Bishop Hill What we agree on
May 24, 2011 Climate: Models Climate: Surface Climate: WG2 Climate: solar One of the interesting moments from the Cambridge conference was where Dr Eric Wolff of the British Antarctic Survey tried valiantly to find a measure of agreement between the two sides. I didn't get the details written down, but Dr Wolff has kindly recreated what he said at the time for me, for which many thanks are due.
In the table below, Dr Wolff's summary is in the left hand column and my comments are on the right. Blank implies broad agreement.
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*Everyone in the room agrees that CO2 does absorb infrared radiation, as observed in the lab |
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*I think everyone in the room agrees that the greenhouse effect (however badly named) does occur in practice: our planet and the others with an atmosphere are warmer than they would be because of the presence of water vapour and CO2 |
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*I'm not sure if everyone agrees that the effect does not saturate with increasing CO2, but we heard a very clear presentation about that from Francis Farley |
Professor Farley's explanation was to imagine CO2 as being like ink poured into water. You can add more and more ink and so there is no end to the extra absorbtion you can get. Saturated absorbtion bands are a red herring. This assessment made sense to me. I've set up a separate thread because I imagine some people will want to discuss this.
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*It seemed that everyone in the room agreed that the CO2 concentration in the atmosphere has risen significantly over the last 200 years |
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*Almost everyone in the room agrees that this is because of anthropogenic emissions (fossil fuels, cement production, forest clearance). We did hear Ian Plimer arguing that volcanic emissions of CO2 are more important than most scientists claim, but he did not explain why they would have changed in a step-like fashion in 1800, after tens of thousands of years with no such changes; and even he agreed that some of the increase in CO2 is anthropogenic. |
This is not an area I've ever questioned, but I'm looking forward to finding out more from Ian Plimer about his ideas. I'm not sure I understand Dr Wolff's reference to 1800 either. |
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***I then suggested that if we agree all these statements above, we must expect at least some warming. |
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Then moving to whether we already see effects: |
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*I think everyone in the room agrees that the climate has warmed over the last 50 years, for whatever reason: we saw plots of land atmospheric temperature, marine atmospheric temperature, sea surface temperature, and (from Prof Svensmark) ocean heat content, all with a rising trend. |
Yes, but I would like to get some idea of whether the warming we have seen is statistically significant. i.e. a response to Doug Keenan's article in the WSJ.
I think Lucia's work has shown fairly clearly that the trend since the start of the century is very unlikely under 2deg/century, so the analogy is not a good one. |
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*We probably don't agree on what has caused the warming up to now, but it seemed that Prof Lockwood and Svensmark actually agreed it was not due to solar changes, because although they disagreed on how much of the variability in the climate records is solar, they both showed solar records without a rising trend in the late 20th century. |
I didn't take this on board at the time. It would be interesting to see Svensmark's opinion. If the warming really cannot be shown to be statistically significant, how important is this kind of attribution? |
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*On sea level, I said that I had a problem in the context of the day, because this was the first time I had ever been in a room where someone had claimed (as Prof Morner did) that sea level has not been rising in recent decades at all. I therefore can't claim we agreed, only that this was a very unusual room. |
Not something I know much about, but Morner's concerns seem important. I find the idea that we can't see the adjustments to the data disturbing. |
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*However, I suggested that we can agree that, IF it warms, sea level will rise, since ice definitely melts on warming, and the density of seawater definitely drops as you warm it. |
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*Finally we come to where the real uncertainties between scientists lie, about the strength of the feedbacks on warming induced by CO2, with clouds a particularly prominent issue because they have competing effects that are hard to quantify. I suggested to the audience that we could probably agree that the likely range of warming from a doubling of CO2 was 2-4.5 degrees C (which is actually the IPCC range). This was the first time I really got any dissent, so I then asked whether we could all agree on at least 1 degree (implying no positive feedbacks at all, even from increased water vapour and sea ice loss). I got one dissenting voice for that, but there wasn't a chance to find which of the preceding statements he had disagreed with (it would be necessary to disagree somewhere up the line to be consistent with dissenting on this one). |
I'm very uncomfortable about the idea of making a prediction about temperature when it is so likely that there is something missing from the models - this seems the most plausible explanation for the temperature trend since 2000/1. Under the scientific method, shouldn't we find out what this is before we start testing again? We may be able to agree that the no-feedback warming is 1 degree C, but there is a great big unknown in the shape of the feedbacks. The idea of overall positive feedbacks seems unlikely to me, given that the Earth's temperature doesn't seem to have got out of control in the past. |
So there you go. Quite a lot of agreement on the basics, but some pretty interesting differences kicking in one we get on to the detail of what it means. We can discuss the agreement or otherwise in the comments. If I get some time I might put together a survey to get a better idea of how strong our agreement or disagreement on Dr Wolff's points is.
I also thought it would be interesting to see if we can get a measure of agreement on some sceptic talking points too. A couple of mainstream scientists I met at Cambridge have agreed to take a look at the specific points I raise above - namely the question of whether the warming in the temperature records is statistically significant and to what extent Lucia's work shows that the IPCC models have overstated the warming. I have discussed Lucia's work with a couple of other scientists since, and neither seemed to have strong objections to her work, although they were disinclined to place much weight on the results.
Underlying both of these areas is a simple question of whether the variability in the surface temperature records can be described with an AR1 model. Doug Keenan seems to me to have shown quite conclusively that it cannot (Doug's technical background document is required reading on this subject).
So my question for climate scientists would be this:
"Do we agree that the AR1 assumption for surface temperatures is inappropriate?"
Reader Comments (160)
Shouldn't we be measuring Ocean Heat Content instead of Surface Temperature as Roger Pielke Sr has indicated at some length?
Richard - absolutely agree. There is more heat content in the top 6 feet of the ocean than in the entire atmosphere. Using Surface stations is like Doctors wheeling in a patient with a suspected fever into A&E, and rather than put a thermometer in his mouth they dangle it 4 inches above his forehead.
phinniethewoo
"CO2 is transparent"
No, it is semi-transparent, or at least behaves in that manner. My post at 5:04 (if I may be so bold).
On the topic of computer models, the computer-modelled ash cloud has just been tested by Ryanair and found to be absent.
Missing ash?
"Professor Farley's explanation was to imagine CO2 as being like ink poured into water. You can add more and more ink and so there is no end to the extra absorbtion you can get. Saturated absorbtion bands are a red herring. This assessment made sense to me."
As you pour more and more ink into a sink, eventually you can no longer see the drain plug, yes? I.e., the photons coming from the drain plug can't reach you. The system has been saturated. What is so hard about that?
A worthy effort on the part of Wolff, but the fact that the ink analogy was so readily accepted shows that we have a long way to go to educate scientists in the reality of climate science. A very long way.
I included links in one thread here giving an estimated volcanic CO2 flow for the earth. I'm too busy to recreate the comment, but the total is huge, on the order of 100 GT/year. Plimer is right. NOAA's CO2 cycle chart doesn't even show volcanic CO2, an omission so stark that it raises a big red flag. There are apparently deficiencies in the isotope method of distinguishing anthropogenic CO2 from natural.
Agree,CO2 can absorb infra-red but as averred above in very narrow band widths, it immediately jettisons photon charge, like many other atmospheric gaseous molecules, it is by no means a unique property to CO2 molecules.
CO2 in every way is a minor [atmosphere] gas but one that is vital to us, it is life, it receives a bad press.
All of their [alarmist] conjectures: are supposition, mainly 'backed up' by 'computer models' - that's not scientific method, that's astrology.
Sea levels are not proof of aught, indeed concentration measurements [CO2 in atmosphere] are only 'accurate' Circa 1958.
Everything is palaver and guesswork, I wouldn't concede anything to this lot of conceited nerds.
End.
Bish' treading on their territory, is not in your interests but does give them favour.
Bishop,
Thanks for posting Wolff's summary; interesting.
Your comment to Wolff's last point is exactly opposite to how I would phrase it:
The idea of overall positive feedbacks (i.e. a climate sensitivity greater than one) seems very likely to me, given that the Earth's temperature seems to have responded substantially to relatively small changes in radiative forcing (of which reenhouse forcing has often been an important component).
Bart
Tell me more - (give me a link?)
And then (please!) tell me about AR1.
Bart, To slightly misquote the M.Rice-Davies observation, 'Well you would, wouldn't you?'
I'm with Harry Dale Huffman and Joseph Postma. The "greenhouse effect theory" is false. The gravitational compression of the atmosphere explains the "average temperature of the Earth" (and Venus) and the adiabatic lapse rate. Sure, carbon dioxide affects heat transfer through the atmosphere, but the parallel processes of radiation, convection and latent heat will adjust to maintain the physical lapse rate. The atmosphere helps cool the surface during the day and the stored energy (mainly latent heat) prevents it cooling so fast at night.
"Radiative forcing is a thing not known in physics. It was invented by the IPCC to make bovine scatology smell good. It tries to fool people into thinking "climate scientists" with their alarmist "greenhouse effect" theory know what they are talking about.
@ phinnie..
#1 yes, let's suppose....
... this works well, apart from the abundance of H²O at a narrow temp. range being available to conditions you had set as conditions. the consequence might be: such planet would be not so white anymore.
#2 add any...
... yes, considering the above, true to earth, it doesn't mater what atmosphere you append, assuming there was none. it also does not matter what constitution this atmosphere has. add any gas (or mixture), just keep a look at the pressure in order to get the right TEMP!
#3 measure..
... according to #1, color does matter a little, but will stay unmeasurable.
this is consensus out through our universe.
BTW: it is Bob Dylan's birthday: http://www.youtube.com/watch?v=ITl-n55Mn7s
I can't take Bart Verheggen seriously having visited his website and looked at various articles and links. He clearly is not an expert in the physics of the climate; he just accepts unquestioningly the "consensus" view of the IPCC.
Now that's a real scientist talking real science! If I'd tried presenting a report saying it "seems very likely OK to me, as it seems to have been OK before", I would have been looking for a new job. But I wasn't working in "climate science", where anything goes.
With Philip on this one.
Climate science does seem to, here and there, lean heavily on what sounds 'reasonable' and the like. By the same logic one argues for 'positive feedbacks', one can very well argue for 'negative feedbacks' as well. This 'feedback', 'forcing', 'sensitivity' business is just smoke and mirrors.
methinks that Philip and Shub are verging onto the tribal here - the behaviour one associates with WUWT and Tamino and DeepClimate and Stoat and RC et al. Can we not be dispassionate here? Bart is an CAGW believer but he does let other people post on his site - thus living up to his free-thinking Dutch origins.
Shub,
"This 'feedback', 'forcing', 'sensitivity' business is just smoke and mirrors."
I thought smoke and mirrors was the geoengineerers' antidote:-)
simpleseekeroftruth
thanks I got that wrong indeed.
CO2 is transparent to our eyes only of course not vs whole (IR) spectrum.
opastun
a transparent gas over the whole spectrum would support my gedankenexperiment but there is no such gas I guess.
an atmosphere does allow sunlight to loose some more feathers (energy) via photon-electron(atom) interaction
Fourier was clever chap,
myeah dylan we were young and innocent (or not that innocent mb)
diogenes
Of course, Bart is different from Tamino and Deepclimate and Realclimate and...
My point was solely limited as a commentary to how one can apparently take a position about the issue of the so-called feedbacks (and not anything related to Bart's openness to invite and accept comments on his blog)
he is scrubbin the VS-BV thread tho (slap on the wrist)
I will get my coar.
coat
grins at Shub...let's not lower ourselves to the levels of Halpern and Foster and Romm...
"I can't take Bart Verheggen seriously having visited his website and looked at various articles and links. He clearly is not an expert in the physics of the climate"
May 24, 2011 at 8:23 PM | Phillip Bratby
So you are an expert in the physics of the climate are you Philip? Strewth. Being an expert must be easier than I thought.
For a minute, I thought you were the guy who regularly made pronouncements like 'there is no such thing as a greenhouse gas' which were so ridiculous, that even the other posters on this website avoid engaging with you on them, as to do so inevitably involves demonstrating that you're one disc short of a box set.
Yup, I am saddended once more. I asked a question with zero weight and, for the sixth time, it got ignored with zilch response.
Agreed that I come here with minimal scientific credentials, a history of irrational rantings but this is my web-site of choice where so many, of obvious talent, merge with others with no answers but the odd straight question.
I'll repeat my question but this time I'll ask the obvious rather than leave it unsaid as a unwarranted compliment to those who visit this site.
My question was straightforward; I'll repeat it but more directly than hitherto.
As the Oceans warm, they exude CO2. As does the rest of the planet for whatever rationale. Since the LIA, what is the estimate of the CO2 ppm added to the atmosphere because of the delta T experienced?
Is it 0.1 ppm, 1 ppm , 10 ppm or whatever?
An ignoramus, like me, would like at least a guess! I can understand the Chicken and the Egg bit but unless we we can attach numbers to the process we end up confusing cause and effect with the climate phrenology scripting of Mr Gore's Mockumentary.
royFOMR
for water at low pressures the temperature sensitivity iof CO2gas mixed in H2Oliquid s quite high. however this is at 1 bar.
10m-200 deep (1 bar 0.1MPa) CO2 becomes liquid and a liquid mix with H2O. concentrations will vary and form a concentration gradient between upper(CO2 gas) and lower (CO2 ice)
@200m deep (20bar , 2MPa) things are different again we have the phase diagram of CO2 with H2O to follow and we have at 4 degrees breakout and forming of Clathrate CO2 ice which will be in a mix with CO2liquid+H2Oliquid
The temperature sensitivities below are less than in upper layer I think, however this maybe does not matter .This is a complicated phenomenon because 3 phases are here in flux and will need to find a balance with a new surface temperature.
500M cb km ocean water?
I think this is many many ppm , I have no idea. If you put a gun to my head I say 50ppm
it could be 0.5 it could be 500 so I say 50ppm
I am also ignoramus btw.
i liked the venus story above
this thing might take time to settle which is maybe the reason for the 800y lag between warming and CO2 rise.
Thanks for your response PTW.
You made a guess, I appreciate that.
We hear a lot about fossil-fuelled CO2 atmospheric accumulations but given the 33:1 disadvantage vis a vis 'twixt natural v. man-made 'Carbon Pollution' I would love to know just how much the post-LIA and natural outgassing of Oceanic CO2 contributes to atmospheric CO2 concentrations.
I'm more than happy to concede that we've warmed up Globally since the LIA, I'm even slightly orgasmic that we've added loads of fossil-fuelled CO2 to the Atmosphere since the 1950's.
I am a tad disturbed, however, that we've poorly established what the relative proportions of natural versus man-made amounts of CO2 have been when without quantification, Oceanic outgassing has been iognored.
Prove me wrong and I will listen. Ignore me and I'll remain a non-warmistador.
My own position is that mankind has a very limit understanding of what causes different climates and what causes climates to change.
There is no point in any further discussion about the details of that poor understanding - it's like disccussing the finer points of theology with an atheist.
Roy
A doubling of CO2, it has been stated = 1 degC average(?) temperature rise. That doubling is unlikely to be possible by anthropomorphic action affecting the carbon cycle. Even if it did happen, natural events from the past suggest a net benefit to life.
What we are asked to believe is that there is a positive feedback mechanism with atmospheric CO2/H2O which causes additional atmospheric heat retention. This has not been proven. What we do know is that CO2/H2O readily mixes to form carbonic acid and that returns to Earth as rain where it is neutralised by interaction with forms of CaCO3 - calcium carbonate: part of the carbon cycle. Temperature changes involved in that reaction do not occur in the atmosphere.
The 'proof' that we are expected to accept for the positive feedback hypothesis is that temperatures have been rising rapidly since mankind industrialised and particularly since after WWll with more intense usage of fossilised hydrocarbon as fuel. That process is anthropomorphic and produces CO2, is the only change of significance to the atmosphere, atmospheric temperature is rising beyond what can be expected from additional CO2 alone, is outside the boundaries of normal climate variation and therefore the positive feedback hypothesis is proven. That is the science. From there we move to mankind's actions are reckless etc.
IMHO you are right to question CO2 concentration assumptions but the far, far bigger question is about the feedback hypothesis. Solar variabilities and clouds, argue some, are little understood so we must strive to do so. Laudable as scientific endeavour, as is your question, but if applied with the same rigour as the positive-feedback-is-real-because-it-can't-be-anything-else proof, climate science will remain dominated by swivel-eyed agenderists.
Roy, you ask a simple question and it is remarkable that there does not appear to be an 'official' answer. However, Prof Eric Wolff did effectively recognise and effectively quantify the oceanic contribution of CO2, in his answers on the initial Antarctic Fox thread. Not from coming out of the LIA, but from the coming out of the Ice Age proper. Irrc he suggested that from ice core data, typical CO2 levels were c. 180ppm during the big freeze, and rose to 250-300ppm by the time we / the oceans warmed up by about 5C in the Holocene. So ignoring ocean lag and possible increased CO2 uptake by plants which can grow faster in higher temperatures (and possible CO2 release from warming tundra) I assume/guess that if a 5C rise gives an extra 70-120ppm, the 1C rise we have seen since the end of the LIA will have instigated around an extra 14-25ppm CO2 from the oceans?
@Philip Bratby
Do you have a reference to a peer-reviewed paper which argues against the greenhouse effect (defined as we discussed last week) with a clear scientific analysis ?
Doug K's work would be better if he used the right global temperature series. he used Gisstemp.
IPCC used CRU.
Kind of a vital nit. should probably rerun the analysis.
I'm with diogenes on this - let's not be too tribal. Bart's comment was almost completely polite, albeit disagreeing with the host, and his blog is fairly welcoming also.
I think the big argument in favour of large positive feedbacks is the existence of ice ages. We know that at some point in time, it was 5 degrees C colder than now globally. There's also some indirect evidence that various forcings were not very different then. E.g. the sun had not completely shut down. So people come up with the idea that relatively small changes in forcing (a drop, in this case) had been amplified by something or other, probably water vapour. I'm pretty sure that the evidence available that this 'something or other' can deliver the goods of a strong positive feedback is weak, so this description may not be correct. But any proper theory of climate that wishes to claim with very strong confidence that CO2 cannot lead to significant warming must come up with non-positive feedback theories to explain the ice ages. As a sceptic, I feel I'm allowed to say that I suspect that positive feedbacks don't occur, but I don't feel it is sensible to proclaim that the idea of a positive feedback is either insane or a scam.
Jack Hughes wrote "My own position is that mankind has a very limit understanding of what causes different climates and what causes climates to change." I'm sure that's true at one level, but if we always used that as an argument not to investigate further, we'd still be living in caves. In fact, we know a huge amount about climate. Not enough, and here I agree with Jack, to have policies like the Climate Change Act.
The further you look back in time the more you realise that our climate is basically a perpetual drunken walk in the park. You may identify a few cycles, a repetition of behaviour like a drunk trying to pat a head of a small dog passing by, but it is essentially random.
Fred Bloggs,
I think Harry Dale Huffman's experience shows why you won't find it in peer-reviewed journals. You'll have to read articles like his and Joseph Postma's and make up your own mind which theory is more plausible.
j - from the Ice core data, I would contend that ice ages are the big argument in favour of significant negative feedbacks. Even this interglacial (which has already gone on far too long compared with the four), is just a blip in the overwhelmingly cold last half million years or so:
http://www.foresight.org/nanodot/wp-content/uploads/2009/12/vostok.png
(summary at http://wattsupwiththat.com/2009/12/09/hockey-stick-observed-in-noaa-ice-core-data/ )
sorry missed a word - ... compared with the previous four...
I went down to the greenhouse first thing this morning to check on the greenhouse gases. Everything seemed normal so I assume the nitrogen concentration was about 80%. I was able to breathe normally so I assume the oxygen content was about 20%. There must have been a fair bit of water vapour as I have had to do a lot of watering recently. Carbon dioxide levels must have been about normal as the plants were green and flourishing. However I noticed that after I had been in there about 20 minutes it started to get warm. I am very confident (more than 90% certain) that this was due to back-radiation from the increased carbon dioxide concentration resulting from my exhaling. I have no other explanation for it. I don’t think it was due to the fact that the sun had appeared from behind a tree. To confirm my explanation, I opened the door and window and let the excess carbon dioxide escape. Immediately the removal of the excess carbon dioxide and the resulting fall in back-radiation led to a fall in temperature. I am very confident (more than 90% certain) that this fall in temperature was not due to natural convection allowing cold air in through the door and warm air to escape from the window.
Isn’t it strange how after many years involved in using the laws of physics and involvement in calculations of complex heat transfer and fluid flow, one is not allowed to be an “expert in the physics of the climate”? Do the traditional methods of calculating heat transfer and fluid flow not apply to the climate? Are conduction, convection and radiation different in the climate? It’s almost as if people think there is one type of physics for the climate and one type of physics for the rest of the universe and never the twain shall meet. Mind you given that the climate is mainly studied by “environmental scientists” at such places as the School of Environmental Sciences at UEA, it is not surprising that the laws of physics do not seem to apply to the climate. It is much easier to apply the laws of “environmental science”, where everything can be explained as a result of burning fossil fuels and to hell with the laws of physics.
Physics rules.
Because I was responsible for the left hand column of the original post, I anticipated that I should wait and see everyone’s comments and then try to respond to some of the more directly raised issues. However, having just very quickly trawled through them, I realise there is way too much for me (or anyone else to deal with): your stances range from those who just worry about the range of possible effects to those who simply don’t accept anything. I am not a natural blogger, and I won’t be returning here on a regular basis. I can see that a whole load more comments appeared since I drafted this, but I think I'd better post what I have.
So, what I am going to do is to first make some general observations, then comment on a couple of specific points made in the right hand column of the original post, and then on one or two issues that jumped out at me (either because they were interesting or because they were so wrong they require a comment).
I should first state the rationale for the summary I made at the Downing event. The meeting was about the science and economics of climate change, and I was asked to lead a discussion that came between the science talks and the two economics talks. I therefore felt the most useful thing I could do was to try to summarise what we had heard, as a basis for the discussion of whether society should do anything in response to that, and if so what. In particular I did hear a surprising number of things on which almost everyone in the room could agree, and it seemed worth emphasising that, rather than rehearsing old arguments.
I notice in the thread here several comments about who sets the “terms of the debate”, and about the “context of the debate”. While such phrasings may make sense in discussing energy policy, it is a strange way to discuss the science. Our context is the laws of physics and our observations of the Earth in action; our aim as scientists is to find out how the Earth works: this is not a matter of debate but of evidence. I think some of the comments on this blog come dangerously close to suggesting that we should first decide our energy policy, and then tell the Earth how to behave in response to it.
Now to some comments on the right hand column of the original post:
Regarding Plimer’s proposal that volcanic emissions were more important than we thought, I said: “he did not explain why they would have changed in a step-like fashion in 1800”. My point is that for at least the last several thousand years until 1800, the CO2 concentration in the atmosphere had not changed by more than a few ppmv per century, implying that sources and sinks were roughly in balance. After that the concentration has steadily increased. The only way that can occur is if, from about 1800, there was a change in either the strength of the source or of the sink. Thus if volcanoes were “causing” the recent increase, then around 1800 their emissions would have had to rise above their stable long-term rate, and then stayed high. This is however a rather hypothetical discussion because the change in the isotopic composition of CO2 in the atmosphere over the industrial period is not consistent with an increased volcanic source anyway.
Regarding the idea that the “temperature increase stopped in 2000”: my point is that we know there are natural variations (due eg to El Nino) that cause runs of a few years of temperature colder than the average or a few years warmer. Look on the record
(eg http://www.bis.gov.uk/assets/biscore/science/climate-change/fig-7-large.png)
at the decade around 1910 for example when there was a long run of cold years on a flat background. Such a period superimposed on a trend would look like the last decade (but more so). The point of my analogy is that you can’t determine the trend over several months by measuring the gradient in a run of a few days. Similarly, you simply can’t determine a multidecadal trend by measuring the gradient over a few years because all you get is the “noise” of natural variability.
Professor Morner claims that globally sea level has not risen at all; he dismisses the evidence, from both satellites and the global tide gauge network, that it has. I simply don’t understand the point about “can’t see the adjustments”. The people producing both the tide gauge and satellite data have published extensively about how they treat the data. There are numerous reasons why a single site can show a sea level signal, either real or apparent, that departs from the global mean. Morner has published specifically about the Maldives, where his morphological interpretations suggest that a sea level fall has occurred. This has been comprehensively discussed in a paper by Woodworth (Global and Planetary Change, 49, 1-18 (2005)), who concludes that Morner’s interpretation is not consistent with the data from tide gauge stations in the region.
I am not the best person to discuss models and feedbacks in detail (see comment on expertise below). However, I could not let two issues pass. Firstly, when models are run out for a century into the future, they do indeed show runs of years with flat temperatures amidst a trend. You can clearly see such periods in Fig 10.5 of the IPCC AR4 Working Group 1 report (page 763). No-one can tell you when such runs will occur, but they do occur in the models (because of El Nino and other natural factors). I am therefore not clear why this is evidence that something is missing. Regarding positive feedbacks: a positive feedback implies amplification, but not a system out of control; this is only the case if the sum of the gain factors is greater than 1.
Finally, a few specific issues that interested or worried me.
I am surprised that Philip Foster raises doubts about the CO2 increase of the last 50 years on the basis of supposed problems with the Mauna Loa record. He must know that, even ignoring ice cores, our knowledge of CO2 over the last 50 years is based on numerous stations worldwide, all of which show the same trend.
I gave (and then wrote) a summary, not a book, so of course I did not cover every sub-clause that could have gone into my statements. Because I did not explicitly state it, one writer implies that I don’t know that CO2 emits infrared as well as absorbing it. Of course I do; indeed, this property is precisely why its effects do not saturate (but fall logarithmically), because it allows the height from which the emitted radiation finally escapes to rise into regions with less and less air.
Geckko accidentally made an important point. S/he did not like the statement: "We can agree that if it warms the sea level will rise", because it was too simplistic. Well, as a scientist I always like to boil things down to a statement that my brain can grasp, but that contains the essential explanation of an observation or process. And this one does, for example being demonstrably what was observed in going from a cold ice age world, with sea level 120 metres below the present level, to the present. However, you are right: there are factors that could make this statement false, such as increased snowfall when it warms, adding more ice into ice sheets. As soon as several such competing processes have to be taken into account, our brains cannot predict the outcome, and so we have to resort to putting all the “millions of assumptions” into a numerical model and seeing which of them “win”. An argument for models?
Coldish made a good point about expertise, and this is where I am going to go into a slightly more challenging area. I freely admit that I am not an expert on all, or even most, aspects of climate. When I reach a topic that I have not previously studied, I go to those who are experts, either in person or by reading their work. I maintain scepticism about some of their conclusions, but my working assumption is that they are intelligent and that they have probably thought of most of the issues that I will come up with. Can I observe as an outsider to the blogosphere, that it surprises me that so many people, presumably mostly with even less knowledge and training than me, seem absolutely convinced they have mastered every area of climate science.
However, Coldish specifically mentioned IPCC, and I think there is also an interesting point to make about that. At the Downing event, there seemed to be two IPCCs in the room. To some it was a huge plot, masterminded by some mysterious power that manipulates troublesome scientists. To me and the scientists in the room, it is (at least in WG1) simply a set of well-researched review papers, describing the present state of the peer-reviewed literature. I mention this only because I think the former view is a type of groupthink where, because people form an extreme opinion in their private space, they think it is widely held, or even true.
Refs for a climate more sensitive than the no-feedback case:
http://www.agu.org/meetings/fm09/lectures/lecture_videos/A23A.shtml
http://rsta.royalsocietypublishing.org/content/361/1810/1831.full.pdf
http://www.pnas.org/content/107/2/517.full
http://www.jstage.jst.go.jp/article/sola/1/0/1_181/_article
http://epic.awi.de/Publications/Khl2011c.pdf
http://ajsonline.org/cgi/content/abstract/311/1/1
http://www.columbia.edu/~jeh1/mailings/2011/20110118_MilankovicPaper.pdf
http://www.earth-syst-dynam-discuss.net/2/211/2011/esdd-2-211-2011-print.pdf
More useful listings:
http://agwobserver.wordpress.com/2009/08/15/papers-on-ghg-role-in-historical-climate-changes/
http://agwobserver.wordpress.com/2009/11/05/papers-on-climate-sensitivity-estimates/
The point is that our knowledge of past climate changes, and specifically the change in temperature and the radiative forcing, points to a climate sensitivity somewhere in the IPCC "likely" range. Over different time periods, with different mechanisms at play, using different methods by different people: A consistent yet uncertain picture emerges. Armwaving is not enough to wave that picture away. In science it isn't.
[BH adds: Thanks Bart. So much to read, so little time...]
Quote, Eric Wolff, "Regarding positive feedbacks: a positive feedback implies amplification, but not a system out of control;
errrr .............. wrong on both counts.
As any engineer would know, positive feedback without a stabilising force will ultimately lead to oscillation and eventual saturation, i.e. a system out of control.
Climate change is not the same as climate instability.
So Bart if there is a positive feedback howcum the Medieval Warming and Climate Optimum did not spiral out of control and indeed were followed by cooling?
There have been many instances in the past whereby rising levels of atmospheric CO2 have not led to a corresponding increase in global temperatures. The relevant ice core data clearly shows that, where the lag between temperature and levels of atmospheric CO2 shows instances of global temperatures decreasing whilst CO2 continuing to rise.
To state that man-made releases of atmospheric CO2 are a game changer is to denounce this planet's 4 billion year past existence.
CO2 did not drive global temperature in the past, the ice core data, or even drives it now, no Hot-Spot.
All we are seeing is a beautiful theory being protected from some ugly facts.
Eric Wolff wrote:
"I think some of the comments on this blog come dangerously close to suggesting that we should first decide our energy policy, and then tell the Earth how to behave in response to it."
Isn't that exactly what our politicians in Britain are about? Green energy policy = sort out the boondoggles and then see what happens.....then, when the lights go out - run around like headless chickens and blaming equally stupid former administrations.
Energy policy should be never be determined by [horribly inexpert - should I say Green] politicians with axes to grind and advocates to please, politicians should be - the last people on Earth to be deciding energy policy.
AGW, a limited correlation is not causation, of course further study is an absolute necessity - but the gun has been jumped here, the AGW advocates are running the show and the AGW show is the only one in town.
Your cloaked sarcasm Eric is noted but rebuffed, like many in your world, the door is already shut and the science settled - how can science ever be settled, or are you a higher entity? - no probably not but the 'omniscience' complex abounds in alarmist circles.
In the end; too much cyber jiggery pokery and statistics, and not a lot of empirical evidence - prove nothing.
AGW at it's inception was a political vehicle, designed to legitimise changes in energy policy, like a religion it has taken on a life of it's own - so that everything and every terrestrial weather event and even geophysical phenomena is, or has been attributed to human outgassing of a minor Atmospheric molecule - this is mass hysteria Eric or, as you prefer - Groupthink.
A conspiracy Eric? yes you are damn right there is, the scientific community closing ranks and the political elite imposing their will by diktat - that's a conspiracy alright Eric.
No one doubts or belittles your remarkable expertise Mr. Wolff but there are other darker motives and politics is never open and honest, it is a shame science has been besmirched but blackened it has been and the reason for this, lies on your own doorstep Eric and with your fellow travellers.
We are heartily sick of a constant stream of scientists hiding behind the sometimes entirely bogus concept of 'peer review' - it is no longer enough.
Prove it, we ask, where is the body of evidence and find that none is forthcoming - just; "peer review" - not good enough. Yes, yes loads of ifs and buts, our government is committing our nation to a slow economic suicide because of some bogus scientific conjecture - can you not empathise with this frustration we feel and the only retort is: the blank answers....."the science is settled!" - No it ain't.
Mac,
"All we are seeing is a beautiful theory being protected from some ugly facts."
Indeed so.
@Philip Bratby
I read the HDH piece and it seems kind of cute. Even if you do take his arguments at face value, he does not show that the GH effect exists, just that it is not significant. However, I am not sure it is as simple as he claims.
Also HDH's credibility index suffered a major dent when I looked into his other work.
Sorry should be "he does not show that the GH effect does NOT exist"
Neil - lets not forget the Roman and Minoan Warm periods also:
http://jonova.s3.amazonaws.com/graphs/lappi/gisp-last-10000-new.png
Eric - the graph you posted to show the cool years post 1910 is a little scary
[ http://www.bis.gov.uk/assets/biscore/science/climate-change/fig-7-large.png ]
I prefer this one which uses raw data - http://oi49.tinypic.com/rc93fa.jpg - as it doesn't frighten the children so much.