cosmogenic condensing nucei? - Do you mean Vizier? I thought that work had been withdrawn. In any case would not a 11 year climatic cycle be apparent in our climate if it were so sensitive to solar flux variation. Furthermore I'd thought that there was no evidence of a significant* trend in solar energy flux. (*i.e. a significant proporation as compared to the 11 years sunspot cycle - were a long term trend less than the sunspot cycle it'd be less apparent than the sunspot cycle).

land albedo changes due to changed land use? - Warming from gound up, so how can this explain the strato cooling. And would it account for polar amplification? Most of the Earth is ocean, and were such massive albedo to blame then it should be apparent from sattelite measurements.

Oceanic albedo changes (algae) due to anthropogenic disturbing of the food chains? - Again from the surface up heating, stratospheric cooling should not be an indicator. How massive would this need to be for even a 0.5 degC global temp increase? I've never heard of evidence for this. Once again albedo should be apparent with the technology available.

Airliner water vapour emission in the stratosphere? - This should be apparent by a shift in the lapse rate, i.e. a particular layer sources the heating would mess up the exisitng profile. In any case following 9/11 aircraft were grounded and a study showed a warming, not a cooling. Implying that aircraft contribute to cooling by increasing albedo, not to warming.

Soot, haze? Again increase in albedo, not a warming issue. And as areas such as Europe and US have cleaned up their air quality in the latter part of 20th century, why have we not seen a net cooling?

Thanks Andre, I'll stick with CO2, causing a net increase in global energy balance and amplified by water vapour. Off now, will reply tomorrow.

 

[Andre]

I'll stick with CO2, causing a net increase in global energy balance and amplified by water vapour.

But the cumulative feedback is negative which James Lovelock could have predicted :

http://www.aai.ee/~olavi/cejpokfin.pdf

Temporal variability of daily time series for total solar irradiance at the top of the atmosphere, the Microwave Sounding Unit (MSU) based global, hemispherical and zonal average temperature for the lower troposphere and stratosphere together with5 surface air temperature data, measured at various meteorological stations have been studied by means of the structure function. From the growth rate of the structure function in the time interval between 32 and 4096 days it follows that the variability of the series
represents an anti-persistent (AP) behavior. This property in turn shows a domination of negative feedback in the physical system generating the lower tropospheric temperature variability. Distribution of the increments over various ranges and correlations between them are calculated in order to determine the quantitative characteristics describing temporal variability.

 

[Antiphon]

Water vapor is a strong infrared absorber and is extremely abundent as pointed out.

I vote for H20.

Edit: Cosmic rays can seed cloud formation. Condensed clouds are much
more effective at absorbing IR than the concentration of CO2 which we
have. Solar and Extrasolar events probably underlie our global thermal
epochs, not backyard barbecues, cattle and the unfortuante burning of
our limited oil resources.

 

[CobblyWorlds]

Hi Andre,

If H2O does not amplify the small CO2 warming then the models must be wrong. In that case how do you account for http://www.gfdl.noaa.gov/reference/bibliography/2002/soden0201.pdf

Hi Antiphon,

To the best of my knowledge there is no major ongoing trend in cosmic rays that would account for the observed warming trend. Do you have such infor?

Again I refer you to my point regarding the 11 year solar cycle. Why, if the sun is causing the recent warming does the climate not exihibit an 11 year cycle. After all the 11 year cycle is far greater than and +/- trend in solar radiation (agin to the best of my knowledge - but I could be wrong!)

 

[Andre]

f H2O does not amplify the small CO2 warming then the models must be wrong. In that case how do you account for http://www.gfdl.noaa.gov/reference/bibliography/2002/soden0201.pdf

As always the caveats are hidden somewhere:

Although it is possible that other processes, such as clouds, could act in place of water vapor to provide the strong positive feedback necessary to amplify the cooling,...

Now it happens to be the scholar view that volcanic aerosols do act as condensation nuclei, increasing the cloud cover.

http://www.open.ou.nl/dja/Klimaat/System/crucial_role_of_aerosols_a.htm
http://www.newmediastudio.org/DataDiscovery/Aero_Ed_Center/Category/A_sulfate.html

But not a single reference to that process.

Well, nice try.

 

[CobblyWorlds]

"Well, nice try." Ditto Andre, you've missed the point...

You selectively quoted:

"Although it is possible that other processes, such as clouds, could act in place of water vapor to provide the strong positive feedback necessary to amplify the cooling..."

This is where you left it. But this paper is about water vapour and the model's ability to correct the predict level of water vapour given that Clausius-Capeyron only specifies an upper limit, and that the process that govern relative humidity have uncertainty associated with them.

So here's the penultimate para in full.

"To reproduce the observed temperature record after the eruption of Mount Pinatubo,
the model requires a strong positive feedback, equivalent in magnitude to that predicted for water vapor. Although it is possible that other processes, such as clouds, could act in place of water vapor to provide the strong positive feedback necessary to amplify the cooling, (but this time let's finish that statement) the observational evidence clearly indicates a reduction in water vapor that is consistent with the model predictions."

i.e. the model is able to reproduce the water vapour levels due to a well observed global temperature change event. So the doubts that some express about CO2 amplification by water vapour, are looking a bit less founded. What actually caused the change is secondary, the correct prediction of the water vapour response is the key issue.

 

[CobblyWorlds]

Actually Andre, to be fair I should own up that you nearly got me there. Whilst trawling around for data of the strato and tropo residence times for Pinatubo's suphate aerosols (which bear out your contention re the duration of cooling) I realized that wasn't the issue, a kick-self moment for me there! I should have been more specific as to why I'd posted the link to Soden, it wasn't a deliberate trap - just me being vague. :)

 

[Andre]

I think not that I missed the point being:

...Although it is possible that other processes, such as clouds, could act in place of water vapor to provide the strong positive feedback necessary to amplify the cooling...etc..."

Now, nowhere in the article the authers acknowlegde the role of aerosols (notably sulphates) in providing condensation nuclei. More aerosols, more clouds? They don't account for that in the model.

 

[Andre]

About the influence of aerosols on clouds and albedo this page may be useful:

http://www.atmosphere.mpg.de/enid/3__Clouds__particles_and_climate/-_Particles_and_climate_tl.html

 

[CobblyWorlds]

To quote from the final para of the study. "We note, however, that Mount Pinatubo does not provide a perfect proxy for global warming, because the nature of the external radiative forcing obviously differs between the two. Nevertheless, the
results described here provide key evidence of the reliability of water vapor feedback predicted by current climate models in response to a global perturbation in the radiative energy balance."

What Soden was doing was trying to demonstrate only that the models showed a good correlation with the observed levels of water vapour.

The aerosol induced increase in atmospheric albedo is the driving force that causes the change in water vapour that THEN amplifies the initial change in radiative forcing. That aerosols lead to the global decrease in temperature is not in any doubt. But being able to show that the models can replicate the change of water vapour is crucial for demonstrating the underlying model behaviour that leads to projections amplifying the initial positive forcing of anthropogenic CO2. As water has a short residency time, 10 days or so in the troposphere, it's not a forcing but a feedback.

I accept that there may be some effects of cloud that are not understood, the conflicting work of Richard Lindzen and Big Lin throws some interesting light on this. (Iris Hypothesis). BUT that is not the main issue being investigated here. It's the relationship between forcing and it's effect on temperature on a global scale, and the subsequent impact of temperature on water vapour concentration.

Off for the weekend now, will reply on Monday

 

[reasonmclucus]

Century-millenium scale oceanic oscillations?
Decadal atmospheric oscillations?
Interacting oscillations all in warm phase currently?
Solar activity, influencing cosmogenic condensing nucei?
land albedo changes due to changed land use?
Oceanic albedo changes (algae) due to anthropogenic disturbing of the food chains?
Airliner water vapour emission in the stratosphere?
Soot, haze?

I found http://segovia.mit.edu/publications/2002/sretoc.pdf interesting.

You left out the terracalories of heat generated by human activity. Some human technology operates at temperatures over twice the temperature of the air as measured in degrees Kelvin. The internal combustion engine operates above the boiling point of water. The catalytic converter can be hot enough to start fires in dry grass.

That heat has to go somewhere and the air is a ready absorber of heat.

I have heard that it is actually low temperatures that are increasing. If that is the case a likely cause would be an increase in the water vapor content of the air(which can result from combustion of hyrdrogen containing fuels or increasing evaporation of surface water) which places a floor under air temperature. The water vapor content sets the dew point which normally is the lowest temperature air at the surface can fall to.

Changes in heat circulation are another potential factor considering that the main change seems to be in temperatures in the northern areas of the northern hemisphere.

 

[reasonmclucus]

land albedo changes due to changed land use? - Warming from gound up, so how can this explain the strato cooling. And would it account for polar amplification? Most of the Earth is ocean, and were such massive albedo to blame then it should be apparent from sattelite measurements.

Oceanic albedo changes (algae) due to anthropogenic disturbing of the food chains? - Again from the surface up heating, stratospheric cooling should not be an indicator. How massive would this need to be for even a 0.5 degC global temp increase? I've never heard of evidence for this. Once again albedo should be apparent with the technology available.


Thanks Andre, I'll stick with CO2, causing a net increase in global energy balance and amplified by water vapour. Off now, will reply tomorrow.

If one area, of the atmosphere or surface areas, is warming and another cooling it would be likely that changes in heat distribution rather than net warming is occurring.

I have yet to see any numbers indicating that it is possible for CO2 to generate the necessary 500 to 700 calories per gram necessary to heat the atmosphere. CO2 only absorbs a narrow band of IR that is not widely produced.

 

[Pengwuino]

Im not even going to pretend i know what's the real science behind the global warming issue

 

[Andre]

You left out the terracalories of heat generated by human activity

Yes that's correct. We did the calc's on that and it turned out to be negliglible. Besides we're focussing on CO2 here. There can be another anthropogenic cause indeed like the change in water vapor and cloud cover.

 

[CobblyWorlds]

Hi Reasonmclaus,

"If one area, of the atmosphere or surface areas, is warming and another cooling it would be likely that changes in heat distribution rather than net warming is occurring. "

I don't quite get what you're getting at here. The global average temp is increasing. CO2 will increase the net energy of the Earth and then this minimal net energy increase (warming) will increase humdity (water vapour concentration) thus increasing the 'greenhouse' capture of heat. Thus the globe warms on average.

"I have yet to see any numbers indicating that it is possible for CO2 to generate the necessary 500 to 700 calories per gram necessary to heat the atmosphere. CO2 only absorbs a narrow band of IR that is not widely produced."

See IPCC Third Assesment Report Part 6 (I think), there's a table which contains the equations used to account for the increasing saturation of absorption bands as CO2 concentration increases. CO2 increases from current atmospheric concentrations are still able to increase absorbed energy.

PS http://www.gfdl.noaa.gov/reference/...2/soden0201.pdf demonstrates the ability of models to correctly reproduce water vapour levels under changes of forcing. Thus the models can be viewed as more robust in their projections of water vapour amplification of CO2 driven warming.

 

[Antiphon]

...no major ongoing trend... [cosmic rays seeding clouds]

I don't know if it's an ongoing trend. That part is difficult to separate out.
Here's a pretty balenced overview of where it's thought to be.

http://www.deas.harvard.edu/climate/pdf/carslaw-2002.pdf

 

[reasonmclucus]

Hi Andre,

If H2O does not amplify the small CO2 warming then the models must be wrong. In that case how do you account for http://www.gfdl.noaa.gov/reference/bibliography/2002/soden0201.pdf

Hi Antiphon,

To the best of my knowledge there is no major ongoing trend in cosmic rays that would account for the observed warming trend. Do you have such infor?

Again I refer you to my point regarding the 11 year solar cycle. Why, if the sun is causing the recent warming does the climate not exihibit an 11 year cycle. After all the 11 year cycle is far greater than and +/- trend in solar radiation (agin to the best of my knowledge - but I could be wrong!)

Try the following:

http://www.climateark.org/articles/1999/whatdrev.htm

http://science.msfc.nasa.gov/ssl/pad/solar/sunspots.htm

I believe the following requires AAAS membership for access.

http://www.sciencemag.org/cgi/content/full/308/5723/847

 

[reasonmclucus]

Hi Reasonmclaus,

"If one area, of the atmosphere or surface areas, is warming and another cooling it would be likely that changes in heat distribution rather than net warming is occurring. "

I don't quite get what you're getting at here. The global average temp is increasing. CO2 will increase the net energy of the Earth and then this minimal net energy increase (warming) will increase humdity (water vapour concentration) thus increasing the 'greenhouse' capture of heat. Thus the globe warms on average.

The global average temp is mathematically worthless. It is derived by adding only the high and low temperatures which may not be representative of temperatures for an entire 24-hr period. Any average temperature should use temperatures taken at specific intervals during the day, preferably at 10 minute intervals or less. The figures for global changes indicate only a .5 C change during the 20th Century which translates to about a .16% change(the per centage has to be determined using the Kelvin scale to avoid the abritrary "0" point of the C and F scales.)

the amount of water vapor in the air exists independently of the amount of CO2. Combustion of hydrogen containing fuels and variations in evaportation rate(which is affected by the amount of water not covered by ice among other factors) affect the amount of water entering the atmosphere. Variations in particles upon which water can condense to form water droplets affect the amount of water leaving the atmosphere. Water will condense on solids with temperatures below the dew point.

"I have yet to see any numbers indicating that it is possible for CO2 to generate the necessary 500 to 700 calories per gram necessary to heat the atmosphere. CO2 only absorbs a narrow band of IR that is not widely produced."

See IPCC Third Assesment Report Part 6 (I think), there's a table which contains the equations used to account for the increasing saturation of absorption bands as CO2 concentration increases. CO2 increases from current atmospheric concentrations are still able to increase absorbed energy.

PS http://www.gfdl.noaa.gov/reference/...2/soden0201.pdf demonstrates the ability of models to correctly reproduce water vapour levels under changes of forcing. Thus the models can be viewed as more robust in their projections of water vapour amplification of CO2 driven warming.

Does the assessment include actual measurement of the energy in the radiation CO2 absorbs along with experimental data showing that CO2 in fact generates heat that is transmitted to other atoms? Science is based on verification through expermentation and observation. Even Einstein's theories have been tested with actual observations when possible.

The link doesn't work.

 

[CobblyWorlds]

Sorry the link should be http://www.gfdl.noaa.gov/reference/bibliography/2002/soden0201.pdf ) That should work.

I'm not sure exactly how the 3 equations given in table 6.2 or chapter 6 of the IPCC Third Assesment Report are produced. However that's where they're listed. And I have no reason to doubt them. They are, after all, in IPCC TAR.

 

[CobblyWorlds]

Hi Reasonmclucus, (got the name right this time)

"The global average temp is mathematically worthless. " Do you mean mathematically or realistically? I really don't know where to start here. Obviously the temperature of an object can be determined by taking mean temperatures and averaging. As to the time of day issue, I don't know how exactly met stations do their work. But we have sondes, ground stations, and satelite all showing a warming. Furthermore this warming appears to be backed up by the pattern of glacial retreat at altitude in the tropics and temperate lattitudes, for just one observation. So that suggests that the measured increase is, at least in trend real.

"the amount of water vapor in the air exists independently of the amount of CO2. " Correct, but CO2 in the atmosphere increases temperature and THAT is what increases water vapour level. In Soden et al, it is shown that the models correctly account for changes in water vapour due to the reduction in solar forcing by aerosol driven albedo changes from Mt Pinatubo.

PS the 2 first links you post to appear to support my contention that Solar activity does not account for the current warming. I can't access the 3rd one, does that stand against what I'm saying?

 

[reasonmclucus]

Hi Reasonmclucus, (got the name right this time)

"The global average temp is mathematically worthless. " Do you mean mathematically or realistically? I really don't know where to start here. Obviously the temperature of an object can be determined by taking mean temperatures and averaging. As to the time of day issue, I don't know how exactly met stations do their work. But we have sondes, ground stations, and satelite all showing a warming. Furthermore this warming appears to be backed up by the pattern of glacial retreat at altitude in the tropics and temperate lattitudes, for just one observation. So that suggests that the measured increase is, at least in trend real.

"the amount of water vapor in the air exists independently of the amount of CO2. " Correct, but CO2 in the atmosphere increases temperature and THAT is what increases water vapour level. In Soden et al, it is shown that the models correctly account for changes in water vapour due to the reduction in solar forcing by aerosol driven albedo changes from Mt Pinatubo.

PS the 2 first links you post to appear to support my contention that Solar activity does not account for the current warming. I can't access the 3rd one, does that stand against what I'm saying?

An average of the numbers in a set needs to represent all the members of the set. Using only a high and low number may distort the result. For example, determining the average age of people living in a census district by only using the ages of the youngest and oldest residents would not guarantee an accurate result.

In temperature fluctuations, the low or high temperature at any given location might be the same for a long or short period. For example, in summer the overnight temperature might drop slowly reaching a low point just before dawn. In winter the temperature might drop to the dew point within a few hours after sunset and remain there until morning.

The article you referred to doesn't measure the actual energy being radiated which is necessary to determine if there is sufficient energy to warm anything. If you'll look closely at the graphs, the models only come close in situations of slow gradual change. In situations with fluctuations the models fail with the slopes of the curve moving in different directions. The model may show an upward slope when the actual measurement has a downward slope.

The main impact of water vapor on atmospheric temperature doesn't involve radiation. Instead in involves the fact that water vapor contains 540 calories of heat per gram that must be released if it condenses. With water's much higher coefficient of heat than air the result is that the condensation of a gram of water vapor releases sufficient heat energy to warm over 2 kg of air by 1 C. This characteristic is the reason the water vapor content of air sets the lowest temperature that the air can fall to called the dew point.

 

[Andre]

PS http://www.gfdl.noaa.gov/reference/bibliography/2002/soden0201.pdf demonstrates the ability of models to correctly reproduce water vapour levels under changes of forcing. Thus the models can be viewed as more robust in their projections of water vapour amplification of CO2 driven warming.

So let's investigate that in detail:

The magnitude of this cooling is documented by satellite measurements of lower tropospheric temperature from the microwave sounding unit (MSU). The MSU data indicate a peak global cooling of ~0.5 K nearly 18 months after the eruption, after which the temperature slowly returns to pre-Pinatubo levels...

The observed anomalies are computed using a 1979 to 1990 base climatology and expressed relative to the pre-eruption value, defined here as the mean anomaly for January 1991 to May 1991.

So we compare the temp dip with the average of the previous values. Now let's have a http://home.wanadoo.nl/bijkerk/Pinatoba.JPG at the MSU data prio to and after Pinatoba.

And yes Pinatoba is clearly preceeding a trophosphere temperature dip. No surprise there but we see similar sort of dips in 1982, 1984, 1989. This makes it very clear that without the Pinatoba eruption a similar dip could have occurred. So comparing the dip with average values has no meaning as we don't know what the real driver behind this cyclic behavior is. So, we don't know which part of the post-Pinatoba cooling is Pinatoba related and which part is natural cycle. Conclusion, the water vapor feedback is based on very shallow observations and cannot be considered proven.

And I keep wondering how this kind of papers passes the peer review.

Data source: http://vortex.nsstc.uah.edu/data/msu/t2lt/tltglhmam_5.1

 

[CobblyWorlds]

Hi Reasonmclucus,

If the use of maxima and minima on ground sites were a factor that significantly impacted the accuracy of temperature, then this should be apparent in variance between MSU and ground readings. Indeed there is a small unaccounted for difference. See the IPCC Third Assessment Report Chapter 2 Observed Variability and Change for an in depth account of the science up to 2000. I’ve never heard this point raised before, do you have any references to it?

The study I refer to Soden et al does not need to address “the actual energy being radiated” in order to demonstrate the good agreement between the model predictions and the observed reality. You argue with regards the agreement claimed by the authors, and indeed there is a small variance, see fig 2. But if there were NO variance I would be very suspicious of such a result. Due to the complexity of the atmosphere exact agreement is not likely. Soden et al was peer-reviewed and as it stands against the sceptics case you can bet there’ll be a small army of them working to attempt to undermine it’s support for the model’s ability to predict the water vapour amplification of temperature shifts.

Water does indeed impact air temp close to the dew point. But above the dew point the factor you state is not a major factor. Furthermore the energy balance mechanism you allude to is a short-term localised factor. And it cannot account for the globally observed increase in temperatures. With an atmospheric residency time of around 3.6 years against water’s 11 days, CO2 remains a long term forcing that can account for the recent observed warming when amplified by water vapour increases.

 

[CobblyWorlds]

Hi Andre :(

Looks like you got me here...

"And yes Pinatoba is clearly preceeding a trophosphere temperature dip. No surprise there but we see similar sort of dips in 1982, 1984, 1989. This makes it very clear that without the Pinatoba eruption a similar dip could have occurred. So comparing the dip with average values has no meaning as we don't know what the real driver behind this cyclic behavior is. So, we don't know which part of the post-Pinatoba cooling is Pinatoba related and which part is natural cycle. Conclusion, the water vapor feedback is based on very shallow observations and cannot be considered proven. "

Oh the logic! or lack of it. ;)

1) Is there an increase in strato temps associated with "1982, 1984, 1989." No? See http://www.metoffice.gov.uk/research/hadleycentre/CR_data/Monthly/upper_air_temps.gif So we have an indication of mechanism, unique to events like Pinatubo ElChihin etc. This allows the authors of that paper to use the event as they state.

2) "Conclusion, the water vapor feedback is based on very shallow observations and cannot be considered proven."

Using the same logic I will prove that nights are being overlooked and those of us paid on a daily as opposed to an hourly basis are beeing conned by a conspiracy!

When it's dark outside it's night, we ALL know that. Now I remember what 'the scientists' called an eclipse some years back. And it did indeed go dark. Now they try to tell us that this was not a night, they'll say things like 'it was by a different mechanism', 'it only lasted for about 5 minutes'. But I know their game, they're just trying to diddle me out of a days pay! They should have counted the day before this eclipse thingy as one day and the day after as another, so you see one day lost!

These 'scientists' with their logical deduction and big words they're all in it together.


Got any more thoughts on the Global Temperature trends displayed in all measuring systems - as I showed under our Stratosphere debate? It really is amazing how we can see the temperature rising, we can see the effects of this in global pattern of glacial retreat, the warming seas, changes in climate observed. And at the same time we see an increase in CO2, which as shown in Soden et al produces a variation in water vapour that is correctly modeled. And it's all just a coincidence, not a syndrmoic pattern.

What a puzzle. ;)

 

[Andre]

Nice try but look again:

http://home.wanadoo.nl/bijkerk/El-chichon-Pinatobo.JPG

So:

Is there an increase in strato temps associated with "1982, 1984, 1989." No?

Indeed, no

Check also:
http://volcano.und.edu/vwdocs/Gases/chichon.html

A puzzle indeed why the atmospheric reaction on both eruptions is so different.

 

[CobblyWorlds]

Hi Andre,

My analogy stands.

1982 and 1991 were incidents of volcanic aerosol injection, yet El Chichon, as you indicate occurred during an ongoing background dip in temperature - as you kindly demonstrate in your graph http://home.wanadoo.nl/bijkerk/El-chichon-Pinatobo.JPG . So I'd have agreed with Soden et al that this does not represent a good clean effect to study, whatever cooling it caused was added to another effect already underway due to another process. So it is tricky to draw conclusions. Yet with Pinatubo the cooling appears during a peak and thus the effect is most likely to be arguably due to Pinatubo's aerosol injection. Indeed the models show good agreement with the physical understanding of the processes involved, although that is not the main point of the study.

Why were the two eruptions different? Well how long is a piece of string? In essence it is not for the report author's to address such issues. As I describe above they have chosen a good alternate scenario to critically analyse the response of the models in predicting water vapour levels in response to a forcing. In this case a reduction in temperature, but it still shows a positive feedback (reinforcing the original perturbation).

You also stated 1984 and 1989, a propo of what? As I pointed out, whilst these were cooling incidents they were not associated with strato warming at all. Such a warming is on a theoretical and observational level assoc with stratospheric aerosol injection. The 1984 coincides with the tail end of the warming from El Chichon - as again shown in your graph.

So once again you are referring to the normal cycles (night) due to effects other than an atypical event with it's own cause and characteristics (eclipse) and trying to refute claims made on a reasonable basis that the event was atypical (eclipse darkness) and thus not comparable with a typical event (night time period of darkness). In Chichon we have the equivalent of a solar eclipse just before nightfall. With Pinatubo it's at midday.

Soden et al's paper supports the models ability to model water vapour reaction to a change in forcing.

 

[Andre]

How bold to persist with all the evidence shouting something else.

So what to we see, the lower stratosphere temperature (MSU-4) apparently reacting on the two (three) major aerosol producing volcanic eruptions. But the lower trophosphere MSU-2 is following it's own logic, warming after one event and cooling after another. Yet, you happily persist in a 100% relationship of Volcanoes and the lower troposphere.

We may have to go over the scientific method again; in particular the part that covers the reproducability.