Water Vapor Feedback

[The_Global_Warmer]

Will see a permenant jump in global temps because of the water vapor feedback??

Because forcing is rising. The water vapor feedback should be very strong.

It should be enough to make a new equilibrium.

Can anyone post satelitte data that tracks global water vapor levels???

[chubbs]

Here is satellite total precipitable water (TPW) that I have posted recently. The current nino has spiked TPW but it should fall back when nina returns. This data shows that the  water vapor feedback is rapid when SST and temperature changes. So I wouldn't call it a new equilibrium - more of a steady long-term increase combined with shorter-term ENSO variability.

 

[salbers]

Water vapor feedback is more like a continuous amplification of other radiative forcing, though the ENSO adds temporary radiative forcing on top of this. Apparently the ENSO effects give the impression of more long term feedback than actually exists as per this paper:

 

http://journals.ametsoc.org/doi/abs/10.1175/2009JCLI3052.1

[blizzard1024]

Here is satellite total precipitable water (TPW) that I have posted recently. The current nino has spiked TPW but it should fall back when nina returns. This data shows that the  water vapor feedback is rapid when SST and temperature changes. So I wouldn't call it a new equilibrium - more of a steady long-term increase combined with shorter-term ENSO variability.

 

tpwrss.png

This is a total misinterpretation of the water vapor feedback. This is total precipitable water which is from the surface to the tropopause. It includes the lower atmosphere. Warmer temperatures, especially over the oceans like during a strong el nino, lead to more surface evaporation. This leads to higher TPW.  It is only the water vapor in the UPPER troposphere that matters when it comes to GHG forcing. The upper troposphere's water vapor content varies mainly from convection and other processes. So total TPW mirrors lower level temperatures, that's it. It says nothing about where it matters...the upper troposphere.  

[Sophisticated Skeptic]

wow...the deniers really are out in full force today.

[Msalgado]

I find it hard to believe that a satellite derived TPW measurement is over representing the surface while failing to capture increases in the upper troposphere.

[blizzard1024]

I find it hard to believe that a satellite derived TPW measurement is over representing the surface while failing to capture increases in the upper troposphere.

 

The upper troposphere water vapor concentration is dominated by tropical convective processes and deep vertical motions by extratropical cyclones. The planetary boundary layer with its diurnal mixing will see increased water vapor through evaporation when temperatures increase. This moisture then either remains in the boundary layer( when there is no precipitation or clouds) or gets transported upward by precipitation processes. If precipitation increases globally either from convection or extratropical cyclones this actually is a sink of the water vapor at mid to high altitudes. Hence increasing precipitation is a sink of the primary GHG. Therefore you cannot assert that upper tropospheric water vapor increases when surface evaporation does. But during strong el ninos there is more tropical convection so in the very short term there could be increases in water vapor high up but this is temporary and will drop once the el nino switches to la nina.  Some of Desslers work from Texas A and M shows this. But he mis-interpretes this change in ENSO phase as a positive water vapor feedback since it is warm during el ninos and cool during la ninas.

[blizzard1024]

wow...the deniers really are out in full force today.

Don't call people denialists. Many are the real scientists who understand enough about science to question climate change. Plus how do you know that someone on this forum did not have a relative killed in the holocaust. The idea behind denialist is to equate them to the holocaust deniers.  IMO this is a very serious ad hominem attack on certain people. This person and others should be warned IMO. This is a very serious allegation and could be quite offensive.  

[chubbs]

 

Don't call people denialists. Many are the real scientists who understand enough about science to question climate change. Plus how do you know that someone on this forum did not have a relative killed in the holocaust. The idea behind denialist is to equate them to the holocaust deniers.  IMO this is a very serious ad hominem attack on certain people. This person and others should be warned IMO. This is a very serious allegation and could be quite offensive.  

 

Don't play the poor victim card. You are the one making unfounded accusations about data sets being fudged, scientists cheating to feed their families, etc. That's not science that's denialist BS. 

[HailMan06]

Don't call people denialists. Many are the real scientists who understand enough about science to question climate change. Plus how do you know that someone on this forum did not have a relative killed in the holocaust. The idea behind denialist is to equate them to the holocaust deniers. IMO this is a very serious ad hominem attack on certain people. This person and others should be warned IMO. This is a very serious allegation and could be quite offensive.

Don't play the poor victim card. You are the one making unfounded accusations about data sets being fudged, scientists cheating to feed their families, etc. That's not science that's denialist BS.

He posted a carbon copy response to me in the climate banter thread. You can see right through the faux outrage.

[chubbs]

The upper troposphere water vapor concentration is dominated by tropical convective processes and deep vertical motions by extratropical cyclones. The planetary boundary layer with its diurnal mixing will see increased water vapor through evaporation when temperatures increase. This moisture then either remains in the boundary layer( when there is no precipitation or clouds) or gets transported upward by precipitation processes. If precipitation increases globally either from convection or extratropical cyclones this actually is a sink of the water vapor at mid to high altitudes. Hence increasing precipitation is a sink of the primary GHG. Therefore you cannot assert that upper tropospheric water vapor increases when surface evaporation does. But during strong el ninos there is more tropical convection so in the very short term there could be increases in water vapor high up but this is temporary and will drop once the el nino switches to la nina.  Some of Desslers work from Texas A and M shows this. But he mis-interpretes this change in ENSO phase as a positive water vapor feedback since it is warm during el ninos and cool during la ninas.

 

The data generally show water vapor increasing with temperature throughout the troposphere as predicted by climate models. Lets look at your simple argument outlined above. Of course precipitation is a sink. If evaporation and boundary layer moisture increase one would expect both precipitation and upper atmosphere water vapor to increase.   Consider the simple case of boundary layer air lifted into a cumulus cloud. If the air parcel starts out warmer and holding more water vapor near the ground. It will also be warmer and able to hold more moisture after it is lifted into the upper atmosphere.  In addition any condensed cloud water in the upper atmosphere can return to a vapor state if mixed with air from outside the cloud and re-evaporation would be more likely if the upper atmosphere had lower relative humidity as you propose.  Of course these simple arguments are not conclusive. Instead complex models are needed to evaluate water vapor evolution in a warmer world. However the simple arguments show there is no reason to throw out established science as you propose.

[blizzard1024]

The data generally show water vapor increasing with temperature throughout the troposphere as predicted by climate models. Lets look at your simple argument outlined above. Of course precipitation is a sink. If evaporation and boundary layer moisture increase one would expect both precipitation and upper atmosphere water vapor to increase.   Consider the simple case of boundary layer air lifted into a cumulus cloud. If the air parcel starts out warmer and holding more water vapor near the ground. It will also be warmer and able to hold more moisture after it is lifted into the upper atmosphere.  In addition any condensed cloud water in the upper atmosphere can return to a vapor state if mixed with air from outside the cloud and re-evaporation would be more likely if the upper atmosphere had lower relative humidity as you propose.  Of course these simple arguments are not conclusive. Instead complex models are needed to evaluate water vapor evolution in a warmer world. However the simple arguments show there is no reason to throw out established science as you propose.

 

First of all, what data shows an increase in water vapor through the troposphere specifically the upper troposphere. Second, climate models??? Do you know that climate models when first run have an excess or deficit of energy and fail to simulate the present climate. Climate modelers "balance" the models by varying cloud cover to get the model to not gain or lose energy when first run before changing GHGs. The models do not simulate explicitly cloud cover, or tropical convection. These are HUGE when it comes to the Earth's energy balance. How these react to small forcings from doubled CO2 as they often use the models to simulate is unknown and likely to be a negative feedback. More water vapor could easily mean more low clouds and higher albedo. World wide cloud datasets that alarmists deem inaccurate (of course) show an inverse relationship from global temperature and low cloud cover. The only way to get clouds and moisture to the upper troposphere is through convection or an extratropical cyclone (tropical cyclones too but these are rare compared to the other two). But there is always compensating subsidence with these storms which leads to drying. Plus, the upper troposphere has warmed very little compared to the surface as per satellite and radiosonde data. So it is doubtful that any significant water vapor feedback is occurring.  The reanalysis data shows a drying upper troposphere but of course the alarmists say that dataset isn't good either. Their heavily adjusted surface dataset is the gold standard. /sarc   You don't understand the real climate and refuse to see the climate for what it is other than the IPCC narrative.

[blizzard1024]

 

 

Don't call people denialists. Many are the real scientists who understand enough about science to question climate change. Plus how do you know that someone on this forum did not have a relative killed in the holocaust. The idea behind denialist is to equate them to the holocaust deniers.  IMO this is a very serious ad hominem attack on certain people. This person and others should be warned IMO. This is a very serious allegation and could be quite offensive.  

 

Don't play the poor victim card. You are the one making unfounded accusations about data sets being fudged, scientists cheating to feed their families, etc. That's not science that's denialist BS. 

 

 

You are very naive when it comes to academia. I will leave it at that. Plus, name calling?? That is very childish and pretty much admits that you have no answer for whoever is challenging you. This forum is full of this. That is a typical human behavior when you are outmatched, resort to name calling. This is what children on the play ground do. I wish all of you would stop it and provide some reasonable evidence that CO2 is leading to the observed warming. Climate models don't cut it. Ice core data actually hurts CO2 case since CO2 passively follows the temperatures. There isn't much left except a measly 3.7 W/M2 from doubling which is about 1% extra forcing for the total GH effect. You need a very unstable climate system for anything interesting to arise and since the great ice sheets melted, the holocene has been pretty stable climate wise. Even if we saw 2-3C warming, the rate of warming is very slow because of the huge heat sink called the oceans!! Earth's creatures can adapt if this happens over centuries. Heck it was warmer 6-8K years ago versus today and polar bears, the present species of arctic birds and other animals etc survived.  This is a non issue and the research money needs to be invested into more useful aspects of atmospheric science. 

[donsutherland1]

The data generally show water vapor increasing with temperature throughout the troposphere as predicted by climate models.

That's correct. There's also a fairly recent research that indicates that the water vapor increase represents a positive, not negative, feedback on temperatures.

 

Summary: http://phys.org/news/2008-11-vapor-major-player-climate.html

 

Full piece: http://www.pnas.org/content/111/32/11636.full.pdf

 

It will be interesting to see what subsequent research reveals, but right now, the data lean toward the idea that increasing water vapor may amplify the warming occurring on account of increased greenhouse gas forcing.

[blizzard1024]

That's correct. There's also a fairly recent research that indicates that the water vapor increase represents a positive, not negative, feedback on temperatures.

 

Summary: http://phys.org/news/2008-11-vapor-major-player-climate.html

 

Full piece: http://www.pnas.org/content/111/32/11636.full.pdf

 

It will be interesting to see what subsequent research reveals, but right now, the data lean toward the idea that increasing water vapor may amplify the warming occurring on account of increased greenhouse gas forcing.

 

Thanks for providing the paper. I like to read the paper instead of just the abstract!!!

[Sophisticated Skeptic]

Don't call people denialists. Many are the real scientists who understand enough about science to question climate change. Plus how do you know that someone on this forum did not have a relative killed in the holocaust. The idea behind denialist is to equate them to the holocaust deniers.  IMO this is a very serious ad hominem attack on certain people. This person and others should be warned IMO. This is a very serious allegation and could be quite offensive.  

 

 

fasting with Glenn Beck are we... ?

[donsutherland1]

Thanks for providing the paper. I like to read the paper instead of just the abstract!!!

I try to provide a link to complete papers when such papers are available. Unfortunately, some papers are not publicly available without a subscription or payment.

[chubbs]

You are very naive when it comes to academia. I will leave it at that. Plus, name calling?? That is very childish and pretty much admits that you have no answer for whoever is challenging you. This forum is full of this. That is a typical human behavior when you are outmatched, resort to name calling. This is what children on the play ground do. I wish all of you would stop it and provide some reasonable evidence that CO2 is leading to the observed warming. Climate models don't cut it. Ice core data actually hurts CO2 case since CO2 passively follows the temperatures. There isn't much left except a measly 3.7 W/M2 from doubling which is about 1% extra forcing for the total GH effect. You need a very unstable climate system for anything interesting to arise and since the great ice sheets melted, the holocene has been pretty stable climate wise. Even if we saw 2-3C warming, the rate of warming is very slow because of the huge heat sink called the oceans!! Earth's creatures can adapt if this happens over centuries. Heck it was warmer 6-8K years ago versus today and polar bears, the present species of arctic birds and other animals etc survived.  This is a non issue and the research money needs to be invested into more useful aspects of atmospheric science. 

 

I don't see your issue.  A 1% increase in forcing amplified by a factor of 2-3 by feedbacks gives a roughly 1% increase in temperature (3K vs 287K base). The answer hasn't changed significantly since I was in school 40 years ago.

[blizzard1024]

I don't see your issue.  A 1% increase in forcing amplified by a factor of 2-3 by feedbacks gives a roughly 1% increase in temperature (3K vs 287K base). The answer hasn't changed significantly since I was in school 40 years ago.

 

Your assuming this is all linear. It is not. It is highly non-linear. Plus you are assuming a climate that is very sensitive which the observations are not showing. You believe the 2-3 times amplification of any forcing.

[blizzard1024]

I try to provide a link to complete papers when such papers are available. Unfortunately, some papers are not publicly available without a subscription or payment.

 

I read this paper. My problems are this  1) the trends in the 6.7 micron water vapor data are very uncertain and to claim it has not changed between 1979-2005 is highly uncertain. This makes the idea that increased water vapor content due to the increased temperatures at these levels (due to higher emission) suspect.   2) my bigger problem is that they assume their climate model is a replication of our climate so much that they can attribute man-made forcings vs natural forcings. But definitively thought provoking. Thanks for posting.

[chubbs]

Your assuming this is all linear. It is not. It is highly non-linear. Plus you are assuming a climate that is very sensitive which the observations are not showing. You believe the 2-3 times amplification of any forcing.

 

I am going by what I read in the scientific literature. You are the one going by "beliefs" and "assumptions" that are well outside established science. The 1979 Charney report (link below) described the scientific basis for a 2 to 3.5C sensitivity including water vapor feedback. It is all cut and dried and worked over many times since then. Spencer and Lindzen had a go at changing the consensus but were not successful. There is currently no scientific controversy about water vapor feedback.

 

I am not assuming the climate is sensitive. The data is showing it. The temperature rise since 1970 of roughly 0.8C  is completely consistent with an ECS of 3C. I have looked at the temperature and forcing data and it all lines up well with expectations. Furthermore we know from the recent ice ages that the earth is sensitive to changes in forcing since the orbital shifts that triggered the ice ages have a relatively small effect on solar forcing. Those ice ages would not have occurred without feedbacks amplifying the forcing.

 

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiIjc2go5TLAhXLPB4KHfoFDNoQFggdMAA&url=http%3A%2F%2Fweb.atmos.ucla.edu%2F~brianpm%2Fdownload%2Fcharney_report.pdf&usg=AFQjCNGSCVukTIyPRhEoN4QOuZo3-n6bpQ&cad=rja

[Msalgado]

The upper troposphere water vapor concentration is dominated by tropical convective processes and deep vertical motions by extratropical cyclones. The planetary boundary layer with its diurnal mixing will see increased water vapor through evaporation when temperatures increase. This moisture then either remains in the boundary layer( when there is no precipitation or clouds) or gets transported upward by precipitation processes. If precipitation increases globally either from convection or extratropical cyclones this actually is a sink of the water vapor at mid to high altitudes. Hence increasing precipitation is a sink of the primary GHG. Therefore you cannot assert that upper tropospheric water vapor increases when surface evaporation does. But during strong el ninos there is more tropical convection so in the very short term there could be increases in water vapor high up but this is temporary and will drop once the el nino switches to la nina.  Some of Desslers work from Texas A and M shows this. But he mis-interpretes this change in ENSO phase as a positive water vapor feedback since it is warm during el ninos and cool during la ninas.

 

First of all none of what you said addressed my point.  The column measurements of TPW are an indication upper tropospheric water vapor increases.  Secondly, yes, precipitation is the sink.  However, by raising the temperature of the atmosphere, you decrease the efficiency of precipitation in removing the water vapor.  That's the point of it becoming a feedback mechanism.  Also you seem to be having difficulty in understanding what a feedback is.  The fact that outside forcing is needed to increase the temperature and thus the TPW amounts does not mean that the water isn't providing additional heating.  That is by definition what a feedback is.

[Msalgado]

Also, I'd love to see an explanation for the documented increase (net) globally of precipitation that doesn't involve increases in water vapor in the atmosphere.

[blizzard1024]

First of all none of what you said addressed my point.  The column measurements of TPW are an indication upper tropospheric water vapor increases.  Secondly, yes, precipitation is the sink.  However, by raising the temperature of the atmosphere, you decrease the efficiency of precipitation in removing the water vapor.  That's the point of it becoming a feedback mechanism.  Also you seem to be having difficulty in understanding what a feedback is.  The fact that outside forcing is needed to increase the temperature and thus the TPW amounts does not mean that the water isn't providing additional heating.  That is by definition what a feedback is.

 

 

TPW is water vapor in the entire column which is heavily weighted in the lower troposphere. There is much less water vapor in the upper troposphere and that is why changes in water vapor here can have a significant influence on radiative balance.  You seem to be totally confused...   "However, by raising the temperature of the atmosphere, you decrease the efficiency of precipitation in removing the water vapor.  That's the point of it becoming a feedback mechanism."   Please explain this. Raising the temperature has little to do with precipitation efficiency as far as I know. Its how much CCN you have etc....and vertical motion.

[Msalgado]

TPW is water vapor in the entire column which is heavily weighted in the lower troposphere. There is much less water vapor in the upper troposphere and that is why changes in water vapor here can have a significant influence on radiative balance.  You seem to be totally confused...   "However, by raising the temperature of the atmosphere, you decrease the efficiency of precipitation in removing the water vapor.  That's the point of it becoming a feedback mechanism."   Please explain this. Raising the temperature has little to do with precipitation efficiency as far as I know. Its how much CCN you have etc....and vertical motion.

 

I understand what TPW is.  I am not disputing that there is more water in the lower troposphere.  I am disputing your claim that this somehow means that upper tropospheric water isn't increasing along with lower tropospheric water.  Your claim is that the increase in TPW is entirely at the lower levels which is simply wrong.

 

As for the second portion, when you have the same amount of water in the air, lets say a dewpoint of 70, is it easier to get a parcel that is at 75 or at 100 to the dewpoint?  Obviously the higher temp.  This leads to a higher vapor pressure deficit which leads to more evaporation which increases TPW.  Yes, most of this water remains in the lower troposphere but you do increase precipitation which results in more water in the upper troposphere.  This it where it feedsback.  

 

Hotter temps cause more evaporation because precipitation will not be achieved as easily.  Thus, the sink operates at a lower efficiency when the temperatures go up.

[blizzard1024]

I understand what TPW is.  I am not disputing that there is more water in the lower troposphere.  I am disputing your claim that this somehow means that upper tropospheric water isn't increasing along with lower tropospheric water.  Your claim is that the increase in TPW is entirely at the lower levels which is simply wrong.

 

As for the second portion, when you have the same amount of water in the air, lets say a dewpoint of 70, is it easier to get a parcel that is at 75 or at 100 to the dewpoint?  Obviously the higher temp.  This leads to a higher vapor pressure deficit which leads to more evaporation which increases TPW.  Yes, most of this water remains in the lower troposphere but you do increase precipitation which results in more water in the upper troposphere.  This it where it feedsback.  

 

Hotter temps cause more evaporation because precipitation will not be achieved as easily.  Thus, the sink operates at a lower efficiency when the temperatures go up.

Good discussion. Let me help you here. Ok let's say dewpoints increase from 75 to 100F from warmer temperatures by some process. This is extreme but it will work for the sake of argument. The instability would go through the roof probably approach 10K J/KG of CAPE and likely there would be a massive convective storm. There would be incredible upward motion extreme rain/hail etc and transport of water vapor to the upper troposphere. However...... There would be massive compensating subsidence and drying around the storm which dries the upper troposphere. Plus if the precipitation efficiency is high (depends on the size, and number of cloud condensation nuceli) but given there are loads of CCN around it likely would be very high, you would suck out a lot of water vapor especially in the mid to upper troposphere. You can't assume that when water vapor increases in the lower troposphere that it does higher up. That's where the science is not settled. There's plenty of evidence from peer reviewed research that suggests there is slight drying up there. But even these studies along with the ones that say water vapor is increasing in the upper troposphere are uncertain.  

[Msalgado]

Subsidence does not remove water from the atmosphere.  The drying you are mentioning is simply the lowering of RH as a parcel underoging subsidence is warms adiabatically.  That does nothing to the total water content of the parcel.  I'm aware of papers that have tried to claim this is the dominant factor in the UT, but the majority do not and those that do I do not buy due to mass conservation.  You can't just wish the added water vapor away through subsidence.

 

In any event, the trend in UT WV is positive over decades of measurement which coincides with the increase in precipitation at the surface.  Your argument doesn't make physical sense and isn't back up by observations.  

[blizzard1024]

Subsidence does not remove water from the atmosphere.  The drying you are mentioning is simply the lowering of RH as a parcel underoging subsidence is warms adiabatically.  That does nothing to the total water content of the parcel.  I'm aware of papers that have tried to claim this is the dominant factor in the UT, but the majority do not and those that do I do not buy due to mass conservation.  You can't just wish the added water vapor away through subsidence.

 

In any event, the trend in UT WV is positive over decades of measurement which coincides with the increase in precipitation at the surface.  Your argument doesn't make physical sense and isn't back up by observations.  

 

High precipitation efficiency removes water vapor. Radiosonde observations actually show drying in the UT. But this has been disregarded because it is hard to measure water vapor at these altitudes. The satellite retrievals are rife with uncertainties. You are correct. The subsidence just evaporates the liquid water drops to water vapor. But we know little about precipitation efficiency and there is evidence of heavier rain events with warming. Plus higher low-level water vapor could lead to more low cloud cover and increase albedo. The complexities are vast.

[salbers]

This topic has a thorough coverage in this paper: http://www.pnas.org/content/111/32/11636.full.pdf

 

For example, they remind us that the 6.7 micron wavelength can be sensed by satellites to examine upper tropospheric water vapor.

[arationofreason]

Let us address feedback of any kind, positive water vapor feedback and the impossibility of feedbacks in a climate system limited by its energy, the sun.

 

The 1/(1-f )equation which is too often quoted for both positive and negative feedback aficionados does not apply to to the climate system.  It applies to a an electronic amplifier with an independent , well regulated power supply to provide power which the amplifier with its feedback is controlling.

The climate system when discussing the effect of adding CO2 to the atmosphere bears little relationship to a feedback amplifier.  First there is no well regulated power source.  The power is supplied by the sun and in this limited case is a constant.  The power source thus is analogous to a circuit with a limited power available having an internal impedance, unregulated source, of energy which is determined by the surface characteristics mainly of the ocean and the wind/wave modulation  of the thermal impedance of its surface/atmosphere interface.  Any atmospheric effect (lower temperature) which would allow more energy(mostly in the form of water vapor) to flow from the surface will lower the temperature of the surface because of its thermal impedance and thus has a self limiting (negative feedback) energy source.  The vague concept of additional water vapor increase in the boundary layer intercepting more IR and re radiating it to the surface to cause more evaporation is a non-starter.  Anything which raises the surface layer temperature of the atmosphere reduces the temperature gradient and thus limits(negative feedback again) the flow energy from the source, the surface volume. Stated more fundamentally; the source of energy is the surface volume , there is no source of energy in the atmosphere to evaporate more water vapor, the source of energy is the surface itself. any energy in the atmosphere must come from the surface itself.  It would be equivalent to a high impedance power source driving energy into a restrictive load and thinking the increase in voltage appearing in the load would some how extract more current from the source which is already limited by the current which it can drive into the load by its own impedance and the impedance of the load.

 

Is there any CO2 greenhouse effect?  The latest (4th) conjecture put forth by the IPCC consists of doubling the thickness of the CO2 blanket which causes the final radiation of the cO2 spectrum to be emitted into space from a higher altitude.  If this occurs in the 6.5C/km lapse rate portion of the atmosphere, it would radiate less power and force the earth atmosphere and therefore the surface temperature to rise.  (I keep looking and would like to find a study which shows that the radiation altitude change takes place in the troposphere ie the atmospheric temperature lapse rate rather than the tropopause..or even above in the stratosphere) The following discusses the effect on the earth climate if this conjecture is correct.

 

 

Exploring the IPCC  AR-5 CO2  Greenhouse (Yes Virginia, there may be a greenhouse effect)

 

Introduction

 

Theme:

Doubling CO2 which may have an IR blanketing effect on the upper atmosphere adds no energy to the earth system and therefore will cause essentially no change in the shape and function of the natural random chaotic atmosphere in balancing a constant solar energy input with the IR radiative output to space.

 

Assuming the latest 'greenhouse' conjecture put forth by the IPCC specifically; that the increase altitude at which the CO2 portion of the IR spectrum is colder than before the CO2 doubling is valid;

An AGW thought experiment is proposed to investigate the climate effect of doubling atmospheric CO2 in a century:

It must be a thought experiment which isolates the change in CO2 and holds all energy inputs constant since we cannot control for all of the unknown variables which confound our attempts at verification measurements and attributing measured temperature changes such as:

 

"The problem with AGW  is that climate models have to deal with many more variables than weather models. They have to model all of the variables that weather models contain including for instance Solar activity including  cosmic ray cloud effects, orbital effects and minor changes in radiation intensity, plus: (for instance)

• Land biology

• Sea biology

• Ocean currents

• Ground freezing and thawing

• Changes in sea ice extent and area

• Aerosol changes

• Changes in solar intensity

• Average volcanic effects

• Snow accumulation, area, melt, and sublimation

• Effect of melt water pooling on ice

• Freezing and thawing of lakes

• Changes in oceanic salinity

• Changes in ice cap and glacier thickness and extent

• Changes in atmospheric trace gases

• Variations in soil moisture

• Alterations in land use/land cover

• Interactions between all of the above

• Mechanisms which tend to maximise the sum of work and entropy according to the Constructal Law."

 

However we can devise a simple thought experiment which holds all other ill-defined  as well as unknown energy modulation variables constant to evaluate the effect of the CO2 input variable on an otherwise constant earth energy climate model.

 

CO2 Greenhouse:

In this reference the IPCC Figure SPM5.1 as well as others published by the IPCC AR-5 WG-1 attributes a reduction of  1.85 watts/m2 IR radiation to space due to a doubling of the CO2 blanket thickness at the top of the troposphere.  Although there may be reasonable arguments about where exactly in altitude and temperature lapse rate curve some or all of the CO2 spectrum is effectively radiating, assume for purposes of this discussion that  100% of this conjecture is true . It therefore represents the maximum CO2 "greenhouse"  quoted from the latest effect calculated by NASA .

 

A Constant input Power Model:

How does the climate respond to the conjecture of this blanket effect of CO2 doubling at the top of the troposphere where it will radiate 1.85 watts/m2 less IR to space from the edges of the 15 u band?   Obviously the earth must heat up to provide a temperature increase in the water vapor to increase its radiation by this amount to drive the earth energy toward a steady state average balance. While the driving force is the increase in CO2 of 1%/year, the earth  will always respond to catch up with a required atmospheric temperature increase, otherwise the earth's  mass temperature would continue to rise without any compensating  energy balance in radiation to space.  A warming scenario based on the steady state solution is described here.

 

The earth has dealt with much larger transient inputs to the system including changes in power input and has managed to provide the earth with incredible climate stability (particularly upper average temperature) for hundreds of thousands of years.

 

Paradigm shift:  To isolate the CO2 GH effect from all other variables, remembering the Law of Conservation of Energy, in this scenario nature has no additional or reduced energy to work with and thus will continue with the hydrologic solution which has evolved over the millennia to balance the constant solar power by  shifting the missing CO2 GH radiation over to a compensating increase in water vapor radiation.

 

Model approach:

Since CO2 increase adds no additional energy to the system:

Our challenge is to understand how the climate will adjust to the absolute energy balance requirement.  Calculating changes in conduction, convection and radiation in the random chaotic atmosphere have proven to be more challenging than we can ever hope to address with our limited computing power not to mention limited understanding of the detailed spatial and temporal physics of cloud formation in the hydrologic cycle.  Perhaps the correct approach is to let the natural system recalculate and rebalance as it has done for millennia  and observe the result.

   As the CO2 accumulates blocking the  calculated reduction in IR spectrum ~20 milliwatts/m2 each year over the coming century, the earth will accumulate this energy raising its surface temperature  and the surface strata atmosphere temperature by dT/year . Thus the atmospheric water vapor will increase its radiation an average 20 milliwatts/m2 each year to the some 220 watts/m2 which it is already radiating to space along with some 20 watt/m2 through the "IR window".

 

 Since in this experiment the solar input to the earth including cloud effects, volcanos and all other energy inputs (some of which are listed in the introduction) to the earth are held constant to allow us to concentrate on the effect of CO2  'forcing' alone,  the energy flux into the earth and from the surface to the atmosphere is thus constant. This requires that the average surface/atmosphere temperature gradient is constant and unchanged as required by a constant energy flux albeit at an increasing temperature of both surface and atmosphere of dT/year.  Most of this energy transfer remains the constant evaporation rate of water containing its latent heat of vaporization.   The surface radiation which remains constant through the constant surface/atmospheric strata temperature gradient  continues to be captured at the same constant rate and immediately thermalized by the GH gasses.    The atmosphere temperature lapse rate curve moves 'to the right ' by dT each year along with the surface temperature increase so that by the end of the century it will be displaced by 100dT higher temperature thus  the constant water vapor pressure will radiate an additional ~1.85 watts/m2 to space.

 

Climate physics:

  Since the lapse rate is constant, the cloud behavior, constant water content, vertical temperature profile, energy release and conformation need not change and indeed will have no additional energy(water vapor) input to do so.  Since its condensation level is a function of temperature, clouds will start at an average altitude increasing by dz=dT/6.5C/km each year so that by the end of the century the clouds need not change in form, size. extent, temperature or temperature gradient  but be 100dz=100dT/6.5C/km higher occupying exactly the same temperature gradient as before the 100 dT shift in atmospheric temperature started.  Since the clouds have no  change in energy or in temperature gradient they will radiate IR in exactly the same fashion but into an atmosphere which has a reduced water vapor pressure(increased altitude) and so radiate upward more efficiently.  The clear atmosphere water vapor will have exactly the same water vapor pressure gradient as before but each year will radiate at a temperature dT higher throughout all altitudes.  In other words nothing need be changed except the altitude of the clouds which have exactly the same temperature profile and conformation as before except at an increased altitude dz.   We see that the natural atmosphere solution (that we have described as random chaotic) which nature has developed over the millennia to maintain energy balance will require no  change except that cloud height will rise by dz each year to maintain their vertical temperature profile and that clear air fixed water vapor pressure will be radiating at an increased temperature, dT each year.

 

For illustration; some calculation of the average energy flow and temperature changes of a one dimensional average temperature and radiation model is shown.

 

A very minor energy balance adjustment;

Since the surface temperature will increase by 100dT by the end of the century, the radiation through the IR window will increase thus requiring slightly less (~1%) water vapor energy radiation thus reducing the overall atmospheric temperature increase requirement to slightly less than that  described below.

 

Temperature increase;

Raising a 255K black body(which seems to be favored by NASA) by 100dT= .5K will increase the radiation to space calculated from the Stephen-Boltzmann radiation equation by 1.886 watt/m2 which will suffice to balance the CO2 IR spectral reduction due to the CO2 blanket at the end of the century .

Thus the 20 milliwatts/m2 yearly increase in water vapor radiation will require an increase of dT=5 millideg C/year * for a century to balance the CO2 blanket accumulation over the century. (* Yes, we know that dT is a 4th root function of power  but at these small increments to the base temperature of 255K  it  is within ~5% of linear and matters little in understanding the big picture)

 

Change in nominal cloud base (and top) altitude is; dz=.005/6.5 = .77 m/year or 100dz= 77 m/century.

To state the obvious, the earth  need not employ any new different or complex physics (indeed, considering CO2 increase alone) there is no increase or change in energy flux (vaporization rate) available to power any change).  The earth and atmosphere temperature will increase by the required 0.5K over the century to shift the required 1.85 watts/m2 missing from the CO2 blanket to the water vapor radiation budget.

 

Stating the law of conservation of energy in this context:

Again stating the obvious; (although the back radiation/positive water vapor feedback is disproven physics) for those who  choose to retain this paradigm in their thinking,  there is no additional energy flow (constant gradient) therefore no additional water vaporization  and thus whatever the present day situation re. water vaporization/radiation is, there can be no change,  whatever one might believe re. water vapor/radiation feedback there is no additional power to drive an increase in such a  'loop'.

Any tendency to raise the  surface strata temperature  above(below) normal would reduce (increase) the temperature gradient thus limit any change in energy flow(most importantly WV).   With a constant energy flow available this is a self-limiting and unchanged constant average surface strata gradient at the new nominal steady state average earth  surface and atmospheric temperature of 288 +.5 K. (15.5C) and average atmospheric radiation temperature of 255+.5K.

 

If any of you remain inspired for whatever reason to continue with your avocation to study  the  random chaotic climate physics, all I can say is join the rest of the fleas on this elephant's hind leg and keep your eye on the prize, everyone needs a goal in life.