Bishop Hill Met insignificance
May 27, 2013 Climate: Statistics Climate: Surface This is an ultrasimplified version of Doug Keenan's post this morning.
The Met Office has consistently said that the temperature rise since 1850 is too large to have been caused by natural causes. Questioning from Lord Donoughue elicited the information that they came to this conclusion by modelling temperatures as a straight-line trend (global warming) plus some noise to represent normal short-term variability.
However, would a model in which temperatures went up and down at random on longer timescales, but without any long-term trend at all, be a better match for the real temperature data? Doug Keenan has come up with just such a "temperature line wiggling up and down at random" model and it is indeed a much better match to the data than the "gradual warming plus a bit of random variation" model used by the Met Office. In fact it is up to a thousand times better.
In essence then, the temperature data looks more like a line wiggling up and down at random than one that has an impetus towards higher temperatures.* That being the case, the rises in temperature over the last two centuries and over the last decades of the twentieth century, look like nothing untoward. The global warming signal has not been detected in the temperature records.
*Here I'm only referring to the two models assessed. This is not to say there isn't another model with impetus to higher temperatures which wouldn't be a better match than Doug's model. It's just nobody has put such a )third model forward yet. (H/T JK in the comments)
Reader Comments (193)
EM- I forgot to ask. Why do you believe in AGW?
[If the answer is "because of the evidence", please be specific.]
May 29, 2013 at 9:33 PM | Martin A
Not a questoin to be answered in a soundbite, but I 'll try. First "belief" I do not believe in AGW as an article of faith. I regard it as the hypothesis which best fits the evidence.
1) Temperature
Over the last two million years the Milankovich cycles have driven a temperature cycle of amplitude about 5C. If you do the maths 1C of this is due to the orbital changes and most of the rest to CO2. Best fit is that the temperature and CO2 concentration drive each other up and down in a positive feedback loop, with temperature usually leading.
Over the last 150 years temperatures have increase at a rate not observed in any previous data, with no natural forcings observed which can account for the energy flows involved.
2) CO2
Laboratory measurements show that CO2 absorbs and reradiates in the infra-red in a manner which generates back radiation and slows the cooling of a surface generating IR.
The OLR measured by satellites and surface measurements of downward IR in Earth's atmosphere show absorbtion of IR at wavelengths consistent with lab observations. The energy flows and temperatures observed are consistent with both CO2 as a 280ppm greenhouse and the energy imbalance expected as a result of extra CO2 released by industry
Paleo data linking temperature and CO2 and the likely climate sensitivity derived from them are also consistent with the physics of CO2.
3)Antropogenic
In the paleo data temperature changes lead CO2 changes as the positive feedback cycles drive them both up and down. In the 20th century data we see a massive increase in CO2, way beyond the nomal 280ppm expected of an interglacial, not preceded by the temperature rise which would normally precede a CO2 increase. We are producing that CO2. In the past this has been the precursor of a positive feedback cycle and increased temperature. We are seeing the temperature rise follow the CO2 increase, with a correalation coefficent of about 0.75.
4) Miocene and Pliocene.
Before the Ice ages began Earth was in a high temperature, high sea level, high CO2 pattern relative to present conditions. All indications, from temperature and CO2 to changes in ice and weather, suggest the long term climate trend is towards those conditions.
5)Short term changes
Other factors such as solar insolation, AMO, ENSO, aerosols etc influence energy flow.. These speed up, slow or pause change, but none operate on a sufficient scale to expain the changes or to stop them for moe than a few decades.
Dave Salt quotes:
'Entropic Man (May 29, 2013 at 7:57 PM) said "If you want to falsify CAGW using the natural variation argument AND HAVE IT GENERALLY ACCEPTED BY THE SCIENTISTS you need to have an alternative explaination showing how and why the energy changes we have seen occurred..."'
ET does not understand falsification. If a theory implies observation statements that are found to be false when checked against experience then the theory is false and must be revised if it is to be saved.
No one knows how or why the energy changes have occurred. We do know that they fall within the range of historical data; consequently, they are compatible with natural variation and require no special explanation such as might be offered by CAGW enthusiasts.
EM - Thanks for the detailed discourse. I see, as they say, where you are coming from - although I either disagree with or am deeply unconvinced by your points.
"I regard it as the hypothesis which best fits the evidence."
That perhaps explains why you think that someone disagreeing needs to produce an alternative that better "fits the evidence".
I have the feeling that the following viewpoints don't appeal to you:
- Where we lack experimental evidence of what's claimed, it's better simply to say "we just don't know".
- The gross simplifications of reality, incapable of physical measurment, accepted in climate science ("forcing", "feedbacks", "climate sensitivity", the GHE black body model analysis) equate to little more than argument by hand waving.
Entropic says
'The energy flows and temperatures observed are consistent with both CO2 as a 280ppm greenhouse and the energy imbalance expected as a result of extra CO2 released by industry'
Isn't 'are consistent with' a lovely meaningless phrase?
Two completely orthogonal things can be 'consistent with' each other. That I had jam sandwiches for my tea 'is consistent with' London taxis generally being lack in colour. Doesn''t mean that the two things are related in any way.
You'd think by now - after 30 years - that the warmists would have looked a little deeper into the tealeaves (or at the seaweed on the windowsill) to be able to come up with something a bit more persuasive than 'is consistent with'.
I wonder why they haven't? (rhetorical)
Just a quick note of thanks to Entropic Man (May 30, 2013 at 1:27 AM) for making a geniune effort to engage in sensible/constructive debate... a very rare occurence when the subject is CAGW :-)
Entropic Man (May 30, 2013 at 1:27 AM) said "Over the last 150 years temperatures have increase at a rate not observed in any previous data, with no natural forcings observed which can account for the energy flows involved."
But I thought the anthropogenic CO2 increase only became significant in the mid-20th Century. If so, the logical conclusion must be that the previous ~100 years worth of warming was driven by 'natural' but as yet unaccounted sources. In which case, why could not these same unaccounted sources be responsible for the more recent warming?
EM - a valiant attempt to explain your position, and well thought through. However, I disagree with you that AGW is the hypothesis which best fits the evidence.
1) Temperature
"Over the last two million years the Milankovich cycles have driven a temperature cycle of amplitude about 5C. If you do the maths 1C of this is due to the orbital changes and most of the rest to CO2."
Historical data for the last two millenia show warmer (MWP dairy farming in Greenland, etc.) and colder (LIA frozen Thames and Hudson, etc.) temperatures - indicating a temperature cycle of the amplitude you suggest - that do not seem to be related to either the Milankovich cycle, or to CO2.
2) CO2
"Laboratory measurements show that CO2 absorbs and reradiates in the infra-red in a manner which generates back radiation and slows the cooling of a surface generating IR."
You are basing an argument that does not fit the data (see above) purely on raditaive physics, while not accounting for the conduction, convection and condensation elements of an overall thermodynamic effect.
3)Antropogenic
You are basing your argument on ice core data, the methodology of which is called into question by disagreements with historical chemical measurements and stomata analysis data.
4) Miocene and Pliocene.
"All indications, from temperature and CO2 to changes in ice and weather, suggest the long term climate trend is towards those conditions"
See above points. The long term data seem to suggest a negative feedback effect that bounds the 5 degree temperature cycle you mention in point 1. The evidence for this is a billion years of life on Earth.
5)Short term changes
(No factors) "operate on a sufficient scale to expain the changes or to stop them for moe than a few decades"
This does not follow, given the points above. A 0.8 degree rise over 150 years, in the transition between LIA and MWP climates, seems to be what we would expect, regardless of human activity.
To me, at least, an Occams Razor test of the above points does not lead to AGW being the simplest, or most likely, explanation.
Entropic Man (May 30, 2013 at 1:27 AM) also said "The OLR measured by satellites and surface measurements of downward IR in Earth's atmosphere show absorbtion of IR at wavelengths consistent with lab observations."
As a physics undergraduate, I remember performing lab experiments to measure CO2 absorption, so I have no problem with this statement. However, my understanding is that the mechanism that puts the 'C' into CAGW is the net feed-back from other physical sources and processes (e.g. water vapour, clouds, vegetation, ocean currents), which is generally referred to as 'sensitivity'.
My point is that it's the sensitivity, not the basic absorption/radiative properties of CO2, that is in question and that real-world data suggests that this is actually much lower than the values implied by CAGW (i.e. >>2C).
In which case, why could not these same unaccounted sources be responsible for the more recent warming?
May 30, 2013 at 11:37 AM Dave Salt
And also have switched off for the last 15 years, during which period, CO2 levels have continued their increase.
David Salt,
The lab experiments derive the radiative forcing equation.
delta f = 5.35 * ln(C/Co)
The change in forcing in Watts is proportional to the natural logarithm of the relative change in CO2 concentration. For a doubling of CO2 that is 5.35 * ln2 =3.7W. This is approximately the extra energy needed to increase Earth's surface temperature by 1C. This part of climate sensitivity, an expected increase of 1C per doubling is due to the direct effect of CO2. Secondary effects cascading from this, such as you mentioned, mostly increase the overall effect. Put them all together and you have the overall climate sensitivity.
The reason why there is so much room for argument is that the secondary forcings are only exactly measurable once the warming process has gone to completion. Until then they can only be derived by calculation, by simplified laboratory experiment and by measuring the ongoing warming.
Theo Goodwin.
I understand falsification.
The temperature/CO2 interaction I described leads to coherent explainations for a wide variety of past climate states from Snowball Earths, through the Permean, Miocene and Pliocene into the recent glacial /interglacial cycles and the modern CAGW. To falsify those, vague references to possible unknowns or uncertainties.is not enough. You need specific points.
I look forward to your list with interest. For example, you state that the 1880 to present record is compatible with natural variation. To back that up you need specific data showing the energy flows involved are sufficient to explain the record, while increased CO2 is not. There are some natural variations, solar influx especially, which add variability but you need to show they are sufficient, not just say so. Contrary to the expectation of many sceptics, climate scientists are aware of these effects and include their effects where appropriate.
It also matches the system behaviour you would expect from the known physics. To falsify that would require a number of generally accepted formulae relating to absorbtion, radiation and energy transfer by gases and solids to be wrong, along with a great chunk of quantum mechanics Since these are regularly validated by their successful use in other branches of science, and in engineering practice, you might find falsifying the physics of CO2 difficult.
"delta f = 5.35 * ln(C/Co)
The change in forcing in Watts is proportional to the natural logarithm of the relative change in CO2 concentration. For a doubling of CO2 that is 5.35 * ln2 =3.7W. This is approximately the extra energy needed to increase Earth's surface temperature by 1C. "
EM - do you have a reference for this? And do you mean W / m^2 ?
Using your formula shows that radiative forcing over the last 16 years increased by 0.5 W/m^2, as CO2 rose from 365 ppm to 400 ppm, but this had no effect on temperature. Is this correct, and if so, how do you explain it?
....you might find falsifying the physics of CO2 difficult.
May 30, 2013 at 3:31 PM Entropic Man
If I might take it upon myself to answer the comment addressed to Theo Goodwin....
I don't think anyone (except for those strange people the Dragon Slayers, who seem to consider that the whole of quantum/radiation physics is totally erroneous) has any intention of attempting to falsify the physics of the interaction of CO2 molecules with electromagnetic radiation. We take it as firmly established and not open to question, except perhaps for further refinement of measurement precision.
But it's an enormous step from laboratory measurements of how CO2 absorbs and radiates infra-red light to go on to greenhouse calculations for the real climate system. If it were a simple calculation involving black (or grey) bodies and absorption/re-radiation by a shell of CO2 I think we'd all be in agreement.
But there seem to be huge chasms where understanding is lacking - the calculation would involve transport of heat by convection and other mechanisms than radiation, together with a proper understanding of the role of water vapour. Does increased heating due to CO2 increase the level of water vapour in the atmosphere? Perhaps so. Does the increased level of H2O lead to increased temperature due to GHE? Perhaps so. Does the increased concentration of water vapour lead to more/thicker clouds? Perhaps so. Do more/thicker clouds result in more reflection of incoming visible light back to space? Perhaps so. Do more/thicker clouds resulting in greater precipitation, with resulting changes in heat transfer? Perhaps so. Overall, does the presence of water vapour enhance or diminish the effect of CO2? Who knows. And that's just a minute selection of the things that potentially come into it.
I remember reading the paper where the 5.35 ln(.) formula was obtained (by curve fitting to the output of numerical models, not by lab measurement). It's a simple enough formula, but does it represent physical reality? The climate scientists believe so but the whole concept of radiative forcing can only exist in computer models and is, so far as I can see, a gross simplification of reality that is intrinsically incapable of being tested. I can see that, to you, it describes what happens. To me, it is hand-waving guesswork.
What I'm rambling on about is that Climate Science is prone to taking an immensely complex system, grossly oversimplifying it, and presenting it as reality without experimental confirmation.
EM - I know we are not going to convince you. We are grateful, as has been stated, that you have taken the trouble to explain your views.
Conversely, your view of things is going to remain unconvincing to those of us who disbelieve simplified models until they have been extensively tested by physical measurement. I can see that, to you, these models provide the best explanation of things and I think we respect your views on that.
I'm not goiing to have time to keep up with multiple conversations here, but I'll try to deal with each comment at least briefly.
Latimer Adler
I use "is consistent with" as shorthand for " matches the behaviour expected of this part of the system if the hypothesis is correct" You were a scientist yourself (a chemist?) and should know that all of it is conditional, even the bits which we tend to acccept without thinking about it.
I do not like expressing myself in terms of certainties, despite the expectations of those uneducated in how science operates.
Roger Longstaff
Temperature
The Viking Greenland and American mainland colonies struggled and then died out. Look at Marcott et al or another source of temperature data for the period and you find a steady decline . Without any anthropogenic effect this is to be expected of the latter stages of an interglacial.
The LIA correalates well with the Maunder minimum in terms of reduced solar insolation and the associated temperature drop. There is even a small drop in CO2 at the same time.
CO2
See my later comment to David Salt regarding the direct effect of CO2 and the secondary forcings. The former can be observed in isolation under lab conditions, the rest mostly out in the field.
3/4 Our assessments of the validity of the paleo data differ. A topic for another day? Be careful with stomatal data. CO2 is not the only external variable affecting stomatal density. Among others , variability in water availability, temperature and light intensity must be excluded before you can use stomata as a proxy for atmospheric CO2 content.
Short term changes.
There is enough noise in the system from other temperature drivers that a linear pattern of temperature rise linked to CO2 is going to oversimplify the actual changes. The paleo pattern changed over millennial timescales. Even the first anthropogenic doubling will take two centuries. Variations over a couple of decades are not going to tell you very little about the long term trend. Note that even though the global land/sea surface temperature has paused over the last decade, the heat flow imbalance has continued and the heat is going somewhere. Ice melting has absorbed some, but information on where the rest has gone is sparse. If it is the deep sea, the next El Nino may be a whopper, even by 1998 standards. ;-)
I did indeed mean Watts/M^2. You'll find reference to the formula in various sources, though the primary data is paywalled in a spectroscopy database in the US. The 3.7W/C comes from AR4; I dont know the primary reference offhand.
Splitpin
See above
Martin A
Ultimately the problem is that the experiment is underway and the uncertainties are big enough to allow both the pessimists like myself and the optimists like yourself wriggle room on questions like climate sensitivity, the response time of different parts of the system and the emerging phenomena like rapid ice melt or jetstream instability. It will probably be well into the 2100s before anything resembling a final assessment of the effect of anthropogenic CO2 can be made. Be careful of accepting or dismissing models too casually. They have weaknesses and strengths.
Even your personal expectation that it will get colder next Winter is a mental model of your reality. If you can think of a better way of "extensively testing by physical measurement", the future state of the climate it would save an awful lot of argument.
Operating on the information available, we all make the best interpretations we can, quantifying the uncertainties as we go. Notice that IPCC, tasked with producing advice to governments, is explicit about the existance of the uncertainties, and their probable limits.
On a personal note, I have read widely in science down the years, and regard CAGW as a piece which fits well with others around it in the jigsaw puzzle we call scientific understanding. If I thought otherwise I would be arguing on your side.
Thank you all. This style of discussion is much more fun!
May 30, 2013 at 4:39 PM Roger Longstaff
Here's a downloadable source for the paper http://folk.uio.no/gunnarmy/paper/myhre_grl98.pdf
I'm sure EM does mean W m^-2. And he means watts, not Watts.
So, they may 'politically' use the argumentum ad ignorantiam, but they are 'deeply stupid' if they use it scientifically.
Or have I misunderstood?
May 30, 2013 at 6:19 p.m. Martin A
I (strongly) approve of your earlier comments (FWIW), but I was taught (many, many decades ago), that if the unit referred to a real person (James Watt, FRS, FRSE [19 January 1736 – 25 August 1819]), it would be capitalised, otherwise not (m, c &c.).
The 's' is, of course, incorrect. The unit is the Watt.
I read the Myhre paper, not for the first time. I don't see an experiment in there, Just calculations from theory. All very fine, but next you have to gp blinking into the daylight to check your figures with reality. I don't see that step in Myhre and I am not aware of anybody else having a go. That seems to me to be an AMAZING circumstance. Is that science as these guys practice it?
Now, there is also the Harries et al 2001 paper which attempted to measure absorption by CO2 seen from satellites. With great difficulty it shows the absorption, changing over decadal timescales. But it shows the minor absorption band to be unchanged. That is, it is saturated. Now, if part of the CO2 absorption spectrum is saturated, the doubling figure does not work over a range of CO2 concentrations which we are currently going through. So Myrhe needs to cater for that, you can't assume that CS is a fixed figure per doublimg, ad infinitum.
If an oxfordshire housewife can figure this out from plodding through papers, what is going on?
Myrhe's figures are calculated and modelled, they aren't verified in the field.
Harries shows a saturated band which is unacknowledged elsewhere. Saturation in BOTH bands would kill CAGW dead. In one band, especially the minor one ,it is an inconvenience
Harries measures the change in absorption but presents them in units of..what..brilliance..which do not translate into heat units. This is so unhelpful one wonder why he didn't take the step of giving us a watts/sq m figure. Or does it not show what it ought?
Be careful of accepting or dismissing models too casually. They have weaknesses and strengths.
I spent a good part of my life making models of one sort or another for critical customers so I'm not going to dismiss them nor accept them casually.
A validated model can be immensely valuable. Ask the DC10 pilot who, noticing that all the tail cables ran through the same duct, practiced flying DC10's on the simulator using just the engines to steer. When the rear floor of a real DC10 he was piloting collapsed, leaving him without tail controls, he brought it back and landed it.
[Not sure if this is the same story https://en.wikipedia.org/wiki/United_Airlines_Flight_232 I must look it up in one of my books about accidents.]
As I have said before on BH, an invalidated model is usually worse than having no model at all. Saying "we simply don't know" is better than kidding yourself you know what is happening when you don't.
Even your personal expectation that it will get colder next Winter is a mental model of your reality.
Hint - you are not talking to an O-level class here.
If you can think of a better way of "extensively testing by physical measurement", the future state of the climate it would save an awful lot of argument.
It does not exist. The arguments arise because some, including the dear old Met Office, don't see the need for it or think they have done so when they have not.
Myrhe's figures are calculated and modelled, they aren't verified in the field.
May 30, 2013 at 7:39 PM Rhoda
That's right. EM was kidding himself/forgetting here when he said the 5.35 ln(.) formula came from lab measurements. Some of the input data to the Myrhe's models came from lab measurement but that's not the same thing.
And, anyway, as I think we've discussed before, it's debatable whether the notion of "radiative forcing" has any real physical meaning.
The unit is the Watt.
May 30, 2013 at 7:35 PM Evil Denier (appearing as the Pedant-General)
You are wrong.
And whoever (mis)taught you many, many decades ago was wrong.
The convention is that, if the unit is named after a person, the abbreviation is capitalised.
(W, J, Hz,...).
If the unit is not named after a person, the abbreviation is lower case.
(s, m, g,...).
A unit itself, whether named after a person or not, is lower case. (watt, joule, hertz, second, metre,...)
And I think the 's' *is* correct normal usage. You say "we are travelling at one hundred miles an hour" or "I'm charging this battery at about 20 amps". Likewise "This generator can provide up to two kilowatts".
We disagree (on this).
I would distinguish colloquial speech from formality (happens!).
Enough. We've both made our points.
EM, thank you for your comments. We will clearly have to agree to disagree, and have the conversation again in 2100. While I admire your spirited defence of AGW I must say that I think your "missing heat" explanation is a horribly weak link in your argument - "the heat flow imbalance has continued and the heat is going somewhere".
Martin, thanks for the link to the Myrhe paper. I have not seen it before and will read it carefully, but at first glance I agree with Rhoda.
THE VALUE OF MODELS
As an example of the usefulness of validated models, I previously gave an example of a DC-10 where the pilot had, of his own volition, practised using the engines to steer in a flight simulator. The link I gave was to a different incident than the one I knew about. Here is the one I had in mind, illustrating how useful models can be.
A news report of the time:
American Airlines Flight 96 was out of control.
http://en.wikipedia.org/wiki/List_of_scientific_units_named_after_people
"This is a list of scientific units named after people.(...) Note that by convention, the name of the unit is properly written in all-lowercase, but its abbreviation is capitalized."
Martin & Rhoda,
I agree with your comments on the Myhre paper. It is interesting that it was published in 1998 - the time when warming stopped - presumably it was thought that it produced validated GCM results up to that point, and that was a partial verification. Do GCMs still use it? In any event any radiative physics formulae applied to GCMs are uselss if conduction, convection and condensation are not properly accounted for in the thermodynamic system. Albedo, in particular, is a key parameter in the radiation calculations - and nobody claims to be able to model that!
As "radiative forcing" is supposed to have increased by 0.5 w/m^2 over this period, while global temperatures have flatlined, this is almost enough to invalidate GCM methodology in my opinion. The only other explanation would be an equal and opposite effect, of unknown origin (the "missing heat" argument smacks of desperation to me). Occam's Razor gives me a clear answer.
Entropic Man (May 30, 2013 at 3:06 PM) said:
"The lab experiments derive the radiative forcing equation.
delta f = 5.35 * ln(C/Co)
The change in forcing in Watts is proportional to the natural logarithm of the relative change in CO2 concentration. For a doubling of CO2 that is 5.35 * ln2 =3.7W. This is approximately the extra energy needed to increase Earth's surface temperature by 1C. "
If this is indeed the equation derived in Myhre et al. (1998), I note that the derivation is based upon a curve fit that starts with 270ppm value (i.e. the ~1850 pre-industrial level). Therefore, assuming that a doubling of CO2 concentration results in a global temperature increase of only 1C and that there is a linear relationship between forcing and temperature rise, our current 400ppm should have given ~0.5C rise since 1850, which is roughly what we have observed.
As this equation represents only the direct effect of CO2 radiative absorption and excludes any feed-backs, it tends to suggest that the latter are rather small (essentially zero) and so effectively remove the 'C' from CAGW.
EM please let me know if I've oversimplified this or missed some important element because, if I'm correct, this piece of evidence seems to falsify your thesis.
P.S. I note that the evidence you listed to support your belief in CAGW is very similar to those presented by another poster called BBD... are you the same person or have you both taken your evidence from the same sources (e.g. Skeptical Science, Real Climate)?
Entropic Man (May 30, 2013 at 3:06 PM) said:
"The lab experiments derive the radiative forcing equation.
delta f = 5.35 * ln(C/Co)
The change in forcing in Watts is proportional to the natural logarithm of the relative change in CO2 concentration. For a doubling of CO2 that is 5.35 * ln2 =3.7W. This is approximately the extra energy needed to increase Earth's surface temperature by 1C. "
If this is indeed the equation derived in Myhre et al. (1998), I note that the derivation is based upon a curve fit that starts with 270ppm value (i.e. the ~1850 pre-industrial level). Therefore, assuming that a doubling of CO2 concentration results in a global temperature increase of only 1C and that there is a linear relationship between forcing and temperature rise, our current 400ppm should have given ~0.5C rise since 1850, which is roughly what we have observed.
As this equation represents only the direct effect of CO2 radiative absorption and excludes any feed-backs, it tends to suggest that the latter are rather small (essentially zero) and so effectively remove the 'C' from CAGW.
EM please let me know if I've oversimplified this or missed some important element because, if I'm correct, this piece of evidence seems to falsify your thesis.
P.S. I note that the evidence you listed to support your belief in CAGW is very similar to those presented by another poster called BBD... are you the same person or have you both taken your evidence from the same sources (e.g. Skeptical Science and Real Climate)?
EM and BBD are not the same person. EM is more open to discussion and, although not about to reverse his views, he does seem to recognise that other views than his can be held for reasons other than stupidity or brainwashing by Big Oil.
EM's views of science do seem to have been coloured by his time in school science labs. In the school lab, there is often a simple formula that tells you all there is to know and is usually confirmed by the experiment.
Perhaps that explains why EM will, in all seriousness, quote a simple formula for things that even the Met Office regards as requiring a GCM on a supercomputer. (Mind you, perhaps, in view of the MO's predictive success, EM is on the right track after all.)
A response on statistical models and global temperature is the official response from the Met Office on its blog, with Tags: bishop hill, climate, climate change, doug, doug keenan, global warming, john hirst, julia, julia slingo, keenan, Met Office, slingo. Pride of place, Bish - not bad :)
I would have said that EM is more like BitBucket - who is also reasonable, and usually plays with a straight bat.
Come on EM, 'fess up - are you BB, or BBD?
The Met Office response to Doug Keenan's post is here.
"Pride of place, Bish - not bad :)"
That's just the alphabetist world that we live in.... ;-)
We have discussed the Myhre paper of 1998, which shows increased radiative forcing with CO2 concentrations, however figure 1 of Prof Slingo's paper shows no increase in radiative forcing after 1998 - which is consistent with no global warming from that time. Therefore, the 35 ppmv rise in atmospheric CO2 during this period clearly had no effect at all.
Richard Betts - is this correct?
Hi Roger
No, it's not correct. Figure 1(b) shows net radiative forcing from all causes, not just CO2. It also includes other GHGs, aerosols and solar forcing. For example, you can see downward spikes following major volcanic eruptions (e.g.: Mt Pinatubo in 1991) as this temporarily causes a negative radiative forcing due the increased stratospheric aerosol concentrations.
Cheers
Richard
I'm not BBD or BB. WYSIWYG. I'm an old teacher who draws on other people's ideas and data, but tries to make up his own mind where possible. I tried to educate my pupils to check for themselves. Hence back-of -the -envelope calculations like this.
5.35* ln(400/270)/3,70 comes out at 0.57C for direct CO2 sensitivity for CO2 added so far. With the temperature rise around 0.8C so far, the gives a minimum overall sensitivity of 0.8/0.57=1.4C to equilibrium if CO2 release stopped tomorrow. Any delayed response due to ice melt etc which soak up heat without an immediate temperature change have been ignored, which is why I regard these as minimum figures for overall sensitivity.
For a doubling 5.35*ln2/3.7=1.002C. If the overall sensitivity increased in proportion it would be at least 1.4*1.002/0.57=2.46C/doubling.
You may now see why I am dubious of low climate sensitivities.
I think your "missing heat" explanation is a horribly weak link in your argument - "the heat flow imbalance has continued and the heat is going somewhere".
May 30, 2013 at 8:14 PM | Roger Longstaff
I know. Nothing like a good puzzle!
Let me give you a few pieces for the jigsaw, then you can be just as perplexed as the rest uf us.
The global land/ocean temperature rise described by GISS and Hadcrut4 has levelled off for the present.
The BEST land record is still rising, which suggests that sea surface temperatures may even have dropped!
"No warming since 1998" makes a good propoganda soundbite, but 1998 was a strong El Nino year. If you look at the 5-year average graphs for the business-as normal years, they show an inflection from 2003, so I prefer to date the change from 2003. That's still a decade without measured warming.
There is still a 0.5W/M^2 imbalance of incoming over outgoing energy averaged over the Earth's surface.
CO2 concentration continues to rise.
Mean sea level rose 3.2mm/year during the noughties.
In the last two years mean ea level rose by 20mm.
There is an inflection in the Arcticminimum ice extent graph in 2003, an increase in the downward slope.
Estimated total ocean heat content is increasing, even though surface temperatures are not.
Summer ice extent continues to decrease
Ice sheet volumes in Greenland and Antarctica continue to decrease.
ARGO buoys in the Greenland sea show increasing temperatures at depth.
Winter ice extent around Antarctica is increasing, though still well below mid-1960s levels.
Temperature tends to increase more slowly in La Nina conditions. We've had a fairly ENSO neutral decade.
See the problem?
Measured temperatures have stopped rising.
The secondary indicators which would be expected to correalate with temperature are still changing. There's still a net energy input to the climate. A lot of professional and amateurs are having a great time trying to reconcile this paradox. Have fun.
And it's cold outside. Perplexing indeed.
EM thanks - an impressive list. But your argument is predicated on the statement:
"There is still a 0.5W/M^2 imbalance of incoming over outgoing energy averaged over the Earth's surface."
Would you therefore agree that, either a whole host of variables (many poorly understood) have combined to somehow produce an equal and opposite "forcing" over the last decade, or that the 0.5 w/m^2 assumption is just plain wrong? Which do you think is the more likely?
(Also I have missed a step here, could you explain "5.35* ln(400/270)/3,70 comes out at 0.57C for direct CO2 sensitivity" - the method of deriving temperature from radiative forcing?).
Richard, thanks also for your comment. While figure 1 shows temperature rising with net radiative forcing between about 1975 and 1998, temperatures also rose a similar amount between about 1910 and 1945 when there was little or no increase in forcing. How can that be explained in terms of AGW?
If atmospheric carbon dioxide was to be added to figure 1, over the same timescale, I think that the chart would show the AGW hypothesis to be on very thin ice indeed.
Dear EM, if you can quantify the imbalance in W/m^2 terms do you have figures for the actual incoming and outgoing? How are they derived? If it is part of your hypothesis that an unquantified amount of heat is going into the ocean, can't you see that to the rest of us that gives you a magic get-out-of-jail-free card whereby you can make any sum work out the way you want it too. Rather like RBs magic aerosols which explain every variation, provided we do it post-facto.
Are you familiar with the concept of epicycles?
Martin A
Watts and watts...
Not that you need supporting evidence, but this provides it:
Link
I'm not sure why anyone to would object to pluralisation, although phrases like "I went a hundred mile an hour" were often heard colloquially when I was younger! For those who are bothered by it, they can simply use the abbreviation and slake their thirst for the upper-case at the same time, e.g. 1000W...
EM, from your earlier post I assume that you are using the formula:
delta C = 1.45 * ln ( final concentration of CO2 in ppmv / initial concentration of CO2 in ppmv)
Wher delta C is the change in average planetary surface temperature, in degrees Celsius, due to a change in CO2 concentration.
Is this correct, and if so, is there a reference or do you have a derivation?
I would have said that EM is more like BitBucket - who is also reasonable, and usually plays with a straight bat.
(...)
May 31, 2013 at 4:35 PM Roger Longstaff
No, BB had a streak of unpleasant nastiness (which he liked to describe as "humour").
EM never shows any nastiness so far as I have noticed.
Jun 1, 2013 at 11:00 AM jamesp
Jamesp - Thank you. I think the point that Evil Denier was making was that a unit itself is not plural:
eg "The watt is the unit of power; the henry is the unit of inductance", which I don't think anyone would dispute.
There is a form of affectation (as I see it) that uses the singular where the plural is appropriate: "We were in Kenya in the 1950's, huntin' lion". But the authority of common usage, as well as logic, says that there is nothing wrong with using the plural for scientific units.
@Roger Longstaff
Any fule kno delta T = 0.7 × forcing.
Martin
Now you've got me wondering how you write more than one henry.. :-)
Entropic Man (May 31, 2013 at 11:51 PM) said "...5.35* ln(400/270)/3,70 comes out at 0.57C for direct CO2 sensitivity for CO2 added so far. With the temperature rise around 0.8C so far, the gives a minimum overall sensitivity of 0.8/0.57=1.4C to equilibrium if CO2 release stopped tomorrow."
But an assumed rise of 0.6C, which is what I took, would give a 'baseline' (i.e. no feed-backs) of 1C, which shows just how sensitive 'sensitivity' is to the uncertainty in the observed data. This is one of the main reasons why I'm concerned that CAGW is being over-sold and why I believe it is very dangerous to base national and international energy policies on such an immature and uncertain science.
I know state the 'precautionary principle' to justify action now but, frankly, I believe that's just gambling the possibility of future problems against the certain of damage caused by badly conceived and poorly executed political fixes... bio-diesel anyone?
5:25 jamesp
According to http://physics.nist.gov/cuu/pdf/sp811.pdf plurals are formed according to normal rules of English. Hence henries
lux, hertz and siemens are exceptions to this.
Roger Longstaff
No wonder my calculation looked a bit odd. I cocked up.
I'll try again.
Forcing is calculated by delta f = 5.35 * ln(C/Co)
delta f is the change in radiation at the surface.
5.35 is a constant of proportionality.
ln is natural logarithm, log base e.
C is the initial CO2 concentration
Co is the initial concentration
For the CO2 increase to date the forcing is 5.35 * ln(400/270) = 2.1 W'M^2
To get the resulting temperature rise divide through by the watts required to increase equilibrium surface temperature by 1C.This is estimated in AR4 as 3.7W/C.
2.1/3.7= 0.57C
From the GISS land/ocean temperature graph at http://data.giss.nasa.gov/gistemp/graphs_v3/ the temperature change shown in the 5-year average is from anomaly -0.2 in 1880 to 0.6 in 2010, an increase of 0.8C.
The ratio of the total forcing to the CO2 only forcing is 0.8/0.57 = 1.4.
For a doubling of CO2 to 54ppn the forcing due to CO2 would be 5.35 * ln(540/270)= 3.71W/M^2
The temperature rise would be 3.71/3.7=1.002C.
If the same ratio applies , a doubling would produce a rise of 1.002 *1.4 = 1.41C
This is a climate sensitivity of 1.4C/doubling. It's in the lower half of the uncertainty ranges quoted by Otto or Lewis. Good news for sceptics.
Of course, it relies on the formula from Myhre et al. (1998) and the GISS temperature record, both of which some sceptics regard as unreliable :-)
EM
Just how would you describe the concept of "climate sensitivity"? As a sceptic, this gives me problems. The paper by Myhre, which is far from empirical, gives me no faith in it. as for GISS, you could replace that by any temperaqture index of your choice, but the fundamental concept of sensitivity seems like a papering over of inconvenient cracks....things happen in the atmosphere which we cannot describe qualitatively let alone quantitatively, so we call it sensitivity and assign it a coefficient.