We have been expecting too much from the IPCC about its confidence level increase: the explanation may actually be simple… and surprising.
Guest essay by Stephane Rogeau
Image: From IPCC FAQs
Many people are wondering what actually made the IPCC raise its confidence level about the fact “human influence has been the dominant cause of the observed warming since the mid-20th century” from 90% to 95%, since its last report in 2007.
Most of the time, it is argued that there has been no warming since 2007 whatsoever, which makes the increase of confidence level in the IPCC’s statement very dubious. But it may be the other way around: because there has been no warming, the IPCC raised its confidence level! And it actually makes sense… at least inside the thought paradigm of the UN organization.
The reason may actually be simple, for one reason: the theoretical warming due to anthropogenic CO2 is, for the IPCC, a given.
It is what makes the climate models “work” (i.e. match more or less historical records). It is actually the basis of the IPCC’s line of reasoning: we cannot find any other way to match our models with the data than by entering feedback assumptions that give climate sensitivity to CO2 the value x… therefore its value has to be around x.
Based on this given assumption that cannot be disproved by facts anymore, and knowing the quantity of CO2 released by human activity, one can easily calculate the theoretical human-induced contribution to global warming since 1951 (let’s call it HIC). Discrepancy with observed global warming (OGW) is, of course, due to natural variability. Therefore, the proportion of human influence in observed warming between 1951 and year “n” is simply p(n) = HIC(n) / OGW(n). If, in year n, the theoretical human-induced contribution since 1951 is for example 0.4°C, and the observed global warming is 0.5°C, then the calculated proportion of human influence is 80%.
Obviously, as we release more and more CO2 into the atmosphere, the human-induced contribution is an increasing function of time: HIC(2012) >HIC(2007). On the other hand, the so-called “hiatus” means OGW(2012) = OGW(2007), as no warming has been observed since 2007. Then it’s just basic arithmetic: p(2012)>p(2007).
Long story short: the proportion of human influence in observed global warming has increased since the last IPCC report because temperatures have leveled off. Translated in terms of confidence level: if the IPCC was 90% certain that human activity was responsible for more than half of the observed warming in 2007, it is not surprising that the confidence level for this same proportion has now risen to 95%.
To conclude: the less warming, the more confident the IPCC about its claims to policy-makers.
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Ah, must be the season to share tortured data.
I think you’re enjoying your weather more than anyone should. Must be the season to share torturing data. 🙂
I may be rebreathing some of your CO2 come Sunday….
“e cannot find any other way to match our models with the data than by entering feedback assumptions that give climate sensitivity to CO2 the value x…” — OP
In the better part of humanity’s time about the planet, if we didn’t know we had 95% confidence that the cause of it was an anthropogenic spirit. In the more enlightened modern era, the era of the rational and scientific man, if we don’t know then we have 95% confidence that it’s anthropogenic.
What some call confidence, I perceive as hysterical desperation. Once a learned person leverages their buttocks to a construct, only the strong pill of delusion will suffice once the construct breaks down. And delusion is easy to spot to those outside the delusion.
What new proof that anthropogenic CO2 is causing the atmosphere to rise has been brought forward since 1990 that gives them such an increasing degree of certainty?
JohnWho says:
November 21, 2013 at 5:18 am
What new proof that anthropogenic CO2 is causing the atmosphere to rise has been brought forward since 1990 that gives them such an increasing degree of certainty?
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the adjusting of past temperatures to make them colder than what was in the original data is much closer to completion.
people were shorter in the past than now, so when they read thermometers they were looking up, which caused the readings to be too high. Now that people are taller they read the thermometers straight across, making modern readings much more accurate. Thus historical temperatures must be adjusted downwards to be correct.
Simple, as the rate of warming decreses we can be more confident that half of it is anthropogenic.
The IPCC’s confidence level goes up in direct proportion with their desperate demands for more money.
This article has repeated my objections to using such meaningless issues as “is human influenced
warming of a larger magnitude than natural warming.” especially in an unconditional sense.
An answer of yes to the question can be either good or bad, depending upon what’s happening naturally. A significant cooling trend would make one wish for more CO2, not less. Of course, it’s understandable that when the IPCC makes claims in these terms, skeptics reply in those same terms.
And as long as the time span in question is known, one can make claims, although the answer will pertain only to that particular time span. Mostly, this is a concept that only adds to the confusion of the public, who may think there is a single answer for all time frames. Whether humans are the main cause of some warming trend is not of any particular importance. We really want to know two things : how much warming do we get via human influences, in the future, that is? , and what is the natural temperature trend for the future? We cannot, at this point, provide a firm answer for either question.
aaron: I think you said it better in one sentence than me in a long article! 🙂
@cleanenergypundit: “‘Arrhenius-right-or-wrong -or-misused’ in simple terms ‘for dummies’ like me.”
I’m not terribly certain what you’re asking, but I’ll take a crack at it in a general sense. Is there a buffer? Surely, so; and we don’t need radiative gasses for it. Remember that if we’re not in a quantum radiative mode, then we’re colliding molecules. Or, essentially, atmospheric gasses act as if they’re in a pinball machine. The surface imparts energy to them by kicking them back up the table, where they go collide with anything and everything. But as the atmosphere is largely transparent to incoming radiation, we don’t heat from the top down, but the middle out. So when the sun comes up heats spreads from the surface to below it, and into the atmosphere. But when the sun goes down it necessarily cools from the radiating surface-ish of the atmosphere. So there’s a hysteresis involved in all cases.
CO2, for its part, is something of a sad child. For if we consider that CO2 is hung like christmas tree ornaments — fixed in space at tasteful distances — then there are no kinetics involved. It’s purely radiative. And if you sort out what the radiation has to do to reach equilibrium in a layered model, where each layer has a 50/50 shot of catching any given photon of the right ‘type’ then you find the infamous ‘feedbacks.’ That is, from the surface looking up, you will see your normal black body temperature curve that you’d expect to see given the temperature of the atmosphere. And then a large second peak on the portion under feedback. In no manner is it not a feedback, or proper amplification, in every instance.
Which is exactly the opposite of what we find. Rather than a large second peak in IR, or any other band for a radiative gas, we find a ‘notch.’ That is, there are no feedbacks. No question that the radiation is absorbed, but it is lost by conversion to a perfectly bog standard black body radiation due to collisions. To deal with this, without quantum fuzziness, is the same as what we did to Newton’s child of gravity. Rather than rewrite gravity in a quantum mode, we add a small relativistic correction term and get on our way. It is an epicycle to be certain, but it is also accurate. Likewise, in thermo, we need only add a small corrective to the constituents of the lapse rate equations. Which is to say: It’s works like a non-radiative buffer in every normal manner, if that’s how you wish to consider it. You need only account for the initial absorption of the frequencies of a given ‘type’ being emitted from the surface. Which is also to say that, ignoring convection, heat works in that model just as it does in solid phase matter.
The only significant hazard in this is when you model the Earth as being in global equilibrium. Which is, you take the total energy received on the daylight side of the Earth, and then distribute it evenly across the entire surface. That is, there is no night time. And as we’d quite rather avoid nasty issues of convection, we simply have a habit of pretending that gas is immobile. Both manners provide absolutely absurd temperature increases at the surface. But the knowably wrong radiative feedback model is far less wrong in magnitude, compared to observation, than acknowledging that there are no radiation feedbacks. As that latter goes up exponentially with the number of layers, while the former at a constant fraction.
But then, without convection, or a pulsed input for inrradiance: We’re not actually modelling Earth in any fashion.
Ric Werme says:
November 21, 2013 at 5:00 am
Ah, must be the season to share tortured data.
albertalad says:
November 21, 2013 at 2:48 am
Lol – perfect remark. I’m currently @ur momisugly -30C as I write so this will put the IPCC over the 100% threshold any day now!
I think you’re enjoying your weather more than anyone should. Must be the season to share torturing data. 🙂
I may be rebreathing some of your CO2 come Sunday….
—
Yeah, Ric, the forecast here in western New Hampshire is for cold, snow, and wind Sunday (single digit wind chills). There’s a 10K Turkey Trot race on Sunday that I always do – may skip it this year if it’s as cold as they’re forecasting…
Flydlbee says:
November 21, 2013 at 2:37 am
Not only that, but when global temperatures fall off the cliff and we drop into the next Ice Age (which is a certainty), the UN can blame 100% of it on man’s influence.
What?
Man is responsible for Global Warming, AND man is responsible for (Extreme) Global Cooling?
Who knew?
And here I thought the last 30+ Ice Age episodes were sans humanity!!
Now, where do I go to find that initial jawbone?
(I smell a scam–aren’t mathematical limits wonderful?)
I would like to know where the IPCC get their 95% probability that humans have caused more than half the warming, but this article doesn’t explain it. What it sets out to do is explain how much warming is due to humans, which is a different thing.
IPCC don’t tell us either. They say there is a 95% probability that humans have caused at least half, and one could infer there must be another (lower) probability that humans have caused 2 thirds, and an even lower probability that humans have caused 3 quarters.
It is interesting to observe that the probability increases with each publication though. Shall we have a vote on what AR6 will produce? I’m going for 97.5%, and I am 95% certain of that.
“Submitted for your consideration:”
1.- The assertion from AR5’s Summary for Policymakers, that it is “extremely likely” (95%+ confidence level) that human activity has caused “more than half” of the global warming since 1950
2.- New study shows half of the global warming in the USA is artificial
Posted on July 29, 2012 by Anthony Watts
PRESS RELEASE – U.S. Temperature trends show a spurious doubling due to NOAA station siting problems and post measurement adjustments.
I think Anthony might have identified the “human activity” which caused the “more than half” of the global warming since 1950.
Could some one please tell me how many adjustable parameters a typical climate model has. I would like to know effectively how many pieces of information need to be established from hind casting. My motivation is that ill-posed problems (chaotic problems?) are notoriously limited in how much information can actually be recovered from the existing data series.
observa says:
November 21, 2013 at 2:48 am
“Now if you took a bronze statue of Al Gore and put a thermometer in its mouth…”
Yup that is where I would stick the darn thermometer. Not.
cleanenergypundit says:
November 21, 2013 at 2:31 am
When you ask if Arrhenius was right or wrong, it is not as simple as that. On the whole his work (as given in your link) is meticulous given the limitations of the primitive equipment available at that time.
He is certainly right in knowing that CO2 and water vapour in the atmosphere have a warming effect on the surface of the Earth and he correctly determines the effect of CO2 to be ‘logarithmic’.
He is almost certainly wrong to accept Luigi DeMarchi’s opinion that ‘ice ages’ cannot be caused by celestial events such as orbits, inclinations etc. He thus tries to calculate what changes in CO2 levels would be required to produce glaciation and interglacial periods.
The warming effect of the greenhouse gases is not “trivial or totally irrelevant”. Although Arrhenius rejects previous estimates that the Earth would be at minus 200 degrees C without these gases, a figure of -20 deg.C would be about right.
This article operates under the false assumption that the period of 2007-2013 is long enough to reliably discern whether there has been warming. Well, it isn’t – statistical reliability needs a sufficient amount or period of obervations. The increase in certainty however is because this period is added to the existing data which were already showing the warming. It’s statistical basics: increasing the amount of obervations increases the reliability of your results.
Darth Vader finds you lack of faith in the Forcing disturbing.
Jquip says: cleanenergypundit says: MikeB says: Brian H says:
Nah, What the IPCC is saying is that CO2 radiative forcing increases by 1.5 (w/m)^2 every single day for infinity. To put that in perspective that is 550 more (w/m)^2 every year. So in less than a years time CO2 forcing is higher than the Suns forcing.
Vince Causey says:
November 21, 2013 at 6:21 am
It is interesting to observe that the probability increases with each publication though. Shall we have a vote on what AR6 will produce?
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next report will be 110% certain, though if they were truly certain they would be 200% certain. 95% certain simply means there is still a possibility that they are wholly and completely wrong.
@jim Rose: “Could some one please tell me how many adjustable parameters a typical climate model has.”
Every climate model uses a global temperature model from some vendor. So they all include temperature as one adjustable parameter. How many more they have after that, I couldn’t say.
@Genghis: “Nah, What the IPCC is saying is that CO2 radiative forcing increases by 1.5 (w/m)^2 every single day for infinity”
True enough. But in global equilibrium each day is infinitely long.
Flydlbee says:
November 21, 2013 at 2:37 am
Following this technique, if the climate cools, the confidence level will go over 100%.
Exactly.
IPCC relies on models, however their climate models do not have the real physics of CO2 effect in the atmosphere inside, but just a “guesstimation” which is wrong.
What is the real physics of CO2? What happens to the net heat transfer in the atmosphere?
1) CO2 has some bandwidth of IR where it is opaque, especially around the main resonance of wavenumber 667. This means that IR radiation in this bandwidth will not travel more then 10-12 meters in the air. If anything happens in this bandwidth between the atmosphere and the soil it happens only in the very first 10-12 meters of the atmosphere. Increasing CO2 concentration shortens the visible path to 9-11 meters etc.
2) There is no such heat transfer by radiation through CO2 in the atmosphere.
Nobody has ever done the calculation of the net heat transfer that would be done between the various CO2 strata in the atmosphere as the numbers are infinitesimally small.
3) Changes in the radiative spectra from the top of the atmosphere to the “universe”. There are some attempts at calculating it and measuring it.
The models replace this with a guessed “forcing” from the top of the atmosphere which was 3.7 W/m2 and was reduced at 3.4 W/m2 for CO2 doubling + the addition of feedbacks which augment the error with the feedback value.
It does not fit the real physical process and so they fail again and again.
This is the reason why they see a hot spot there where it does not exist. This is the reason why they have a warming bias. And adjusting and recalculating the value does not approximate the true physical behavior of the atmosphere.
It works only for the part where warming went in sync with CO2 increase, but they fail miserably in history, all the tries to model climate from animal farts are the nonsense where this line of thoughts leads.
Heh heh..
http://i2.photobucket.com/albums/y48/mikeishere/IPCCprediction.gif