Diving into the Deeps of Decarbonization

[UPDATE: Comment from Anthony: There has been a tremendous amount of discussion and dissent on this topic, far more than I ever would have imagined. On one hand some people have said in comments that Willis has completely botched this essay, and the Kaya identity holds true, others are in agreement saying that the way the equation is written, the terms cancel and we end up with CO2=CO2. It would seem that the cancellation of terms is the sort of thing that would rate an “F” in a simple algebra test. But, I think there’s room for both views to be right. It seems true that *technically* the terms cancel, but I think the relationship, while maybe not properly technically equated, holds as well. Here is another recent essay that starts with Willis’ premise, where CO2=CO2 and expounds from there. See: What is Kaya’s equation?

Further update (modified 3AM 7/12/14): Willis has posted his response in comments, and due to my own travels, I have not been able to post it into the body of the message until several hours later, see it below. – Anthony]

Guest Post by Willis Eschenbach

pathways to deep decarbonizationAnother day, another new piece of mad garbage put out by the UN. It’s called “pathways to deep decarbonization”, all in lower case (8 Mb PDF). Their proposal is to get CO2 emissions down to zero.  I didn’t get far into it before I cracked up laughing and lost the plot.

It starts with the following definition:

Deep decarbonization requires a very significant transformation of energy systems. The ultimate objective of this transformation is to phase out fossil fuel combustion with uncontrolled CO2 emissions. Only fossil fuels in conjunction with CCS [carbon capture and storage] would remain.

But that wasn’t the funny part. That was just depressing. The funny part came later.

Now, out here in the real world the most charitable way to describe this lunacy of forcing the nations of the world to give up fossil fuels is to … to … well, now that I think about it, there is no way to describe this as anything but a pathetic joke which if implemented will cause untold economic disruption, disaster, and death.

In any case, in order to figure out how to “phase out fossil fuel combustion”, they go on to describe what they call the “principal drivers” of CO2 emissions, viz:

The simplest way to describe the deep decarbonization of energy systems is by the principal drivers of energy-related CO2 emissions—for convenience, since the focus of this chapter is on energy systems, we simply refer to them as CO2 emissions. CO2 emissions can be expressed as the product of four inputs: population, GDP [gross domestic production] per capita, energy use per unit of GDP, and CO2 emissions per unit of energy:

CO2_{emissions} = Population * \frac{GDP}{Population} * \frac{Energy}{GDP} * \frac{CO2_{emissions}}{Energy}

That was where I lost it …

Now, at first glance that looks kind of reasonable. I mean, emissions must go up with population and with GDP per capita, and go down with energy efficiency.

Here’s why I laughed. Lets apply the usual rules of math to that equation. We know that if a variable occurs both on the top and bottom of a fraction, we can cancel it out. Starting from the left, Population on the top cancels Population on the bottom. Then GDP on the top cancels GDP on the bottom. Then Energy on the top cancels Energy on the bottom … and we’re left with …

CO2_{emissions} = CO2_{emissions}

Pretty profound, huh? CO2 emissions are equal to CO2 emissions. Who knew?

OK, now let’s build their equation back up again. But instead of using gross domestic production (GDP), we’ll use gross beer production (GBP) instead.

CO2_{emissions} = Population * \frac{GBP}{Population} * \frac{Energy}{GBP} * \frac{CO2_{emissions}}{Energy}

Note that this is identical to and equally as valid as their whiz-bang equation, in that it simplifies down to the same thing: CO2 emissions = CO2 emissions.

And as a result, the clear conclusion from my analysis is that the best way to fight the evil menace of CO2 is to figure out a way to make beer using less energy …

Now, there’s a carbon reduction program I could get behind.

Best wishes to all,

w.

The Usual Request: If you disagree with someone, please quote the exact words you disagree with. This prevents misunderstandings, and lets us all understand your objection.

PS—Due to a cancelled flight, I’m stuck here in a hotel in LA on my way back from the Ninth International Climate Change Conference, which I’ll write about another time, and sitting in my hotel room wishing I were home. Not much to do but read boring UN documents … at least this one was funny.

PPS—Although it’s not mentioned in the document, their goofy equation is known as the “Kaya Identity“. Apparently, the number of innumerate people on the planet is larger than I had feared.

==============================================================

Willis Eschenbach says:

Well, yesterday was a long day. Up early to get to the airport, and this time the flight actually flew. Go deal with the rental car. Roll on home.

Then change clothes, I’d spent the night without luggage. Hang out with the gorgeous ex-fiancee and catch up. Put in a load of wash. Put the trash in the trash bin, the recyclables in their bin, the kitchen scraps in the garden waste bin. Roll all three of them up the driveway to the street. Unpack. Pack. Wash the dishes. Make coffee. Scrub the toilet.

Then when I got around to opening up my computer in the afternoon, after waking up from its normal sleep and running for about 15 minutes … it died. Dead. As in when I turned it on, It ran for about 5 seconds, and croaked …

So … that meant another 45 minute drive to the “local” Apple store. It also meant about an hour’s worth of waiting for an appointment. Then another three hours while they worked on the machine before finally getting It to run again. Net result?

It’s now 10 PM, and I’m back where I was last night … on line again. Oh, and a couple hundred bucks lighter.

Anyhow, that was how my day went. I hope Bart had more fun than I did.

Regarding the comments, I’m overjoyed that there is much discussion of the issue. My point, albeit poorly expressed given some of the comments, was that since the Beer Identity Is equally as true and valid as the Kaya Identity, it is obvious that we cannot use the Kaya Identity to “prove” anything.

So yes, the Kaya Identity is true, but trivially so. We cannot depend on it to represent the real world, and it can’t show us anything.

For example, folks upstream said that we can use the Kaya Identity to show what happens if the GDP per capita goes up by say 10%. According to the Kaya Identity, emissions will also go up by 10%.

But according to the Beer Identity, if Gross Beer Production per capita goes up by 10%, then CO2 emissions have to go up by 10% … and we know that’s not true. So clearly, neither identity can serve to establish or demonstrate anything about the real world.

What I tried to say, apparently unsuccessfully, is that by itself, the Kaya Identity cannot demonstrate or show or prove anything about the real world. If there is anythlng true about it, that truth must exist outside of the Kaya Identity. Otherwise the Beer Identity would be a valuable guide to CO2 emissions … but we know that’s not true.

Finally, l hear rumblings that Anthony shouldn’t have published this piece of mine. This totally misunderstands Anthony’s position in the game. The strength of WattsUpWithThat is not that it is always right or that it publishes only the best stuff guaranteed to be true.

The beauty and value of WUWT that it is the world’s premier location for public peer review of climate science. On a personal level, WUWT is of immense use to me, because my work either gets falsified or not very quickly … or else, as in this case, there’s an interesting ongoing debate. For me, being shown to be wrong is more valuable than being shown to be right. If someone can point out my mistakes, it saves me endless time following a blind alley.

And indeed, there is much value in the public defenestration of some hapless piece of bad science. It is as important to know not only which ideas are wrong but exactly why they are wrong. When Anthony publishes scientific claims from the edges, generally they are quickly either confirmed or falsified. This is hugely educational for scientists of all kinds, to know how to counter some of the incorrect arguments, as well as giving room for those unusual ideas which tomorrow will be mainstream ideas.

So it is not Anthony’s job to determine whether or not the work of the guest authors will stand the harsh light of public exposure. That’s the job of the peer reviewers, who are you and I and everyone making defensible scientific comments. Even if Anthony had a week to analyze and dissect each piece, there’s no way that one man’s wisdom can substitute for that of the free marketplace of ideas … which is why it’s not his job. Bear in mind that even with peer review, something like two-thirds of peer reviewed science is falsified within a year. And Anthony is making judgements publish/don’t publish on dozens of papers every week.

So please, dear friends, cut Anthony some slack. He’s just providing the arena wherein in 2014 we practice the blood sport of science, the same sport we’ve had for a few hundred years now, ripping the other guys ideas to bits, also known as trying to scientifically falsify another person’s claims that you think don’t hold water. It is where we can get a good reading on whether the ideas will stand up to detailed hostile examination.

It is not Anthony’s job to decide if mine or any other ideas and expositions and claims will wtthstand that test … and indeed, it is often of value for him to publish things that will not stand the test of time, so that we can understand exactly where they are lacking.

So please remember, Anthony is just providing the boxing ring. It is not his job to predict in advance who is going to win the fight. His job is to fill the cards with interesting bouts … and if this post is any example, he is doing it very well.

Best to everyone,

w.

===============================================================

And a final update from Anthony:

While Willis wants to cut me some slack, and I thank him for that, I’m ultimately responsible for all the content on this website, whether I write it or not. While some people would like nothing more than to have content they deem “wrong” removed, such things generally present a catch-22, and cause more problems than they solve. Of course some people would be pleased to have WUWT disappear altogether. Some days, I’m one of them, because it would allow me to get my life back.

The value is being wrong is learning from it. If you don’t learn from it, then being wrong deserves every condemnation thrown at you. I plan on being wrong again, maybe as soon as today, though one never knows exactly when your training and experience will lead you down the wrong path. In this case I was wrong in thinking that this simple terms cancellation argument pretty much made the Kaya identity useless. I’m still unsure how useful it is, or whether its usefulness is mainly scientific or political, but rest assured I now know more than I ever thought I would know about it, and so do many of you. And there’s the value.

I thought this was relevant, and worth sharing:

“For a scientist, this is a good way to live and die, maybe the ideal way for any of us – excitedly finding we were wrong and excitedly waiting for tomorrow to come so we can start over.”  ― Norman Maclean

Thanks for your consideration – Anthony Watts

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Daniel G.
July 10, 2014 1:52 pm

Treating each of the factors as a separate variable and varying the numerical value of one factor to see it’s effect of CO2 emissions assumes those factors are independent of one another. That’s called a static model. In reality changing the value of a factor will likely cause the value of another factor to change; a dynamic model. So it’s really difficult to attribute the change in CO2 emissions to one single isolated factor. Yes, people do that, but without realizing the assumption they are relying on. Those factors in the equation are surely correlated with each other. This is one reason simple-minded models often fail to predict actual outcomes. Viz., increase GDP per capita and energy intensity is likely to change with it.

Not necessarily, whether you make the asssumption of indepedence or not doesn’t matter. Of course if you decrease energy intensity (increasing energy efficiency), the chances are that the GDP per capita is going to increase, by more consumption of energy, creating a rebound effect.
But this doesn’t make the identity wrong.

Daniel G.
July 10, 2014 1:54 pm

@sinewave:
Given that, do we have a similar identity that describes CO2 a few million years ago when Population, GDP and Energy were all zero but CO2 was still positive?
We are talking about energy-related CO2 emissions.

The simplest way to describe the deep decarbonization of energy systems is by the principal drivers of energy-related CO2 emissions—for convenience, since the focus of this chapter is on energy systems, we simply refer to them as CO2 emissions.

milodonharlani
July 10, 2014 1:54 pm

Does this mean everyone will have to eat unleavened bread?

July 10, 2014 1:55 pm

Can I really ruin someone’s day?
The Kaya Identity is UTTERLY USELESS for solving for peanut M&Ms.
Plain M&Ms are of a uniform size, and thus, can be used in such an equation; peanut M&Ms are not.
Thank you…come again.

DanMet'al
July 10, 2014 1:57 pm

Michael J. Dunn says: July 10, 2014 at 1:44 pm
A voice of reason. . . not Willis tell us how we are all wrong.
Dan

richardscourtney
July 10, 2014 1:58 pm

Pete Brown:
I take sever umbrage at your disgraceful post at July 10, 2014 at 12:56 pm .
At July 10, 2014 at 12:02 pm I objected to your misrepresentation of my opinion then wrote

NO! ABSOLUTELY NOT! THAT IS AN OUTRAGE!
I disagree with the equation because it is bollocks!
The equation is deliberate ‘Alice In Wonderland’ nonsense. As I have repeatedly explained, it means nothing and it says nothing, but it can be pretended to say whatever its user wants to promote.
I don’t think I can state this more clearly that I did in my post addressed to tttt at July 10, 2014 at 9:13 am where I wrote of the equation

At July 10, 2014 at 6:02 am you reply to me

The point of the equation, be it political or not, is to show how an example of different factors for CO2 emissions and discuss the effect of these factors.

YES! That is what I have been saying!
However, you and some others are refusing to see that the factors are not real and can – with equal validity – be claimed to be anything. Substitute bullsh*t for Energy and the equation still works only it now indicates that CO2 emissions are affected by bullsh*t but not Energy.
With that substitution the equation would have unchanged validity but be more honest.

I repeat what I wrote in my post addressed to you at July 10, 2014 at 8:56 am which you pretend to be answering.

I am rejecting “the logic of what is being represented”. Please note that I am NOT disagreeing with the equation. I am saying the equation is illogical: it is a naked Emperor and I am refusing to engage in a discussion of the colour of the “logic” used to dress it up.
You have ignored that and have made your untrue assertion presumably because you cannot defend the equation which is – and can only be – a tool for pure political propaganda.

Your disgraceful post I am answering misrepresents all that by saying

richardscourtney says:
July 10, 2014 at 12:02 pm

I disagree with the equation because it is bollocks!

Ah. I see. Thanks. I wasn’t quite sure if that was your point from your previous remarks. Now I know. Good of you to take the time to elaborate. Good then. Great.

Clearly, you are incapable of defending the equation from logical argument, and you know you cannot defend it.
You follow that offensive nonsense by trying to put words in my mouth as a method to change the subject presumably in hope that will hide how daft your arguments are. Well, that’s bound to work (not).
Richard

Joseph Murphy
July 10, 2014 2:03 pm

JJ says:
July 10, 2014 at 1:38 pm
————-
One equation is demonstrating a relationship, the other is being used as a sort of memory tool. I shouldn’t say it doesn’t have meaning, it doesn’t have any meaning on its own. I am not arguing with guys anymore (literally, not snarky), I understand the point you are making.
—————–
JJ says:
July 10, 2014 at 1:38 pm
It is silly to say that M = C * B/C * P/B * M/P is meaningless, but that M = C*X*Y*Z has meaning, when the X, the Y and the Z in the latter are given their meanings by the former.
————–
I would say that our ways of thinking are reverse from each other.

Björn from Sweden
July 10, 2014 2:10 pm

Are you still debating this nonsense?
CO2=(pop/pop)(gdp/gdp)(E/E)CO2
Throw in some more variables:
How ABOUT CARBONTAX, CT!…(CT/CT)-and randomly rearrange the terms to gain new insights!
Alrighty: CO2=E(CT/pop)(pop/gdp)(gdp/E)(CO2/CT)
How profound, all this time I was an AGW genious and I didnt know it!
Algebra released the creative genious in me.

Bryan
July 10, 2014 2:15 pm

Nancy C says:
July 10, 2014 at 1:19 pm
If any frustrated commenters ever check back here, I just want to say, I appreciate your persistence, and thanks to everything everyone’s said, I think that I, for one, understand what this kaya identity is a little better.

Nancy, thank YOU for sticking with it, and for your comment at 1:19 pm, which perhaps will help other people understand that an identity can be useful.

gnomish
July 10, 2014 2:15 pm

yeah, the kaya joke is like telling someone that doing something will make hair grow on his palms.
you don’t care if it’s true or not- you only want to see if he looks.
now we see who looked.
funny, right?

richardscourtney
July 10, 2014 2:16 pm

DanMet’al:
At July 10, 2014 at 1:57 pm you say

Willis tell us how we are all wrong

Well, perhaps you can tell us what use this ridiculous equation is except as a tool to spout political propaganda.
This missing information is especially important when the equation supposedly determines CO2 (emissions) but calculates from CO2 (emissions) per unit energy which requires one to know CO2 (emissions).
Obviously, if you were to explain this in comprehensible fashion then those of us whom you call “know nothing charlatans” would know something because we would know what you explained. Alternatively, if you don’t explain it then we would again know something; i.e. you are merely another anonymous troll come here to spout disruptive nonsense.
Richard

Curt
July 10, 2014 2:18 pm

Some years ago, I had a real-world experience that showed at least the potential utility of an identity like this. It was very similar to the M&M example that several people have used here.
At the time, the state of the art for slicing bacon into packages meant that you had to average 17 ounces for a package labeled as 16 ounces so as virtually never to go under the listed weight and risk government penalties. (In other words, there was a +/- 1 ounce variation.)
I helped a major food company (one you’ve all heard of) reduce the average to 16.25 ounces per package (+/-0.25 ounce variation), a 0.75 ounce reduction, by monitoring the accumulated weight from each slice and slightly modifying the thickness of the last couple of slices.
They illustrated the importance of this improvement to me by going through an identity very much like the ones discussed here to show the overall savings in bacon yielded by this reduction per package. In the analysis they showed me, they held the other terms constant, which was at least a good first-cut (sorry!) approximation. (I would guess that their MBAs went beyond this and calculated the increased sales that might result if they cut their prices to reflect their reduced cost, and so on.)
In another area, I use the equation
Force = Pressure x Area
all the time. But pressure is defined as force per unit area. So is this equation just a tautology? No! Often I have a pressure measurement — even if that measurement came from the total force on a spring at the end of a cylinder of a given area in a gauge — and a measured area on which that pressure acts.
So the question is whether the individual terms in an identity like this are useful or not. I think the terms in the Kaya identity are useful. You can say to a politician: So you want to reduce our CO2 emissions by 30% over the next 20 years. Here is ONE valid way of calculating the emissions. What are you going to cut? Population? No? How about GDP per capita? No? OK, that leaves energy per unit of GDP (efficiency) and CO2 per unit of energy (decarbonization). How are you going to get the 30% with those.
I think the Kaya identity is a useful way of focusing analysis here.

JK
July 10, 2014 2:19 pm

Thanks, Nancy C.
I find the first way you explain it (“two CO2 numbers should have to be the same, but in a way they’re not”) a bit confusing, but the way you explain the mph example is very clear: we’re on the same page.
I would only add I wish that other commentators would focus on the meaning of the numbers rather than arithmetic, which seems to me quite straightforward.
The question is whether concepts such as GDP / population, energy / GDP and CO2 / energy are any more useful for understanding the economy than thinking in terms of total beer production or Al Gore’s Waist Line.
To put it in terms of M&Ms, the warehouse manager might say:
M&Ms = crates * (boxes / crate ) * (packets / box) * (M&Ms / packet)
and use this to calculate how many more M&Ms will ship if they put more M&Ms in each packet, more packets in each box, etc.
Willis might come along and point out that actually the following identity works just as well, substituting global beer production for number of boxes shipped:
M&Ms = crates * (GBP / crate ) * (packets / GBP) * (M&Ms / packet)
In terms of arithmetic the second formula is just as true as the first.
But it is not as useful to the warehouse manager. Why? Because in reality there is a definite relationship between boxes and crates (one pack in the other) and also between packets and boxes (again, one pack in the other). In constrast, in reality, there is no relationship between the number of crates shipped and global beer production, or between the number of boxes shipped and global beer production.
The Kaya identity is useful to the extent that GDP / population, energy / GDP and CO2 / energy are useful for understanding the economy, and specifically emissions form energy production. Willis’ version is less useful to the extent that global beer production is less useful for understanding these questions.

Michael 2
July 10, 2014 2:20 pm

Bryan says: “understand that an identity can be useful.”
Really? A formula of the form X = A * (B/A) * (C/B) * (X/C) is not useful.
You see, you must GUESS at the “X” for the forth term on the right hand side. Whatever you choose it will magically appear on the left hand side as though you have proved something.
Consider the special case of ZERO. You decide there is ZERO Global CO2 emission. What happens? The zero cancels everything, giving Zero as the answer. Good math, but stupid.
What about 1? Work it out. What you will end up with is 1.
No matter what you DECIDE is Global CO2 emission, the Kaya Identity will produce that EXACT value. The complexity of it is a smokescreen and serves no purpose. Really! Give it a shot and see for yourself. Pick some random number for the numerator of the 4th term. Pick real or random numbers for everything else (but not zero). You will end up with the number you started with.
Now then, if you simply insert the laboratory measured value of co2 per unit of energy produced, THEN suddenly you have a meaningful formula.

Michael 2
July 10, 2014 2:25 pm

JK says: “Because in reality there is a definite relationship between boxes and crates (one pack in the other) and also between packets and boxes (again, one pack in the other).”
Also tomatoes and olives and a billion other things that relate to each other but have absolutely nothing to do with a magic card trick that always gives back exactly what you put in.
Our argument here is that the Kaya Identity is NOT USEFUL. An equation is designed to produce an answer on the left hand side based on stuff you know and can measure on the right hand side.
But that’s not what is shown. What is shown is the ANSWER being used to develop the ANSWER and what is in the middle is completely irrelevant, a different story.
If it is important to know that M&M’s fit into packets that fit into crates, PLEASE don’t use the Kaya Identity to explain it — just say it.

David in Texas
July 10, 2014 2:26 pm

Jason L says:
It most definitely DOES NOT tell you this. [reduce population… reduce C02]
I concede your point. You are right. I am wrong.
I was imprecise. Given that the ratio of CO2 emissions/Energy remains constant a reduction in population will reduce C02 emissions.
To use the same variable (CO2 emission) here on the same side of the equation may be silly, may be a tautology. But, I don’t believe that it is a math error. Maybe it is error in the sense that the author intended the formula to show four terms, the population and three ratios, but failed with the last term. It would have been better stated as the “average C02 emissions per unit of energy”. Over some limited time frame, say one year, that would be constant.
Calling it “a stupid maths error” is what I object to, because 1) I don’t see a mathematical error, and 2) it is a logical informal fallacy, “Appeal to ridicule”. We, skeptics, should be better than that.
I would be more concerned about how the formula is used. Consider the ratio “average CO2 emissions per unit of energy”. A command economy could quickly change that value through a mandate: “it’s now illegal to use fossil fuels”. The other terms are not fixed though. Surely, almost instantaneously total energy usage would plummet as would GDP. Population would also fall (more slowly) due to deaths and infertility. But, I have no doubt that CO2 emissions would fall.
In a market economy, I would expect that the ratios Energy/GDP (that’s related to the inverse of energy efficiency) and CO2 emissions/Energy would decrease over time. I am less sure than others that CO2 emissions would fall though, especially in the short- to intermediate-run, because I would expect GDP and population to increase.

Daniel G.
July 10, 2014 2:42 pm

Our argument here is that the Kaya Identity is NOT USEFUL. An equation is designed to produce an answer on the left hand side based on stuff you know and can measure on the right hand side.

… Pick some random number for the numerator of the 4th term. ….

That is already moving the goalposts, but fine. I already have said multiple times. You plug the ratios in, not the variables in the numerators.

Daniel G.
July 10, 2014 2:48 pm

In a market economy, I would expect that the ratios Energy/GDP (that’s related to the inverse of energy efficiency) and CO2 emissions/Energy would decrease over time. I am less sure than others that CO2 emissions would fall though, especially in the short- to intermediate-run, because I would expect GDP and population to increase.

This is another way of expressing the fact that a growing economy needs more energy. More energy means more emissions, so you really need to be efficient and emit little co2 per unit of energy, to reduce emissions. Again, the Kaya identity proves to be useful.
After all that being said, I don’t know why should anyone care to reduce CO2 emissions, but that is not what is in discussion.

Michael 2
July 10, 2014 2:49 pm

Curt says: “You can say to a politician: So you want to reduce our CO2 emissions by 30% over the next 20 years. Here is ONE valid way of calculating the emissions. What are you going to cut? Population? No? How about GDP per capita? No? OK, that leaves energy per unit of GDP (efficiency) and CO2 per unit of energy (decarbonization).”
It is not valid, not the Kaya Identity anyway. The problem is in the 4th term. You must use a laboratory measurement NOT THIS FORMULA.
http://en.wikipedia.org/wiki/Kaya_identity
P.S. — reducing population is the preferred solution for a great many AGW advocates and is the first parameter listed. Of course your instinct will be to have other people reduce their population first.
P.P.S. I haven’t imagined myself saying to a politician that I want to reduce CO2 for any reason. I *would* like cleaner air and solar power for their own benefits and not because I think CO2 is dangerous. Shucks, I put some in my flavored water almost every day!

Michael 2
July 10, 2014 2:52 pm

Daniel G. says: “That is already moving the goalposts”
Yep, and you moved it. The Kaya Identity is right there for the whole world to see — it requires on the right hand side the very item that you are trying to calculate.
Nor is it an accident. It is deliberate. Here is a derivation of it:
http://www.manicore.com/anglais/documentation_a/greenhouse/kaya_equation.html
The result is that you can plug ANY value into “Global CO2 Emissions” in the 4th term and get it right back on the left hand side like a magic card trick.
Along the way you get to display whatever you feel like for the other three terms. It makes no difference to the equation. If you feel those terms are important, it is because you feel they are important.

Chucky77
July 10, 2014 2:53 pm

The CO2 identity and the M&M identity are very different in the following respect. If I’m managing a candy factory and we put a fixed and known number of M&Ms in each package, and a fixed and known number of packages in each retail box, and a fixed and known number of retail boxes in a shipping box, then by knowing how many shipping boxes are loaded on a truck I can do the obvious multiplication and determine how many M&Ms are on the truck. Furthermore, I can change any one of those factors at will and with assurance I’ll always know how many M&Ms are shipped. This is a static model, and it will work as expected. The variables are under my control. They really are independent of one another.
No so with the CO2 example. If we change any one of the cited factors that may cause a change in one or more of the other factors. And it probably will. Unless we know how a change in one factor changes the others, using that model to prediction CO2 emissions is just whistling in the dark. Moreover, the relations among those “independent” (but not really independent) factors will differ from country-to-country. Russia will be different from India. All will be different in various ways because those are different economies. For a given pair of variables the correlation may be negative in one pair of countries and positive in another pair of countries. We don’t know the relationships among those “independent” factors. We may try to estimate them. The only way to truly estimate them is to make some changes and see what happens. If we foolishly use this model as if the situation is static we’ll most likely be disappointed in its ability to predict.
This is very different from the M&Ms.
Nearly all social-economic models are static, but they are used in dynamic environments. That’s one reason government policies disappoint politicians and voters. A recent classic example involves high income people leaving New Jersey and moving to Florida. Raise the taxes in NJ and watch the wealthy people leave. It’s quite predictable. What’s missing, of course, is how many in each tax bracket will leave and even take their jobs with them. So just increase the taxes and see what happens. Politicians do that.
SimCity is a great game and training device. There’s too much crime in the downtown area of the city. Raise taxes and hire more police. Downtown crime goes down but Sims in the suburbs leave and take their money with them. The police pension fund eats up money for fixing streets. The Sims are not happy and more of them leave. That’s a dynamic situation.
Please keep your eye on how models are used. To simplistically say “here is the effect of changing this variable” in the CO2 model looks good at a big show and tell. But it may flop big-time in the real world. The problem is politicians assume somebody knows what they are doing, and they do dumb stuff like killing the coal business without understanding the consequences.
Yes, I created models for a living; about 50 years including 10 years freelance. Not models like we are discussing here, but models for technology and forecasting. In a time when people pump accumulated data through software and build what passes as models with little or no understanding of how those numbers came to be, most models are dangerous. I’d put the Kaya model, or identity, in that category because it will be used in dynamic situations with no clue to how the “independent” variables are related to one another.

graphicconception
July 10, 2014 2:56 pm

I am going to side with Willis on this.
I am seriously concerned about the number of people who think this is useful in some way.
Formulas are useful if you can insert a number of measurable or known things on one side to determine a useful answer.
The identity quoted does not do that. For instance, GDP per capita cannot be measured. You need to measure the GDP; count the people; then divide one by the other. The same for Energy/GDP. You cannot measure it. You have to work out total energy; sum the GDP; then divide one by the other. The same for Emissions/Energy. You can’t measure it. you have to determine both quantities first then divide one by the other.
Let’s look at the sin, cos, tan example to see the difference. http://commons.wikimedia.org/wiki/File:Sin_Cos_Tan_Cot_unit_circle.svg
Sin and cos vary between plus and minus one. Tan varies between plus and minus infinity. So you could measure sin and cos and calculate the length of the tangent even if your ruler is not long enough or your paper is too small.
Anyway, the identity is not right. It says:
CO2 = Pop * GDP/Pop * Energy/GDP * CO2/Energy
This is the real formula:
CO2 = GDP * Energy/Pop * Pop/GDP * CO2/Energy
As can now be clearly seen, CO2 goes up if Pop/GDP increases. The Kaya Identity says the opposite! Useful stuff indeed.

Michael 2
July 10, 2014 2:57 pm

David in Texas says: “I concede your point. You are right. I am wrong.”
True, but not for the reason you suppose.
“Given that the ratio of CO2 emissions/Energy remains constant a reduction in population will reduce C02 emissions.”
No. The correct ratio is amount of energy used per person. If you cut the population in half, and the other half doubles its consumpion, you have not changed energy or CO2.
Africa sometimes reduces its population by large numbers. How large a change was there in global CO2? Probably almost nothing.
But the identity, as published, does not discuss the ratio of CO2 emissions per unit of energy. That is a simple thing to measure in a laboratory, and the 4th parameter should have been exactly that number — a constant that you plug into the formula.
How exactly you derive that constant is a different way and a different formula. You cannot just use the left hand side as a parameter on the right hand side.
Plain to see that the effectiveness of doing so relies upon how few people understand algebra.

Michael 2
July 10, 2014 3:03 pm

I should also point out that GDP is completely irrelevant. It cancels out of the equation and should be.
When a nation, such as Iceland, recalibrates its currency by dropping some decimal points, all values denoted in Kronur suddenly change, including obviously its GDP. But what is the impact on the economy? Nothing. It’s an administrative change.
So global GDP can be changed instantly on a whim by whoever decides what it is and what currency to denote it.

Daniel G.
July 10, 2014 3:05 pm

Emissions/Energy. You can’t measure it. you have to determine both quantities first then divide one by the other.

That is the only important part. You can take a smaller sample than actually going and trying to measure everything. Like in d = vt. How do I measure velocity: take 5 secs, then displacement in 5 secs, v = (displacement in 5s)/5s.
Anyway, if people think the use of the identity is to calculate energy-related co2 emissions, they are somewhat misguided. The use is to serve as reference for logical argument regarding co2 emissions.

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