Guest Post by Willis Eschenbach
Andrew Lacis and the good folks at GISS have a new paper, Atmospheric CO2: Principal Control Knob Governing Earth’s Temperature, Andrew A. Lacis, Gavin A. Schmidt, David Rind, Reto A. Ruedy 15 OCTOBER 2010 VOL 330 SCIENCE [hereinafter “Lacis10”]. Although most commenters have dismissed their work as being derivative and not containing anything new, I find that they have actually made a couple of unique and novel errors. I have two main difficulties with their paper. I have a problem with one of their theoretical claims, and I also have large issues with their model results. First, the theoretical claim. Lacis10 says:
Because the solar-thermal energy balance of Earth [at the top of the atmosphere (TOA)] is maintained by radiative processes only, and because all the global net advective energy transports must equal zero, it follows that the global average surface temperature must be determined in full by the radiative fluxes arising from the patterns of temperature and absorption of radiation. This then is the basic underlying physics that explains the close coupling that exists between TOA radiative fluxes, the greenhouse effect, and the global mean surface temperature.
Figure 1. Global Energy Budget from Trenberth et al.
Let me examine this claim one piece at a time.
They start by saying:
Because the solar-thermal energy balance of Earth [at the top of the atmosphere (TOA)] is maintained by radiative processes only …
This is not clear. What does “maintained” mean? I think they mean that on average outgoing radiation must perforce equal incoming solar radiation, which is true. As seen in Fig. 1, 341 W/m2 of incoming solar is balanced by the 102 W/m2 of reflected solar plus 239 W/m2 of outgoing longwave.
Next they say:
… and because all the global net advective energy transports must equal zero, …
“Advection” is defined by the American Meteorological Society as “the process of transport of an atmospheric property solely by the mass motion (velocity field) of the atmosphere;”
Since advection merely moves energy around, you’d think that advection wouldn’t change the average global temperature. However, while energy is conserved, temperature is not conserved. Suppose we take two equal areas, say the part of the planet from 30N to 30S (average 25°C) and the rest of the planet including the poles (average 4°C).
Advection (also called “atmospheric transport”) moves about 20 W/m2 from within the tropical and subtropical area of 30°N/S to the temperate and polar area outside of 30°N/S http://www.sp.ph.ic.ac.uk/~arnaud/PAPER/Czaja_Marshall_jas06.pdf. Using blackbody calculations for simplicity, from the 20 W/m2 energy transfer the equatorial area cools by three degrees, while the same area at the poles warms by five degrees. And as a result, the average temperature of the two areas warms by a full degree, simply from advection.
So while the authors are entirely correct to say that the net advective energy transports equals zero, the same can not be said about the effect of net advective energy transport on temperature.
However, let’s ignore that. Let’s say that both of those statements are true for the purposes of this analysis. Given those statements, they then say:
… it follows that the global average surface temperature must be determined in full by the radiative fluxes arising from the patterns of temperature and absorption of radiation.
Here’s where we really part company, on two points. First, surface temperature is not “determined in full by the radiative fluxes”. There are also sensible heat fluxes from the surface to and through the atmosphere (conduction/convection, called “Thermals” in Fig. 1) as well as latent heat fluxes (evaporation and transpiration, or “Evapo-transpiration in Fig. 1). Both of these cool the surface without changing the TOA “solar-thermal energy balance of the earth.” Either I don’t understand their conclusion, or I disagree with it. What am I missing?
Second, there is no logical “it follows” path to get from the two statements
“solar in = solar + longwave out”
and
“net advective energy transport = 0”
to their conclusion
“global average surface temperature must be determined in full by the radiative fluxes”.
I cannot think of, and they do not provide, any logical chain of reasoning that connects the third statement to the first two.
So that’s the theoretical problem with the paper. They claim that the surface temperature of the planet is “determined in full by the radiative fluxes”. I say no.
Next, the model problem. They base all of their claims on making very large changes in the variables of the GISSE global climate model. The model problem is that like many other climate models, GISSE has the cloud feedback backwards. The GISSE model says that clouds are a positive feedback. There’s a good study of the question by De-Zheng Sun et al., 2009, Tropical Water Vapor and Cloud Feedbacks in Climate Models: A Further Assessment Using Coupled Simulations, Journal of Climate, 22, 1287–1304 [hereinafter Sun09].
Among other things, Sun09 says:
A more serious concern raised by the study of Sun et al. (2006) is the finding of a common bias in the simulation of the cloud albedo feedback in the leading climate models: with the exception of the GFDL model, all the models they analyzed in that study underestimate the response of cloud albedo to the surface warming.
This finding from Sun 2006 were reconfirmed in Sun09. Here’s an illustration of the problem:
Figure 2. Solar (albedo) cloud feedback (blue bars), cloud longwave (yellow bars), and net cloud feedback (red bars) in models and observations of the equatorial Pacific (5°S-5°N, 150°E-250°E). Net feedback is the sum of the longwave and albedo feedbacks. Period of study 1983-2004. DATA SOURCE Sun09 Table II. See Sun09 notes for Table I and Table II for details on the data.
Note the errors in the modelled albedo feedback (blue bars). In the tropics, solar albedo feedback works as follows. Increasing warmth means increasing clouds. Increasing clouds means more sunlight is reflected into space. This cools the earth, and is a negative feedback.
While most of the of the models at least get the sign of the cloud albedo (solar reflection) feedback correct (more clouds means less sunshine hitting the earth, a negative feedback), the UKMO Hadgem1 and the GISS EH models don’t even get the sign of the albedo feedback correct. The rest of the models underestimate the size of the albedo feedback, with values as low as 16% of the observed cloud albedo feedback.
There are also a very wide range of values for the longwave, some of which are very small compared to the actual observations.
In addition to the albedo and longwave problems, a larger issue is the net cloud feedback (red bars). All but one of the models show positive net cloud feedback. The observations and one model show negative feedback.
Now, the Lacis10 authors are using their model to determine (among other things) what happens in the deep Pacific tropics when the non-condensing GHGs are removed from the atmosphere.
Obviously, the first thing that would happen if GHGs were removed is that the planet would start to cool. The immediate response in the tropics would be that daytime cumulus would decrease. This would allow more sunshine to heat the earth, which would be a negative feedback on the cooling from the lack of GHGs.
In addition, the number of tropical thunderstorms would decrease. This would slow the Equator-to Poles atmospheric transport. Once again, this would warm the earth, and would also be a strong negative feedback on the cooling.
The GISS model, on the other hand, says the opposite. It says that as the Earth cools from the lack of GHGs, the change in clouds would make it cooler yet … and unsurprisingly, it says that the net result would be that the planet would spiral into a permanent snowball. Fig. 3 is a figure from the Lacis10 paper, showing how they think it would evolve:
Figure 3. Lacis10 description (their Fig. 2) of the evolution of GISSE model when non-condensing GHGs (everything but water vapor) is removed.
I find this graph quite odd. Immediately after the GHGs are removed, surface temperature starts to drop. That makes sense. But concurrently, there is a steep increase in clouds, from 59% coverage to 69% coverage in one year. This doesn’t make sense. A warmer world is a wetter world. A warmer world is a world with more moisture in the air, and a world with more rainfall and more clouds. Conversely, a cooler world is a dryer world, with less clouds. What would cause the modelled clouds to increase in coverage as the earth cooled? This may be related to the reversed sign of the GISS albedo feedbacks shown in Fig. 2.
(In addition, the GISS Model E normally shows about 10% less cloud coverage than the real Earth. See Present-Day Atmospheric Simulations Using GISS ModelE, (PDF 2.2 Mb), page 169.)
Finally, Fig. 4 shows the atmospheric transport feedback and the total atmospheric feedback, again from Sun09. This is the net cloud feedback shown in Fig. 2, plus the water vapor feedback and the atmospheric transport feedback. (Water vapor feedback is similar in observations and models, and is not shown.)
Figure 4. As in Fig. 2, for atmospheric transport feedback (blue bars) and total atmospheric feedback (red bars). Total atmospheric feedback is the sum of the feedbacks of water vapor, cloud longwave, cloud shortwave, and atmospheric transport. Fewer models are shown than in Fig. 2, because of lack of data for the remainder. See Sun09 for details.
As with the net cloud and the cloud albedo feedbacks, the atmospheric transport feedback is also underestimated by many models. Atmospheric transport is the movement of energy out of the Equatorial area of the study. This transport of energy out of the area increases as the temperature goes up, so it is a negative feedback. It reduces the size of an expected increase.
And as a result of all of the model underestimations, the net feedback for the observations is much larger than any of the models. And indeed, some of the models go so far as to claim positive feedback in the deep tropics area studied.
So that’s my second problem with the Lacis10 paper. Given the huge variation in the feedbacks of the different models, and given that all but one of them show positive cloud feedback in the tropics, there is absolutely no reason to place the slightest credence in the GISS ModelE results reported in Lacis10. Let me close with this quote from James Hansen, pp 2-3 (bulleting mine):
2.4 Principal Model Deficiencies [of the GISS ModelE climate model]
Model shortcomings include
• ~25% regional deficiency of summer stratus cloud cover off the west coast of the continents with resulting excessive absorption of solar radiation by as much as 50 W/m2
• deficiency in absorbed solar radiation and net radiation over other tropical regions by typically 20 W/m2
• sea level pressure too high by 4-8 hPa in the winter in the Arctic and 2-4 hPa too low in all seasons in the tropics
• ~20% deficiency of rainfall over the Amazon basin
• ~25% deficiency in summer cloud cover in the western United States and central Asia with a corresponding ~5C excessive summer warmth in these regions.
I mean, how could you not trust a model with specs like that?
w.
Kwik wrote above:
“…The warmers have got it the wrong way around. You [Willis] got it right.
Slowly this will be discovered. I think the warmers already know it in their hearts. But it is hard to accept.”
Just like they paid heed that the ice cores show that there is a lag of several hundred years before CO2 responds to temperature change?
Willis wrote above:
…“I think you and others misunderstand what Lacis10 said. Advective energy transports indeed must equal zero. If you are moving energy from one place to another, what one loses the other gains. Net zero. As I pointed out, while energy is conserved, temperature is not.”
But, if say the upper troposphere is warmed by convection, cellular advection, evapo-transpiration, and mechanical work, does that not result in greater escape of HEAT via radiation (EMR) to space? That happens as a consequence of air temperature, (related to HEAT), proportionally to T to the fourth power, so the greater the temperature increase, the greater the rate of change to EMR. The advective energy is thus converted to HEAT, and then to EMR which are different forms of energy. That means that a portion of the original advective energy no longer exists. So, unless an equal amount of advective energy is created via a reverse of this process, (which I can’t conceive), then the net of all advective energies cannot be zero.
This consideration does not contradict “conservation of energy”
Consider the “advective energy” of water flow into a hydro-power station. On the out side, the “advective energy” is much reduced. (In + out does not = zero). Where did it go?
Sorry, I meant in minus out does not = zero
Bob_FJ;
You got it wired!
What do I win?
😉
Bob_FJ;
There’s also the wee matter of “work”. Relocation of mass requires work. Work absorbs/’extinguishes’ energy. The theory of entropy increase says it will eventually degrade to heat, but that may be delayed by eons.
@Bob_FJ
> Consider the “advective energy” of water flow into a hydro-power station.
> On the out side, the “advective energy” is much reduced.
> (In + out does not = zero). Where did it go?
Energy and momentum are always conserved. It’s the law.
So where does all of that ‘motion’ (Latin=’momentum’) in the Niagara Falls go when it hits the bottom?
The Earth’s rotational and translational momentum is perturbed a wee bit by all of that commotion. How much? Just enough to conserve kinetic energy and momentum. (Up to the kinetic energy converted to heat, sound and electricity).
JD;
Energy can be stored, and when it does work becomes a kind of potential energy, pending unwinding of the work done. Energy is not “conserved” strictly speaking, as it may be transformed in various ways. The heat and pressure that produce coal and diamonds has done work which “traps” energy in ways that may or may not be released prior to the heat death of the universe, e.g. Crumpling of the crust raises mountains which will persist for millions of years before their stored potential energy is released. And so on.
So it is invalid to demand that every calorie of heat be tracked to its new lair when the wind blows. You’d need to know the work function of every displaced atom and molecule to balance that budget.
> Energy is not “conserved” strictly speaking…
That’s not correct. For physicists, who always speak strictly, energy is always conserved, in one form or another (as I pointed out). Up to quantum uncertainty, of course, so there may be nano-scopic delays in conservation, which can’t be observed at the macro level.
The point I was making was the apparent loss of motion (‘momentum’) can be explained by the huge mass of the Earth, which absorbs the momentum of falling water and moving air masses without any noticeable reaction.
Momentum is always conserved, and can’t be converted to other forms. Once motion is created it can never be destroyed.
John Day wrote:
“…Momentum is always conserved, and can’t be converted to other forms. Once motion is created it can never be destroyed.”
In the example I gave of the hydro-power station, the kinetic energy of the inflowing water is reduced, mostly by driving the turbines to generate electricity. Or, in your words, the ‘momentum’ is converted mostly to electricity. There is also some conversion to heat, because of losses. (inefficiencies)
In your example of Niagara falls, there is not much to slow the flow, but some work is done, with consequent conversion to heat.
@Bob_FJ
Momentum and energy are different concepts. Momentum is a vector quantity, energy is a positive scalar. Both are conserved, but in different ways.
The momentum of the water flowing through a turbine is transferred, indirectly, into the Earth, which causes a very tiny, virtually undetectable change in the Earth’s momentum, conserving the total vector sum of momenta before and after impact. Generation of heat is an energy issue and has nothing to do directly with the concept of momentum.
Thought experiment: imagine the turbines floating out in space, where there’s no Earth anchoring them firmly to one spot. Then the millions of tons of flowing, water hits the blades. Does the motion disappear? No. Even though the water will be ‘weightless’, it still has mass and will drag the turbines along with the flow.
John Day wrote in part:
“Momentum and energy are different concepts. Momentum is a vector quantity, energy is a positive scalar. Both are conserved, but in different ways.,,
Well that could become an interesting discussion but it is off-topic, so I‘ll desist.
I take it that you agree that my analogy of hydraulic kinetic energy, (equivalent to Lacis 10’s “advective energy”), being converted largely to electrical energy in a turbine-generator, is correct.
Thus, “advective energy” can cease to exist in complex ways, by virtue of conversion to different forms of energy. Thus the assertion that on earth, the atmospheric (?) “advective energies” net to zero, is faulty.
I’m glad I wasn’t drinking hot coffee when I read this, Willis, or I’d be checking the prices for a new laptop screen. Wow! What a nice cut. If you don’t mind, I’m saving that one for the next time I’m refereeing and looking for just the right weight of a comment to recommend rejection while sounding nice. I’m not sure whether this constitutes damning with faint praise or patting on the head with faint damnation, but it’s just the right comment for certain types of papers. Thanks for making my day.
Just out of curiosity: Have you or someone taken the time to discuss the implications of Figure 2 for the discussions about modelling over on Dr. Curry’s blog? It seems this gels down to a very simple and graphic demonstration of a key problem with models. I would go so far as to say that, until this problem is addressed, there really isn’t much else worth talking about over there. Well, there’s also the verification/validation issue, but they’ve been talking it to death, I infer from my last few visits, and the tropical hot spot issue, which is talked to death elsewhere already.
John Day;
I assumed, over-generously, that you’d understand the implicit “within the relevant frame” in my energy conservation comment. We are not solving for the energy budget of the multiverse; only for a rather limited and finite time and space block. There is no requirement that energy remain balance or persist in relevant or recognizable form within that block; it may “retire” as something as simple as change of position of mass, or a chemical transformation, or escape into distant frames, etc., and conversely enter the frame from others.
So as Bob points out, it is inadmissible to demand or expect netting of advective flows to zero in any practicably measurable sense. There are many bolt-holes and escape hatches, plus side stage doors for new actors to join in.
mod: typo “remain balanced”
WILLIS,
Further to my comment above, It also occurs to me that if that were not enough, there is a further problem with the assertion that the net of “advective energies” on Earth are zero.
If we consider the troposphere, these advections vary randomly in speed etc, from modest to high velocities. (such as; jet streams, near surface westerlies, and Hadley cells). Additionally there are seasonal, diurnal, and hemispheric variations. Thus, any consideration of how all this stuff might add up to zero requires a time-frame to be defined for a complete cycle, but unfortunately, different time-frames apply for different bits of it. Thus, quite apart from the previously mentioned problem of conversion of advective to different energy forms, it is not viable to assert a global net result, because a sensible time-frame for it to be defined within is not possible.
But, it gets worse:
There are also marine advections such as the thermohaline circulation, (Ocean conveyor belt), which takes very many years I seem to remember, and the ENSO (El Nino/La Nina), of quite short random oscillations, and so-on. And, the various energies in the troposphere and the oceans feed one into the other with great complexity.
Bob_FJ says:
December 12, 2010 at 3:41 am
Remember what the Lacis10 authors actually said. They said:
Nothing that you have described in your post negates that. They said nothing about radiation, nor about temperature. Yes, advective transport can move energy to where it is more easily radiated to space. And that radiation will result in the system having less energy. But that is radiative transport, not advective transport.
Advective transport simply means moving energy. You can’t advectively transport energy from A to B and somehow magically end up with more energy when you get there. With advective transport, whatever one location gains, another location loses. And the net is zero.
Brian H says:
December 12, 2010 at 4:17 am
The mechanical work done by the sun is mostly a) the driving the Hadley circulation of atmosphere and ocean from the equator to the poles, and b) the refrigerative cooling of the surface through the evaporation/condensation of water. That work is completely converted to heat, on a short timescale, by the solid parts of the earth acting as a fluid brake on the global circulation. Think about it the other way around. If the forces driving the atmospheric and oceanic circulation suddenly ceased, the global circulation would come to a stop in days or weeks, rather than centuries or eons.
There’s a good discussion of this in Thermodynamic optimization of global circulation and climate
, Adrian Bejan and A. Heitor Reis (PDF).
WILLIS Concerning your comment above, it seems to me that you did not understand what I was saying. Let me add that I’m on your side, and I admire your enthusiasm in these things, but sometimes you do get things wrong. I also notice that your post crossed mine which expanded on another aspect of the issue. Rather than plough through what you have apparently misunderstood so far, perhaps you could consider my more recent comment.
John Day says:
December 10, 2010 at 12:29 pm
Lacis et al. don’t offer any detailed explanation of this deficiency, but suggest it might be due to “pressure broadening” of the CO2 absorption lines. I’ve seen that claim by other AGW apologists, but have not found any substantive explanation of how line broadening (in Earth’s high pressure atmosphere) ‘enables’ the CO2 GH effect on Earth but not on Earth. I’m skeptical, sounds like hand-waving to me. (But please correct me if this is a well-understood mechanism.)
Here’s a comparison at the surface conditions of Mars and Earth to illustrate the pressure broadening effect:
http://i302.photobucket.com/albums/nn107/Sprintstar400/Mars-Earth.gif
Phil,
Reur photobucket image of CO2 absorption bands.
I’m very interested. Do you have a reference as to its source and method of derivation etc?
Well if you take Trenberth’s Energy Balance cartoon as Gospel Truth (and I do, because he’s a Kiwi); and I haven’t seen any competing alternatives of great rpute; that still leaves you absolutely nowhere; except you have some numbers to mess with.
It’s quite impossible to deduce the Temperature of the earth from Trenberth’s energy budget; because unfortunately; the earth (Mother Gaia) dosen’t pay ANY attention to Trenberth; or his energy budget. She follows the laws of Physics, and follows the principles of experimental science, in that she pays attention to what is actually happening in real time.
And the first thing she notes is that the TSI is 1366 W/m^2 (+/- 0.1% or so), which is a far cry from Trenberth’s 341 number.
As a result, the Temperature on the sunlit portion of the earth (mostly ocean) goes way higher, than is possible with a steady 341 all over the planet. At 341, the Temperature is shooting for about zero C
At 1366, the Temperature goal is 394 K, not 288 or 273. Ok lets step back a bit to say 1000 W/m^2; the target is still 364 K.
The point is that these much higher actual input flux levels are STORED in the deep ocean; and they DO NOT DECAY IN 24 HOURS to any AVERAGE temperature, because the earth is NOT INFINITE THERMAL CONDUCTIVITY !
That’s why Trenberth’s budget is total BS, when it comes to explaining the Temperature; and also why the water vapor feedback GH effect can completely self start even with zero other GHGs in the atmosphere including no CO2. I leave O3 in there since it is simply a byproduct of the stardard atmosphere gas O2.
There’s lots of places on earth below 255 K despite the unprecedented high CO2 levels; which seems completely incapable of catching fire; yet there is plenty of H2O vapor; even though there isn’t supposed to be any without CO2.
The point is if you use a sill modle that doesn’t fit ANY known planet; then you expect to get silly results.
This one roatates; and it responds in real time to what is actually happening; not to some dumbed down average .
George E. Smith
Re Trenberth’s cartoon.
Yep!
There’s that naughty business of T to the fourth power.
I find his simplistic illustration of up and down radiation a tad irritating too. (magnitude & distribution)
I’m not too sure that the higher actual levels of solar radiation are stored in the deep oceans though. It’s only blue light that gets down 100 m maybe, and ~40% of near infra-red is absorbed in the skin. Surely, the ocean is thermally stratified, convective, and wave action can‘t mix down too far? Turn-over currents, e.g. ENSO, are confined to smallish areas?
It’s a bit of a travesty really, and he got it wrong about hurricanes too
SORRY,
Where I said : and ~40% of near infra-red is absorbed in the skin.
I meant: and ~40% of sunlight is in the near infra-red, which is absorbed in the skin of the water