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)
At a quick reading, there are many areas missing or treated too lightly in the above comparison:
1. The impact of UHI and what proportion of the measured increase is accounted by it.
2. The recent advances in experimentation on cosmic ray theory, knowledge about changes in the magnetic fields in the sun and between sun and earth, plus the apparent similarity of cycle 24 to those esrlier cycles when the earth was very cold.
3. Recent non peer reviewed research suggesting that when adjusted for distance from the sun and differences in atmospheric pressure, that despite the 97% CO2 Venus atmosphere, its temperature almost exactly equates with earth.
4. The most recent satellite lower atmospheric temperature (April 2011) is alost exactly the same as in 1980 - quite different from published global indices.
5. Why focus only on the last 50 years? Global temperate as measured by global indices rose from about 1850 to 1880, from 1911 to 1943 and 1976 to 1998 by almost exactly the same amont. This cannot be explained by human CO2 emission.
6. Is the feed back from water vapour positive or negative?
7. The role of clouds, ocean currents and so forth in the climate system.
7. The climate is a fully determined, chaotic system. As such forecasting beyond a few months into the future is futile and a nonsense of the first order.
There is much more that cannot be explained by CO2 but at least that's a start for the discussion.
We should not allow the terms of the debate to be determined by the warmists.
It is high time that we demand an even playing field, with all issues on the table for serious discussion.
We should set up a debate between recognised practicing professional mathematicans on the topic of the feasability to forecast elements of a chaotic system forward for 50 to 100 years.
Collecting a team for the Affirmative may prove to be an insumountable problem.
Perhaps promote AusieDan's Point 5 to an agreed position.
Climate Skeptic website says:
"It is obviously true that past climate change was caused by natural forcings."
Dan's right - its dangerous to get sucked into the details of their beliefs.
I would step back and ask this question:
Is climate science advanced enough to build national and international policies on its predictions?
The only test of this is how good are the predictions ?
I would want a list of detailed predictions about today that were made 5 years ago and check how they turned out.
Anything else is bubblegum.
[BH adds: I agree. But in order to test the predictions we need an agreed statistical model for the surface temps]
There are many people who would disagree with the second point, namely
Nobody can even agree on a definition of "the greenhouse effect". See, for example, Section 1.0 of http://greenhouse.geologist-1011.net/
Then go and look at websites such as that of the Met Office, DECC, Defra, BBC etc and read lots of different definitions. I suspect they deliberately use different descriptions to make it impossible to pin down what "the greenhouse effect" really is supposed to be.
Fully agree with Aussie Dan.
And before engaging in debate, it is in my view essential to remember that, at this very moment we are travelling along a policy path which will enormously increase energy costs and replace sound and tested technology with "renewables" which are unproven (at best) or which are demonstrably useless for large scale generation. The implications of this are profound to our economies in the "developed West". They are even more profound in the poor third world and will likely hugely damage the potential there for beneficial development.
This is the context for any debate, then.
We should also remember that this policy is a direct product of a basic assumption (that mankind is fundementally and significantly affecting the climate).
This assumption is 'demonstrated' by a bunch of similar half-arsed computer models (I could expand if goaded) which have failed to show any predictive skill, or even hindcasting skill without being "adjusted" by factors using data that appears to have been plucked in some cases from thin air.
It is the bold assertion of the warmists (nervously fingering their bulging wallets) that the science is more or less settled and all the 'right chaps' seem to agree. (The politicians are even more brazen, naturally).
Yet there are a number of factors (tropical tropospheric "hot spot" for one) which indicate that the models aren't just 'imperfect', they are flat wrong. There is no evidence that sea levels are generally rising by more than the 200mm / Century that has been measured since the last ice age. All the wild eyed and doom laden predicions have been shown to be flat false or wildly exaggerated. And not a week goes by without your blog or WUWT posting about a new peer-reviewed (if that matters) paper which at least calls into question how well we understand the basic mechanisms.
And with respect, Wolff's position seems to be "well, this cAGW theory seems plausible (providing you accept all the stuff which appears to be incompetent and / or fraudulent and ignore inconvenient stuff that points in other directions). And all the "best" chaps think it is OK. So it's gotta be right!"
And so the band still plays on.
Shall we try to get Dr Wolff to give his position on theory versus practice, rather than trying to guess what it is? I think it would be wise to try too avoid to much heat at this point, given that Dr Wolff was willing to engage here yesterday.
Following the release of a report by the Australian Climate Commission, all talk in the media is about how sure we can all be on "The Science" of Climate Change. Even the Opposition Leader declares that his party accepts "The Science" of Climate Change. But as in Dr Wolff's summary above, I suspect that there would be as many versions of "The Science" as there are people in the room. The differences would only appear when you probed each person's view at a deeper level.
A bit like asking 5 economists for an opinion and getting 6 different answers.
*Everyone in the room agrees that CO2 does absorb infrared radiation, as observed in the lab
Why didn't he also say:
"*Everyone in the room agrees that CO2 does emit infrared radiation, as observed in the lab"
This is a bit like saying: "everyone agrees that modern cars have better brakes" ... QED modern cars must result in slower traffic. OK, that's going right the other way, but there is no question that CO2 can act as a vector to help cool down the atmosphere by being able to emit at wavelengths that other air molecules can't. Obviously, this effect increases higher up in the atmosphere where the CO2 blocking is least (and emission predominates).
Another massive flaw in this whole discussion is that it's a static model. Something like half the heat lost at the surface is lost via evaporation. That evaporative heat is then dumped when clouds are formed. Therefore around 50% of all the surface heat is a direct heat input at cloud level. Which means that 50% of heat is involved in a dynamic heat movement and not this static analysis which "compels" people to believe in greenhouse warming.
This really is noddy science. Hand waving arguments, ignoring half the effects, simplifying ad adsurdem.
The AR(1) assumption is not at all plausible. For one thing, were this so, the partial autocorrelations should be close to zero for lags greater than 1 year, but this does not seem close to being true in the data I have looked at. The temperature series appears to need differencing, and then the significance of the trend will be substantially lower.
You are right to press this question Bish. I should like to see the AGW camp approach this issue with proper rigour
Good to see quite a bit one can agree with in Dr Wolff's summary, even if his leap from common ground to the 2-4.5 C estimate is not justified.
Regarding the 1C no-feedback estimate, this is not as solid as sometimes suggested (for example, Curry's "CO2 no-feedback sensitivity" posts).
Regarding solar attribution, I'm not aware that Svensmark has changed his opinion since 2007's "Reply to Lockwood and Frohlich" - "...they argue that this historical link between the Sun and climate came to an end about 20 years ago. Here we rebut their argument comprehensively." and "Contrary to the argument of Lockwood and Frohlich, the Sun still appears to be the main forcing agent in global climate change."
Lastly, I think you may have meant to say: "is very likely under 2deg/century".
"whether the warming in the temperature records is statistically significant"
Now I've had a look at this, and because the climate noise is a 1/f^n type noise, statistical significance is a very hard thing to gauge. I literally couldn't find anything on the statistics of 1/f noise - as far as I can see it either isn't possible, or there isn't one single meaning to "significance" with 1/f noise.
What I can say, is that when I run series of 1/f noise, about 1 in 10 are similar enough to the global temperature series to have caused the same hysteria if they had occurred. As we'd have got the same hysteria for a downward trend, that about 1 in 5 "normal" temperature series.
So the temperature series is not "typical" but it is well within what you would expect.
However 150 years is a very small time in which to develop a noise model, particularly if the last 50 years are suspected of being different from the first 100. Worse still, the kind of frequency analysis is highly susceptable to the adaptation features of trees in the paleo climate record - and given the discreditable way these have been compiled, I'm not tempted to waste my time trying to extend the noise model back - basically don't trust these reconstructions at all.
Here is how I think CO2 works. A photon (of infrared radiation) is emitted from the Earth, in the general direction of space. The photon travels up through the atmosphere, but will sometimes hit a molecule of CO2, in which case the molecule absorbs the photon. After a very short pause, the molecule emits a new photon, in an entirely random direction. If the random direction is downward, then the photon will probably end up being absorbed by something on Earth. If it's sideways, then it will probably just keep on going until it hits another molecule, and the process restarts.
If the random direction is upward, then the photon continues going up. It might reach outer space, or it might hit another molecule of CO2. The more CO2 in the atmosphere, the more likely it is that the photon will hit another molecule; after hitting another molecule, there is some probability of the new photon being emitted downwards. In this way, the more CO2 in the atmosphere, the more likely it is that the photon will not be emitted to outer space.
Can we agree there was a global MWP?
Can we agree it was warmer than now?
Meanwhile on the Doug Keenan stuff (earlier raised by VS at http://ourchangingclimate.wordpress.com/2010/03/01/global-average-temperature-increase-giss-hadcru-and-ncdc-compared/) - this also relevant to a current thread on Judith Curry's blog (http://judithcurry.com/2011/05/16/null-hypothesis-discussion-thread/) that is discussing Dr Trenberth’s statement that:
“Given that global warming is “unequivocal”, and is “very likely” due to human activities to quote the 2007 IPCC report, the null hypothesis should now be reversed … “
The CO2 explanation never seems to cover night and day, what if during the night cycle the absorbed photons have enough time to end up being escaping into space, even if it reduces the effect it still matters but seems to be ignored.
If CO2 doesn't saturate at all, as seems to be implied by the ink and water analogy, why does official climate science attempt to calculate a forcing for a doubling of CO2? If it doesn't saturate at all, surely it's effect would be linear?
First of all, I see a lack of order in the presentation.
Logically, you observe a phenomenon and then you try to explain it, no the other way round.
So:
1) Do we observe warming in the last, say, 50 years?
2) If so, how long has this warming been happening?
3) Were there periods of warming before statiscally different from the present one?
4) If so, what caused the previous periods of warming, and why those cannot be accounted now?
etc, etc.
Like all alarmists he jumps straight from a univariate and exogenous model of the world to either explain or impute
For example: "We can agree that if it warms the sea level will rise".
Well, yes in an infinitely simplified MODEL of the planet. He has made an extremely stretching claim, but doesn't even acknowledge how many millions of assumptions are required to make it true in fact (that warming atmosphere/seas WILL lead to sea level rise in reality).
Or another example: "I then suggested that if we agree all these statements above [radiative properties of CO2, rising concetrations, anthropogenic source etc.] , we must expect at least some warming. "
Yet again, there are millions of assumptions required to his grossly simplified model to reality.
The analogy is an economist: "Then I suggest that we must expect output to fall if interest rates are increased"
Well, only in the gorssly simplified model. In the real world we haven't really a clue.
*I think everyone in the room agrees that the greenhouse effect (however badly named) does occur in practice:
This one is a bit glib to me.
The chart I'd like to see, but have never seen, is one with years along the x axis. On the y axis you would have human emissions of CO2, and on the same axis, you would have observed changes in the amount of atmospheric CO2. Both these two lines would have to have the error bars plotted.
Now if you have two lines that are beautifully correlated, i.e. with a very close relationship between changes in CO2 and human emissions of it, the conclusion must be that human CO2 is driving changes in net atmospheric CO2.
If you don't find such a correlation, then you cannot rationally assert that human CO2 emissions are the main driver of rising CO2, meaning there's no emissions problem, and hence no solution is required.
From what I have read, the amount of CO2 in the atmosphere and the annual changes to it absolutely dwarf human CO2 emissions*. In fact, IIRC, whether we emitted zero CO2 or exactly as much as we already do, it isn't detectable.
* Homeopathic practitioners would presumably argue that human CO2 can still have an effect, so add them to the consensus, I suppose.
There's a dangerous illogicality in climate science, the assumption that because a GHG absorbs IR, the extra energy heats the gas of which the GHG is a minor component.
At room temperature about 5% of CO2 molecules have sufficient vibrational energy to emit that quantised E-M energy. The number of such emissions per unit time is fixed by the statistics, specifically the Principle of Equipartition of Energy. Absorbing a quantum changes the statistics so an extra IR photon is emitted simultaneously; thermalisation may not take place.
But then some wise guy argues 'Ah, but if I shine IR through an IR absorption cell with IR transparent ends, the CO2 heats up'. That's true but it may well be because the re-emitted IR is randomly directed, hitting the IR absorbing sides of the cell. This is why the BBC polycarbonate bottle experiment is so dangerously deceptive, more so than the 'stops convection' argument implies
My view is that real global warming from GHG gases could be from the increase of optical path length increasing the probability of absorption of that IR energy by second phases, particularly water in clouds in effect acting as the walls of the bottle. However, because the overlap of IR bands for CO2 and H2O is minor, the warming effect of extra CO2 may be very low indeed, far smaller than the 0.5K which appears to be the present best estimate of the 100% thermalisation model.
People should read this article by one of the US's top physicists: http://www.firstthings.com/article/2011/05/the-truth-about-greenhouse-gases
'The frightening warnings that alarmists offer about the effects of doubling CO2 are based on computer models that assume that the direct warming effect of CO2 is multiplied by a large “feedback factor” from CO2-induced changes in water vapor and clouds, which supposedly contribute much more to the greenhouse warming of the earth than CO2. But there is observational evidence that the feedback factor is small and may even be negative.'
A person from the Antarctic Survey is unlikely to have sufficient basic science to report properly. There is some serious intellectual horse power being applied to the physics as the serious lack of basic science in 'climate science' becomes apparent. The trouble is, the peer review scam means contrary ideas are repressed to maintain control of the subject by the partisans and amateurs who run it.
Since this conversation will probably turn to the paper by Cohn and Lins, I thought it would be useful to post the link here.
Aussie Dan has a crucial point when he says we should not let the terms of the debate be determined by the warmists.
Dr Wolff's summary is a salesman's progress statement, listing the areas where the customer (i.e. the sceptic) is sold, and the sales objections Dr Wolff needs to overcome to clinch the deal.
It would be good if someone with a more complete grasp of the issues than I have summarised in the sam way from a sceptic's point of view. But for startes t would be interesting to see if we could agree such issues as 'Mann's hockey stick is an illusion'; 'the UHI effects are uncertain'; 'we don't know if feedback is positive or negative'; 'the temperature record has been fiddled with in an unacceptable way'; 'if feedback is indeed positive then we can't explain why the seas didn't boil away when CO2 levels were far higher than today'; 'there is a big vested interest for climate scientists to create alarm'; 'if AGW is disproved many thousands of people will lose their jobs'.
Zxcvbnm,
I think you miss the point that the CO2 emits energy at a diferent wave length to that absorbed and only absorbs in a narrow band. CO2 will not absorb a wave length it has emitted.
As for saturation, the "ink" and "water" are not limitless. The CO2 may be increasing but the amount of any wave length emited by the earth is not. If emitted radiation increases then the cause of any increase in temp is not caused directly by the CO2 but by an increase in incoming radiation (sun). You get the law of diminishing returns as you increase CO2.
that's a gross simplified statement the radiation absorption spectrum is quite narrowband
certainly compared to H2O.
CO2 does not affect all IR
J4R, there is good evidence that there is a lot more CO2 in the atmosphere now than there was in the last few hundred years, and good evidence for the anthropogenic model of how it got there (carbon budget). I really don't think it is productive to cast doubt on that. For those who think that the fairly small amount of CO2 compared to nitrogen and oxygen can't have an effect (ca. 2000 times less CO2 than N2, maybe 5000 times less CO2 of broadly anthropogenic origin than of N2), you don't have to be a homeopath to believe that small quantities of a substance can have an effect that is greater than larger amounts of another substance. Per kilogram of body weight, human tissue contains not far from one kilogram of water. The amount of cyanide ion sufficient to kill you is about 2 milligrams per kilo of body weight. Thats close to a million times less than the amount of water that is there.
I note from his CV that Dr Wolff has published a number of papers on the physics and chemistry of ice and snow. I think one can assume that he has expertise in that specialised field. However I'm not clear what (if any) expertise he has within the broader field of climate science. This is not a criticism of Dr Wolff - the field is (IMO) simply too broad for any one person to comprehend. Like many other scientists in employment, Dr Wolff presumably has limited time to read the primary literature in other fields than his own and so has little alternative but to accept what he is told about climate by the IPCC. Which would be OK if the IPCC represented the whole spectrum of scientific opinion on climate. It doesn't, so, like many good scientists, Dr Wolff seems to have been misled into believing, for instance, that "...the likely range of warming from a doubling of CO2 was 2-4.5 degrees C (which is actually the IPCC range)." If Dr Wolff is reading this, I would implore him to take time to read some more of the primary literature on climate, including the work of climate scientists who are dismissed or ignored by the IPCC.
Zxcvbnm, you need to remember that molecules exchange energy between themselves in ways other than through infrared emission and absorption. If a molecule of CO2 absorbs a photon, it can indeed emit it again, but a more likely process involves collision with another molecule, and conversion of the energy to translation energy. The reverse can occur also (translational to vibrational exchange). All these collision processes are roughly at thermal equilibrium, so there are also CO2 molecules high in the atmosphere that undergo collision with a neighbour and thereby gain energy, which they can emit as infrared light. There's a very thorough discussion of the physics of CO2 on the Science of Doom webpages.
Note CO2s IR absorption spectrum visavis solar radiation is one thing.
but CO2 is also a good fire retardant it makes for a good black body scaffold ie an absorbed photon will be relaxed via its many possible interactions with many other molecules.
One would think planet earth to be a red filter for solar radiation as there is green plant life. But it isn't because the atmosphere plays black body with what plants leave. So CO2 and H2O certainly enable this black body function, but CO2 is a trace gas.
One wonders if the warming of the atmosphere is not merely temporary burning heat?
If that's so , then the moment we switch substantially to nuclear fusion, all this extra heat will dissipate in a few years?
petrol is about 25% of our fossil fuel burning? (rest coal and gas)
the calorific burning value for petrol is 35MJ per l
there is about 100 million barrel oil burnt per day. 1 barrel is 160l.
so that is 1.6 10**10 liter per day
so that is about 50 10**16 J per day burnt for oil
so that is about 2 10**18 J for fossils brning
now there is 500 M sqkm earth surface , 2 km full density, so about 10**9 cb km
so about 10**18 cb m of air.
the specific heat capacity of air is about 1KJ/kg K, an it weighs about 1 kg/cb m
so 500 days burning fossils will heat our air 1 degree celsius if the heat cannot escape immediately
of course it does escape mostly ,otherwise we would have heated the atmosphere by about 10degrees allready but there will be some build up, which grows over the years.
that said, the build up disappears ofcourse when you stop burning.
Which we will when fusion/algae solutions kick in
th problem is to believe in fusion/algae and invest in the R&D for it. But leftwingers only want to park their buddies, dead wood, which means building CO2 rich windmills and cap&trade commisarriats. They have no urgency at all.
Spain must be so fucking rich by now with all these windmills.
I don't mean for this to be a word-game type query, but is "statistical significance" necessary for there to be a trend effect? Or is "statistical significance" a qualifier of the goodness of our perception of the trend?
in other words, could the "thing" be progressing but not enough to meet our standard for quantifying say the "slope" of the trend?
No Hot-Spot - No AGW - Simples!
I have a question. CO2 outgasses from warming water, how much CO2 has been emitted by the warming oceans since the LIA?
David C, you're right that these "We can all agree that..." exercises are rhetorical devices aimed to frame the debate. I made the point in a thread about Simon Singh that they almost look like a catechism. I like most of the points in your alternative catechism! Though my sense is that the UHI and temperature record concerns might get a bit over-hyped by sceptics, and it is also possible to conceive that feedbacks are not linear, so that they could be positive in some ranges of temperature and CO2 concentration, but negative at higher temperatures. This means that you can logically believe that feedbacks can be such that increasing CO2 makes the world quite a bit warmer, but that the seas don't need to boil away at higher CO2. The fact that it is logically tenable doesn't mean it is true, of course.
The Professor's suggested default assumption of warming of 2 - 4.5C depends, as he admiits, on a very high ratio of positive feedbacks pushing up what is assumed to be the natural 1 C.
No such positive feedback ratio has been proven or even srongly supported by evidence. I suggest that it is overwhelmingly more likely that the feedbacks (probably primarily that more heat means more atmospheric water, means more clouds, means higher reflectivity) are mainly negative. I base this on history. Had positive feedbacks predominated the climate would be enormously unstable and periods warmer than now would have led to a runaway greenhouse effect, at least up until the feedbacks became negative (if they didn't we would be Venus). Since both the Medieval warm period and the Climate Optimum (9-5,000 BC) were warmer than now, the latter considerably so, without being dragged to a runaway effect by positive feedback the feedback effect must be negative. If a system shows long term stability feedbacks simply must be negative.
I am less sanguine about feedback effects being negative in a cooling direction because the history of ice ages suggests otherwise.
We have a laboratory experiment that strongly suggests that rising levels of atmospheric CO2 should produce warming.
We have a theory, the AGW hypothesis, that fundamentally assumes CO2 is 'trapping heat' in the tropical troposphere so producing additional heating of the surface.
We have models, all models, that assumes CO2 is 'trapping heat' in the tropical troposphere so producing additional heating of the surface in there projections.
We have the lab experiment, the theory and the modelled projections ............ but we don't have the data to prove that AGW hypothesis is correct.
What we do have is data that shows that the AGW hypthesis is probably incorrect, for there are significant discrepencies between projections and observations. The surface is warming faster than the troposphere.
Instead of trying to protect a beautiful theory from ugly facts, instead of looking for missing heat that never was missing, instead of finding other poor excuses, such a aerosols, deal with the reality that this planet's surface is warming faster than the troposphere.
Why are increasing levels of atmospheric CO2 NOT trapping additional heat in the troposphere?
Without a cause there can be no effect!
I agree with Geoff - the ink and water analogy is a very poor one. Iirc, roughly 80% of the IR is bounced back by H20 and about 12% by methane. Nearly all the rest is destined for CO2 molecules.
Given that we have increased atmospheric CO2 from 280ppm to 290ppm in the last 200 years, and there hasn't been any significant warming - http://oi49.tinypic.com/rc93fa.jpg - and no evidence that the this slight warming isn't due to natural variation as we have seen throughout the Holocene -
http://jonova.s3.amazonaws.com/graphs/lappi/gisp-last-10000-new.png - I would argue that we are already at, or very close to the saturation level.
So even without the need for any maths it is easy to see how a doubling of the number of CO2 molecules from say 250ppm to 500ppm will have an insignificant effect as most of the IR has already been reflected by the H20 and existing CO2. It is a clear case of diminishing returns, or more precisely Beer-Lambert Law, and above 250-300ppm I doubt increasing CO2 levels will have any perceptible forcing on global temperatures.
This is all a distraction from the real issue which is cloud cover; again irrc the alleged forcing from CO2 reflecting back IR equates to about 3W/m2? Whereas even a 1% or 2% change in cloud cover over the tropics and mid latitudes (where incoming solar radiation energy is on average is 1300W/m2) will obviously have a significant effect on global average temperatures. http://calderup.wordpress.com/2011/05/21/roll-up-roll-up-for-the-paradigm-shift/
Climate scientists have clearly succumbed to what happens in most scientific fields - the experts spend more and more time looking more and more closely at the fine detail, not realising that they have lost sight of the bigger picture and reality.
The definitive evidence, which trumps all theory, is at
Venus: No Greenhouse Effect
Ignoring me on this subject is the worst scientific mistake. As I recently posted on "climaterealists" and "wattsupwiththat":
"The comparison of Venus/Earth atmospheric temperatures shows that Venus (with 96.5% atmospheric CO2) is not made any warmer than the Earth (with only 0.04% CO2) by its much greater concentration of CO2. The Venus atmosphere at a given pressure is 17% hotter than the Earth atmosphere at the same pressure level, over the entire range of Earth tropospheric pressures, and that is entirely, precisely, due to Venus being closer to the Sun. Their temperature versus pressure profiles, corrected for their different distances from the Sun, are essentially the same, although by current (Happer's) thinking the Venus profile should be higher than the Earth's by more than 11°C (96.5% is more than 11 "doublings" of 0.04%). There simply is no sign of a greenhouse effect at all. That is therefore an established physical fact, and it is the DEFINITIVE physical fact for science.
"What is wrong with current science, that so many refuse to heed this definitive evidence? Because they are tied to a dogma that they will not question, and will not allow to be openly questioned: That the atmosphere can only be warmed from the ground, that the surface must first be warmed by the Sun and the atmosphere then warmed by the surface. But the Venus/Earth comparison indicates this common belief among scientists is simply wrong; as I have explained at the above link, both planetary atmospheres must be warmed by absorption of the same portion of the incident solar radiation, and that portion must be in the infrared. You don't have to be a world-famous scientist to understand this. Incident heat from the Sun is taken up directly by the atmosphere and by the surface, independently of one another.
"Scientists are right that absorption of infrared radiation heats the atmosphere, but the source of that heat is incident solar, not the surface. And adding more CO2 does not add more heat to the atmosphere, as the Venus/Earth comparison proves. There is enough infrared absorption, even with no CO2, to heat the atmosphere to the limit of its ability to hold the heat. The heat content of the atmosphere is a function only of its distance from the Sun and its density (which varies with its depth), and is constrained by the observed temperature lapse rate, as long recognized in the precise quantitative definition of the Standard Atmosphere. Venus's surface temperature is far higher than Earth's, because its atmosphere is far deeper, and far denser at the bottom, than Earth's.
"My simple comparison of the Venus/Earth temperatures is thus a revolutionary finding, and one that physicists and climate scientists like James Hansen, who has championed the "runaway" greenhouse effect from the very beginning of his career (and continues to make fearful, apocalyptic claims to the public about it), should have done long ago, and rejected the greenhouse effect then. (The Venus data was collected in late 1991). And scientists who reject the current climate consensus, but still claim the greenhouse effect is real, are not getting to the bad science at the heart of the controversy. There is NO greenhouse effect at all, as they believe they understand it. They understand a falsehood, and continue to mislead the world on the basic science of the atmosphere. That almost everyone still believes in the greenhouse effect, after so many years of study, and after the definitive Venus/Earth evidence against it, tells us the problem is one of runaway, religiously-held dogma, among scientists (of all people!), not runaway climate."
Only an unrecognized endemic incompetence among all scientists prevents the clear verdict of the Venus/Earth comparison from being front-page news around the world, and the death knell of the political climate alarmism. And it is not peer-reviewed for the same reason, as I submitted the analysis to "Physics Today" back on February 7, 2011, and they declined to publish this important evidence in late April. There is no responsible authority, no "law", to turn to, except to be open to the public. That is all I can do now.
I have given Eric the benefit of the doubt when he was critisized by Vaclav for reiterating warmist agenda. Looking at this more detailed presentation, I do think that Vaclav had a point.
Regarding CO2 measurements, Plimer has a section in his book about it and this raises v.considerable doubts about the certainty of the data use. The upward curve we see is very selectively created from the ML IR readings and where other methods were used (chemical assaying methods) and overlap in time the results are not in agreement.
Wolff assumed Svensmark's theory did not acount for the warming of the 90s which it does. Lockwood attempted to damn Henrik with faint praise. That was before the recent results became known.
The analogy that adding CO2 is like adding ink to water is fine. It is used by Grant Petty
in his fine book Introduction to Atmospheric Radiation. You put the water over a light source and see how far the light is blocked (extinguished). Ink is for absorption - use milk instead of ink for scattering where the water is milky white looked at from the side. The depth of the water does not matter, only the amount of ink. If you put X amount of ink into a 1 meter tall column of water and let it mix the extinction of radiation effect is the same as if you put X of ink into 1 cm column of water. Still once you have added enough ink the light is completely blocked. Adding more makes no further difference. This is a saturation effect. Visible light through ink and infrared radiation through CO2 seem to me to be the same. So once you have enough CO2 the radiation is blocked completely and adding more will have no more effect. So I can't see why this story impugns the existence of a saturation effect. Also the story as told by Dr. Wolff does not explain why the effect of adding CO2 is logarithmic not linear. I don't know what the form of the
equation is but if it is something of the form T = Tmax*(1 - exp(-x)) where x is the amount of CO2 and T the temperature, then the curve is bounded above by Tmax though setting x = x+d will always increase T. This is what I understand by saturation.
And good for Dr. Wolff ....
harry dale huffman
just open a wordpress blog annex facebook page and clunk your report in it.
see wordpress.com
far better than some arcane paid-for journal that chickenshit reads
Bishop Hill
Since this conversation will probably turn to the paper by Cohn and Lins
I think that a large number of contributors above have listed many, many weaknesses in the assumptions of the "conversation". Most particularly, those comments which point out that the atmosphere is not a surface but a three dimensional volume. In short, the "conversation" and any "statistical models" are bullocks.
Better they spend their time trying to come up with a statistical model describing how many angels can fit on the head of a pin -- once, of course, after they decide what is the size of a head of a pin.
Bishop,
Their are different parameters in a lab to what is included into planetary study.
Not considered:
Planets circular motion and the deflection off a moving object.
Shape of the planet and atmosphere as the planet is largest at the equator and smallest at the poles.
Distances is the suns most heat is at the equator of the sun and the closest distance.
Distance of the year to sun would also give varying degrees of different energy slightly(but still significant).
Planet tilting and the angle differences with this shifting.
Movement away from the sun over billions of years.
Slowdown of the planet over billions of years.
Interaction of the suns magnetic field to the planets is 1 day difference in 4.5 billion years, no matter the density or size(except 3 (the 2 planets closest and the one furthest)).
So, science may not be settled or straight forward to current science mindset of building a model and take measurements off the model and not the real measurements off of actual events.
What we agree on:
1) Humans are increasing the amount of CO2 in the atmosphere by burning hydrocarbons. Then there must be a corresponding reduction in the amount of O2. This has been verified by an O2 sensor placed next to the CO2 sensor on the Hawaiian peak. Agreed that humans are adding measurable amounts of CO2 to the atmosphere by burning hydrocarbons.
2) Increasing the amount of CO2 in the atmosphere will lead to some amount of increased greenhouse effect. Yes, but the ink analogy is useless. The greenhouse effect has to do with altitude, and as the altitude increases the atmospheric density decreases exponentially, which is what makes the CO2 greenhouse effect saturate and the ink analogy useless. Agreed that the increased CO2 will increase the greenhouse effect, but only minutely without feedback.
3) Climate scientists are hiding data and acting in bad faith. This is easily observed by casual observers and should be openly discussed. Reference the leaked UEA emails for prima facie evidence. Agreed that the mainstream climate scientists are conducting their business in bad faith.
peter2108
A common approximation is dT = const * log(C/C0), where dT is change in temperature and C is CO2 concentration. Accepting this formula, there is no asymptotic maximum value for dT but instead a law of diminishing returns.
An atmosphere, as opposed to no atmosphere, increases the residency time of IR by being semi-transparent to it. Longer residency = higher temperature. Anthropomorphic changes to CO2 alone have an insignificant effect on residency, which I believe is accepted by all.
The hypothesis we are being asked to accept is that, through a positive feedback mechanism with atmospheric H2O, temperatures (residence time?) increase further. The stated proof for this is not derived from empirical data (which falsifies it), but from computer models. Computer models are therefore wrong. QED.
There will never be any common ground on a failed hypothesis. My apologies to all who are offended by common sense. And if so, prove positive feedback (hint; you will need unadulterated empirical data).
Let me add my 2 cents on no-feedback climate sensitivity; widely claimed to be 1 C for a doubling of CO2. Not only has this number never been measured, it is impossible to ever measure it. It is a purely hypiothetical and completely meaningless number. Putting any actual value, such as 1 C, is simply scientific nonsense.
Jim,
everything is nonsense in this climate debate.
everything.
As a non-science trained outsider looking in, I was very interested in a recent blogpost here:
http://wattsupwiththat.com/2011/05/23/little-ice-age-thermometers-%e2%80%93-history-and-reliability-2/
and the problems of achieving any accuracy closer than 1 degree F at best. We also know than in recent years, c1990 the stations used to measure land based temperatures were reduced from c4000 to c1200, with only about 200 common between pre and post 1990. EM Smith demonstrated, very convincingly I thought, that the temperature increase recorded post 1990 was very much down to this change of process. Inter alia it included the elimination of stations at higher altitudes and a noticeable gravitation of the new stations away from the poles towards the equator compared with the earlier set.
In short there is a fundamental quality control problem with the raw data used to measure the earth`s temperature; and to date it is a problem that has been dodged. Such a change would not be acceptable, without validation, in any business with any pretension to a sound quality control system and whose livelihood depended on selling quality products to other businesses or to consumers. In short, it does not convince and I do not buy it.
1-Imagine a white ball the size of earth without an atmosphere.
this ball with have some temperature, X..
i guess it must be dependant on the sun and distance to the sun.
2.Now ADD as much CO2 as you want aound that earth. Don't be shy: create an atmosphere
as big as you possible can imagine.
3.Measure the temperature again.
I think it must be the same temperature, because the colour has not changed? CO2 is transparent.
Earths albedo will not have changed.There is no physical way to have this ball change its temperature.
Whatever Arrhenius and Fourier thought up.