The presentations from the Climate Science tutorial last month have all been posted (links below), and Myles Allen (the first presenter for the plaintiffs) gives his impression of the events.
Guest Commentary by Myles Allen
A few weeks ago, I had an unusual — and challenging — assignment: providing a one-hour “tutorial” on the basic science of human-induced climate change to a Federal District Court in San Francisco. Judge William Alsup had requested this tutorial to bring him up to speed on the fundamental science before proceedings begin in earnest in a case brought by the cities of San Francisco and Oakland, on behalf of the people of California, against a group of major fossil fuel companies, addressing the costs of climate change caused, they argue, by products those companies have sold.
The format was straightforward — two hours each for the plaintiffs and the defendants, and the judge had provided us with a series of questions on the essential physics that he wanted addressed, as well as requesting a timeline of how our understanding of climate change has evolved over the past 150 years. My presentation was followed by Professors Gary Griggs, showing detailed projections of sea-level rise and its impacts on California, and Don Wuebbles, presenting key findings from the latest US National Climate Science Special Report (also speaking for the plaintiffs). Between Gary and Don, the Court heard from Theodore Boutrous, a lawyer speaking on behalf of Chevron, one of the defendants.
The case was fairly widely covered, (here’s an example) and most of the attention was, understandably, on what the oil companies had to say: the fact that Gary, Don and I agreed with the IPCC was hardly ever likely to be newsworthy. But I’ve had a few requests since about what I presented — including from some students who spotted that a carefully compressed summary of climate change science might be quite handy revision material. So, with exam season nearly upon us, here it is — or at least, here is what I would have presented if I’d got through it all: in preparing this material, I had completely failed to anticipate the number and depth of Judge Alsup’s questions, so we only got as far as the Charney Report.
Prior to the hearing, Andrew Dessler on Twitter, Gavin Schmidt at RealClimate and Oliver Milman at the Guardian all had a crack at the judge’s questions:
Here are answers to questions posed by the Judge Alsup re: climate science (https://t.co/DLFDT70PdL). Turns out answers to those questions are actually pretty well known. 1/
— Andrew Dessler (@AndrewDessler) March 8, 2018
Answering Alsup's climate questions. Can we crowd source the best responses?https://t.co/Wft3JYQK4S@AndrewDessler @RealClimate
— Gavin Schmidt (@ClimateOfGavin) March 12, 2018
A judge asks basic questions about climate change. We answer them https://t.co/UT11hOHLOr
— Guardian Environment (@guardianeco) March 21, 2018
I was definitely more ambitious and I go into more detail than Gavin, Andrew and Oliver on how attribution works, partly because that’s what I do, but also because just telling the judge “the IPCC says the warming is pretty much all human-induced and 80% of that is CO2” would have been a bit circular, having been involved myself in those IPCC assessments since the 1990s.
My contribution had its ups and downs — a low point was definitely when Judge Alsup declared “your chart sucks” in response to a powerpoint slide (right) which showed an artist’s impression of the Nimbus 4 satellite at the expense of a graph of how the spectrum of outgoing long wave radiation changed in response to rising greenhouse gases between 1970 and 1997. Frustratingly, the chart he wanted (from John Harries’ 2001 paper) was hidden under the pretty picture, but we were already late and I chickened out of breaking open the powerpoint to move figures around in a live courtroom. But the high point came just a few seconds later, when he asked “so, how much did the temperatures [of carbon dioxide molecules emitting energy to space in those critical wavelengths of the infrared] fall over those 27 years?” — showing that, after only half-an-hour, and despite my obscure charts, he had already got a better grasp of the basic mechanism of the enhanced greenhouse effect than many.
I’ve restored that spectrum to its rightful place in the version below, as well as adding some more material on molecular dipoles at the beginning, since Judge Alsup (and others since) had questions about how it was that carbon dioxide molecules could act on infrared radiation over a much larger volume than the molecules themselves actually occupy. I’ve also added some more material later on to address other questions that came up. The material I actually covered at the time is all available on the court record.
The edited presentation runs for just under 45 minutes, and I’ve broken it up into five segments. I’ve also put up the powerpoint in case you want to use some of the graphics in your own teaching. I hope it’s useful.
Tutorial: The basic science of human-induced climate change
Part 1
Part 2
Part 3
Part 4
Part 5
Presentation: The basic science of human-induced climate change
Text adapted from original post at ECI with permission.
Denialists like to bring up the Sun and it is the driver. Well for the past 12 years our Sun has been in a “quiet phase” with little or no sun spots and lower luminosity. The rise in global temperatures have not abated. So that means that though the Sun will affect it even at its reduced state the warming part of it is rising. Only when it eventually comes out of it and it will sometime soon the greater luminosity and heat will drive it up even higher —- faster. Which means we have wasted this grace period. And the effects will also speed up. The water cycle already has increased in speed which explains more floods and also heavier snow falls and the Polar vortex moving out of its usual place stretching down very far almost to the Gulf of Mexico. It is all related. And as the oceans heat eventually they will stop absorbing atmospheric CO2 and start emitting it. Which means that the CO2 taken out of the air by our oceans will be spit back into it adding to the problem. However the continuing ocean heating is causing its own problems as fish and other animals move north or south to cooler climes, a blooming of jelly fish which can take the heating oceans and the acidity and the very dangerous signs of the anaerobic sulfur bacteria is rising from the cooler depths. Then there is the beginnings of the Greening of Antarctica which is now in our lifetimes it is starting. What Nature takes thousands to millions of years to accomplish, humans can do so in hundreds of years and it will speed up even faster once our Sun “wakes up”. If you think it has been fast these last 16 years it will be much faster then.
As of now we are screwed and we did it to ourselves. One of the pitfalls of intelligence.
I wish I could take a peek at 2145, the year of the novel “The Drowned Earth” and see how similar it might be. The billionaires better get cracking for luxury space stations and building archologies in Antarctic.
I would prefer we solve it and start walking it back to something more like it was before the rise beyond the comfort levels.
Dan DaSilva @ #98 — As I stated, see the Wikipedia page on Pliocene climate. There is also a page with more details and references on the Brave New Climate Discussion Forum in the Climate Change section.
99 Kevin McKinney
Thanks for the detailed response.
“talking about historical periods” No, I am thinking of a period where actual thermometers are used. (Reconstructions lack accuracy and precision needed for sub 0.1 degree determinations)
“completely independent of ECS.” Be careful when using the term ECS, I have being schooled here (at RealClimate comment threads) that there is no ECS as such. It is actually models performing detailed and complex calculations simulating molecular interactions and electromagnetic emissions to produce atmospheric molecular vibrations which after a period of time can stabilize and then can be used to infer ECS. ECS is a man made concept. (See what schooling will do for you,)
“All of which is less conclusive than anyone would like.” Well that is life, uncertainty, it is what we have to live with. We try to overcome with theories, our belief in God or radical environmentalism.
Climate scientist are not radicals, just as not all religious people are hardliner fundamentalist. However many people go into lines of work that nurture or confirm their need to contain chaos.
Finally let me redo my statement to something you may agree with: “model spread is NOT completely independent of ECS.” I admit to not doing the hard work required to verify a statement that indicates a very high independence of ECS. I hope this misdeed will not stop your wonderful commentary on my sometimes provocative comments.
PS: I have not seen any hind-casting that is out of wack with temperature record, if you have of one please link.
Thanks, Dan
DDS,
Nigel is right. You are assuming that there is some “curve” to be fit. That is not the case. Temperature is only one of the elements the models reproduce. There is also precipitation, wind patterns (in some models you an even make out cyclonic activity just at the limit of resolution) and so on.
While I believe that you have written code before, it is clear that you’ve not written anything like this.
The frustration of dealing with folks like you and JB and Weaktor is that you aren’t arguing about climate science as it is, but rather some straw man that is the construction of your own mind or one you inherited from the brain trust on Faux and Friends. In your own mind your picture may make sense, but it bears no resemblance to the reality.
Ask yourself this, Dan. If climate scientists are all environmental extremists and hacks, then why has the National Academy explicitly endorsed the conclusions of the IPCC? Are they all green fascists, too? How about the CIA? The Pentagon? Every professional organization of scientists with relevant expertise? How do you make these facts fit in your cozy, little picture?
What do I mean by “curve fitting” in this thread? I mean any process which tries to determine the underlying physics of a process by adjusting the math (or model) so that the output resembles the measured values and then assumes to have found the fundamental process. If you find a measured process which has an output that closely follows f(x)= x*x, is the process actually x*x? The answer is maybe, but it also may involve more complicated factors which are unknow.
Note, I assume nothing about climate scientists other than they are examples of intelligent humans pursuing a noble calling. They are no worse than myself but do understand climate science far better.
DDS:
What nonsense. ‘Climate Science’ does know what the climate sensitivity (ECS) is: it’s a probability density function. For example, Cox et al. 2018 (my emphasis) report they have “reduced the probability of ECS being less than 1.5 degrees Celsius to less than 3 per cent, and the probability of ECS exceeding 4.5 degrees Celsius to less than 1 per cent.”
AGW-deniers often seem convinced that coupled GCMs are developed to output preferred ECS estimates for mysterious ulterior purposes, rather than to test climate scientists’ understanding of AGW’s physical mechanisms. By suggesting that the failure of ECS estimates to converge casts meaningful doubt on the scientific case for AGW, JB and DDS merely reveal how alien they are to the modern culture and practice of the Earth Sciences.
In reality, ongoing efforts to narrow down ECS are an excellent example of the self-correcting nature of Science. That’s clear from recent peer-reviewed reports such as Marvel et al 2016: Implications for climate sensitivity from the response to individual forcings, and Sherwood et al. 2014: Spread in model climate sensitivity traced to atmospheric convective mixing.
But never mind the failure of ECS estimates to converge! IMHO a 95% confidence interval for ECS of 1.5 to 4.5 degrees is more than specific enough to motivate aggressive decarbonization!
@105
So then, your contention is that when Galileo–that investigator so beloved and supposedly emulated by by deniers in other contexts–after having spent much time and effort showing that balls rolling down inclined planes followed a simple x*x equation he could not assume to have found a fundamental process at work?
I’ve watched the 1st 13 minute tutorial video. Quite good actually, but I have some questions/comments:
1) He says the stretching/bending of the CO2 molecule interacts greatly with IR. But he never gets into why exactly that causes heating. He never talks about an IR photon hitting a CO2 molecule, and what occurs when that happens – if this is the mechanism that causes heating, how does it do it? And what happens if an IR photon hits an O2 or N2 molecule – why doesn’t that cause heating? Why doesn’t that collision prevent the IR radiation from escaping to space? And an explanation, perhaps with some calculations of mean beam length, etc. could be useful.
2) At around 11:00 he shows a graph with the brightness temperature of the 1970 satellite and of the 1997 satellite superimposed on the same graph. It appears to me that they are right on top of each other, thus little or no change between the two. Why does he say the graph shows a reduction of energy between 1970 and 1997?
3) They sent these satellites up to study IR from the earth, and the effect of CO2, yet at around 11:35 he notes that they can’t detect in the most important absorption range of 15 microns and a little to the left of that. Why send up an instrument that is blind to the most important part of the spectrum?
DDS 105: What do I mean by “curve fitting” in this thread? I mean any process which tries to determine the underlying physics of a process by adjusting the math (or model) so that the output resembles the measured values and then assumes to have found the fundamental process.
BPL: And you’re absolutely convinced that climate modelers are doing that, right? So that it’s absolutely futile to explain to you that they’re not. Just wanted to make sure.
https://scontent-sjc3-1.xx.fbcdn.net/v/t1.0-9/31870436_1669279999854988_8235741528295735296_n.jpg?_nc_cat=0&oh=b2274e8b009d5eabe23a0370c98d0b24&oe=5B9AA70A
66 Night-Gaunt49
Evolution has been proved over and over to be a fact?
I don’t think that is true with respect to the origin and history our species. It’s a theory – it may be 100% true, no one knows, even if they are 100% positive they do know. AND if it is true, that does not mean that creation is false. Perhaps the first man created was a caveman or a lizard man. :) We will never know as long as we are living on this earth.
I’d say AGW was more provable than evolution because it’s a math problem. It’s in debate because most of us don’t understand the math. You have to make some leaps to say that evolution is a fact.
Troll @~ 111
Ugh. KMN.
Way to crank out the assertions with zero knowledge of the subject.
(He doesn’t know what a theory is. Doesn’t… Oh why bother.)
BTW, evidence can be evidence without “math” (whatever you think you mean by that). Your homework for tonight is to come up with an example of why that might be so.
Better yet, here’s a suggestion; if you simply can’t contain yourself, why not post your OT trolling on the UV thread.
Mr KIA @111
The theory of human evolution is very compelling, and I think completely certain, as certain as you can be of anything in this life. I suggest look at the fossil sequences of human ancestors from early apes to australopithicus, homo erectus and homo habilis to homo sapiens, and notice how they morph one into the other quite smoothly, all explained by Darwinian evolution, while with respect the old testament verision is clearly a creation myth like you find in early greek and roman culture etc , an imaginative guess, and very implausible in light of our current understanding of things. That doesn’t invalidate some of the ethical teachings through the old and new testaments etc.
I would dispute that agw is in debate because people dont understand the maths ( and I presume you mean the physics as well). It might be for a few people, but not most. Consider most people seem to accept einsteins theories and don’t understand the maths. It needs years of university study to understand the complete physics and maths behind much of this.
The reasons for the agw debate are obvious in peoples comments and personal backgrounds if you do some checking on linkedin etc. Look at people who post denialism, and many of them have vested interests, for example they are engineers with links to transport or power industries, and many others have libertarian style political views opposed to environmental laws, a few are eccentrics with huge dollops of dunning kruger syndrome, and some are conspiracy theorests, or some combination of all this.
Their objections to agw all lack rationality, because their real underlying objections are driven by vested interests and politics.So they clutch at any argument no matter how superfical and stupid like CO2 is plantfood, climate changed before, its a liberal conspiracy, data is fake and endless assorted nonsense.
http://lyrics.wikia.com/wiki/Chris_Smither:Origin_Of_Species
Night gaunt, #66
“I don’t believe in Anthropogenic Global Warming (AGW) anymore than I believe in the theory of Evolution. Both have been proven over and over again to be a fact.”
A little bit of a stretch to call these theories facts. I would say these are well established and sound theories supported by quite strong evidences. But ok I got your point and agree on that.
But what is mostly debated is not really just AGW but the C in the CAGW, or say the sensitivity. So you need to find an equivalent for evolution. That would be more about the debate on genetically modified organisms and their long term consequences. Or maybe a theory about an on-going (catastrophic) mass extinction due to anthropogenic causes?
Do you believe in these theories as much as you believe in CAGW?
Re 108
KIA you wrote:
When an IR photon hits a greenhouse gas molecule e.g. CO2, it causes the molecule to vibrate even faster. When an air molecule collides with the CO2 molecule the vibrational energy is converted to kinetic energy and the air molecule is now hotter, while the CO2 molecule returns to its ground state. (The temperature of air depends on the average kinetic energy of its molecules.)
When a “hot” air molecule collides with a CO2 molecule, it can also cause the CO2 molecule to vibrate faster, and the CO2 can emit this additional energy as a photon.
You also wrote:
.
Well spotted! The graphs do not show the effects of more CO2 since they are of the IR window where only ozone is acting. What it shows is that the radiation being emitted in the IR window has increased because the temperature of the surface of the earth has increased.
The satelittes were not sent up to only to measure IR radiation. Harries et al. took advantage of the data from them to use in the paper.
A distinguished climate scientist ignores the uncertainty of climate science and assumes facts which have not been established according to the scientific consensus. Is he refusing the consensus, dare say a denier?
For if science is to be about anything it must be about the truth and in turn it must be about logic. However this is not about cold hard logic, it is about emotion. Simple logic has no sway.
For the human race is a not like cold Mr. Spock we are the good Dr. Leonard McCoy. That is not a bad thing it is human. It is what allows us to love and sadly to hate.
@111
ALL scientific facts require the scientific observer to make many leaps. Such is the nature of scientific inference.
Primarily those leaps involve engaging in decades of intense study and work in science on the part of the scientific commentator–something you are clearly lacking.
KIA 108: But he never gets into why exactly that causes heating. He never talks about an IR photon hitting a CO2 molecule, and what occurs when that happens – if this is the mechanism that causes heating, how does it do it?
BPL: If the photon is the right wavelength, it kicks an electron in the molecule up to a higher energy level. The molecule now has higher energy–if a lot of them have higher energy, their temperature is higher, because they’re moving faster.
KIA: And what happens if an IR photon hits an O2 or N2 molecule – why doesn’t that cause heating?
BPL: Wrong wavelength. They don’t have many absorption lines, so the chance of the photon being just the right wavelength is small. It’s a quantum effect.
KIA 111: You have to make some leaps to say that evolution is a fact.
BPL: Evolution is a fact–we know from the fossil record that different organisms existed at different times, and unless you postulate constant acts of micro-creation, it makes more sense that stage 11 evolved from stage 10. Natural selection is the current consensus theory of how evolution happened. That it happened at all is not really in dispute. We have seen speciation in real time (see the talk-origins site for examples).
Mr. KIA,
A few points regarding your questions in #108:
1)What causes the heating? The Sun–a more or less constant amount of energy coming in and a more or less constant amount of energy leaving at equilibrium. Now decrease the amount leaving–it’s exactly like putting a lid on a pot over a stove. If your question is how the energy trapped by the atmosphere gets transferred to O2, N2…, the answer is that the excited vibrational state of CO2 is long-lived. As such, it is actually as likely or more likely to relax by colliding with another molecule (mostly N2)and transferring the excitation to the N2 as kinetic energy–heat.
2)It is unfortunate that they chose a light grey for the earlier mission, especially given the scale. However, you can clearly see the difference in the 2nd graph and even in the top graph if you look closely at magnification.
3)I cannot say exactly why the IRIS instrument was measuring in the wavelength range it was. However, in general there are reasons why a range is generally selected. I think the detector for this instrument was HgCdTe–a ternary semiconductor that can be tailored to absorb a particular wavelength range by varying the amounts of Hg and Cd. So, why not pick a the exact center of the wavelength? I can think of several reasons:
a) The instrument was not specifically designed just for CO2, but to measure a broad range of compounds in the atmosphere.
b)There really isn’t a whole helluva lot of IR leaving Earth in the center of the CO2 band. This makes it difficult to detect changes, since you are looking right at the top of the troposphere. The real action–and where most of the change is occurring is in the wings of the line. That is why you have the logarithmic dependence on CO2 concentration.
c) You are measuring in the IR, so as you go to lower wave number (longer wave length) there is more thermal noise from the detector and spacecraft itself. They had to actively cool the detectors as it is.
As to the theory of evolution–it has been shown to be true repeatedly, and it is the only mechanism that explains the evidence. I’m not just talking about the fossil record. Consider the human knee or back. If they are “designed,” then the designer is clearly an imbecile, a sadist or both. Intelligent design is clearly inconsistent with the facts–stupid design is more like it. The solutions evolution comes up with need not be optimized; they only have to work well enough. That’s how well they work.
KIA, #108–
At bottom, heat is motion. In fact, that’s an actual John Tyndall title, pretty much:
https://www.amazon.com/Heat-Considered-Mode-Motion-Institution/dp/1145853978
So the motion induced in the GHG molecules is, itself, the heat.
(I probably should stop here, as my understanding of the physics is much shallower than that of many folks here. But perhaps they will correct any misstatements I may make–and if they do, then my understanding will have expanded a bit. So, in the interests of learning, all the way ’round…)
Most of the heat/energy is passed on to other molecules in the atmosphere (including O2 and N2) via collision), but sometimes randomly collisions are avoided long enough for the energy to be re-emitted as a photon once again–emitted, significantly enough, in a random direction, which means just as likely downward as upward.
(This re-emission seems deeply mysterious to me, at least, in that AFAIK about the only characterizations we can place on it are that its quantized in definable ways and that there is a statistical time function of some sort associated–and yet it’s also the most everyday thing imaginable, in that emitted thermal radiation is just what physical objects do, all the time, unless they are at absolute zero. Above that, and they’ll emit radiation with a frequency dependent upon the temperature–the hotter the temperature, the higher the frequency, as implied by idioms such as “white-hot”.)
The implication is that the O2 and N2 molecules–along with argon and whatever else is in the atmosphere–re-emit randomly, too. That’s the origin of ‘back-radiation’–a phenomenon the existence of which has actually been denied by some, despite the fact that it has been studied and measured for about two centuries now, in a pretty interesting byway of science history:
https://hubpages.com/education/Fire-From-Heaven-Climate-Science-And-The-Element-Of-Life-Part-Two-The-Cloud-By-Night
OK, final bit, and I hope I’ve got this right. The question remaining is: What happens to the photons involved? If they ‘interact’ with a GHG molecule as we considered above, they cease to exist as such. They are annihilated, all their energy is transformed into kinetic motion. Which, obviously, explains why that particular packet of energy doesn’t make it to space directly.
But you ask about the contrary case in which a photon ‘hits’ O2 or N2. This is where I’m *really* getting above my pay grade, but the bottom line point is that the photon is not annihilated, and its energy is not transformed into motion. I suspect that its trajectory may be affected, since diffraction, refraction of electromagnetic radiation are all optical phenomena well-known since Newton and before. I’d love to know more about the details: is this case like a perfectly elastic collision, or are there subtler effects on the radiation’s characteristics (polarization, phase shifts, frequency shifts?) If the latter, then how does the energy ‘accounting’ work?
Frankly, I haven’t a clue. But to a pretty good approximation for current purposes, the photon just keeps on going, headed for space (or a GHG molecule, whichever comes first).
N.B.: Don’t forget that this is all frequency-dependent (or wavelength-dependent, which is the same thing, just viewed from the converse perspective). The entire foregoing discussion pertains only to specific wavelengths that correspond to ‘resonant frequencies’ of molecules which are associated with terrestrial temperature ranges. The higher-frequency ‘solar photons’, if reflected by something on the surface (be it an ice-sheet, a body of water, or someone’s windshield) will happily change course and zip right out of the atmosphere again, completely unaffected by GHGs (though not by cloud, of course.)
> We will never know
<a href="https://ipfs.io/ipfs/QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco/wiki/Ignoramus_et_ignorabimus.html"Ignoramus et ignorabimus
Fixing that: https://ipfs.io/ipfs/QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco/wiki/Ignoramus_et_ignorabimus.html
Ignoramus et ignorabimus
10:25 to 12:05
In that first tutorial video, from 10:25 to 12:05, I can see little to no difference between the 2 data curves in graph a. (One is a dark solid line and one is a light gray line.) Does everyone agree with me that the 2 data lines are very nearly the same for graph a? The video is not the sharpest image so maybe I’m missing something. It looks on my screen like the two lines are essentially on top of each other left of the 800 mark – all agreed?
In graph b, there is a dotted straight line and a solid dark line. There is no “key” saying what they are. I think he’s saying the dotted line is the brightness line in 1970, and the dark line is for 1997, right? So the 1.5 degree cooling occurs from around 700 to 770 cm^-1, right? But most of the rest of the graph shows little cooling except for the area from 1200 to 1400 cm^-1 due to CH4, right? It looks like the CH4 has an even greater cooling effect than the CO2 or am I not looking at this right?
Then, I will have to wait until my PBR wears off to think about the net cooling effect on the atmosphere from these small parts of the spectrum. Hmmmmm…..keep your hand off my PBR!
https://www.youtube.com/watch?v=TfBRDgc4d20
KIA wrote, “We will never know as long as we are living on this earth.”
Then, perhaps we should ask Neil Armstrong what he thinks!
But seriously, as stated in Hank’s link “David Hilbert suggested that such a conceptualization of human knowledge and ability is extremely pessimistic. We can find answers to many of these questions, and by considering them unsolvable, we limit our understanding.”
Moreover, evolution has been demonstrated in the geological record and was known to Darwin’s grandfather..
What Charles Darwin achieved was an explanation for the myriad of species through natural selection. This simple mechanism; that species evolve to fit their environment needs no mathematical formulas – it is just basic logic and is being recorded as happening now.
DDS: “A distinguished climate scientist…”
Pray, does said climate scientist have a name? Are you speaking in hypotheticals to cast aspersions onto the field or are you merely afraid to speak in terms of verifiable facts because you are in fact bullshitting.
You are descending ever further into the irrelevancy of “not even wrong.”
The detail on absorption or emission of photons by CO2 is quite complicated. A good place to start is “Vibrational-Rotational bands”
CO2 has internal degrees of freedom in addition to the translational. The vibrational level spacings are typically in the infrared, the rotationals in the microwave. Each vibrational level has a cluster of rotational sublevels. Transitions between these levels is governed by quantum numbers and are allowed or forbidden by selection rules, so the energy of photons emitted or absorbed is subject to these rules.
Energy from the internal modes can be exchanged with other gas molecules in a collision.
sidd
Hank Roberts:
Anyone who rhymes ‘cabbage’ with ‘adage’ is a poetic genius, IMHO.
Chris Smither talks about singing that song in several of the wrong venues.
In one, a woman asked him “You don’t really believe in that, do you?”
And he answered: “It’s not something you believe in. It’s something you know about. Or don’t.”
DDS, #103–
You ask:
Sorry not to reply earlier, I missed that comment originally.
But yes, if I understand your question correctly, all you need is to look at a ‘spaghetti plot’ of global mean surface temperature, including all or many individual model runs. You’ll find that, within a somewhat arbitrarily-defined ‘ensemble envelope’, individual runs are pretty much filling the space at any given time. That means that at any given time, more runs are ‘out of whack’ with the historical trajectory than not. Here’s an example from Chapter 9 of AR5:
https://ipcc.ch/report/graphics/index.php?t=Assessment%20Reports&r=AR5%20-%20WG1&f=Chapter%2009
(I think that link is to all the Chapter 9 graphics, but the plot I’m speaking of is Figure 9-8, the eighth image in the chapter. You can click on the appropriate thumbnail to bring it up.)
You’ll note that the model mean generally tracks the observed temps (here, HadCRUT4) over time, although with some periods showing a ‘bias’–notably, 1910-1930 or so, and 2000-2011 (remember, AR5 came out in 2013.) I expect that, if you were to extract any given model run from the ‘spaghetti’ you’d find that the run would have a similar variance compared to the model mean, but with completely different ‘details’ of when and by how much. (I.e., each ‘run’ has its own ‘weather history.’)
It would even be possible to go back and cherry-pick the model run that best approximated the observed data. But there’d be no reason to expect that there was anything much real behind that ‘outstanding performance’–it’s just chance. One had to be best, after all!
Nor, as previous responses to your comment have indicated, would that necessarily mean that that particular model run also best captured the trajectory of other parameters. Different models have different strengths in terms of parameters that they tend to model best.
Are any model runs so ‘out of whack’ that they show cooling over time? No, visibly, for the CMIP5 models in the graph linked above. Some show a bit more, some show a bit less, and most are pretty close, ‘big picture’, to the observed warming.
131 Kevin McKinney
Thanks for the response, I am studying it.