NIPCC interim report 2011

The Heartland Institute's NIPCC interim report has just been published - see here. This is a summary of the new scientific literature since 2009.

I've taken a glance through the paleoclimate bits and it appears to have been put together in a very professional manner. I was blissfully unaware of just how much evidence has been emerging for the existence of a MWP in the world outside Europe.

If I had a criticism based on what I have read, I would say it's over the authors' tendency to slip into editorial mode - discussion of Mann being engaged in "subterfuge" looks out of place in a scientific report.

Lots of people are not going to like the report of course. Peter Gleick, the president of the Pacific Institute, tweets that the report makes him sick and refuses to link to it. Barry Woods and I have politely asked which bits in particular he is concerned with and he has told us that he doesn't need to do this when someone is arguing that the Earth is flat.

Comments

[Richard Drake]

BBD: You haven't answered my question. You've posed a very large set of much more difficult questions, to which nobody knows the answers. That to me is quite a diversionary tactic.

Sure, we'd love to have a single number - climate sensitivity - that will explain every variation we see, or believe we see in 4 billion years of paleo-climate. To say that is running before we can walk is itself vastly over-optimistic. It's flying to the moon before we've emerged from the womb.

[Dave Salt]

BBD, I take it that you now believe the arguments presented by 'dana181' in this thread...
http://www.bishop-hill.net/blog/2011/6/28/thou-shalt-extrapolate.html?currentPage=3#comments
... that "There's been ~0.6°C warming since 1960, and approximately 100% of that is anthropogenic"?

[BBD]

Richard

BBD: You haven't answered my question. You've posed a very large set of much more difficult questions, to which nobody knows the answers. That to me is quite a diversionary tactic.

I'm sorry, I'm trying to answer your question by posing a question. Well intentioned, but open to misinterpretation. As statements then:

- the only known coherent explanation for the glacial/interglacial cycle is orbital dynamics

- a cold world with a low climate sensitivity cannot warm abruptly and significantly

- low climate sensitivity is incompatible with a glacial/interglacial cycle governed by orbital dynamics

[BBD]

Dave Salt

No, dana1981 is overstating his case. It is reasonable to say that much of the recent warming (post 1975, say) is probably anthropogenic. Some may well be natural. But the balance is unfortunately tilting in the direction of human activity.

[woodentop]

@BBD - the original Milankovitch theory is not without criticism: trying to make it work by invoking a high climate sensitivity seems to me to be begging the question.

At a qualitative level, the model for global climate oscillations over the last million years, in view of the good agreement of the OC diagram with oxygen isotope curves and the general mechanism adopted for orbitally forced climate variations, can be presented as follows. Orbital changes force insolation variations, which in turn induce initial temperature changes (mainly at high latitudes), resulting through positive feedback (due to variations in the volume and area of ice and snow at these latitudes) in still more considerable temperature oscillations involving larger areas.

These oscillations in turn influence more strongly the World Ocean temperature and the atmospheric concentrations of greenhouse gases, the combined action of the totality of factors then determining the resultant global oscillations in ice volume and temperature (climate oscillations). It thus follows that insolation variations and global ice volume changes, rather than variations in the atmospheric concentrations of greenhouse gases (in particular, CO 2 ), have been the underlying cause of global climate changes in the Quaternary.

http://rjes.wdcb.ru/v05/tje03116/tje03116.htm

So while greenhouse gases no doubt have a part to play, they are somewhat late to the party and demoted in importance, at least in this variation on the Milankovitch theory.

On that basis, we're back to questioning the value of paleo/glaciation evidence regarding climate sensitivity (to CO2), which is why Ron Cram's comment above seemed apposite.

[BBD]

woodentop

I agree:

It thus follows that insolation variations and global ice volume changes, rather than variations in the atmospheric concentrations of greenhouse gases (in particular, CO 2 ), have been the underlying cause of global climate changes in the Quaternary.

Milankovitch forcing is the underlying cause of global climate changes in the Quaternery. Greenhouse gasses play a secondary role, but amplify and prolong the initial warming.

Which leaves us with this:

- the only known coherent explanation for the glacial/interglacial cycle is orbital dynamics

- a cold world with a low climate sensitivity cannot warm abruptly and significantly

- low climate sensitivity is incompatible with a glacial/interglacial cycle governed by orbital dynamics

[Shub]

BBD,
You've abandoned lukewarmerism and gone over to full blown warmism?

[HaroldW]

BBD -
In order to deduce sensitivity (delta temp per unit forcing), one has to compute forcing. How are Milankovich factors such as obliquity converted to forcing (W/m^2)? Didn't show up in a (very) brief search.

Thanks

[AsYouLikeIt]

......the Earth is flat...............utter rubish, everybody knows it is a truncated icosidodecahedron.

[Richard Drake]

It's fascinating to ask a question about the relationship between Milankovich and our concept of 'forcing', as HaroldW does. But my question for BBD (and it would apply to anyone interested in this central plank of AGW) was a completely different one:

Are you really more confident of estimating climate sensitivity in the distant past, knowing so little of what was going on, that from today's copious satellite and other measurements?

I count Milankovich a genius. But to say that because he's all we've got in the distant past that that makes that time better for measuring sensitivity than today is barmy. Based on every ounce of experience today (like the unexpected nature of the findings of the CERN CLOUD experiment) it's far too likely that we will be overlooking something. Calling our puny understand of what was going on a change in forcing or a change in feedbacks is itself almost sure to be begging the question.

It's not at all easy to measure climate sensitivity from the data we have today but it is increasingly possible. Here's one crucial statement at the end of Richard Lindzen's presentation three days ago that I wish to understand much better:

These results suggest that the optical properties of clouds depends on aerosols, and that, therefore, feedback factors could be variable

I want to know more, as much as I can. As I said before, I strongly recommend taking in Lindzen's talk to anyone. Because this has been a disgraceful neglect and negation of science in the IPCC process: relying on software models rather than real world data (and even tampering woefully with real world data in the Forster & Gregory 'Bend it by Bayes' case). To go back to the ancient past is also to throw almost all that precious data away. That's why I asked BBD the question I did and why I'm very surprised that he chose not to answer it.

As far as the whole of paleo-climate is concerned I leave the punchline to Lindzen himself:

Moreover, the high sensitivity of some current models would render the stability of the earth over 4.5 billion years dubious. Engineers have long recognized this and generally avoid feedback factors greater than about 0.1.

This is wisdom. No amount of speculation, however interesting, on specific events can possibly overturn it.

[Richard Drake]

I should add that Lindzen gives earlier on in his PDF slides the fullest explanation of what is called the greenhouse effect that I've seen in any of his offerings for the scientifically-literate public. Here are the key bookend sentences:

The following description is, itself, somewhat oversimplified; however, it is probably adequate for understanding the underlying physics. ... In brief, greenhouse warming depends crucially on the existence and properties of dynamic mixing within the troposphere, and not simply on the radiative picture. (Slides 5,14)

Lindzen's argument should I take it be of interest to Phillip Bradby and many others here. Again, the podcast will, we are told, be available shortly.

[BBD]

Well, unsurprisingly, nobody addresses the question: how does a low climate sensitivity under moderate forcing change explain the onset/termination of glacials? Or the MWP, come to that.

This will be because you can't. Considering the implications of glacial/interglacial transitions on climate sensitivity is an extremely useful way of getting a handle on the sensitivity question. Predictably, the question is simply dodged. See the misdirection about modern data vs. paleoclimate data etc.

But logic provides the answer, and I suspect you can see it just as well as I do. Climate sensitivity is not - and cannot be - low. Otherwise the climate would be essentially static, and we know beyond doubt that it is not.

[Richard Drake]

BBD: I already gave my answer, which is that we don't know. That ignorance is independent of whether one believes in low or high climate sensitivity to a doubling of CO2 in the period 1850-2100 - which is a crucial plank of AGW as presented by the IPCC.

There are two strange aspects to this, for me. One is your conversion to a belief in high sensitivity. But the other is much stranger: that you consider 'modern data' a 'misdirection'. Intentionally or not, you are perpetuating the grave error of the warmist tribe by not focusing with laser zeal on the measurement of sensitivity today. Whether from you or the IPCC, it won't do.

[lapogus]

BBD - we have discussed this before. I disagree that that the climate sensitivity is high - the MWP, the Roman, and even the Holocene optima were only 2 or 3C warmer than present. The only periods where there is a truly significant change in global temperatures is when we come out of or descend into an ice age - http://www.foresight.org/nanodot/wp-content/uploads/2009/12/vostok.png - and we are long over due for the latter. Compared to the glacial-interglacial change, the MWP and other warm periods in the Holocene are effectively just noise - http://www.foresight.org/nanodot/wp-content/uploads/2009/12/histo1.png

As I said before, I am very curious about just what it is that is prolonging this interglacial, but think it is more likely to be long term changes to ocean circulation patterns (possibly as a result of geological activity) and heat transfer (i.e. warm water getting into Arctic Oceans to prevent a perennial ice cap forming over Europe) than minor forcing by CO2 or other anthropological activity. Svensmark's thesis also makes a lot of sense to explain the warm and cooler periods within this interglacial.

Source page for graphs above - http://wattsupwiththat.com/2009/12/09/hockey-stick-observed-in-noaa-ice-core-data/

[BBD]

Richard

Of course we know. It's obvious from simple deductive reasoning. Come on.

[PaulM]

BBD I'm afraid you've been misled by the climate science propaganda:

"Otherwise the climate would be essentially static"

This is completely wrong, and follows from the delusion inherent in the entire concepts of 'climate sensitivity' and 'radiative forcing', the delusion that the Earth's temperature is somehow slaved to the 'forcing' by one incredibly simple equation.

The weather is not static even when the sun's input is constant.
A plume of smoke is not static even when the source is constant.
Similarly the Earth's climate would not be static with constant 'forcing'.
Complicated nonlinear systems (in fact even very simple ones) show irregular fluctuations that are hard to predict, even with constant forcing.

[BBD]

PaulM

If I have recently been misled by anyone, it is those who argue that unforced internal variability is somehow sufficient to account for the recent (post-1950) warming.

You, like them, are confusing random behaviour with significant energetic accumulation within the climate system.

And were I you, I would be cautious about the tone of any response. Your previous bordered on the patronising. Not a good idea.

[Richard Drake]

PaulM: I'm sure you know more than I about complicated nonlinear systems or indeed very simple ones. What do you make of the stance of Richard Lindzen, as expressed in his latest presentation or anywhere else? He seems to think that the concept of sensitivity to a doubling of CO2 is worth arguing about - though he admits that it may vary. Is the man from MIT also deluded?

Genuine question. As always, I reserve the right to be sceptical about multiple competing arguments at once :)

[PaulM]

BBD - The goalposts seem to be moving. I thought we were talking about the MWP and whether its existence implied high sensitivity.

Richard - I don't think Lindzen (or anyone else for that matter) is deluded. But like most climate scientists he over-estimates the significance of a naive simple relationship between a small change in the globally averaged temperature and the 'forcing'. It needs to be kept in mind that this is a huge oversimplification. I think you are right in your remarks above, that the honest answer to many of these questions is that we just don't know.

[BBD]

Harold W

You ask:

How are Milankovich factors such as obliquity converted to forcing (W/m^2)? Didn't show up in a (very) brief search.

This is possibly to miss the point. Please see Meyers et al. (2008):

Our analysis indicates that Vostok temperature variance is almost equally apportioned between three components: direct “forcing” from the precession and obliquity orbital-insolation changes (28%), a periodic “100,000” year cycle (41%), and the background continuum (31%). A range of analyses accounting for various frequency
bands of interest, and potential bias introduced by the “saw-tooth” shape of the
glacial/interglacial cycle, establish that precession and obliquity periods account for between 25 to 41 percent of the variance in the 1/10 kyr to 1/100 kyr band, and
between 39 to 66 percent of the variance in the 1/10kyr to 1/64 kyr band. These results are two to four times greater than recent estimates of the same Vostok time series. In all cases, most of the remaining variance is accounted for by the “100,000” year cycle, which is distinct from a background continuum that resembles autoregressive red noise.

The predominance of 1/100,000 year variance in the spectrum, with a strong periodic character (fig. 4C), and high coherence with orbital eccentricity (for example, see Shackleton, 2000), suggests a dominant link to orbital changes. A number of studies have suggested that the 100,000 year cycle may be “paced” by precession and/or obliquity driven orbital-insolation changes (in contrast to direct “forcing” by
eccentricity; Hays and others, 1976; Raymo, 1997; Ridgwell and others, 1999; Huybers
and Wunsch, 2005; Tziperman and others, 2006). For example, Huybers and Wunsch (2005) demonstrate a link between obliquity variability and the timing of glacial terminations. However, due to timescale uncertainties it is not yet possible to provide a definitive test for a precession-scale driver of glacial terminations (Huybers and Wunsch, 2005). Given the inherent modulation of precession by eccentricity, such a linkage could plausibly explain the observed “100,000” cycle, and its strong coherence to the theoretical eccentricity signal (Shackleton, 2000).

[I cannot seem to post proper clickable links any more (BH - any thoughts?) so here is the raw link to Meyers et al. (full text):

[lapogus]

BBD - I just don't agree that there has been a "significant energetic accumulation within the climate system".

http://oi49.tinypic.com/rc93fa.jpg

We have had 3 cold winters in a row, and now a bloody cold summer. Courgettes stopped growing as soon as we pout them outside, and we have had to light the stove on numerous nights in June, July & August. I sincerely wish that some of this recent warming would come this way.

[Richard Drake]

Paul: Lindzen would surely agree it's an oversimplification; perhaps he might quibble with 'huge'? I don't know. One has to engage with the arguments of IPCC WG1 somehow. My own expectation is that if there was a really serious effort to measure sensitivity - not just Spencer and Lindzen but everyone concerned - we would indeed find the situation is as surprising as you suggest. Just as happened with CLOUD at CERN. But we must try to measure sensitivity - or we're not doing science, we're just telling stories.

[BBD]

Missing link for Meyers et al:

http://www.geology.wisc.edu/~smeyers/pubs/Meyers_et_al_2008.pdf.

BH - I am having real problems posting. It's been dreadful for over a week. Lots of 'unable to comment' lockouts inevitably followed by the good old 'connection has been reset'. Curable only by rebooting the router. A true and deep PITA.

PaulM No, the goalposts are where they were. We are discussing climate sensitivity, which applies equally to the onset and termination of glacials and the onset and termination of the MWP. This has all been clearly explained upthread - do please take another look.

lapogus

BBD - I just don't agree that there has been a "significant energetic accumulation within the climate system".

So if not accumulating energy, what has caused global average temperature to rise by 0.6C since the mid-1970s? Not to mention the increase in OHC for the 700m layer (at the very least)? I'm intrigued.

As I said before, I am very curious about just what it is that is prolonging this interglacial

Please see Berger and Loutre, here:

http://www.climate.unibe.ch/~born/share/papers/eemian_and_lgi/berger_loutre02.sci.pdf

On a geological time scale, climate cycles are believed to be driven by changes in insolation (solar radiation received at the top of the atmosphere) as a result of variations in Earth’s orbit around the Sun. Over the next 100,000 years, the amplitude of insolation variations will be small (see the figure), much smaller than during the Eemian. For example, at 65°N in June, insolation will vary by less than 25 Wm−2 over the next 25,000 years, compared with 110 Wm−2 between 125,000 and 115,000 years ago. From the standpoint of insolation, the Eemian can hardly be taken as an analog for the next millennia, as is often assumed.

The small amplitude of future insolation variations is exceptional. One of the few past analogs (13) occurred at about 400,000 years before the present, overlapping part of MIS-11. Then and now, very low eccentricity values coincided with the minima of the 400,000-year eccentricity cycle. Eccentricity will reach almost zero within the next 25,000 years, damping the variations of precession considerably.

[PaulM]

I am just trying to point the error in statements such as
"A variable climate implies a high sensitivity."
I am not interested in discussing climate sensitivity itself, for reasons already stated, and therefore I have to say "I'm out"!

[BBD]

Richard Drake

You say:

BBD: I already gave my answer, which is that we don't know. That ignorance is independent of whether one believes in low or high climate sensitivity to a doubling of CO2 in the period 1850-2100 - which is a crucial plank of AGW as presented by the IPCC.

There are two strange aspects to this, for me. One is your conversion to a belief in high sensitivity. But the other is much stranger: that you consider 'modern data' a 'misdirection'. Intentionally or not, you are perpetuating the grave error of the warmist tribe by not focusing with laser zeal on the measurement of sensitivity today. Whether from you or the IPCC, it won't do.

You do not have the full story. Not that this stops you suggesting that it is me who is misinformed (along with just about everybody else).

You will find this, from Hansen and Sato (2011), informative:

Fortunately, it is not necessary to have a detailed quantitative theory of the ice ages in order to extract vitally important information. In the following section we show that Milankovitch climate oscillations provide our most accurate assessment of climate sensitivity.

3.2. Fast-feedback climate sensitivity

Fast-feedback climate sensitivity can be determined precisely from paleoclimate data for recent glacial-interglacial climate oscillations. This is possible because we can readily find times when Earth was in quasi-equilibrium with its 'boundary forcings'. Boundary forcings are factors that affect the planet's energy balance, such as solar irradiance, continental locations, ice sheet distribution, and atmospheric amount of long-lived GHGs (CO2, CH4 and N2O).

Quasi-equilibrium means Earth is in radiation balance with space within a small fraction of 1 W/m2. For example, the mean planetary energy imbalance was small averaged over several millennia of the Last Glacial Maximum (LGM, which peaked about 20,000 years ago) or averaged over the Holocene (prior to the time of large human-made changes). This assertion is proven by considering the contrary: a sustained imbalance of 1 W/m2 would have melted all ice on Earth or changed ocean temperature a large amount, neither of which occurred.

The altered boundary conditions that maintained the climate change between these two periods had to be changes on Earth's surface and changes of long-lived atmospheric constituents, because the incoming solar energy does not change much in 20,000 years. Changes of long-lived GHGs are known accurately for the past 800,000 years from Antarctic ice core data (Luthi et al., 2008; Loulergue et al., 2008). Climate forcings due to GHG and surface albedo changes between the LGM and Holocene were approximately 3 and 3.5 W/m2, respectively, with largest uncertainty (±1 W/m2) in the surface change (ice sheet area, vegetation distribution, shoreline movement) due to uncertainty in ice sheet sizes (Hansen et al., 1984; Hewitt and Mitchell, 1997).

Global mean temperature change between the LGM and Holocene has been estimated from paleo temperature data and from climate models constrained by paleo data. Shakun and Carlson (2010) obtain a data-based estimate of 4.9°C for the difference between the Altithermal (peak Holocene warmth, prior to the past century) and peak LGM conditions. They suggest that this estimate may be on the low side, mainly because they lack data in some regions where large temperature change is likely, but their record is affected by LGM cooling of 17°C on Greenland. A comprehensive multi-model study of Schneider von Deimling et al. (2006) finds a temperature difference of 5.8 ± 1.4°C between LGM and the Holocene, with this result including the effect of a prescribed LGM aerosol forcing of ‒1.2 W/m2. The appropriate temperature difference for our purposes is between average Holocene conditions and LGM conditions averaged over several millennia. We take 5 ± 1°C as our best estimate. Although the estimated uncertainty is necessarily partly subjective, we believe it is a generous (large) estimate for 1σ uncertainty.

The empirical fast-feedback climate sensitivity that we infer from the LGM-Holocene comparison is thus 5°C/6.5 W/m2 ~ ¾ ± ¼ °C per W/m2 or 3 ± 1°C for doubled CO2. The fact that ice sheet and GHG boundary conditions are actually slow climate feedbacks is irrelevant for the purpose of evaluating the fast-feedback climate sensitivity.

This empirical climate sensitivity incorporates all fast response feedbacks in the real-world climate system, including changes of water vapor, clouds, aerosols, aerosol effects on clouds, and sea ice. In contrast to climate models, which can only approximate the physical processes and may exclude important processes, the empirical result includes all processes that exist in the real world – and the physics is exact.

If Earth were a blackbody without climate feedbacks the equilibrium response to 4 W/m2 forcing would be about 1.2°C (Hansen et al., 1981, 1984; Lacis et al., 2010), implying that the net effect of all fast feedbacks is to amplify the equilibrium climate response by a factor 2.5. GISS climate models suggest that water vapor and sea ice feedbacks together amplify the sensitivity from 1.2°C to 2-2.5°C. The further amplification to 3°C is the net effect of all other processes, with the most important ones probably being aerosols, clouds, and their interactions.

The empirical sensitivity 3 ± 1°C for doubled CO2 is consistent with the Charney et al. (1979) estimates of 3 ± 1.5°C for doubled CO2 and with the range of model results, 2.1-4.4°C, in the most recent IPCC report (Randall and Wood, 2007). However, the empirical result is more precise, and we can be sure that it includes all real-world processes. Moreover, by examining observed climate change over several Milankovitch oscillations we can further improve the accuracy of the fast-feedback climate sensitivity.

Fig. 2 shows atmospheric CO2 and CH4 and sea level for the past 800,000 years and resulting calculated climate forcings. Sea level implies the total size of the major ice sheets, which thus defines the surface albedo forcing as described by Hansen et al. (2008). Note that calculation of climate forcings due to GHG and ice sheet changes is a radiative calculation; it does not require use of a global climate model. Clouds and other fast-feedback variables are fixed with modern distributions. We do not need to know paleo clouds and aerosols, because the changes of those quantities at earlier climates are in the fast feedback being evaluated.

Multiplying the sum of greenhouse gas and surface albedo forcings by climate sensitivity ¾°C per W/m2 yields the predicted global temperature change (blue curves in Fig. 2d and 2e). Observed temperature change in Fig. 2d is from Dome C in Antarctica (Jouzel et al., 2007). The global deep ocean temperature record in Fig. 2e is from data of Zachos et al. (2001), with temperature extracted from oxygen isotope data as described below and by Hansen et al. (2008).

Observed Antarctic and deep ocean temperature changes have been multiplied by factors (0.5 and 1.5, respectively) to yield observed LGM-Holocene global temperature change of 5°C. Climate sensitivity ¾°C per W/m2 provides a good fit to the entire 800,000 years. An exception is Dome C during the warmest interglacial periods, when warming was greater than calculated. We show in section 4 that peak interglacial warming was probably confined to the ice sheets, so deep ocean temperature change provides a better indication of global temperature change.

The close fit of observed and calculated temperatures for 800,000 years includes multiple tests and thus reduces uncertainty of the implied climate sensitivity. The greatest uncertainty is in the actual global temperature changes. Including our partly subjective estimate of uncertainty, our inferred climate sensitivity is or 3 ± 0.5C for doubled CO2 (3/4 ± 1/8 °C per W/m2).

Regardless of the exact error-bar, this empirically-derived fast-feedback sensitivity has a vitally important characteristic: it incorporates all real-world fast-feedback processes. No climate model can make such a claim.

[Full text here: http://arxiv.org/pdf/1105.0968v3]

[BBD]

lapogus

You say:

http://oi49.tinypic.com/rc93fa.jpg

We have had 3 cold winters in a row, and now a bloody cold summer. Courgettes stopped growing as soon as we pout them outside, and we have had to light the stove on numerous nights in June, July & August. I sincerely wish that some of this recent warming would come this way.

First, you've linked to that compostite graph before, and I explained the serious issues with early CET data. Not going over that again, but this graph is intentionally misleading. I recommend that you stop using it.

Second, it's important not to take a parochial view of global phenomena (eg UK weather vs global climate change).

As intuitive data visualisation tools are all-too rare, it's always encouraging to see a new one. Have a look at this:

http://moyhu.blogspot.com/2011/08/javascript-worldview-for-surface-temp.html

[HaroldW]

Thanks BBD for the Meyers et al. article, I shall read it later when I have time. Although it didn't seem to be converting to forcings (that is, to a figure in W/m^2, whether at the surface or at top-of-atmosphere); rather it seemed to be correlating. Which is no doubt helpful, but would not produce a quantitative value for climate sensitivity (K per W/m^2).

Qualitatively, I continue to have grave reservations as to the applicability of a climate sensitivity to the glacial terminations. Climate sensitivity is defined in the context of a smooth, linear (at least locally) temperature response to a forcing. However, glacial terminations show a quite sharp change in temperature, which does not seem to reliably correlate linearly with the Milankovich high-latitude insolation. Hence, it has the appearance of a system with two semi-stable states, with the glacial termination transition between them driven by Milankovich effects, possibly amplified by a resonant response to the annual variation. [And yes, possibly aided by a CO2 feedback as well.] Transitional behaviour of such a system would not correspond to behaviour within a state -- either one.

As to your squarespace difficulties, I can only sympathise. Some months ago I was in a similar position, having to save most posts as the first attempt to post usually failed, and often locked out of posting for some time thereafter. For some reason these problems seem to have cleared up for me, as I have been having little difficulty of late. Perhaps this is natural variability at work ?!

[lapogus]

BBD - I know I have linked to Nik's graph before, and I remember the points you made about the CET being unreliable, which are fair enough. But the unreliability with the CET stems only from the first 100 years, up to 1770 iirc. We were discussing the warming since the 1970s, which I contend is not significant, and which is completely unaffected by the problems of the CET early years. And the CET is only one of 8 long term temperature datasets on the graph. Are you suggesting that the raw data from these other cities (which is unadjusted for UHI) is misleading? If so, in what way? Is it because it does not show any significant warming in the late 20th century? I recommend that you stop moving the goal posts.

[lapogus]

BBD - I am fully aware that UK weather is not a good measure for global warming, and I was not suggesting it was - indeed I stated that I wished some of the warming would come this way. I don't dispute that the planet warmed up a wee bit in the late 20th century. But I don't think it was significant, or a bad thing, or for that matter anything much to do with anthropogenic CO2 emissions.

[BBD]

HaroldW

Please see Hansen and Sato (2011) as linked above in response to Richard Drake.

[BBD]

lapogus

Fine. Believe whatever makes you happy.

[lapogus]

BBD - likewise. But don't patronise me, all I did was link to a graph of historical raw temperature data which suggests that the warming of the late 20th century warming was not significant. Shame we can't even agree on raw data though.

[Richard Drake]

BBD:

You do not have the full story.

No, what I don't have is an answer to my original question. Take your time. It would be wrong to say that I'm very interested. (I am very interested in how we're going to see much better estimation of climate sensitivity from modern data over the next few years. Any help with that or pointers on that will be read. I will come back to the paleo attempts in due course. I have a note of the URL for that purpose. But it strikes as an extremely second order issue.)

HaroldW:

Qualitatively, I continue to have grave reservations as to the applicability of a climate sensitivity to the glacial terminations. Climate sensitivity is defined in the context of a smooth, linear (at least locally) temperature response to a forcing. However, glacial terminations show a quite sharp change in temperature, which does not seem to reliably correlate linearly with the Milankovich high-latitude insolation. Hence, it has the appearance of a system with two semi-stable states, with the glacial termination transition between them driven by Milankovich effects, possibly amplified by a resonant response to the annual variation. [And yes, possibly aided by a CO2 feedback as well.] Transitional behaviour of such a system would not correspond to behaviour within a state -- either one.

Well said. A two state solution sometimes works best. BBD may be exhibiting this with his own shift in estimation of sensitivity. Like PaulM said, I'm out.

[BBD]

Conclusive evidence that neither of you can answer the core question. In fact you have contorted yourselves spectacularly to avoid even addressing it directly.

How can a cold world with a low climate sensitivity accumulate enough energy within its climate system to exit a glacial?

[Richard Drake]

OK, I'm back, with a couple of further questions

1. How can a cold world with a high climate sensitivity accumulate enough energy within its climate system to exit a glacial and remain as stable as it has before and since, apart from the relatively minor differences (as seen from absolute zero Kelvin) between glacials and inter-glacials?

Answer: you don't know. It's not just that you cannot explain every detail but most of all you cannot explain the remarkable stability that has led to the evolution and prospering of complex life. I'm telling you that answer for free.

But climate sensitivity can now begin to be measured, as the Lindzen presentation three days ago describes in some detail, leading to my second question, which is really a strengthened version of my original question.

2. Are you saying that you are completely uninterested in modern measurement of sensitivity, that the argument Hansen makes is so convincing to you that no amount of modern data, appropriately interpreted, could change your mind?

I'm going to assume the answer to that one is yes. But on that I'm open to correction.

[BBD]

Richard

I'm saying that Lindzen is wrong. There are many rebuttals of his ideas out there. This is but one example:

http://dotearth.blogs.nytimes.com/2010/01/08/a-rebuttal-to-a-cool-climate-paper/

I'm saying that you you still haven't answered the question.

I'm saying that a high climate sensitivity does exactly what we observe: responds strongly to moderate forcings (glacial termination) and exhibits significant variability in response to moderate forcings (Minoan and Roman warming, LIA, MWP etc). And now CO2.

Finally, what I have striven to draw to your attention is that all the data - modern instrumental, modelled, paleoclimate - are converging on a median fast feedbacks value of 3C per doubling of CO2. All of it. Not just the paleo.

[BBD]

Richard

I thought I'd linked to the Knutti & Hegerl (2008) review paper on climate sensitivity, but it seems not. I recommend a close reading.

http://www.iac.ethz.ch/people/knuttir/papers/knutti08natgeo.pdf

[not banned yet]

BBD - did you have any views on this post?:

http://bishophill.squarespace.com/blog/2011/6/6/koutsoyiannis-2011.html

[Dave Salt]

BBD, as I've previously noted, Knutti & Hegerl (2008) contains the following caveat...
"Structural problems in the models, for example in the representation of cloud feedback processes or the physics of ocean mixing, in particular in cases in which all models make similar simplifications, will also affect results for climate sensitivity and are very difficult to quantify."

OK, you're claiming Hansen can now derive sensitivity without models, so do you expect the next IPCC WG1 report to declare that the "science is settled" because of this recent revelation?

[BBD]

Dave Salt

K & H (2008) is right to include this and numerous other caveats. Nevertheless, it shows how estimates of sensitivity from different sources tend to converge. This is persuasive.

OK, you're claiming Hansen can now derive sensitivity without models, so do you expect the next IPCC WG1 report to declare that the "science is settled" because of this recent revelation?

This is not. It is rhetoric.

Why not read H&S (2011) for clarification on the methodology?

[BBD]

not banned

wrt the Koutsoyiannis study,:

- why should the known physical properties of CO2 not be operating as expected?

- this would explain much of the recent warming

- what is causing energy to accumulate in the climate system such that the temperature rises?

- can the statistical argument purporting to explain sustained warming account for the mechanisms within the climate system required to cause it?

- is Koutsoyiannis' approach intrinsically incompatible with principle attribution to CO2?

[Dave Salt]

BBD, you say K & H (2008) "shows how estimates of sensitivity from different sources tend to converge" but I would say that it tends to show how estimates spread due to significant uncertain. I'd also note that most estimates are derived using models that are implicitly assumed to include all significant feed-back mechanisms and their interactions, which suggests that they could all be wrong if they've all ignored an important mechanism like Svensmark's cosmic ray hypothesis.

By the way, I asked about Hansen's impact on the next WG1 conclusions because, if you accept this ideas, we are not just in serious trouble but have gone beyond the point of no return... but maybe that's just rhetoric.

[Shub]

BBD,
Your high sensitivity from MWP argument is settled easily. Dave Salt asked the relevant question earlier. There is no such thing as 'sensitivity' of the climate system. It is always sensitivity to a named factor.

If there is such a thing as simply a high sensitivity, and if a previous episode of significant warming (which you've so graciously offered to admit to) occurred with no single attributable cause, then, correspondingly, a confident attribution of current warmth to 'anthropogenic' influences is less sustainable as an explanation.

The earlier false hockey stick explanation made more sense.

[BBD]

Dave Salt

BBD, you say K & H (2008) "shows how estimates of sensitivity from different sources tend to converge" but I would say that it tends to show how estimates spread due to significant uncertain.

Please see their Figure 3 for a synoptic view of the convergent estimates.

I'd also note that most estimates are derived using models that are implicitly assumed to include all significant feed-back mechanisms and their interactions, which suggests that they could all be wrong if they've all ignored an important mechanism like Svensmark's cosmic ray hypothesis.

From Hansen & Sato (2011) emphasis added:

The empirical fast-feedback climate sensitivity that we infer from the LGM-Holocene comparison is thus 5°C/6.5 W/m2 ~ ¾ ± ¼ °C per W/m2 or 3 ± 1°C for doubled CO2. The fact that ice sheet and GHG boundary conditions are actually slow climate feedbacks is irrelevant for the purpose of evaluating the fast-feedback climate sensitivity.

This empirical climate sensitivity incorporates all fast response feedbacks in the real-world climate system, including changes of water vapor, clouds, aerosols, aerosol effects on clouds, and sea ice. In contrast to climate models, which can only approximate the physical processes and may exclude important processes, the empirical result includes all processes that exist in the real world – and the physics is exact.

[BBD]

Shub

There is no such thing as 'sensitivity' of the climate system. It is always sensitivity to a named factor.

You appear to misunderstand the term:

In IPCC Reports, equilibrium climate sensitivity refers to the equilibrium change in global mean surface temperature following a doubling of the atmospheric (equivalent) CO2 concentration. More generally, equilibrium climate sensitivity refers to the equilibrium change in surface air temperature following a unit change in radiative forcing (degrees Celsius, per watts per square meter, °C/Wm-2).

[From http://www.epa.gov/climatechange/glossary.html#C]

[diogenes]

I sense people talking round each other. perhaps an appeal to first principles?

What is sensitivity?
Is it a constant or can it change - and what is the evidence for either view?

[not banned yet]

BBD -

1) How is CO2 expected to operate?
2) Could anything else?
3) If temperature stops rising, does this mean additional energy has stopped accumulating?
4) Are you talking about correlation?
5) How would you define criteria to decide this?

No need to answer - purely rhetorical.

[woodentop]

The Hansen & Sato (2011) discussion at Judith's is, as always, very interesting (and no, I'm not on commission):

http://judithcurry.com/2011/04/18/earths-energy-imbalance/

Much food for thought in manacker's post:

http://judithcurry.com/2011/04/18/earths-energy-imbalance/

And this, which summarises the difficulty in working out a "climate sensitivity" figure:

BLouis79 | April 21, 2011 at 4:52 pm | Reply
“Climate sensitivity” is derived from observation. It has no fundamental mathematical or physical proof. It is not founded in thermodynamics.

Usual physical constants are constant to umpteen decimal places.

Climate sensitivity estimates by various authors vary by an order of magnitude.

Climate scientists would be better off forgetting about it, seriously.

http://judithcurry.com/2011/04/18/earths-energy-imbalance/#comment-63887

[woodentop]

Sorry - manacker's post above should be linked:

http://judithcurry.com/2011/04/18/earths-energy-imbalance/#comment-63272

"Warming in the pipeline" - snigger.

[Shub]

With BBD, I always find him pointing out stuff to me, which I would be trying to point out to him.

Like this:

Me: BBD, X is equal to Y
BBD: Shub, you are mistaken. It is actually X=Y.