BTW, Demonstrable AGW = 0. Again.

[choff]

The proponents lie.

Yeah the global conspiracy of hundreds of scientists. Makes total sense that...
Same problem as all the big conspiracy theories like the moonlanding or the twin tower theories. Too many people would have to be involved.

There is no global conspiracy, never has been. There are political agendas being followed and those agenda's control the grant money for the scientists involved. Funding a study to "disprove AGW" would be met with harsh criticism prior to the study even starting, anyone who was hired to conduct the study would find their careers torpedoed no matter what happened. No conspiracy just politics infecting science.

Also what needs to be understood is that climatology is not a "hard" science. It's just theoretical experimentation with statistical models of various data sets. Pick the right data and model combination and you can "predict" the Earth entering an ice age, use a different model and data set and the Earth explodes into Venus like atmospheres.

Added to the above issue is that body is generating their own data, it's all done via proxy. Their taking data from other scientific studies, modifying them (this is the biggest source of issues, undocumented modification) then creating a model that takes your data creates the results you want. Do this over and over again until you can put it on a big board with an arrow spiking up showing the world exploding into a fireball, unless people do what you say.

I have no doubt the earth's temperature is rising, it has risen and fallen for the better part of the last billion years. My issue is the role CO2 has with the atmosphere, CO2 levels have been several times higher then they are now, and the earth didn't explode into Venus. That fact alone disproves most of the AGW theory, if the Earth's had higher temperatures and higher concentrations of CO2 in the past and didn't explode into a fireball, then us having higher temperatures and higher CO2 now will not cause it to explode into a fireball. The most we're doing is shifting the weather patterns in the atmosphere by altering water vapor levels (the real controller of our climate). It has been experimentally proven that higher amounts of water vapor in the atmosphere reduce total solar energy input due to high atmospheric cloud formations reflecting back solar energy before it gets trapped under the water vapor.

The climate system on this planet has been self regulating for the past billion+ years, the rise of the animal species known as homo sapien in the last 50 thousand years will not alter that fact. Our industrial history is a little over 200 years, ~300 if your counting renaissance. That is incredibly, stupidly small on a global scale. That is what makes most of the AGW proponents claims absurd. Their saying the planets billion+ year old self regulating system is somehow vulnerable and fragile and that the smallest increase in CO2 is breaking it.

International finance wants to sell you carbon credits and create a global carbon based currency, and god help any credible person that says its nonsense. Global warming is real because that golden rule said so, and whoever owns the gold makes the rules. They've taken a harmless gas measured in parts per million, essential for plant life and food production that humans account for 1% of and told us its bad. This is mass mind control perfected, well done Tavistock.

[tomclarke]

International finance wants to sell you carbon credits and create a global carbon based currency, and god help any credible person that says its nonsense. Global warming is real because that golden rule said so, and whoever owns the gold makes the rules. They've taken a harmless gas measured in parts per million, essential for plant life and food production that humans account for 1% of and told us its bad. This is mass mind control perfected, well done Tavistock.

Emotive, but it does not address the science. It is I agree easy to feel that AGW does not really exist because the fuss is politically engineered. But logically, whatever the politics, the science should be judged on science.

Everyone can then decide for themselves what to do about it.

[Diogenes]

You seem as if you are right on the edge of grasping my point.

You grant that H20 diffusion increases with heat. You grant that H20 is a far better absorber of IR and other radiation, ala the "greenhouse effect." You grant that these two things together constitute a positive feedback effect which according to the theory ought to result in an ever increasing temperature.

OK - this is your misunderstanding. Positive feedbacks do not result in ever-increasing temperature unless they are so large as to make the system unstable.

How do you figure that positive feedbacks do not result in ever increasing temperature? My understanding is that a positive feedback will cause a temperature increase until it is offset by some effect which will halt or neutralize it.

Basically there is a stabilising negative feedback from the black body radiation out, which increases as temperature increases.

If other effects are held stable, sure. An Increase in temperature would result in increased radiation, but I think you are oversimplifying by modeling the system as a black body with a fixed radiation emission. I think the system also varies in volume due to the atmosphere increasing in size with temperature.

As long as total other feedback is less positive than this is negative the system will be stable, but with forcing inputs effectively amplified. I'll give you the math if you need it, it is simple.

Math is a great thing, but when you don't put in all the variables, your equation will be incomplete. That is what I think is happening with your's, and other's models. For example, water both absorbs and emits radiation in the spectrum as outlined by the chart I posted up thread, but I believe this chart is for molecular water. I do not believe this chart accurately represents the reflection characteristics of water in droplet form. (in air) I believe water in droplet form will reflect all spectra (to some extent) which possesses a wavelength shorter than double the diameter of the water droplet size.

I believe this characteristic makes water far more reflective than is it's ordinary absorption spectrum. Does your model take this phenomena into account?

Show me your math. I think some of your assumptions regarding forcings and feedbacks are not accurate.

Where I don't think you are following is in the area of what's stopping the positive feedback from creating a runaway greenhouse effect. Water vapor flips from a positive feedback effect, and it BECOMES a negative feedback effect. Rather than continuously increasing the temperature via absorption, it actually reduces temperature via reflection.

All these effects, feedbacks and forcings, are for small peturbations approximately linear.

How can you say that the reflectivity of water is a SMALL perturbation? Is there a larger effect, other than perhaps the Sun itself? I would like to see you produce a list of effects ordered from the largest in magnitude down to barely significant.

As above, a stable surface temperature results from forcings + feedbacks as long as the total feedbacks (including BB radiation - the big one) are negative. Adding a positive H2O feedback to the mix then amplifies the effect of forcings without leading to instability.

But it is my contention that Water flips from being a positive feedback effect, into a NEGATIVE feedback effect, because it forms clouds high in the sky that reflect a significant portion of radiation before it gets an opportunity to warm the atmosphere and the ground beneath the clouds.

Diffusion increases with temperature, and until clouds form, the diffusion and temperature produce a positive feedback effect which eventually becomes offset by the NEGATIVE effect created by denser cloud cover. At some point, the constant diffusion of water into the air results in a balance between heat absorption and radiation reflection. The system attains equilibrium because the opposing forces of positive and negative feedback cancel each other out.

Water is the dominate effect.

For larger changes the system will indeed have many nonlinear effects which come into play. But this is a second-order effect.

Negative feedback can achieve a pseudo stability even with non-linear systems. They may tend to oscillate more, but they will oscillate around an attractor.

My argument is that the system is self regulating, and the dominate component of this regulation is the ability of water vapor to reflect radiation away from the planet. It's reserve ability to accomplish this is so great as to make all other factors trivial and irrelevant. No plausible amount of CO2 or Methane can possibly overcome water vapor's ability to compensate for it.

I can do the maths to show you. Quantitatively the overall greenhouse effect is roughly 50% - the surface radiation is approx 390W/m^2 - the BB radiation to space is approx 237W/m^2. Of this 153W/m^2 greenhouse effect H2O contributes roughly 95 and CO2 roughly 50.

I have no doubt that you can produce an equation that yields a result of some sort. I have doubts that your equations accurately represents the system which you are trying to model with them.

What number are you using for surface area? Did you consider that the radiating area of the atmosphere changes with temperature, and that it is not a constant?

Where do you get your numbers for H2O, and where do you get your numbers for C02? I think water in droplet form emits more than it does in molecular form because it creates trillions of parabolic reflectors which are structures that ought to reflect (to some degree) every wavelength within a range of double the droplet size.

This paper appears to support that contention.

These are total figures. We then consider how the figures change if for example CO2 doubles and therefore forcing is 1.5W/m^2, and methane increases by more than 2 for a forcing of 0,5W/m^2 (this is the current increase in GH effect over pre-industrial times- that 50 becomes 52). That will increase temperature and as a result the H2O GH contribution will also increase (say by roughly 2W/m^2 for example). The total forcing of 4W/m^2 is then balanced by BB radiation feedback of -5.5W/Km^2 to give total surface temp increase of roughly 0.8K instead of the 0.25K expected from CO2 forcing alone.

The negative feedback capabilities of water vapor are simply too large to be seriously impacted by any other gas. Water vapor has too much leverage over any other effect. They (other gases) are as to a mosquito trying to hold back an automobile.

You can see from the maths and figures that the mosquito does have a significant effect. If you diagree with the ballpark figures here we can go through the emmission characteristics at different frequencies and CO2/H2O absorption, and work out from first principles for a single atmospheric layer, then integrate over many layers. I'm prepared to do this at a very coarse level of approximation.

Best wishes, Tom

Now that sounds like a much better way to start. I would like to see how you obtain your figures for H20 and C02 radiation, and why you think the figure for H20 will be a sort of constant. I think it will increase and decrease in relation with the quantity of H20 in the air.

[Diogenes]

The proponents lie.

Yeah the global conspiracy of hundreds of scientists. Makes total sense that....

Intellectual "phase lock" is not a "conspiracy." It is, and has always been, a consistent problem in the scientific community. Stop being an ass.

Same problem as all the big conspiracy theories like the moonlanding or the twin tower theories. Too many people would have to be involved.

In Science, as with Journalism, people all thinking alike can have the appearance of a "conspiracy" without actually being a conspiracy. They just all have the same faulty assumptions, and they act on them in a similar manner. They aren't all coordinating their efforts, they just all happen to individually think and act in a similar fashion.

Again, stop being an ass with all the "Conspiracy" crap. Research Grant Scientists are very much in favor of Government grants for research. It's a simple as that. (With the scientists. With the political movements, it's all about power. )

[Diogenes]

The proponents lie.

Yeah the global conspiracy of hundreds of scientists. Makes total sense that...
Same problem as all the big conspiracy theories like the moonlanding or the twin tower theories. Too many people would have to be involved.

There is no global conspiracy, never has been. There are political agendas being followed and those agenda's control the grant money for the scientists involved. Funding a study to "disprove AGW" would be met with harsh criticism prior to the study even starting, anyone who was hired to conduct the study would find their careers torpedoed no matter what happened. No conspiracy just politics infecting science.

Also what needs to be understood is that climatology is not a "hard" science. It's just theoretical experimentation with statistical models of various data sets. Pick the right data and model combination and you can "predict" the Earth entering an ice age, use a different model and data set and the Earth explodes into Venus like atmospheres.

Added to the above issue is that body is generating their own data, it's all done via proxy. Their taking data from other scientific studies, modifying them (this is the biggest source of issues, undocumented modification) then creating a model that takes your data creates the results you want. Do this over and over again until you can put it on a big board with an arrow spiking up showing the world exploding into a fireball, unless people do what you say.

I have no doubt the earth's temperature is rising, it has risen and fallen for the better part of the last billion years. My issue is the role CO2 has with the atmosphere, CO2 levels have been several times higher then they are now, and the earth didn't explode into Venus. That fact alone disproves most of the AGW theory, if the Earth's had higher temperatures and higher concentrations of CO2 in the past and didn't explode into a fireball, then us having higher temperatures and higher CO2 now will not cause it to explode into a fireball. The most we're doing is shifting the weather patterns in the atmosphere by altering water vapor levels (the real controller of our climate). It has been experimentally proven that higher amounts of water vapor in the atmosphere reduce total solar energy input due to high atmospheric cloud formations reflecting back solar energy before it gets trapped under the water vapor.

The climate system on this planet has been self regulating for the past billion+ years, the rise of the animal species known as homo sapien in the last 50 thousand years will not alter that fact. Our industrial history is a little over 200 years, ~300 if your counting renaissance. That is incredibly, stupidly small on a global scale. That is what makes most of the AGW proponents claims absurd. Their saying the planets billion+ year old self regulating system is somehow vulnerable and fragile and that the smallest increase in CO2 is breaking it.

This is the most intelligent and logical thing i've ever read from you. You get another notch.

[tomclarke]

You seem as if you are right on the edge of grasping my point.

You grant that H20 diffusion increases with heat. You grant that H20 is a far better absorber of IR and other radiation, ala the "greenhouse effect." You grant that these two things together constitute a positive feedback effect which according to the theory ought to result in an ever increasing temperature.

OK - this is your misunderstanding. Positive feedbacks do not result in ever-increasing temperature unless they are so large as to make the system unstable.

How do you figure that positive feedbacks do not result in ever increasing temperature? My understanding is that a positive feedback will cause a temperature increase until it is offset by some effect which will halt or neutralize it.

Stability, or lack of it is based on overall feedback.
"A positive feedback" does not mena the system as a whole has positive feedback. In this case the feedbacks on the earth surface temperature include a factor of:
-5.5 W/Km^2.
In other words, for every degree K rise in temperature, the power lost from black body radiation increases by 5.5W.

Suppose you have a positive feedback from H2O of 2W/Km^2 and a forcing of 1W/m^2 from CO2.

Without the H2O effect the 1W/m^2 would combine with the -5.5W/Km^2 to give 0.18C temp rise.

With the H2O effect the overall feedback is still negative, but only -3.2W/Km^2.

So the temp rise is now 0.3C, and increase (or amplification) of slightly more than 50%.

Basically there is a stabilising negative feedback from the black body radiation out, which increases as temperature increases.

If other effects are held stable, sure. An Increase in temperature would result in increased radiation, but I think you are oversimplifying by modeling the system as a black body with a fixed radiation emission. I think the system also varies in volume due to the atmosphere increasing in size with temperature.

I am vastly simplifying the system. But it would be strange indeed of energy lost from the earth to space did not go up with the earth temperature, whatever extra effects atmosphere adds. And indeed the climate modellers who have looked in detail at the effect of atmosphere find that the result is not that different from black body radiation, however the temperature is a bit lower than the surface temp.

As long as total other feedback is less positive than this is negative the system will be stable, but with forcing inputs effectively amplified. I'll give you the math if you need it, it is simple.

Math is a great thing, but when you don't put in all the variables, your equation will be incomplete. That is what I think is happening with your's, and other's models. For example, water both absorbs and emits radiation in the spectrum as outlined by the chart I posted up thread, but I believe this chart is for molecular water. I do not believe this chart accurately represents the reflection characteristics of water in droplet form. (in air) I believe water in droplet form will reflect all spectra (to some extent) which possesses a wavelength shorter than double the diameter of the water droplet size.

Indeed my approximation is very incomplete. That is why atmosphee radiation balance have much more complex models. Droplets in air => cloud and they include this. You are right that things are more complex with clouds, and whether the effect is heating or colling depends on the height of the cloud.

If you read the detailed work (now quite old) from climate modellers on the effects of cluds you will get the full messy equations.

I believe this characteristic makes water far more reflective than is it's ordinary absorption spectrum. Does your model take this phenomena into account?

My model does not, but people who do this can accurately model clouds. the difficult issue is to determine how temperature affects cloud cover. But for typical cloud cover the basic relationships hols, it is just a slight modification.

Show me your math. I think some of your assumptions regarding forcings and feedbacks are not accurate.

I'm not sure what you are asking for. The example above shows that a positive feedback can exist while the system as a whole stays stable. As for whether the overall feedbacks are negative well it is pretty clear that they are because we get small chnages in earth temperature not jumps. But to prove this you ned detaild quantitative values for all feedbacks, positive and negative.

I think I've answered your original reason for disbelieving the climate science - that you could not see how the system could remain stable with positive feedback from H2O?

But if you want me to write stuf down more formally as a heat balance equation I could?

Where I don't think you are following is in the area of what's stopping the positive feedback from creating a runaway greenhouse effect. Water vapor flips from a positive feedback effect, and it BECOMES a negative feedback effect. Rather than continuously increasing the temperature via absorption, it actually reduces temperature via reflection.

All these effects, feedbacks and forcings, are for small peturbations approximately linear.

How can you say that the reflectivity of water is a SMALL perturbation? Is there a larger effect, other than perhaps the Sun itself? I would like to see you produce a list of effects ordered from the largest in magnitude down to barely significant.

You are misunderstanding. The issue is that extra CO2 in atmosphere makes a small change to what would be the case without the (extra) CO2. This small change is a peturbation in the heat balance, to track it you can treat the whole system as linear, because the changes are small. (1K is small compared with 250K). The overall effects of H2O can be much larger than the change as the result of increased CO2.

As above, a stable surface temperature results from forcings + feedbacks as long as the total feedbacks (including BB radiation - the big one) are negative. Adding a positive H2O feedback to the mix then amplifies the effect of forcings without leading to instability.

But it is my contention that Water flips from being a positive feedback effect, into a NEGATIVE feedback effect, because it forms clouds high in the sky that reflect a significant portion of radiation before it gets an opportunity to warm the atmosphere and the ground beneath the clouds.

Diffusion increases with temperature, and until clouds form, the diffusion and temperature produce a positive feedback effect which eventually becomes offset by the NEGATIVE effect created by denser cloud cover. At some point, the constant diffusion of water into the air results in a balance between heat absorption and radiation reflection. The system attains equilibrium because the opposing forces of positive and negative feedback cancel each other out.

Water is the dominate effect.

It is arguable that change in cload formation could make the overall effect negative. But you need evidence. The evidence (go read the literature) is against you on this. Certainly whether clouds form at high or low altitudes is complex and as one type is positive the other negative whether cloud cover overall makes a positive or negative extra fedback is not going to be simple. However it can be possible to bound the overall effect (because we know what is max change in cloud cover over globe at differnet temps) even if all details are not known.

I'm afraid this is a "go read the literature" for more details.

For larger changes the system will indeed have many nonlinear effects which come into play. But this is a second-order effect.

Negative feedback can achieve a pseudo stability even with non-linear systems. They may tend to oscillate more, but they will oscillate around an attractor.

For small peturbations all systems look linear

My argument is that the system is self regulating, and the dominate component of this regulation is the ability of water vapor to reflect radiation away from the planet. It's reserve ability to accomplish this is so great as to make all other factors trivial and irrelevant. No plausible amount of CO2 or Methane can possibly overcome water vapor's ability to compensate for it.

I can do the maths to show you. Quantitatively the overall greenhouse effect is roughly 50% - the surface radiation is approx 390W/m^2 - the BB radiation to space is approx 237W/m^2. Of this 153W/m^2 greenhouse effect H2O contributes roughly 95 and CO2 roughly 50.

I have no doubt that you can produce an equation that yields a result of some sort. I have doubts that your equations accurately represents the system which you are trying to model with them.

What number are you using for surface area? Did you consider that the radiating area of the atmosphere changes with temperature, and that it is not a constant?

For BB radiation from earth I'm looking at other people's work. No doubt there is a correction for atmospheric expansion. But if so this cannor affect the overall negative sign of the BB radiation feedback.

Where do you get your numbers for H2O, and where do you get your numbers for C02?

I was giving exmplary numbers, I got them from an internet page somewhere.

I think water in droplet form emits more than it does in molecular form because it creates trillions of parabolic reflectors which are structures that ought to reflect (to some degree) every wavelength within a range of double the droplet size.

This paper appears to support that contention.

I think what you mean is that clouds are more opaque (for given thickness) than air. Also whereas air has absorption (and therefore re-emmission) that peaks in infra-red, clouds absorb visible light equally. So they would be less good at providing GH effect. But actualy this has been calculatd, and it epends on the type (and height) of the clouds.

This stuff is basic and has ben worked out in detail by many people. Unless they are all in conspiracy together I would trust the generally accepted ideas.

These are total figures. We then consider how the figures change if for example CO2 doubles and therefore forcing is 1.5W/m^2, and methane increases by more than 2 for a forcing of 0,5W/m^2 (this is the current increase in GH effect over pre-industrial times- that 50 becomes 52). That will increase temperature and as a result the H2O GH contribution will also increase (say by roughly 2W/m^2 for example). The total forcing of 4W/m^2 is then balanced by BB radiation feedback of -5.5W/Km^2 to give total surface temp increase of roughly 0.8K instead of the 0.25K expected from CO2 forcing alone.

The negative feedback capabilities of water vapor are simply too large to be seriously impacted by any other gas. Water vapor has too much leverage over any other effect. They (other gases) are as to a mosquito trying to hold back an automobile.

You can see from the maths and figures that the mosquito does have a significant effect. If you diagree with the ballpark figures here we can go through the emmission characteristics at different frequencies and CO2/H2O absorption, and work out from first principles for a single atmospheric layer, then integrate over many layers. I'm prepared to do this at a very coarse level of approximation.

Best wishes, Tom

Now that sounds like a much better way to start. I would like to see how you obtain your figures for H20 and C02 radiation, and why you think the figure for H20 will be a sort of constant. I think it will increase and decrease in relation with the quantity of H20 in the air.

Umm, I think I left out /K. So the overall feedback for H2O is a difference in heat loss that varies linearly with temperature (for small chnages in temp). As you say, this is because greater temp => more H2O vapour => more GH effect => less heat loss.

Overall this is modelled (in linear approx) as x W/Km^2

where x detemined the size and sign of x determines whether positive or negative.

[hanelyp]

There is no single theory of AGW to disprove. There are a whole load of different bits of evidence, from completly different areas of science,

There are a multitude of models, but it looks to me like they all involve CO2 as a greenhouse gas and H2O as a multiplier. Even dismissing that, the mutability of the broader concept makes it scientifically untestable.

Those are two elements in the equation which are demonstrably and absolutely true. They rest on physics, not complex models. But there are many other strands of evidence of course.

CO2 as a greenhouse gas is solid physics. H2O as a warming multiplier rests on untested assumptions and grossly simplified models about cloud formation. The other strands of evidence suffer from poor quality control, and evasion of independent review.

[tomclarke]

There are a multitude of models, but it looks to me like they all involve CO2 as a greenhouse gas and H2O as a multiplier. Even dismissing that, the mutability of the broader concept makes it scientifically untestable.

Those are two elements in the equation which are demonstrably and absolutely true. They rest on physics, not complex models. But there are many other strands of evidence of course.

CO2 as a greenhouse gas is solid physics. H2O as a warming multiplier rests on untested assumptions and grossly simplified models about cloud formation. The other strands of evidence suffer from poor quality control, and evasion of independent review.

Water vapour is clearly a feedback. The evidence it is positive is overwhelming, and does not depend on climate models.

See Dressler, here speaking less formally answering some skeptic arguments, but with more formal and detailed work quoted (some by him) to back up his arguments. I'll happily go through the details if you disagree. It will take some time.

These arguments do not depend on climate models, nor on data which is uncertain, and the magnitude of the direct H2O vapour feedback (2W/Km^2 if I remember right) is definite.

The "less clear" feedback is from clouds. But there is evidence that this is overall smaller in magnitude than water vapour, and no evidence that it is negative.

There is a smaller but certainly positive feedback from ice-albedo changes. Bio-feedbacks are very complex but again they are much smaller.

So, looking at the evidence overall (without GCMs) the evidence for positive feedbacks is pretty compelling. Its magnitude is unclear because there are some (smaller but not insignificant) feedbacks which are much more dificult to determine.

There are then three separate strands of evidence to tie down these uncertain feedbacks:

(1) Direct physical modelling. This can put some limits on the specific feedback.

(2) GCMs which attempt to determine otherwise unknown parameters by fitting to historic temperature data

(3) Partial climate models fitting to data from other direct physical models.

It is understandable that you are skeptical about the GCMs (2) because validation is so complex. But the information from (1) and (3) remains.

The science, when independently validated in the light of further independent analysis and newer data, turns out to be mostly right, as you would expect. I'll give you two examples:

(1) Mann's 1000 year temp reconstruction (Mann, Bradley & Hughes 1998). Ground-breaking work but still remarkably accurate in the light of modern reviews (Wahl & Amman 2007). Note that although (as might be expected) modern work is better informed and more accurate than Mann's original reconstruction the overall results are very similar. Look also at WA2007 to see that this remains true even if tendentious temperature proxies are removed.

(2) Land-station historic temperature data. The BEST project set up specifically to reinterpret data in an independent and more skeptical manner has broadly validated existing work.

Best wishes, Tom

[tomclarke]

I'll just sumarise the quantitative physical stuff:

(C) Forcing: X2 CO2 => 2W/m^2

Feedbacks:

(Fbb) BB radiation: -5.5W/Km^2 (stabilises system)

(Fv) H2O vapour: 2W/Km^2

(Fc) Cloud changes: small compared with 2W/Km^2, sign unclear

(Fi) Ice albedo change: small positive. (see Energy Balance Climate Models: A Reappraisal of Ice-Albedo Feedback Lian & Cess 1977 for some early work, or many many other studies).

(Fbio) Bio-feedbacks: small, sign unclear. (this is feedbacks due to albedo change, we don't consider CO2 balance).

Total feedback:
F = Fbb + Fv + Fc + Fi + Fbio

Total forcing:
C

temperature change as result of forcing:
C/F

Fv is dominant in the non-BB feedbacks and reduces overall feedback from -5.5W/m^2K to -3.5W/m^2K (ball park figures).

Considerable uncertainty in other feedbacks means this value could be in range -1.5 to -4.5 W/m^2K (ballpark figures)

That means the CO2 forcing could result in temp change in range:
1.3C - 0.4C (ball park figures)

the above is grossly approx and the figures are probably in detail wrong but it gives you some idea of how the stuff fits together, and where are the uncertainties.

[hanelyp]

Tom, with so many positive feedbacks, how is it that the climate hasn't slammed hard into disaster long before humans came along?

[palladin9479]

Tom, with so many positive feedbacks, how is it that the climate hasn't slammed hard into disaster long before humans came along?

That's the issue. If any of the current AGW "Global Warming" theory was correct, then this world would of exploded into a fireball atmosphere long before humans evolved and started walking upright.

Taking the proxy data from prior to the last ice age, put it into Mann's model and you know what you get ... fireball earth, even though history has proven there was an ice age.

The entire AGW theory is basically "I turn on my car, a cloud is formed that eventually starts a chain reaction that kills the world". The assumptions are so asinine that it's impossible to avoid the "fireball earth" scenario. Hence I can't take them seriously, especially when they use the phrase "the science is settled". I mean seriously ... everyone is in general agreement that it's impossible to accelerate faster then the speed of light, yet even now there are people attempting to discover if that's wrong. Science is built on the bricks of doubt and disagreement, no matter what the generally accepted rule is, there will be, should be, those willing to challenge that rule.

Otherwise we would of never got past Aristotle's "everyone is made up of four elements with different shapes" theory. Or "the earth is in the center of the universe and everything rotates around it".

[tomclarke]

Tom, with so many positive feedbacks, how is it that the climate hasn't slammed hard into disaster long before humans came along?

That's the issue. If any of the current AGW "Global Warming" theory was correct, then this world would of exploded into a fireball atmosphere long before humans evolved and started walking upright.

The two big feedbacks we know precisely, and that are large, are -5.5 & +2. This combines to make -3.5, and other feedbacks, whether positive or megative, are all smaller. So the system is still comfortably negative feedback overall.

Actually the -5.5. BB radiation feedback is not usually called a feedback. But it is, and it explains why the system is stable. I did not myself understand what was going on till I noticed its exixtence in the heat balance.

As for whether that has always been true in the part, I expect not - there have probably been times where feedbacks are all positive and sudden change happens. There have been a few extinction-level events where most life is wiped out, and such a sudden climate change would be a candidate. Remember that most of the feedbacks have limited total effect - for example once you have melted all that ice the feedback vanishes. So positive feedback regimes still do not mean frying, they just mean a temperature jump either up or down till the positives that create the jump have saturated.

Taking the proxy data from prior to the last ice age, put it into Mann's model and you know what you get ... fireball earth, even though history has proven there was an ice age.

The entire AGW theory is basically "I turn on my car, a cloud is formed that eventually starts a chain reaction that kills the world". The assumptions are so asinine that it's impossible to avoid the "fireball earth" scenario.

The above two paragraphs don't make sense to me. Care to elaborate? And state with refs what is "Mann's model" (which I've never heard of).

There is no question of overall positive feedback at the momnet - although you can't rule it out if you go on increasing CO2

Hence I can't take them seriously, especially when they use the phrase "the science is settled". I mean seriously ... everyone is in general agreement that it's impossible to accelerate faster then the speed of light, yet even now there are people attempting to discover if that's wrong. Science is built on the bricks of doubt and disagreement, no matter what the generally accepted rule is, there will be, should be, those willing to challenge that rule.

Otherwise we would of never got past Aristotle's "everyone is made up of four elements with different shapes" theory. Or "the earth is in the center of the universe and everything rotates around it".

Are you thinking that no-one in the scientific establishment is willing to challenge the consensus? The IPCC report details many different GCMs with different assumptions and very different resulting values for climate sensitivity. The issue is that on the internet there are a whole load of scientifically incompetent ideas around which are (I think for political reasons) promoted by Watts etc.

The "moderate skeptics" are part of the mainstream climate consensus. They are not scientifically incompetent, but then equally they don't argue with the overall conclusion that we have CO2 induced AGW, because the evidence for that is so large.

The problem (with perception) is that a lot of people don't read the science in detail and get their sense of what is hapenning from a few polemic web sites or articles in the popular press.

[seedload]

I tend to disagree with the conclusion that natural variability is only seen over long time scales. I don't think that has adequately been established.

It is a bit subtler than that. The reasons for variability are more or less all known.
biosphere changes
solar irradiance changes
changes in solar wind/GCR
volcanic/meterorite hit changes
earth orbital changes
ocean current changes

I see. So, what is the effect of "biosphere changes" quantitatively? My understanding is that the often quoted 33 degrees C of GHG warming is not an actual measure of GHGs contribution but rather a measure of the current balance between the pure radiative equilibrium case for GHGs which is about 60C and the effects of the biosphere (ie convection) which reduces this number to the order of 33C.

I think your point is that all reasons for energy balance changes are known and, other than GHGs, they are known to be small. But, unless my understanding is completely incorrect, I fail to see how an effect that cancels nearly half of the theoretical GHG contribution is insignificant. Nor do I see how there cannot be natural variability in this effect that accounts for relatively large historical (or current) variability in global temperature.

I don't think either of us can have a highly predictive intuition here...

....Human civilisation could only have developed in a phase where climate is relatively stable, which means positive feedbacks not too large compared with natural forcing changes.

Did you really follow dissing my intuition with trotting out intuition of your own:)

Regarding civilization needing a stable climate, I find it hard to accept that civilization needed climate more stable than that of today. So, I don't think you can use the fact that civilizations formed to make any claim about past stability as compared to today's stability. Natural variability on the order of the warming of the last hundred years would not have prohibited the formation of civilizations, IMHO.

Interestingly enough, stepping back a bit, it is extreme natural variability which nearly wiped us out and probably pushed our evolution towards adaptability in the first place. Africa of ~70K years ago had immensely variable climate with extremes of lush vs arid happening on time scales of several hundred years. That fact is probably here nor there with respect to variability since the last inter-glacial, but it is interesting.

[tomclarke]

I tend to disagree with the conclusion that natural variability is only seen over long time scales. I don't think that has adequately been established.

It is a bit subtler than that. The reasons for variability are more or less all known.
biosphere changes
solar irradiance changes
changes in solar wind/GCR
volcanic/meterorite hit changes
earth orbital changes
ocean current changes

I see. So, what is the effect of "biosphere changes" quantitatively? My understanding is that the often quoted 33 degrees C of GHG warming is not an actual measure of GHGs contribution but rather a measure of the current balance between the pure radiative equilibrium case for GHGs which is about 60C and the effects of the biosphere (ie convection) which reduces this number to the order of 33C.

This would be vegetation altering albedo, and vegetation type/extent changing with temp. Or possibly vegetation altering air/ground water equilibrium through transpiration. Small effects

I think your point is that all reasons for energy balance changes are known and, other than GHGs, they are known to be small. But, unless my understanding is completely incorrect, I fail to see how an effect that cancels nearly half of the theoretical GHG contribution is insignificant. Nor do I see how there cannot be natural variability in this effect that accounts for relatively large historical (or current) variability in global temperature.

The cancellation is from a known feedback - the direct effect of more H2O in atmosphere at higher temps. this has been studied in detail experimentally and theoretically. the two match. neither depends on dubious GCMs.

The large variability historically is due to other (known variable) forcing factors:
volcanic and man-made aerosols
solar irradiation chnages (sunspots + earth orbital changes)
ocean current/weather pattern changes (like el nino/la nina etc)

That does not affect feedbacks, but does affect temperature.

I don't think either of us can have a highly predictive intuition here...

....Human civilisation could only have developed in a phase where climate is relatively stable, which means positive feedbacks not too large compared with natural forcing changes.

Did you really follow dissing my intuition with trotting out intuition of your own:)

Regarding civilization needing a stable climate, I find it hard to accept that civilization needed climate more stable than that of today. So, I don't think you can use the fact that civilizations formed to make any claim about past stability as compared to today's stability. Natural variability on the order of the warming of the last hundred years would not have prohibited the formation of civilizations, IMHO.

I'm not claiming this. And you are understandably, since it is a common idea, misunderstanding my point. None of what I've said above requires past variability to be smaller than current variability. Think about it.

Interestingly enough, stepping back a bit, it is extreme natural variability which nearly wiped us out and probably pushed our evolution towards adaptability in the first place. Africa of ~70K years ago had immensely variable climate with extremes of lush vs arid happening on time scales of several hundred years. That fact is probably here nor there with respect to variability since the last inter-glacial, but it is interesting.

I agree. And We would no doubt manage +5C or whatever without destroying human race. It will however be quite extraordinarily expensive for our current technological civilisation. seaboard cities (including London which needs tidal barrage to stay dry at the moment) relocated. Agriculture changes everywhere. Low-lying island states disappear and presumably people have to be loacted elsewhere. Populous delta regions turn into sea, with people moving elsewhere, though perhaps this could be managed gradually rather than via catastrophic flooding.

Compare that with the costs of moving to low CO2 economy... But I am not actually argyuing that comparison, which I have not looked at and it is probably tendentious. I am arguing the basic AGW science, not the "what should we do" politics. It seems a lot of people just disbelieve the science for incorrect reasons.

[choff]

To say nothing of the extented growing season at northern lattitudes, whole regions opened up to agriculture not now viable. They never ran the orchards farther north in China than during the MWP.