Lacis: What is it that determines the terrestrial climate and how it changes?

There's another comment by Andy Lacis at Climate Etc., and just like the original its deeply under-appreciated by the residents. Indeed it would have been unappreciated by me because I don't read her posts much less wade into the comments unless someone draws my attention.

Before we go onto AL's wise words, lets read some very silly ones: Climate and weather model share the same underlying mathematical dynamic. So models are undoubtedly chaotic - this is the kind of stuff that JC chooses to highlight at the top of her posts. You'd be better off with my Oh dear, oh dear, oh dear: chaos, weather and climate confuses denialists and links therein; I remain very fond of Butterflies: notes for a post.

But, without more ado, here is Andy Lacis:

What is it that determines the terrestrial climate and how it changes?

Needless to say the terrestrial climate is the result of complex interactions between the ocean, atmosphere, and biosphere via atmospheric fluid dynamics, thermodynamics, bio-geo chemistry, orbital geometry, and radiative transfer – all processes being driven ultimately by the incident solar energy.

All of these physical processes are modeled explicitly in time stepping fashion in current climate GCMs using a typical spatial resolution of about 1 to 5 degrees in lat-lon, 20 to 50 layers of vertical resolution, and 10 min to 1 hr time resolution. This generates a great deal of time evolution changes in the model-generated wind, temperature, cloud, and humidity fields, accumulated typically in the form of monthly-mean maps of these fields – thus constituting the model generated climate which can be directly compares to similar quantities obtained from global satellite observations as a direct test of climate model worthiness.

Although a climate modeling simulation may typically begin from an initial reference model atmosphere (similar to initiating an initial value weather forecast calculation), the essence of a climate modeling simulation is that of a typical boundary value problem in physics, i.e., the initial starting value does not really matter. For equilibrium sensitivity evaluations, the objective is to reach the equilibrium point toward which the model is being forced independent of the initial conditions. Sometimes model runs are initiated at different points in time to generate ensemble averages, averaging out natural variability effects (which will have different phases for differently initiated runs). Climate models are also used to simulate transient climate change, which then resembles a hybrid between an initial value weather-type model run, but with changing boundary value forcings.

The input solar energy to the climate system has been accurately measured over several decades. Its annual-mean value is 1360.8 W/m2 with an 11-year sunspot cycle variability by about 1 W/m2 (Kopp and Lean, 2011). This puts the global-mean incident solar energy at 340.2 W/m2. However, what actually defines the SW forcing (for a 0.3 global albedo) is the amount of solar energy that is absorbed by the climate system. This, for the sake of this discussion, we will take as being equal to 240 W/m2.

The actual value could be 239W/m2, 242W/m2, or 235 W/m2. The precise value does not matter that much because the climate system’s response is “smoothly continuous” to this SW forcing. While that may be a postulate in need of proof, suffice it here to say that the climate system does not respond like the Mandelbrot fractal set where a small parameter shift in some particular direction might encounter multiple singularity-type responses. The 240 W/m2 is a round number, and is consistent with the accuracy limitations of the ERBE measured value. With SW = 242 W/m2, the climate system would be slightly warmer than with 240 W/m2 (and slightly cooler if SW were 235 W/m2).

The Earth is never in precise SW-LW energy balance equilibrium, but it is always striving to get there. Current climate models exhibit some of the real-world behavior. When models are run for thousands of years with fixed external forcing, they exhibit a natural variability over a broad range of time scales relative to some reference point that can be identified as the global energy balance point of equilibrium. Such behavior is not found in simple 1-D models that can be iterated to energy balance equilibrium to however many decimals required.

In energy balance equilibrium, the thermal energy emitted to space by Earth would be LW = 240 W/m2. If the Earth’s atmosphere were absent, or totally transparent, (but with still the 0.3 global albedo), the surface temperature of the Earth would warm in response to the 240 W/m2 SW forcing until it reached a temperature of about 255 K (with LW = 240 W/m2), at which point Earth would be in SW-LW energy balance equilibrium. But the actual global-mean surface temperature of Earth is about 288 K, and the thermal radiation emitted upward by the ground is 390 W/m2. This global-mean surface temperature difference of 33 K, and the corresponding LW flux difference of 150 W/m2 between the ground surface and top of the atmosphere is a measure of the terrestrial greenhouse effect.

Note that the global SW-LW energy balance at the top of the atmosphere, and the 150 W/m2 greenhouse effect, are described and established completely by radiative means. There is absolutely ZERO convective energy going out to space. Likewise, there is ZERO convective energy represented in the 150 W/m2 greenhouse number. Thus it is radiative transfer modeling that completely describes the SW and LW fluxes as well as the 150 W/m2 strength of the terrestrial greenhouse effect.

So, if radiation accounts for all that, where then do the atmospheric dynamics effects come in? Atmospheric dynamics effects are key to establishing the atmospheric absorber-temperature structure that is used by the radiation model to calculate the SW-LW fluxes and the greenhouse effect. If there were no atmospheric dynamics to establish the (convective/advective) atmospheric temperature profile, radiative energy equilibrium could be calculated for the existing atmospheric absorbed distribution. But, the global-mean greenhouse effect for such a radiative equilibrium atmosphere would be about 66 K instead of the present radiative/convective value of 33 K. This demonstrates clearly the importance of why accurate rendering of both the radiative and dynamic climate system processes is so essential.

The key point of all this is to note that the dynamic processes of the climate system are many orders of magnitude slower than the radiative processes. Thus the radiative calculations can be performed on an effectively static temperature-absorber structure without any loss of generality, totally independent of whatever the atmospheric dynamics may be doing.

Assuming for a moment that the radiative calculations can be performed with 100% accuracy, the GCM calculated response to a radiative forcing (say, doubled CO2) should then be representative of the Earth’s climate system response (to the extent that atmospheric dynamics of the GCM simulation can produce a GCM-generated climate that closely resemble that of the Earth).

Given the “smoothly continuous” response of the climate system, whether SW = 242W/m2, or 235 W/m2, or that there happen to be small to moderate difference in the GCM generated cloud fraction, cloud heights, or water vapor distribution, relative to Earth’s current climate distributions, the calculated response to doubled CO2 should then closely resemble that of the Earth’s climate system response.

The radiative part of the climate system processes is a much easier process to model compared to the dynamic processes, so much so, that it is not preposterous to be thinking in terms of 100% accuracy for computing the radiative heating and cooling effects for a specified temperature-absorber distribution. To this end, Mie scattering theory is an exact theory for calculating radiation scattering by spherical cloud droplets, and similarly, line-by-line calculations using the comprehensive HITRAN absorption line database provide the means for calculating gaseous absorption by atmospheric gases with a great deal of precision and accuracy. While line-by-line calculations are numerically too intensive to be included in GCM radiation models, the correlated k-distribution treatment of gaseous absorption can closely approach the line-byline accuracy, as illustrated in my 2013 Tellus B paper

Clearly, most of the climate modeling uncertainties reside in our inability to model the atmospheric and ocean dynamical processes with sufficient accurately. Those aspects of modeling climate change that depend for the most part on radiative processes are going to be far more certain than those that are associated more directly with atmospheric dynamics, and especially ocean dynamics.

As a result, the radiative effects arising from the different climate forcings, their effect on the strength of the terrestrial greenhouse effect, and the attribution of the relative strengths of climate forcings and feedbacks, are aspects of global climate change that are mostly radiative in nature. Accordingly, these quantities have a significant robustness that stems from very basic physics with little dependence on arbitrary assumptions or parameterizations.

Regional climate changes, on the other hand, are very dependent on the horizontal energy transports by dynamical processes which must necessarily include significant parameterizations to account for the unresolved sub-grid eddy transport contributions. For the longer time-scale variability, current ocean models are only barely able to simulate some El Nino-type variability, with no skill for decadal-scale variability. But note that this form of natural variability consists primarily of oscillations about a zero reference point, and thus does not produce a bias to the steadily increasing global warming component. Also, the radiative effects listed above become more robust in the form of global averages because the horizontal energy transports must by definition average to zero globally, thus averaging out any regional differences associated with differences in regional climate change.

The one really big advantage in modeling radiative process effects over dynamic processes is the feasibility of attribution. Although the modeling of radiative transfer effects is straightforward and simple in concept, it is not so simple as to be preformed on the proverbial back of an envelope – capable computer is required.

As described in Table 2 of my 2013 Tellus B paper, attribution analysis was performed on this nominal 150 W/m2 measure of the atmospheric greenhouse effect. Where actually does the 150 W/m2 come from? It is not simply the flux fraction that gets absorbed by the atmosphere – that is an oversimplified and erroneous assumption – rather, this 150 W/m2 is a combination of layer-by-layer absorption and emission that occurs throughout the atmosphere. If all absorbed are removed from the atmosphere, the greenhouse effect goes to zero. If all contributors are in the atmosphere, it is 150 W/m2. We show explicitly what happens to the LW flux difference when the absorbers are inserted into atmosphere one-by-one, or removed one-by-one.

Those results are summarized in Table 2 of the Tellus B paper. They show that of the total terrestrial greenhouse effect, water vapor accounts for about 50% of the effect; clouds contribute 25%; CO2 accounts for about 20%; and the other minor greenhouse gases like CH4, N2O, O3, and CFS account for the remaining 5%. Now we apply a little physical reasoning. Water vapor and clouds are FEEDBACK effects – meaning they can’t stay in the atmosphere on their own power; they condense and precipitate out; their equilibrium concentration in the atmosphere is strongly limited by the Clausius-Clapeyron relation. (See Section 3 of my Tellus B paper; water vapor and clouds are fast-acting feedbacks; if perturbed, they return to equilibrium distribution in only a couple of weeks).

CO2 and minor greenhouse gases are all non-condensing at current climate temperatures – meaning, once you stick them into the atmosphere, they are not going to condense and precipitate out; they are going to stay in the atmosphere and perform their radiative effects essentially forever, or until atmospheric chemistry finally does them in. These non-condensing gases constitute the radiative FORCINGS of the climate system.

The definition of climate sensitivity is f = (forcing+feedback)/forcing. What this means is that the climate sensitivity derived just from the current climate temperature-absorber structure of the atmosphere is: f = (0.25 + 0.75)/0.25, or f = 4. Given the Hansen et al. no-feedback global surface temperature change of 1.2 K for doubled CO2, this analysis gives a “structural” climate feedback sensitivity of 4.8 K for doubled CO2.

A bit too high? But note that this is not a “perturbation” type of feedback sensitivity evaluation, so it is completely missing the negative lapse rate feedback (which is about 1.2 K according to Hansen et al., 1984). This gets us to 3.6 K for doubled CO2. There is still a further small reduction (for which I don’t have a precise value at this time) that is needed to account for the fact that when all of the non-condensing greenhouse gases are removed, water vapor doesn’t actually go all the way to zero, being supported at about a 10% value relative to current climate by the Clausius-Clapeyron relation.

The net result of these adjustments is that a climate feedback sensitivity of about 3 K for double CO2 is obtained just from the current climate atmospheric structure, which is in good agreement with paleo-climate reconstructions and direct climate GCM modeling results. This implies that the 1 to 2 K climate sensitivity inferred for doubled CO2 in some studies is not going to be self-consistent with the current climate temperature-absorber distribution.

These deductions based on the radiative transfer analysis performed on temperature-absorber structure of the atmosphere are fairly robust and self-consistent. Their principal certainty/uncertainty is directly constrained by how well the GCM generated atmospheric structure resembles the real-world, keeping in mind the “smooth continuity” that is expected for the climate system response for both the real-world and climate GCMs.

It is also clear form this analysis that atmospheric CO2 (being the principal non-condensing gas in the atmosphere) does indeed perform as the LW climate control knob. That is clearly demonstrated in rather complicated Figure 13 of my 2013 Tellus B paper, where the equilibrium response of the climate system is evaluated for different concentrations of atmospheric CO2 ranging from 1/8x (snowball Earth) to 256x (uninhabitable hot-house).

What stands out in Figure 13 is that it is the exponential nature of the Clausius-Clapeyron relation dependence on temperature that makes water vapor, driven by atmospheric CO2, a very formidable cause-and effect combination that could take the terrestrial climate to extremes that we would rather not think about. Cloud feedback effect does not appear to be a major player since the cloud SW albedo effect is largely counteracted by the cloud LW greenhouse effect.

Humans have had the means at hand to self-destruct for decades. Fortunately, they have refrained from dropping H-bombs to quell every pesky brushfire as they frequently erupt. Now, by burning all of the available carbon resources in the coming decades, humans would appear have another option available to achieve their self-destruction.

Comment by me

On the "initial value problem" vs "boundary value problem" issue: there's a question of terminology, and discipline. Technically, GCMs (weather or climate) are both integrated forwards from an initial state; and in that sense are IVP. But as said, the climate of the GCM doesn't actually depend on the initial state3 and so its natural to thing of it as a boundary problem, with the various forcings as the boundaries.

That was a sensible comment. More amusing is this from JC's: Michael Larkin: "Would some kind soul please explain, in layman’s terms, what “initial value” and “boundary value” problems are?" curryja: Hi Michael, try these links
Michael Larkin: "Thank you, Dr. Curry. I’ve checked those out, but found them a bit inscrutable because they immediately leap in with talk of differential equations...". Ah, you get quality commentators at JC's.

3. Well, that's certainly true for atmosphere-only GCMs. For atmosphere-ocean GCMs its clearly not true over the 100 year timescale, as shown by the "cold start" problem; but its true-ish.


More like this

This is a copy (do I say, "reblogged"?) of a comment made by Andrew Lacis1 at Climate Etc (cite) just recently. As DA replied, its a breath of fresh air, but probably won't fare well there. So I'll give it more prominence (ha!) here. There's also a followup: Lacis: What is it that determines the…
This post comes about as an attempt to write down, slowly and carefully, a simple version of the "idealised GHE model". This apparently simple concept causes lots of confusion, though mostly amongst people who want to believe there are fatal flaws at the heart of climate science. Before I go on:…
Most normal people would have been content to have produced one game-changing theory of climate but David Evans is not a normal person. No! He has squillions of degrees from Really Prestigious universities and has, on his own, invented entire new types of Fourier analysis. So it is with no…
New Research on the Effects of CO2 Pollution A paper just published in Nature reports on the direct measurement of the effects of human greenhouse gas pollution on the heating of the Earth’s atmosphere. This is empirical verification of anthropogenic global warming. Since the Industrial Revolution…

‘Prediction of weather and climate are necessarily uncertain: our observations of weather and climate are uncertain, the models into which we assimilate this data and predict the future are uncertain, and external effects such as volcanoes and anthropogenic greenhouse emissions are also uncertain. Fundamentally, therefore, therefore we should think of weather and climate predictions in terms of equations whose basic prognostic variables are probability densities ρ(X,t) where X denotes some climatic variable and t denoted time. In this way, ρ(X,t)dV represents the probability that, at time t, the true value of X lies in some small volume dV of state space.’ (Predicting Weather and Climate – Palmer and Hagedorn eds – 2006)

'Small changes in initial or boundary conditions imply limited predictability with (Lyapunov) exponential growth in phase differences.' James McWilliams (2007) – Irreducible Imprecision in Ocean and Atmospheric Simulations, PNAS

[For weather, yes. For climate, no. See the butterflies post -W]

Model solutions diverge to a boundary defined by the trajectory of solutions determined by sensitive dependence to variable starting points and boundary conditions and by the topology of the global attractor for the particular set of equations. But hey – let’s call it a boundary value problem.

[That was garbled. What do you actually mean? -W]

The problem with Lacis is he goes over such old ground in such a predictable fashion and while Michael Larkin is certainly an unsophisticated questioner - the answer to the question is simple.


[That stuff will work wonderfully at WUWT, where people can't tell the difference between weather and climate. It won't work outside in the real world -W]

And here's the model I accidentally left out -…

This skirmish in the climate wars began with Lennart Bengtsson.

‘As a result of chaos theory, weather and climate cannot be predicted, and how future climate will turn out will not be known until future is upon us… This should be clear to anyone, simply by moving back in time and contemplating what has unfolded from that viewpoint.’

This is true without a doubt – but it leaves Wally Broecker’s wild beast – or perhaps it is Didier Sornette’s dragon-king – snapping at our heels.

[No, its not "true without a doubt", its rubbish. Even you woudn't believe it, if you thought about it -W]

There is a middle position. Between dragon-kings and dinosaur thinking – skirting the inchoate no mans land of blogospheric babble – that is the true heart of the climate dilemma. The true heart is how we evolve as a global civilization this century to provide health, education, safe water and sanitation, sufficient food, security, opportunity and freedom from oppression.

[Don't run away from the science to the politics -W]

The climate equation is thus.

Impact = population X affluence X (CO2 from fossil fuels + black carbon + tropospheric ozone + land clearing + loss of soil carbon + nitrous oxide + methane + sulphide)

Population pressures are the easiest to address. In principle the 8 Millennium Development Goals – – are in combination the best approach to constraining population growth. Ignore for a moment that this is a UN program and so doomed to failure. All of our western governments have committed to raising aid to 0.7% of GDP and this is probably best not sent off to the World Bank but used to supplement existing bilateral aid programs.

You may note that the eradication of extreme poverty is one of the laudable goals. This is in fact best achieved by free trade and the adoption of democracy and models of fair, transparent and effective market regulation. Perhaps it might be best not to use the US as a model. Affluence allows the moderation of most factors in the brackets of the equation – It is quite a good thing for people and the environment.

This is as good a starting point for actual progress on development and multi-gas mitigation as any –

But other than returning the human race to a hunter gatherer state – the only thing that is going to moderate the burning of fossil fuels is technological innovation. This is not a quandary but an opportunity. I am proposing a billion dollar global energy prize stumped up by the UN. That should get people’s attention. Maybe Wally will win a prize. And no I don’t care that giving people cheap and abundant energy would be like giving a child a machine gun.

Robert I Ellison
Chief Hydrologist

By Chief Hydrologist (not verified) on 28 May 2014 #permalink

Dr. Lacis is a fine example of a scientist writing with clarity but without condescension for a lay audience. He also knows that pitching his communication low enough to reach the whole room would render it pointless.

The man is a treasure, and he appears not to mind exposing his fine work to some determinedly ignorant sods at Aunt Judy's. A quixotic impulse to enlighten the heathen, no doubt, but these are some mighty thick heathens he's tilting at, judging by the responses. I wish him luck.

Just about the Greenhouse effect calcs.
In my mind I am imagining these calcs are based on Black body calcs, so the 255k would represent the maximum possible emission temp for the Solar Irradiance for a black body. So the actual greenhouse effect is larger, as the Earth is no black body... Am I making a mistake?

By Nathan Tetlaw (not verified) on 28 May 2014 #permalink

An excellent comment. He must have the patience of a saint to be actually trying to engage in such a discussion at JC's.

[Nick Stokes is the one who really deserves a medal -W]

By And Then There… (not verified) on 29 May 2014 #permalink

Yes the Earth isn't a perfect black body. But its emissivity is still very high in the Infrared bands. In the visible range it can vary from snow & ice which reflect 80-90% of incident SW to water which only reflects around 10% (at low angles of incidence). Rocks, soil, vegetation have a wide range of emissivities in between
In the Infrared in contrast most substances have emissivities above 95% so as far as LW radiation is concerned the Earth is effectively a very dark grey body.

By Glenn Tamblyn (not verified) on 29 May 2014 #permalink

Thanks Glenn!

By Nathan Tetlaw (not verified) on 29 May 2014 #permalink

Thank you for posting this, I'd have missed it otherwise.

[Nick Stokes is the one who really deserves a medal -W]

Yes, I agree. His ability to contribute - constructively - to discussions on contrarian sites is quite remarkable. I really think I would have thrown my laptop across the room in frustration if it had been me.

By And Then There… (not verified) on 29 May 2014 #permalink

In the SalbyStorm text corpus, I found ~133 insults/ad hominems by dismissive commenters directed at real skeptics like Nick, who accounted for 24, #1, with next largest at 18.

Just to pick a random example: of rhino-skin:
'{Nick Stokes} says:
July 8, 2013 at 11:43 pm
Murry Salby was apparently professor for five years. Does anyone know of any scientific papers that he wrote (published or not) in that time?
REPLY: Nick, sometimes I think your head is up your arse. This is one of those times. How could he publish in that sort of environment? – Anthony

[I'm fairly close to writing a post on this. WUWT, and JC's, are toxic; but not only are they toxic, they're infested with "skeptic" trolls, and people indistinguishable from children. The natural question is, why aren't they moderated out? And the natural answer might be, "who can moderate that many comments"? But (a) WUWT's mods can; and (b) a little light moderation would cut down the volume hugely, by factors of two or three, as the trolls lose their self-satisfaction. But (and this is my theory) neither AW nor JC want that - they need the volume, both to feed their ego and to keep the place toxic-proof against others -W]

By John Mashey (not verified) on 29 May 2014 #permalink

The irony is that both AW and JC would like to be taken seriously by the scientific community (AW in particular; JC may be self-aware enough to know that she is burning her bridges). But few scientists will bother engaging unless they dramatically improve their signal-to-noise ratio -- which they refuse to do for the reasons you state.

By Don Brooks (not verified) on 29 May 2014 #permalink

AL has indeed shown a lot of patience on that thread but NS shows such patience daily. A thick skin and a strong stomach is needed for that. With such attributes, it may be a constructive challenging mental exercise. One also has to quickly dispense with the notion that more than a small minority of the denizens are open to changing their mind when presented with evidence. The idea is maybe a few lurkers or passerbys will read and comprehend it, and notice the rabid reaction from the denizens. That's what made AW so furious with NS this week. His was an early comment, not drowned out by the usual attaboys from the tribe.

WMC: I think you meant JC, not JS earlier.

[You're right; fixed -W]

I haven't looked at Climate, Etc much, but in the SslbyStorm exercise, it was clear that Watts and dbstealey especially were quite attentive to suppressing real skeptics , while letting pseudoskeptics say almost anything.

[Agreed. So its not lack of moderation-attention. But I'm pretty sure I've see JC make that excuse; and to be fair, she does have a real life outside her blog -W]

By John Mashey (not verified) on 29 May 2014 #permalink

"Now, by burning all of the available carbon resources in the coming decades, humans would appear have another option available to achieve their self-destruction."

All that actual scientific discussion above to melt back down into emotional hyperbole.

By Joe Mehma (not verified) on 29 May 2014 #permalink

Nick Stokes seems not long for this world at WUWT. Anthony is now saying he is "sure" Nick is a "paid troll". The ban hammer cannot be far behind.

"climate feedback sensitivity of about 3 K for double CO2"

When one correlates observed temperature with GHG forcing, one arrives at about half that rate, 1.6 K for CO2 doubling:

'What is it that determines the terrestrial climate and how it changes?"

Perhaps it's implied but the discussion ignores most of actual climate.

Orbital mechanics, earth rotation, polar energy deficits, equatorial energy surpluses, location of oceans and mountains - these are what determine most of climate.

CO2, of course, does effect the net energy balance, but climate is so much more.

[ -W]

On the non-linearity of atmospheric fluid flow, because CO2 is non-condensing, and occurs at levels above the 'weather', its effect is largely independent of dynamics, giving us some confidence in a warming effect.

Precipitation, however, is largely determined by fluid dynamics, giving us very little confidence in how it might vary, other than to increase in the global mean.

Predictions of clouds, storms, wind, and maybe even humidity also suffer from chaos.

[I don't think you know what you're talking about -W]

Well, we know who WMC is. He is a climate troll and I really enjoyed the "discussion" between him and Pointman.

[But didn't you find it a touch one sided? -W]

By Jimmy Senkov (not verified) on 29 May 2014 #permalink

Oh come on, Eunice:

When one correlates observed temperature with GHG forcing, one arrives at about half that rate, 1.6 K for CO2 doubling

You ignore negative anthropogenic aerosol forcing and the difference between the transient and equilibrium response to net forcing increase.

It's very ho-hum.

"CO2... occurs at levels above the ‘weather’"

Say what?

[I did wonder. Some of it does, I suppose, in the stratosphere. Though I'm not sure what the point was -W]

By Don Brooks (not verified) on 29 May 2014 #permalink

'A vigorous spectrum of interdecadal internal variability presents numerous challenges to our current understanding of the climate. First, it suggests that climate models in general still have difficulty reproducing the magnitude and spatiotemporal patterns of internal variability necessary to capture the observed character of the 20th century climate trajectory. Presumably, this is due primarily to deficiencies in ocean dynamics. Moving toward higher resolution, eddy resolving oceanic models should help reduce this deficiency. Second, theoretical arguments suggest that a more variable climate is a more sensitive climate to imposed forcings (13). Viewed in this light, the lack of modeled compared to observed interdecadal variability (Fig. 2B) may indicate that current models underestimate climate sensitivity. Finally, the presence of vigorous climate variability presents significant challenges to near-term climate prediction (25, 26), leaving open the possibility of steady or even declining global mean surface temperatures over the next several decades that could present a significant empirical obstacle to the implementation of policies directed at reducing greenhouse gas emissions (27). However, global warming could likewise suddenly and without any ostensive cause accelerate due to internal variability. To paraphrase C. S. Lewis, the climate system appears wild, and may continue to hold many surprises if pressed. '

[Or, from the same paper: Removal of that hidden variability from the actual observed global mean surface temperature record delineates the externally forced climate signal, which is monotonic, accelerating warming during the 20th century. -W]

The wild reference was to Wally Broecker's wild beast.

'The climate system has jumped from one mode of operation to another in the past. We are trying to understand how the earth's climate system is engineered, so we can understand what it takes to trigger mode switches. Until we do, we cannot make good predictions about future climate change... Over the last several hundred thousand years, climate change has come mainly in discrete jumps that appear to be related to changes in the mode of thermohaline circulation.'

And to Dideir Sornette's dragon kings.

'These dragon-kings reveal the existence of mechanisms of self-organization that are not apparent otherwise from the distribution of their smaller siblings. We present a generic phase diagram to explain the generation of dragon-kings and document their presence in six different examples (distribution of city sizes, distribution of acoustic emissions associated with material failure, distribution of velocity increments in hydrodynamic turbulence, distribution of financial drawdowns, distribution of the energies of epileptic seizures in humans and in model animals, distribution of the earthquake energies). We emphasize the importance of understanding dragon-kings as being often associated with a neighborhood of what can be called equivalently a phase transition, a bifurcation, a catastrophe (in the sense of Rene Thom), or a tipping point.'

[A classic example of someone making up a name in order to make their work more cited. But its irrelevant here -W]

Judy is about to post something from me on model chaos and climate abrupt change. You have my email. I am happy to supply a copy - and discuss the science openly.

[And you have mine: wmconnolley (at) If you'd like to supply me a copy, please do. If its fun enough, I'll critique it here. I do hope you have more of a clue than Tim Ball, who is utterly clueless:… -W]

The implications of decadal variability - and Wally's wild beast together - are the important policy boundaries de jour. At this stage your scientific myopia is part of the problem and not part of the solution.

[Language like "wild beast" or "uncertainty monster" is kinda fun, but not useful -W]

By Chief Hydrologist (not verified) on 29 May 2014 #permalink

Let's not forget this 2011 golden oldie guest post by CH at JC's:

"All global warming in the past 50 years, the period in which the IPCC say most warming occurred because of anthropogenic greenhouse gas emissions, happened between 1977 and 1998. This is exactly the same period as the last warm El Niño dominated Pacific decadal mode. In the instrumental record, the trajectory of global surface temperature mirrors the Pacific Ocean states. Cool to the late 1970’s, warm to 1998 and cool since. Sea surface temperature is negatively correlated to marine stratiform cloud. Multiple satellite data sources show that over most of the period of warming there was planetary cooling in the infrared band where greenhouse gases were expected to result in warming – and strong planetary warming as a result of less cloud reflecting less sunlight back into space. As a testable hypothesis, the current cool La Niña mode of the Pacific decadal pattern will lead to increased cloud cover and global cooling over another decade or three.

And that cooling is scheduled to start any day now .... any day now ..... tomorrow maybe .... or the day after .... soon.

[It would appear - see my note in CH's comment above - that CH isn't reading the paper's he is quoting -W]

By Kevin O'Neill (not verified) on 29 May 2014 #permalink

What a nice lot of interesting stuff, but I don't envy WMC his self-imposed duty of clarity (particularly with Chief Hydrologist and his ilk. Responses to sundry of "I don't think you know what you're talking about" are delightfully straightforward. Sometimes I just say "no" or "nonsense" which is even less polite. As a semi-informed layperson, however, I'd like to point out that differential equations (my downfall, I wasn't interested enough to do the work, and it was all downhill from there (or not, anyway, on to other interests more appropriate, or I thought so)) are not necessary for straightforward reasoning. One doesn't necessarily have to do much maths to tell the difference between reality and obfuscation. At least I don't think so.

Which brings me to another observation, which may or may not be useful. At least in the US, before university, it's quite popular to dislike knowledge, eggheads, and what have you. Instead of getting past the hump of learning that knowledge can be fun. Lots of people retain their adolescent dislike of being made to appear foolish, or being afraid, or something ...

This effect has been exacerbated by the prevalence of smartphones at a young age, and other social amplifications, that make it fairly hard to pass through the educational system and actually learn how to think. It's the rule rather than the exception, which explains why the obviously untrue holds such sway in our elections.

Well, that may be a bit over the top, but at some perhaps more moderate level, it affects a lot of people who are not likely to show up at Stoat's or other similar places. Too bad, because all this is quite entertaining and enlightening.

By Susan Anderson (not verified) on 29 May 2014 #permalink

Synchronized chaos?

[Its an idea, but it hasn't got much traction. I think its one of those things that works better in carefully constructed coupled PDEs than in reality -W]

Maybe NDT and his pooch can help.…

[I've seen the dog-and-master analogy elsewhere, a couple of years ago. Incidentally, while I'm sure NdGT has his heart in the right place, remember that anything on TV is, fundamentally, something on TV and not to be relied on. See for example… -W]

Watts and Curry are masterful gatekeepers who know how to satisfy their admirers by choosing who to scold and who not to scold.


BBD, SO2 emissions peaked some decades ago so aerosols are not a likely suspect.

What WMC said. Use *global* forcing data.

You have ignored the offsetting effects of negative aerosol forcing and confused transient and equilibrium. Consequently you substantially lowballed a TCR estimate and then tried to claim that this was evidence that ECS was over-estimated.

Ho-hum. Please stop.

The point of Cosmos is it just might reach a good few people who wouldn't otherwise watch. However, the graphics are imo quite ugly. NdGT toots his own preferred horn, egotistical or otherwise, but his choices put in a lot of human interest, direct stories, and indirect talk about denial.

None of us need to know more from that kind of source, I'd guess, even those with whom we disagree. Though perhaps if they believe what they see, they might actually be forced to follow some of their ideas through a bit further.

By Susan Anderson (not verified) on 30 May 2014 #permalink

Eh, moderated again. Perhaps because I used the E-word? Let's see...

[Hush, no clues. And indeed, not in future -W]

To be fair to Wally, he used "ornery beast," meant to, successfully IMO, convey a quality of sudden, unpredictable behavior. I find myself unable to work up to similar attitude of fairness toward Judy, but even if I could I don't think I'd find "uncertainty monster" to be in the same league.

By Steve Bloom (not verified) on 30 May 2014 #permalink

Or perhaps just Eunice. :)

By Steve Bloom (not verified) on 30 May 2014 #permalink

@ Susan Anderson #27
"One doesn’t necessarily have to do much maths to tell the difference between reality and obfuscation. "

Indeed not, and as an English major, I appreciate this affirmation.

#30 continued. Haven't seen more than a few minutes of the new Cosmos but this week's looks interesting. The analogy is a nice concise counter to how deniers "interpret" data points, or AL's explanation condensed. Public communication of science is something Sagan mastered and is badly needed in today's media environment, and NDT has that potential. I would not be surprised to see a few stumbles along the way.

My limited understanding about initial value vs. boundary value is about time scale. If we're talking average temperature over a hundred years, whether you start counting in Summer or Winter, it's not going to matter. If you want to know the temperature tomorrow, that particular initial value piece is relevant.

Where I think it get's problematic in climate modeling is fast response and resolving phenomena like clouds. These are abrupt changes that are initial value problems that need to be incorporated and driven in the larger construct of the boundary value problem. It seems to me that these kinds of abrupt transients that are generated due to initial conditions are not understood well enough to know whether or how they contribute to system damping and therefore the final boundary. There are both large and small effects that are not linear. The particular details of the phenomena may limit the temporal and spatial resolution of the larger boundary value problem as well as the solution.

[IVP vs BVP isn't really about time scale. Its about whether the final solution cares about the initial state (within a fairly wide choice of initial state). If you start a 100 year climate integration from today's atmospheric state, or tomorrow's, or a year ago's, it makes no real difference to the final state. In that sense, its a BVP. Then you can discuss how that applies to the initial ocean state -W]

By Tim Beatty (not verified) on 31 May 2014 #permalink

Lennart Bengtsson has unwittingly provided us with a good example of the logical danger of relying on "observational purism" [a term derived from William's footnote]

Consider this example used by LB as part of his justification for joining the GWPF.


I have always tried to follow the philosophy of Karl Popper that I believe is particularly important when you are dealing with complex systems of which the climate system is a primary example. For this reason empirical evidence is absolutely essential. The warming of the climate system since the end of the 19th century has been very modest by some ¾°C in spite of the simultaneous increase in greenhouse gas forcing by 2.5-3 W/m2.

The context of this remark is that it is intended to help with predictions about the future. According to the science however the evidence given above is incomplete and thus misleading, for example, it omits the
committed warming cw

This omission would be quite natural to an observational purist who would be content to look at the warming so far. This particular criticism of observational purism does not depend on the magnitude of the cw.* The trouble is that the logical approach is too superficial; by refusing to consider the underlying mechanism, i.e. the science, it opens the door to
the neglect of significant variables and thus to the
making of bad simplistic forecasts e.g. by LB's readers.

What about Popper? This comment is long enough, but my guess is that he should neither be given the credit nor the blame (LB provides no reference).
*. It is also unaffected by the second main omission i.e. that of the varying contribution of cooling by aerosols.

[Popper is, IMHO, something of a red flag. His work, of its own, is excellent and valuable; but much like Feynman tends to get abused by people with simplistic views -W]

By Geoff Wexler (not verified) on 31 May 2014 #permalink

The habit of stating that climate is a boundary value problem is unfortunate as it's not. What is true is that climate is not affected by all the details that are essential for weather forecasts.

Some simple energy balance models of stationary Earth system solve a boundary value problem, but in general we have a typical initial value problem solved using methods of initial value problem, but limit our interest to statistical properties of ensembles of solutions obtained using a set of initial values. We are interested also in the time dependence of these statistical properties. Thus the nature of IVP is essential.

By Pekka Pirilä (not verified) on 31 May 2014 #permalink

Re: #42.
Not quite pure ... as always.
I forgot to mention that LB's reference to 'forcing' involves some radiation transfer calculations I don't think that affects my point.

By Geoff Wexler (not verified) on 31 May 2014 #permalink

@WC fair enough on the description/definition. But isn't one of the goals is understand at what timescale the BVP solution is possible within a certain confidence interval? Or even if the BVP has a confidence that isn't affected by random transient events?

As an example, a switching power supply is BVP which has a certain output voltage and ripple. The question of when the boundary is reached, with a certain margin of error seems relevant.

In an intuitive sense, it's not that the butterflies affect what the output is, but rather when. Without a climate modeling background I see a couple fundamental limits.

One is natural climate variability. That error/residual goes to zero at boundary condition. But when does it become insignificant such that we can say we are with 95% of the boundary?

Another is transients. These may by independent like volcanic eruptions. These seem to be a constant error/residual that is likely present at the boundary. A harder case is model transients that dependent on the state of the model (i.e. like feedbacks). they aren't necessarily linear, may be abrupt and short lived and affect convergence time and residual error.

GCMs are supposed to decadally accurate models but how can that be if nature simply doesn't deal with transients? What is decadally accurate mean in terms of the BVP solution?

[I think you're getting a bit confused. I think that when you say "boundary" you mean what most people would call "equilibrium". If we double CO2, and run the simulation out, what is the equilibrium state, and how long till we get to 95% of it, say? In which case, whatever "weather" events that happen along the way aren't too interesting. If you think of it like this, and you construct simplistic PDEs, then you can end up with bistable states, and your final state is affected by the path you take; but its not clear that is applicable to climate -W]

By Tim Beatty (not verified) on 31 May 2014 #permalink

William –
I appreciate your re-posting of my comments from Judy Curry’s Climate etc. Nothing that I have posted at Judy’s should in any way be interpreted as being exclusively “for” Climate etc. Rather, whatever I have been posting there was really just something that was being tossed out into the public forum. Judy runs a free-wheeling blog that has become a magnet for mostly the climate denier types. But there have been a hand-full of commentators there who actually have a good understanding of climate science issues. Why they post there, I don’t know. I comment there (between proposals and research papers, and if a topic of interest comes up) because the blog format is favorable for making detailed, often lengthy comments. I have no illusions that the typical Climate etc. denizen will ever understand or appreciate what I have posted there. I basically write to clarify my own thinking on how best to explain the basic physics of global climate change – a topic that most skeptics want to avoid. And, I tend to steer clear of the complicated discussions that deal primarily with the statistical analysis and interpretation of semi-ambiguous climate data – the favorite topic of climate deniers, since there is no simple explanation, and where they think they can score all kinds of nonsensical points. At Judy’s, in the posted comments, I am writing to explain climate more to myself than in trying to engage a fossil-minded audience. This, for me, makes writing that much easier. It would take me a lot more effort to write sensible comments for RC where I would feel like I would be preaching to choir, and where most of what I would say would already be old news to most of the participants.

A Lacis - Why do ostensibly competent persons like yourself persist in using the term "equilibrium" regarding climate dynamics, sensitivity and the like? Surely you know that the correct term is "pseudo-steady-state"?

Tom C -- What is wrong with the word (not term) "equilibrium"?

By David B. Benson (not verified) on 01 Jun 2014 #permalink

Why do ostensibly competent persons like yourself persist in using the term “equilibrium” regarding climate dynamics, sensitivity and the like? Surely you know that the correct term is “pseudo-steady-state”?
Possibly because - as you've just illustrated - most know what is meant by the term "equilibrium" and it is more suitable to that format than "pseudo-steady-state" - which we could maybe extend to "quasi-pseudo-steady-state" :-)

By And Then There… (not verified) on 02 Jun 2014 #permalink

46 -


You and I would agree on the principles of radiative forcing and observations.

We disagree on this statement:

"Now, by burning all of the available carbon resources in the coming decades, humans would appear have another option available to achieve their self-destruction."

It sounds not like science but appeal to emotion.

Manners, dear. That would be "Dr Lacis".

For someone without much of a clue what they are talking about (see your previous commentary above), you are comically outspoken.

David B. Benson -

The very first definition of term is "a word...".

Equilibrium is used to deine systems that are at rest, both wrt spatial and time gradients. By applying this - ahem - term to the climate you are implying a level of stability that nowhere near applies in real life. Steady-state is the - ahem - term used to describe systems that are not evolving over time but might have drastic spatial gradients. Of course, since climate is always evolving over time, albeit possibly on larger time scales than the component phenomena time scales, the correct - ahem - term, is pseudo steady state.

[Nasty rhetorical cough you have there. You need to get it seen to before it gets worse -W]

Tom C,
A more serious response. Technically I guess you're right that the climate system will never strictly settle to some fixed equilibrium. However, given a certain set of conditions, there will be an equilibrium state to which the system will tend. That is - I think - what Andy Lacis is referring to when he uses that term.

By And Then There… (not verified) on 02 Jun 2014 #permalink

equilibrium ---
n. A condition in which all acting influences are canceled by others, resulting in a stable, balanced, or unchanging system.
n. Physics The state of a body or physical system at rest or in unaccelerated motion in which the resultant of all forces acting on it is zero and the sum of all torques about any axis is zero.

By David B. Benson (not verified) on 02 Jun 2014 #permalink

As it's all a big conspiracy, I suggest "crypto-steady state."

By Steve Bloom (not verified) on 02 Jun 2014 #permalink

I might add that undoubtedly I have the climate denier cult to thank for getting me to write the 2010 Science paper that describes atmospheric CO2 as the principal climate control knob. Specifically, it was Bishop Hill’s unearthing of my critical remarks on the IPCC AR4 Report that convinced me that this Science paper was necessary, even though the basic physics of atmospheric CO2 as the principal driver of anthropogenic climate change, with water vapor and clouds as the fast feedback effects of the climate system, was all basically understood in the Hansen et al. (1984) paper. We might now understand the physics of global warming a bit more clearly and convincingly, but others may claim that it was all understood by Svante Arrhenius in 1896, but that nobody paid attention.

Similarly, the objective to describe the global warming problem more fully in terms of the basic physics involved in our 2013 Tellus B paper can be connected to formulating common sense physics based responses to any number of inane pronouncements and misrepresentations being bounced around at Judy Curry’s. So, here also, it was mostly repackaging the basics of climate science and providing more detail on radiative transfer modeling issues, and on the speed and nature of the water vapor and cloud feedback response. Perhaps the one new item was to note that the ≈3K equilibrium sensitivity for doubled CO2 can also be inferred directly (by radiative flux attribution) from the atmospheric temperature-absorber structure, in addition to the geological ice core record and climate model simulations of equilibrium and transient climate change.

"Cloud feedback effect does not appear to be a major player since the cloud SW albedo effect is largely "counteracted by the cloud LW greenhouse effect."
Sorry, not true, The cloud SW albedo effect always comes before the cloud LW greenhouse effect. In essence an increase in water vapor with any increased heat from the sun or from CO2 forms more cloud , greater albedo, less heat to get into the greenhouse.
This is what stops any life threatening increase in temp for now over 2 billion years ands is the reason why climate sensitivity is much less than the doctor asserts.

At no point does A Lacis insist that the earth *will* reach equilibrium. "Equilibrium" is defined in the following sentences as a point towards which the earth system tends:

AL: "For equilibrium sensitivity evaluations, the objective is to reach the equilibrium point toward which the model is being forced independent of the initial conditions."

AL: "The Earth is never in precise SW-LW energy balance equilibrium, but it is always striving to get there. When models are run for thousands of years with fixed external forcing, they exhibit a natural variability over a broad range of time scales relative to some reference point that can be identified as the global energy balance point of equilibrium."

And note the subjunctive "would be" rather than "will be" in this sentence:

AL: "In energy balance equilibrium, the thermal energy emitted to space by Earth would be..."

So in terms of judging this as an attempt to communicate the concept, "equilibrium" was the correct word used in the correct way in my opinion.

By Steve Milesworthy (not verified) on 03 Jun 2014 #permalink

Care to provide some evidence rather than simply asserting something? Here's some evidence for you. Figure 1 of Soden & Held (2006) shows the different feedbacks. According to that paper, clouds provide a small positive feedback, not negative.

If BBD were around, he might ask how we've had any past climate variability if what you suggest were true.

By And Then There… (not verified) on 03 Jun 2014 #permalink


This is what stops any life threatening increase in temp for now over 2 billion years ands is the reason why climate sensitivity is much less than the doctor asserts.

Dr Lacis did not assert. A paper was published in a respected journal, and a link provided.

ATTP is correct: low climate sensitivity would flatten out paleoclimate variability. This is directly contradicted by everything known about paleoclimate behaviour.

This is how you can show yourself that you are mistaken.

This is what stops any life threatening increase in temp for now over 2 billion years

Did you just assert that cloud albedo is is the dominant negative feedback over the last 2 billion years?

Well, that's novel...

I wouldn't engage with angech. There is a very real problem with actual meaning of words. Take this comment made at JCs:

Commenter: And you have to diversify your portfolio before the stock market crashes.

angech: I tried this, but buying more stocks i.e. diversifying only means you lose more money when the market crashes.

As you can see, not only does angech not know what the word diversify means, but apparently is unable to use Google to look it up. There really isn't enough time in a day to deal with every version of ignorance that has been released into the wild. angech's personal jihad on cloud feedbacks is not rooted in a thorough understanding of the science and engagement will not result in anything productive.

By Kevin O'Neill (not verified) on 03 Jun 2014 #permalink

32 -

What WMC said. Use *global* forcing data.
Yes global SO2 emissions have declined for decades and your chart shows aerosols forcing has declined for the last twenty five-years. 'Aer-Cld', shows flat for the last twenty years.

You have ... confused transient and equilibrium.

No, I have not.

I have pointed out that the observed climate response is all that really matters.

[You've asserted that, but I don't believe it. We care a lot about attribution, and the sensitivity of the climate to CO2. That can't be pulled directly out of observations -W]

This is all well and good, but the radiative aspects are, as the IPCC reports indicate, well known.

What I find more interesting is that while no one was looking, more people decided to not make babies.

Global total fertility, according to CIA data book, is now at 2.45, continuing to fall at around 0.03 per year.

The global average replacement rate is around 2.33.

We are very close to declining human population.

This will be at or below the old IPCC B1 population scenario.

With declining population, so too will CO2 emissions decline ( not stop, but decline ).
With declining CO2 emissions, so too will the rate of radiative forcing decline.
With declining rate of radiative radiative forcing, so too will the rate of warming decline.

[All of a sudden, you've changed the subject -W]

"With declining population, so too will CO2 emissions decline."

Not necessarily.

It's quite reasonable to expect we could have fewer but wealthier people who all want cars and air conditioning and all the other nice things in life that take fossil fuels to run.

The real answer, of course, is that nobody knows. That's one of the reasons renewables are attractive: we can all have those nice things but run them on something other than fossil fuels (or use less fossil fuels).

By Don Brooks (not verified) on 03 Jun 2014 #permalink

your chart shows aerosols forcing has declined for the last twenty five-years.

No, it doesn't. You can't read a graph, can you?

Try again.

I said that aerosol negative forcing had offset GHG forcing and so it has. Since you ignore this offsetting, you under-estimate the efficacy of GHG forcing in your "observational" estimate of S. And as WMC points out, you cannot derive S purely from a short time-series of limited and somewhat uncertain observations anyway.

You were and remain wrong. This was and remains tedious.

66 -
True enough, China and India are enjoying rising out of poverty and with that, emitting more per person, but if the developed world, where per capita emissions are falling is an indicator, India and China will also reach a peak and begin per capita declines.

67 -

Right - there is less offset today than there was in 1990.

#69 does not address the point at #67, which is that you have ignored over its entire extent the offsetting effects of aerosol negative forcing and that this has caused you to under-estimate the forcing efficacy of GHGs, mainly CO2.

It's time you conceded the point.

Thanks to Andrew Lacis for the useful comments to to WMC for unearthing them from a site that might not appreciate them as much :-)

By John Mashey (not verified) on 03 Jun 2014 #permalink

BBD in #70 "It’s time you conceded the point."

Good luck with that. Eunice still believes that GHG forcing is decelerating despite linking to a graph that shows it is not. The basic math of a growth rate is a riddle, shrouded in mystery, wrapped inside an enigma for some people.

By Kevin O'Neill (not verified) on 03 Jun 2014 #permalink

#68: The problem with this is that one of the main reasons (actually, if I recall correctly, the only reason) that emissions have been declining in the developed world is that we've off-shored a lot of our carbon-intensive activities (such as manufacturing) to places like China and India. Now, whilst it's possible that they can achieve per-capita declines by pulling the same trick (say, by off-shoring their manufacturing to Africa), it's not possible to reduce global emissions by this route unless we start "off-planeting"...

angech’s personal jihad on cloud feedbacks is not rooted in a thorough understanding of the science and engagement will not result in anything productive.

Angech perhaps is one of those that has gone Emeritus?

From a comment he left at Climate Etc

angech | June 4, 2014 at 3:48 am |

I am a member of the AGU, and am currently a member of the Fellows Committee that selects Fellows for the Atmospheric Sciences Section. In the near term, I will remain a member of the AGU and I am highly supportive of Peter Webster’s efforts to work within the organization to effect change. But I am increasingly conflicted about my membership in the AGU."

By WebHubTelescop… (not verified) on 04 Jun 2014 #permalink

WHUT writes:

angech | June 4, 2014 at 3:48 am |

I am a member of the AGU, and am currently a member of the Fellows Committee that selects Fellows for the Atmospheric Sciences Section. In the near term, I will remain a member of the AGU and I am highly supportive of Peter Webster’s efforts to work within the organization to effect change. But I am increasingly conflicted about my membership in the AGU.”

Here's the list of AGU Atmospheric Sciences Fellows Committee members:

Kuo-Nan Liou (chair)
John P. Burrows
Judith A. Curry
Anthony D. DelGenio
Robert A. Houze
R. Alan Plumb
Patricia K. Quinn
Cora E. Randall
Alan Robock
Raymond Pierrehumbert

I would be very surprised if angech is actually one of these people.

By Kevin O'Neill (not verified) on 04 Jun 2014 #permalink

Thanks for the clarification @WHUT. I was puzzling over the people in that list.

How surprising that Curry would support Peter Webster.

By Don Brooks (not verified) on 05 Jun 2014 #permalink

Re #57.

The cloud SW albedo effect always comes before the cloud LW greenhouse effect

That is nearly 100% wrong for at least 50% of the time. What about the hours of darkness?

Note, absence of differential equations.

By Geoff Wexler (not verified) on 05 Jun 2014 #permalink

How surprising that Curry would support Peter Webster.
Was that irony?

By And Then There… (not verified) on 09 Jun 2014 #permalink

I would include in these discussions a description of the net rate of the energy increase in watts per meter squared or if you wish the energy increase in joules per year or whatever you think is the best convention. I have been mentioning this point because the best way to check these estimates may be to do a sum of the total change in the system's energy. I suspect the potential flaw arises from the statement that attributes x to water vapour, y to clouds, and z to co2 and minor gases. Given the delicate balance (or lack thereof), a tiny change in these x y and z figures does change climate sensitivity. Therefore the best method you can use to check whether your estimates are fairly close is to monitor total system energy as it evolves over time. Does this make sense?

By Fernando Leanme (not verified) on 20 Jun 2014 #permalink