Guest Post by Willis Eschenbach
My thanks to Nick Stokes and Joel Shore. In the comments to my post on the effects of atmospheric black carbon, Extremely Black Carbon, they brought up and we discussed the results of Ramanathan et al. (PDF, hereinafter R2008). Black carbon, aka fine soot, is an atmospheric pollutant that has been implicated in warming when it lands on snow. However, despite many claims to the contrary, atmospheric black carbon cools the surface rather than warming it.
There is an important implication in Ramanathan’s work regarding the canonical claim of AGW supporters that changes in surface temperature slavishly follow changes in forcing. Their claim is that the change in surface air temperature ( ∆T ) in degrees Celsius is a constant “lambda” ( λ ) called the “climate sensitivity” times the change in forcing ( ∆F ) in watts per square metre (W/m2). Or as an equation, the claim is that ∆T = λ ∆F, where lambda( λ ) is the climate sensitivity.
In R2008 they discuss the effect of black carbon (BC) on the atmosphere. Here’s the figure from R2008 that I want to talk about.
Figure 1. Figure 2C from R2008 ORIGINAL CAPTION: BC [black carbon] forcing obtained by running the Chung et al. analysis with and without BC. The forcing values are valid for the 2001–2003 period and have an uncertainty of ±50%. [Presumably 1 sigma uncertainty]
This figure shows the changes in forcing that R2008 says are occurring from black carbon forcing. Here is R2008’s comment on Figure 1, emphasis mine:
Unlike the greenhouse effect of CO2, which leads to a positive radiative forcing of the atmosphere and at the surface with moderate latitudinal gradients, black carbon has opposing effects of adding energy to the atmosphere and reducing it at the surface.
R2008 also says about black carbon (BC) that:
… as shown in Fig. 2, for BC, the surface forcing is negative whereas the TOA forcing is positive (Fig. 2c).
What are the mechanisms that lead to that re-partitioning of energy between the atmosphere and the surface?
Before I get to the mechanisms, I want to note something in passing. R2008 says that the forcing values have an uncertainty of ± 50%. That means the “Atmosphere” forcing is actually 2.6 ± 1.3 W/m2, and the “Surface” forcing is -1.7 ± 0.85 W/m2. This means that there is about a 30% chance that their “TOA” forcing, which is atmosphere plus surface, is actually less than zero … just sayin’, because Ramanathan didn’t mention that part. But for now, let’s use their figures.
PART I – What’s going on in Figure 1?
According to R2008, atmospheric black carbon causes the surface to cool and the atmosphere to warm. The surface is cooled by atmospheric black carbon through a couple of mechanisms. First, some of the sunlight headed for the surface is absorbed by the black carbon, so it doesn’t directly warm the surface. Second, any sunlight intercepted in the atmosphere does not have a greenhouse multiplier effect. Together, they say these effects cool the surface by -1.7 W/m2.
The atmosphere is warmed directly because it is intercepting more sunlight, with a net change of + 2.6 W/m2.
R2008 then notes that the net of the two forcings, 0.9 W/m2, is the change in the top-of-atmosphere (TOA) forcing.
The authors go on to say that because black carbon (BC) has opposite effects on the surface and atmosphere, the normal rules are suspended:
Because BC forcing results in a vertical redistribution of the solar forcing, a simple scaling of the forcing with the CO2 doubling climate sensitivity parameter may not be appropriate.
In other words, normally they would multiply forcing times sensitivity to give temperature change. In this case that would be 0.9 W/m2 times a sensitivity of 0.8 °C per W/m2 to give us an expected temperature rise of three-quarters of a degree. But they say we can’t do that here.
This exposes an underlying issue I want to point out. The current paradigm of climate is that the surface temperature is ruled by the forcing, so when the forcing goes up the surface temperature must, has to, is required, to go up as well. And vice versa. There is claimed to be a linear relationship between forcing and temperature.
Yet in this case, the TOA forcing is going up, but the surface forcing is going down. Why is that?
To describe that, let me use something I call the “greenhouse gain”. It is one way to measure the efficiency of the poorly-named “greenhouse” effect. In an electronic amplifier, the equivalent would be the gain between the input and output. For the greenhouse, the gain can be measured as the global average surface upwelling radiation (W/m2) divided by the global input, the average TOA incoming solar radiation (W/m2) after albedo. For the earth this is ~ 390W/m2 upwelling surface radiation, divided by the input of ~ 235 W/m2 after albedo, or about 1.66. That’s one way to measure the gain the surface of the earth is getting from the greenhouse effect.
Note that the surface temperature is exquisitely sensitive to the surface gain of the greenhouse effect. The gain is a measure of the efficiency of the entire greenhouse system. If the greenhouse gain goes down from 1.66 to 1.64, the surface radiation changes by ~ 4 W/m2 … on the order of the size of a doubling of CO2. Note also that the greenhouse gain depends in part on the albedo, since the 235W/m2 in the denominator is after albedo reflections.
Here is the core issue. For the “greenhouse” system to have its full effect, the sunlight absolutely must be absorbed by the surface. Only then does it get the surface temperature gain from the greenhouse, because some of the surface radiated energy is being returned to the surface. But if the solar energy is absorbed in the atmosphere, it doesn’t get that greenhouse gain.
So that is what is happening in Figure 1. The black carbon short-circuits the greenhouse effect, reducing the greenhouse thermal gain, and as a result, the atmosphere warms and the surface cools.
PART II – Almost Black Carbon
R2008 discusses the question of the 0.9 W/m2 of TOA forcing that is the net of the atmosphere warming and surface cooling. What I want to point out is that the 0.9 W/m2 of TOA forcing is not fixed. It depends on the exact qualities of the aerosol involved. Reflective aerosols, for example, cool both the atmosphere and the surface, by reflecting solar radiation back to space. Black carbon, on the other hand warms the atmosphere and cools the surface.
Consider a thought experiment. Suppose that instead of black carbon (BC), the atmosphere contained almost-black carbon (ABC). Almost-black carbon (ABC) is a fanciful substance which is identical to black carbon in every way except ABC reflects a bit more visible light. Perhaps ABC is what is now called “brown carbon”, maybe it’s some other aerosol that is slightly more reflective than black carbon.
As you might imagine, because almost-black carbon reflects some of the light that is absorbed by BC, the atmosphere doesn’t warm as much. The surface cooling is identical, but the almost black carbon reflects some of the energy instead of absorbing it as black carbon would do. As a result, let us say that conditions are such that ABC warms the atmosphere by 1.7 W/m2 and cools the surface by -1.7 W/m2. There is no physical reason that this could not be the case, as aerosols have a wide range of reflectivity.
And of course, at that point we have no change in the TOA radiation, but despite that the surface is cooling.
Which brings me at last to the point of this post. To remind everyone, the canonical equation says that the change in surface air temperature ( ∆T ) in degrees Celsius is some constant “lambda” ( λ ) times the change in TOA forcing ( ∆F ) in watts per square metre (W/m2). Or as an equation, ∆T = λ ∆F, where lambda( λ) is the climate sensitivity.
But in fact, all that has to happen to make that equation fall apart is for something to interfere with the greenhouse gain. If the efficiency of the greenhouse system is reduced in any one of a number of ways, by black carbon in the atmosphere or increase in cloud albedo or any other mechanism, the surface temperature goes down … REGARDLESS OF WHAT HAPPENS WITH TOA FORCING.
This means that the surface temperature is not simply a function of the TOA forcing, and this clearly falsifies the canonical equation.
In fact, I can think of several ways that surface temperature can be decoupled from forcing, and I’m sure there are more.
The first one is what we’ve just been discussing. If anything changes the greenhouse thermal gain up or down, the TOA radiation can stay unchanged while the surface radiation (and thus surface temperature) goes either up or down.
The second is that clouds can decrease the amount of incoming energy. It only takes a trivial change in the clouds to completely counterbalance a doubling of CO2. This is a major function of the tropical clouds, which counteract increasing forcing by forming both earlier and thicker.
The third is that the system can change the partitioning between the throughput and the turbulence. The throughput is the amount of energy that is simply transported from the equator to the poles and rejected back to space. On the other hand, the turbulence is the energy that ultimately goes into heating the climate system. In accordance with the Constructal Law, the system is constantly evolving to maximize the total of these two.
Fourth, the El Nino/La Nina system regulates the amount of cool ocean water that is brought to the surface, as well as increasing the heat loss, to avoid overheating. (One curious consequence of this is that the surface temperature in the El Nino 3.4 area has not warmed over the entire period of record … but I digress).
Part III – CONCLUSIONS
The conclusion is that the simplistic paradigm of a linear relationship between temperature and forcing can’t survive the observations of Ramanathan regarding black carbon. For the surface temperature to vary without changes in the TOA forcing, all that needs to happen is for the greenhouse thermal gain to change.
w.
APPENDIX- How it works out
For the math involved, let me steal a diagram from my post, “The Steel Greenhouse”
Figure 2. Single-shell (“two-layer”) greenhouse system, including various losses. S is the sun, E is the Earth, and G is the atmospheric greenhouse shell around the Earth. The height of the shell is greatly exaggerated; in reality the shell is so close to the Earth that they have about the same area, and thus the small difference in area can be neglected. Fig. 2(a) shows a perfect greenhouse. W is the total watts/m2 available to the greenhouse system after albedo. Fig. 2(b) is the same as Fig. 2(a) plus radiation losses Lr which pass through the atmosphere, and albedo losses ( L_albedo ), shown as W0-W. Fig. 2(c) is the same as Fig. 2(b), plus the effect of absorption losses La. Fig. 2(d) is the same as Fig. 2(c), plus the effect of thermal losses Lt. These thermal losses can be further subdivided into sensible ( L_sensible ) and latent heat ( L_latent ) losses (not shown).
We are interested in panel (d) at the lower right of Figure 2. It shows the energy balances.
As defined above, the thermal gain ( G ) of a greenhouse is the surface temperature (expressed as the equivalent blackbody radiation) divided by the incoming solar radiation after albedo. In terms of the various losses shown in Figure 2, this means that the greenhouse thermal gain G is therefore:
where
The important thing to note here is that if any of these losses change, the greenhouse gain changes. In turn, the surface temperature changes … and the TOA balance doesn’t have to change for that to happen.
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Willis Eschenbach says:
March 27, 2012 at 11:46 pm
…
On my planet, that shows that surface temperature and atmospheric temperatures are independent variables. Don’t know how it works on yours.
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Now you have successfully built up a strawman and beaten it to death.
Any argument can be proven wrong when put into a different scope. But I was talking about your statement on the paper which is about effects of black carbon, not about reflective aerosols. And in scope of forcing caused by black carbon particles, surface and atmospheric forcings are not independent variables.
Steve Richards says:
March 28, 2012 at 1:41 am
The discussion here between Willis Eschenbach and E.M.Smith proves the worth of WUWT.
I suspect many readers have learnt from this discourse.
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Well, I for one have learnt a great deal from these people who very clearly know an enormous amount about the physics of the Earth’s climate and are generous enough to post here on WUWT. They have my gratitude.
What about you Steve. Maybe you could show us some of your moves… ?
J -> energy
J/s = W -> energy flux or power
J/sm² = W/m² -> energy flux density or power density
For all the recent learned discussion of black, and almost black, soot I don’t seem to recall it being mentioned much until recently when we needed something else to explain away differences between observed and predicted or why we’re all going to die from global warming without it warming. So, where does one find the studies of the annual generation and deposition of black, almost black and any other kind of soot? And where does one find correlations between that and observed phenomena?
I’ve said it before — the effect of BC depends on where exactly it is. It warms the area where it is present, and cools any atmosphere (if any) below it by intercepting/absorbing sunlight from above. If it’s on the surface, it warms that & then by convection/conduction the air above it.
Obviously some falls out on the surface — that causes surface warming. Any in the air warms that air — either high up or right near the surface. So where is most of it?
I can’t say for sure, but working at a coal plant for yrs, I know a bit about BC. Typically the blackest BC flyash particles are the heaviest, and smaller, more completely burned ones are lighter both in weight and blackness. So my SWAG is that much or most of the blackest BC spends little time in the air & deposits on the ground fairly quickly. Lighter, grayer particles are more mobile, and the lightest (almost whitish) particles have the longest “air time”. I’d think that most BC from diesel vehicles reaches the ground very quickly.
So it seems like BC can cause both surface cooling and warming, depending on where exactly it is. What the final word on the subject is, I don’t know.
Thank you Willis, another black box illumined.
Willis, I find the article deeply disturbing, in part because I think upwelling/downwelling radiation models are virtually impossible to get right without solving a diffusion equation (which nobody does AFAICT), in part because the carbon discussion seems to ignore gross first order effects AND radiative diffusion in the greenhouse bands (where the height the atmospheric carbon absorbs sunlight matters), compounding the error.
For example, suppose the carbon particulates for some reason were concentrated near the tropopause — in that case atmospheric warming there would be radiated out preferentially and would block the surface, resulting in net cooling of both surface and atmosphere. Suppose they are a thick layer at the very bottom of the atmosphere. Now the atmospheric warming is in direct thermal contact with the ground and might well amplify the surface temperature and the atmosphere all the way to the tropopause. Suppose it is “uniformly” distributed in the atmosphere up to the tropopause. Now one gets a different result again, because now all of the atmosphere warms, with the top warming slightly more than the bottom and the ground differentially cools. Distribution matters, and particulates presumed large compared to an air molecule will not behave like a “gas” — they will probably exhibit a very distinct gravitational sorting with larger particles and greater density nearer to the ground.
Note well that anyone who has flown into a city has seen the soot from the many, fires below and it is by no means concentrated uniformly — it tends to form a thick layer somewhere in between ground and tropopause, often close to the level where clouds are trying to form. This is no coincidence, of course.
Particulates/aerosols also nucleate clouds out of saturated air, so the soot — depending again on particulate size and density — have a positive effect on albedo. Albedo takes a bit “off of the top” of TOA incoming radiation by reflecting it out. Even a tiny increase in albedo would a) increase the surface cooling and b) completely cancel the atmospheric warming because clouds have a much much higher albedo than transparent, cloud-free air with or without soot until the soot reaches the level of being “smog”, that nasty mix of soot and condensing moisture see note above.
Of course particulates smaller than a certain size (50 microns?) aren’t likely to stably nucleate water droplets and are more likely to be lofted and mixed more uniformly into the air. Soot that does nucleate a cloud (and for that matter, ambient soot too small to participate in the actual nucleation is often scrubbed out of the atmosphere in the ensuing rain. Remember there is an electrostatic force between soot particles of any size and a water droplet in a cloud, and once a particle is captured it doesn’t get out.
Soot is also produced in highly localized places and is nowhere near uniformly distributed in the atmosphere. Some of the places it is produced have a high average humidity, some don’t. The local air currents where it is produced vary, carrying one day to the North, the next to the Southwest, to rain out when it goes Northeast but to get carried far far away when it heads South. How high it gets, how the particulate sizes get sorted out in different atmospheric layers in different directions over different areas, depend in detail and highly nonlinear ways on the entire complex of “weather” — wind speed, direction, humidity, rainfall, cloud cover, temperature.
Finally, soot that deposits on ice or snow has a profound local warming effect on the surface, by directly decreasing the surface albedo, where almost anywhere else it is irrelevant. Furthermore, the warming effect is often delayed — at the heart of every snowflake is (often, usually) a tiny speck of dust or soot. Surrounded by ice, it absorbs little light and has a very small warming effect (the ice/snowflake is net neutral-to-cooling because of its high albedo whereever it falls). However, if snow ever starts to melt in bulk, the dust accumulates on the surface, greying the snow surface as it melts and reducing its albedo. The more snow that has melted, the greyer the surface, the faster the rest melts. Not only nonlinear, but non-Markovian (highly dependent on the recent thermal and precipitation history of the venue). Anybody who has lived in the cold north knows that in spring when the snow starts to seriously melt, it all gets “dirty” from the embedded particulate matter, which speeds up the melt.
The article alleges that “almost black carbon” nucleates clouds but “black carbon” does not so that one is (maybe) cooling and the other is (maybe) warming. It alleges that the monsoon is being affected by it negatively, and yet the figures of the article itself do not substantiate that — in Africa and China it is linked to more rainfall where it is produced, in North Africa the rainfall is reduced even though there is little black carbon produced there or present (suggesting that the cause has nothing to do with it), in India the monsoon is somewhat reduced and of course they produce a lot of soot. However, monsoon patterns in India have a lot more to do with global circulation patterns and a lot less to do with local atmospheric factors. The article does not address how BC can affect the former, because of course if it does nobody knows how.
The last irritating thing about the article is that it alleges that BC produced in the tropics has a profound effect on global average temperatures — based, of course, on its assertion that it doesn’t nucleate clouds while is sister ALMOST BC does so that albedo modulation can be ignored. It makes BC out to be “almost as important as CO_2” in its overall effect on AGW.
Wow, did they really say that? So CO_2 is responsible for only half of the observed global anomaly and the other half is soot? So that we could completely cancel the projected catastrophe from a doubling of CO_2 by eliminating the soot and leaving the CO_2? Oooo, I doubt that they meant to say that, however much they want their studies of soot to be funded and gain as much attention as Demon CO_2. We’re about to see the CAGW wars start where researchers compete for ever more scarce dollars on the basis of claims that what they are studying is a major factor (out of the ‘levnty zillion factors that contribute, usually in unknown ways).
In the end, the article simply shows once again that the problem is too complex for people to make egregious assertions. It speaks of how black carbon is supposedly responsible for a significant decrease in global albedo observed back in the 20th century. However, over the last 15 years global albedo (as measured and now confirmed by NASA experiments) has increased by 6% — enough to cause a roughly 2K drop in global temperature and completely cancel 100% of the increase in temperature post the LIA and last Maunder Minimum.
This in and of itself is ignored in the article, in spite of the fact that the papers confirming this have been out for a while now. Whether the increase in albedo is caused by:
* Modulation of cloud nucleating GCRs that increase the rate of cloud formation.
* Increasing soot from rapidly growing China and India actually increasing global albedo from cloud nucleation, regardless of whether the carbon in that soot is “black” or “almost black” (Bullshit! he sneezes…;-).
* Increases in other aerosols from industrializing nations are doing the same thing.
* The inversion of the PDO has effectively redistributed clouds towards the tropics by shunting cool air further south over supersaturated pacific moisture.
* Other mechanisms known and unknown are causing increased cloud formation — fluctuations in tropical currents, fluctuations in atmospheric circulation patterns, space aliens, deific intervention — we don’t know enough about how clouds are formed in the chaotic turbulent soup of the Earth’s atmosphere to be able to track the chaotic feedback loops that form and break up and reform to produce the cloud cover, hour by hour. We can predict it in the short run, but predicting it in the long run just doesn’t work.
We don’t know why some monsoons are very wet and others are relatively dry, not well enough to predict the monsoon rainfall in India a mere 2-3 years in advance. How then can we detect when it is “anomalous”?
At the moment, the modulation of albedo is the big elephant in the room the CAGW folks are trying to ignore even as it is quietly stamping them to death. They know perfectly well that if it persists, it is going to get very, very cold over the next decade, and stay that way until the albedo goes back down again. And they don’t like any of the possible causes on the list above, because they all confound the story they have told about 20th century GW all being due to anthropogenic CO_2 (and friends, such as “extremely black carbon”).
Why hasn’t the temperature gone up over the last decade and a half? Because the albedo increased, strangely coincident with the decrease in solar magnetic activity with the current quiet solar cycle and consequent increase in GCR levels. Or strangely coincident with the industrialization of the third world and all of the smog they produce. Take your pick. To solve the CAGW problem, perhaps we should burn more coal and adjust those burners to produce more soot just like India and China do! Or resume atmospheric testing of nuclear bombs to get a decent amount of radioactive fallout up there in the stratosphere where it can filter down, nucleating clouds along the way (mid-20th century cooling was strongly coincident with above ground testing of nuclear bombs that dumped enormous amounts of radioactive particulates into the air, hmmm).
We even have a choice between anthropogenic modulation of the albedo and solar modulation of the albedo. In the end, it may not matter which one is correct — the one that gets the most grants is the anthropogenic one because nobody can (yet) control the sun.
rgb
E.M.Smith says:
March 27, 2012 at 4:53 pm
I note again the use of the ‘fuzzy word’ of ‘forcing’ (that I still do not find in my Physics book…) …
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My definition of the ‘fuzzy word’ … ‘forcing’ is “…a propaganda tool used by the News Media to control human behaviour…” When that definition is used all becomes quite clear.
Obviously some falls out on the surface — that causes surface warming. Any in the air warms that air — either high up or right near the surface. So where is most of it?
No, it doesn’t. Or rather, it does, but only on a very small fraction of the surface — the fraction with a high albedo, e.g. snow or ice. Everywhere else it either vanishes without a trace (the 65% of the Earth’s surface that is ice-free ocean or other bodies of water) or is irrelevant (anyplace with plants where it is washed into the ground underneath the shade canopy, anyplace with an already small albedo).
It might be a factor (even an important factor) in the melting of certain glaciers, it is possible that it is a factor in the reduction of icepack in the NH arctic, it is unlikely that it globally important anywhere but the latter.
Up in the air, as noted in my previous reply (that may or may not have gotten through the “login to post” guardians that now plague my post attempts) I do not believe that we even know the sign of the net cooling or heating effect of soot overall. Certainly given evidence of UAH lower troposphere temperatures holding to falling (even as GISS and HADCRUT work hard to produce the illusion of continuing surface warming in the teeth of a non-warming atmosphere) over the last decade when soot production has held steady to increased, there is little convincing evidence that it is heating even the atmosphere, let alone the surface.
rgb
Steve Richards says:
March 28, 2012 at 1:41 am
The discussion here between Willis Eschenbach and E.M.Smith proves the worth of WUWT.
I suspect many readers have learnt from this discourse.
_________________________
Yes, It is enough to make me bookmark the page since it shines a spot light on a major problem in “Climate Science”
I have barely enough physics background to follow the discussion. Unfortunately that is a heck of a lot more physics than the average Joe who never even took Physics in high school much less a few undergrad college courses.
E.M.Smith says:
March 27, 2012 at 4:53 pm
“I note again the use of the ‘fuzzy word’ of ‘forcing’”
‘forcing’ is what they are trying to do to us. There are those who cannot bear the thought of something changing that is outside of their control. Hence the constant use of the term ‘forcing’, which for them has deep psychological implications.
‘the change in net (down minus up) irradiance…”
This defintion of net (down minus up) appears to be at odds with the definition of net in radiation heat transfer. Net is used to tell us what the difference is of absorbed, transmitted and reflected incident radiated heat. Not just up down watts.
– CO2 catches radiation from the surface, and partly radiated it back to the surface, thus making it warmer. In the process, CO2 makes the atmosphere warmer.
– Black Soot catches radiation coming from the sun, preventing that radiation from reaching the surface, thus making the surface cooler than it would have been. In the process black soot makes the atmosphere warmer.
– Not-So-Black Soot catches some radiation from the sun and reflects some radiation from the sun back to space, thus cooling the surface like black soot, but warming the atmosphere less.
All this is very clear, and it was high time someone spelled it out. Thank you Willis.
There is also another effect.
– Black and Not-So-Black Soot get snowed out on glaciers and Arctic and Antarctic ice.
When the snow/ice melts or sublimates, more and more Soot is concentrated on the surface, catching more and more radiation from the sun, thus warming the surface more and more.
This obviously results in increased melting and sublimation.
– On the other hand, Black an Not So-Black-Soot in the air cause less radiation to reach the surface, thus cooling the snow/ice.
I wonder what the net effect will be.
– Maybe in Amsterdam where I live, slightly cooler winters and temporary warming at the end of winter when the snow melts. Net cooling?
– I expect net warming on the glaciers in Switzerland, where sublimation and melting happen all year round, in between periods when snow falls.
– Polar sea ice. Extremely little sunlight in winter with no effect either way; many hours of weak sunlight in summer. Net warming?
Just to complete the picture.
Thanks to the many contributors that point out the issue of black carbon is quite complex. Let me add another.
When BC intercepts energy from the sun and warms the atmosphere it increases the cooling effect of the GHGs in the atmosphere. Hence, GHGs provide an immediate negative feedback that works 24/7 vs. the heating effect that only works while the sun shines.
The whole issue of BC is probably too complex to model accurately in and of itself. What does that say about GCMs?
When BC intercepts energy from the sun and warms the atmosphere it increases the cooling effect of the GHGs in the atmosphere. Hence, GHGs provide an immediate negative feedback that works 24/7 vs. the heating effect that only works while the sun shines.
The whole issue of BC is probably too complex to model accurately in and of itself. What does that say about GCMs?
In general, I agree. Or perhaps not to complex to model accurately eventually, but we aren’t making progress at building accurate GCMs and will not make further progress until we stop leaving important variables out. If we suppose that solar magnetic state is an important factor for whatever reason — something not empirically unreasonable given the strong correlation over millennia between solar state and global temperature — then models that leave this out aren’t going to get the right answer.
No models will get the right answer until models are built that have the right sort of natural variability without CO_2 variation to describe, let’s say, the Holocene, from the Younger Dryas on, in detail, using as input inferred solar state and some natural processes that have the right order of variability. So far if you tried this with GCMs you’d get a completely absurd result because they all assume that the variation of solar forcing (that word again) is nearly irrelevant. This, in turn, has to be assumed in order to make their models fit Mann. Mann has done the world a favor. By flattening the LIA and MWP out of existence he’s created a target world for the GCMs that never existed, making it rather difficult to fit his fantasy hockey stick and fit the rollercoaster the Holocene temperatures have been for everything but bristlecone pines, so to speak.
The thing that I think deserves the most attention is self-organization a la Prigogene. For reasons that I cannot fathom, I never hear of the world’s climate system described as a self-organized driven thermodynamic system far from equilibrium, in spite of the fact that that is precisely what it is. It is the classic example of the kinds of systems studied by Prigogene, Haken, and many others (creating what amounts to an entire sub-discipline of physics). Turbulent rolls are self-organized thermal structures, and they form because they increase the cooling rate compared to thermally stratified fluids. Winds, high and low pressure systems, the oceanic currents, the global oscillations — all of these are self-organized structures in the Earth’s climate system. All of them are subject to changes over short time scales or long that cannot be explained by any sort of linearization. Structures in this milieu for a while may appear to be quite periodic and follow an “empirical law”, but they can in an instant switch to a different period, have a different shape, merge, move. When they do, everything may reorganize in response.
Willis has pointed this out a few times (and I believe it is alluded to above in the context of the “constructional law”) — the Earth almost certainly responds to any increase in “forcing” by also increasing the rate that it sheds heat. That is, net feedback to any forcing is almost certainly negative because positive feedback is associated with critical instability and there is no evidence of positive critical instability in the Earth’s climate record, recent or prehistoric. However, it would be a lot better to have models that exhibit this negative feedback as a direct outcome of self-organization within the system such that the system opposes externally driven changes everywhere except near critical points.
Critical points, in turn, are immediately apparent by means of the Fluctuation-Dissipation theorem. Basically, near a critical point one expects fluctuations to often grow instead of damp, and to have longer life times. Everything varies more wildly. It takes longer for the system to settle down to an “average” behavior. No such behavior has been observed in concert with post-Dalton warming — if anything the climate system is less volatile in the latter 20th century than it was before.
rgb
I have a couple of questions I would like answered:
1) How come that as Carbon Dioxide (CO2) warms up as it receives “Thermal Radiation” (TR) from the Surface, it (CO2) can send the radiation it has gained back down to whence it came, but as the now Atmospheric Black Carbon (ABC) absorbs TR from the Sun it can not direct its TR towards the surface thus offset any cooling.
2) Is this possibly a little taste of a new “emergency theory” just in case the Earth starts to “really cool down”
To me, it sounds like black carbon creates a “virtual surface” for the planet. It’s like moving the surface of the planet upwards (above the actual surface); which consequently shades and cools the real surface while bringing this “virtual” surface higher into the atmosphere warms everything above it by deflecting light and engaging in convection sooner, like a real surface. You can even define the percentage of virtual surface that’s been created by black carbon using the opacity. If we had complete opacity, the real surface would freeze as it would be like living in a cave with no light getting through and all thermal interactions happening at the “virtual” black carbon surface (air is a poor conductor, so not much heat would reach us beneath, we’d be pretty well insulated).
At least, that’s how it seems to me, and what makes sense of all of the data in my mind. Afterall, soot seems like it’s basically just dirt, but up in the atmosphere and mostly carbon instead of silicon oxides.
During a recent BBC documentary on the Arctic, David Attenborough was lowered down a sink hole in the Greenland ice cap, to show what happens to the surface melt water as it disappears down through 100’s of feet of ice.
But what wasn’t mentioned, and I found very interesting, was the color of the ice as he was lowered a fairly short distance into the hole (30 feet?).
The top few feet showed clear bands of white snow and black dirt, with the bands getting finer with depth. But below this was clear blue ice, with no obvious dirt at all.
So at a guess, airborn black carbon had settled into the snow in recent years, where previously it was pure white snow. And since the program was in part about the effect we’re having on climate, why on Earth was there no mention of this obvious feature of the recent ice layers? Presumably as CO2 is clear, so this can’t be anything to do with climate, can it?
Sparks says:
March 28, 2012 at 1:50 am
I can only answer that I have a very active interest in science, but sometimes I don’t do my homework, sometimes I don’t look before I leap …
All the best,
w.
Jim D: If you warm the atmosphere and cool the surface, either or both of two things happen.
What you describe is a pair of opposing feedbacks. What you would get, if you are basically correct, is oscillation up and down from a sort of “set point”. My sense is that such an oscillation is concordant with current knowledge. It’s concordant with Willis Eschenbach’s thermostat hypothesis.
Kasuha says:
March 28, 2012 at 2:19 am
Kasuha, let me review the bidding. I’d said:
to which you replied:
Now you are claiming that my reasoning is faulty because my post is “about effects of black carbon, not about reflective aerosols” … but it’s not. You may be thinking of my previous post called “Extremely Black Carbon”. This one is about semi-reflective aerosols, which is why it’s called “Almost-Black carbon”, meaning somewhat reflective.
More to the point, you object saying that in the “scope of forcing caused by black carbon particles, surface and atmospheric forcings are not independent variables”.
That may or may not be true, but we are talking, not about the independence of the forcings themselves, but the independence of the errors in estimating the forcings. Go back to my claim, which was that there was a 30% chance that those errors in the forcing estimates were sufficient to give a net forcing less than zero.
Those errors in the estimate are assuredly independent, rendering your objection moot.
Regards,
w.
E. M. Smith: Finding that it’s “Unphysical” is just fine with me. It means I can not bother expecting any actual ties to reality. Ive done programming and I can play with ‘toy worlds’, I just prefer not to confuse them with anything real.
You must be a great fan of Schrodinger’s Cat (I don’t know how to do umlauts). Like you, Einstein and Schrodinger objected that to replace a “state” or “particle” with the mean of the distribution of the possibilities did not have physical reality. Yet it is really common in many sciences, as it produces at least a first-order approximation.
Willis Eschenbach’s essay is a presentation of the first-order effects, but not a detailed model of all the details of small variations at places and times, which it also does not claim to be. I don’t “speak for” him, but as a regular reader, I have tell you that he has at other times expressed detailed criticisms, where appropriate, very similar to yours: necessity to consider T^4 power, etc.
O H Dahlsveen says:
March 28, 2012 at 9:24 am
Hey, O H, good to hear from you. Answers ‘r’ us, sometimes wrong but rarely uncertain, that’s me …
Black carbon or any other aerosol that absorbs sunlight. does indeed re-radiate the energy in all directions.
But since only half of it goes down, the surface ends up receiving much less radiation than it would have if the sunlight had hit the surface directly. As a result, the surface ends up cooler.
Can’t help with that question, as I’m reluctant to speculate about other people’s motives when I understand so little of my own … but it would have to be included in the differential diagnosis.
My thanks,
w.
Ged says:
March 28, 2012 at 9:37 am
Yes, that’s a useful way to understand it. That’s why the claim that atmospheric BC warms the surface has always seemed specious to me.
w.
steveta_uk says:
March 28, 2012 at 9:52 am (Edit)
Interesting question. My guess is that as the snow is compressed into ice, the included particles become part of the ice itself rather than being lumps of soot and dust mixed into the snow. I suspect that when that happens the optical properties change, rendering any inclusions of soot or dust much less visible. In other words, I think you could make fairly clean looking ice out of visibly dirty snow.
In support of this, I know that layers of dust in the ice itself are generally not visible to the naked eye, despite Al Gore’s specious claim in his movie “Inconvenient Lies” to be able to see them.
w.