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A phenomenological sequel

Filed under: — rasmus @ 27 November 2007

Grading

Does climate sensitivity depend on the cause of the change?
Can a response to a forcing wait and then bounce up after a period of inertness?
Does the existence of an 11-year time-scale prove the existence of solar forcing?
Why does the amplitude of the secular response drop when a long-term trend is added?

These are perhaps some of the questions that we might hope to see discussed in the sequel to the sequel on solar forcing by Scafetta & West (S&W), a few of which have been discussed before here and here. (I still think those earlier studies were seriously flawed and showed a lack of scientific understanding, by the way).

This time S&W present a set of new arguments and a new set of results which are scattered all over the place. The impression from reading their paper is that the upper range (they call it ‘upper limit’) is probably more representative than the lower estimates for the solar contribution to the global mean temperature.

I think that many of their arguments, on which this impression is built, are shortsighted. For instance, they claim that certain climate reconstructions must be wrong because they give ‘unphysical’ answers. But there is another explanation too that they did not contemplate: their idealistic (one may also argue unphysical) model may also be wrong! Thus, they fail to exclude other explanations.

S&W attach the ACRIM Total Solar Irradiance (TSI) product (not the PMOD product, probably because that does not show any trend) to a TSI reconstruction (Lean 2000 TSI [see Lean, 2004], or Wang et al., 2005) in such a way that the average reconstructed TSI value over 1980-1991 corresponds with the ACRIM mean for the same period – never mind the discrepancies in trend and that such cavalier stitching of data series is one of the deadly sins in climatology (hint: the series is inhomogeneous).

One new aspect of this S&W study is the focus on ‘feedbacks’. They assume the TSI reconstruction is a proxy for the total solar influence and that CO2 is part of a solar ‘feedback’ (isotope ratios suggest the CO2 comes from deep underground reservoirs, but it’s not clear how the sun manages to dig up this carbon from deep below Earth’s surface).

S&W maintain that the climate response is greater for longer time scales (which is reasonable) as illustrated in their figure 4 (reproduced below), and assisted by the simple model illustrated in this figure, they argue that the present warming is a delayed response to past solar changes (presumably before the 1950s). But it is unclear why the temperature then flattened out and even dropped a little between 1940-1970 at the time when it really should have increased fastest. One could argue that something else also happened then, but for an unknown reason, this forcing then seemed to have a shorter relaxation time. Why such an interference would give a quicker response than a solar signal is unexplained (the response to volcanoes is fairly prompt, however).

S&W figure 4
My reconstruction of combined high-frequency + trend response

The study by S&W has some suspicious results. When their simple ‘phenomenological thermodynamical model’ (PTM) is forced by a signal with shorter time scales (high-frequency response representing the ~11-year solar cycle), it produces weaker response than if the forcing has longer time scales (or lower frequency) – as expected. But if you add a long-term trend to the former, the amplitude of the high-frequency response diminishes further (their Figure 4, reproduced above): The amplitude of the higher frequency response in their upper panel (4mm measured in the print) had diminished by ~50% in the lower panel (2mm). This is probably because the relaxation time response has been increased between the two panels and is greater than 10 in the lower panel. The presence of a trend should not affect the amplitude of the higher frequency in such a simple linear system (see my reproduction above).

Their figure 5 (below) does not correspond with the discussion in their paper (see scanned part of the text). Again, their analysis is sloppy in the estimate of change, underestimating the observed temperature change (T(obs) in Fig 5a, the total warming is stated to be ~0.8K since 1900, but the figure suggests it is greater than 0.8K) and exaggerating the solar contribution T(sol). This way, the fraction T(sol)/T(obs) gives the impression of a more sensitive response to changes in the Sun. They then proceed to use the lower T(obs) estimate for Mann & Jones (2003) for the total temperature change (claiming 0.8K, although this is too low), but taking a solar contribution estimated from the Moberg et al. (2005) temperature with more pronounced variations (the right estimated warming should exceed 1.0K – not 0.8K as they claim). Hence the fraction of solar signal to total change T(sol)/T(obs) is spuriously inflated.

S&W Figure 5Copy of S&W discussion of Fig. 5

But what about GHGs if the sensitivity is so high and the relaxation time is so long? We know from laws of physics and lab measurements that the CO2 levels have been increasing and that CO2 absorb infra red radiation. In fact, the Mauna Loa observations done by infra-red gas analysers measure the absorbing properties of air samples – a pure GHG effect on a microscopic scale without feedback effects. The high climate sensitivity and long time delay suggested by S&W would be scary – imagine the GHG warming that is not yet materialised and would be in the pipeline! (Lindzen who doesn’t believe in the lagged response would indeed be surprised if this was the case!).

S&W propose two mechanisms which may amplify the response to solar variations: (i) GCR (here, here, here) or (ii) UV-radiation.

But S&W ignore the issue about the lack of trend in the GCR (Lockwood & Frohlich, 2007; Benestad, 2005), the fact that trends in the diurnal temperature suggest otherwise (IPCC, 2001, 2007), and that there is not a clear trend in the cloud cover. Thus, explanation (i) is not convincing.

The problem with the UV-explanation (ii) is that the stratosphere has been cooling – some of which is due to the ozone depletion. How could they have ignored that?

Finally, the paper oozes of vague but subjective and cherry-picked statements forming the impression that the climate and solar reconstructions of Mann & Jones (2003) and Lean (2000) (why not use more recent reconstructions, by the way?) respectively are less accurate than others. Apparently because these do not give the desired results.

The paper also offers some incorrect references (Kristjansson et al, 2004, do not support the notion that GCR affect the climate). Furthermore, their paper contains little physics, but is little more than a curve-fitting exercise with no cross-validation.

Thus, S&W make a number of unjustified assumptions and sweeping statements which turns it into a mere speculation. In a way, the conclusions are already given when S&W assume that the sun is the predominant cause from the outset. S&W presumes a desired conclusion when arguing that if the TSI variations are small but the temperature variations are pronounced, then this suggests greater climate sensitivity and vice versa. No surprise, their conclusion is that the sensitivity to solar changes is high. Any other conclusion would then be surprising, wouldn’t it?

If they were my students, I’d have flunked their paper.


298 Responses to “A phenomenological sequel”

  1. 101
    David B. Benson says:

    Off-topic, but I now have a minor interest in inter-ocean transfers of water via rain or snowfall. Divide the world’s ocean into just the Atlantic (includes Caribbean, Mediterranean and Arctic) and the Indio-Pacific (plus maybe the Southern Ocean?). Now fairly clearly around Central America it seems that there would be evaporation in the Caribbean with some of the rainfall on the Pacific side of the continental divide. Here in the Pacific Northwest, evaporation in the North Pacific leads to some of the rain and snow on the east side of the continental divide.

    I know essentially nothing about how this plays out in Africa, and in any case don’t seem to know appropriate search terms to aid me in this little exercise. Any assistance will be appreciated. :-)

  2. 102
    Charles Muller says:

    #96 (Tamino) So, the “proof” that there’s no quasi-200 yr solar cycles is… that too many scientists find this cycle when filtering their data ? Hard for me to understand your point, because witjout more precise critics of proxy analysis, this kind of “prior assumption suspicion” may be adressed to any research in any field of climate science. Muscheler, who have been guess author here, have no problem with this periodicity when revieweing the relevant studies (Cl36 and Be10 in ice core, C14 in tree ring, etc.). See for example his contribution (with Beer and Kubik) in Pap et Fox (ed), Solar variability and its effects on climate, AGU, 2005, pp. 221-236.

    I have a question about solar forcing trend. On NCDC paleoclimate database, I download Mike Mann et al. volcanic and solar forcing on Tropical Pacific for the last 1000 yrs. (J Clim 2005). But the highest value of the solar-forcing serie, 0,423, is given for 1989, not far from the second highest 0,418 (1990) and post-1980 values ar globally higher than all pevious, for the XXth century or past millenia.

    How is it possible to get such a hight solar signal on Tropics if there’s no global trend in the past 50 yrs ?

    Ref :
    http://www.ncdc.noaa.gov/paleo/forcing.html
    ftp://ftp.ncdc.noaa.gov/pub/data/paleo/climate_forcing/mann2005/

    [Response: You are aware that these are simply the Crowley (2000) estimates (which are a splice of cosmogenic isotope and sunspot-based solar reconstructions), scaled by a constant geometric factor to account for the difference between equatorial and hemispheric-mean insolation? While the values indeed peak in the 1980s, the trend over the past few decades (including the most recent solar cycle, which is largely subsequent to the 1999 termination of the Crowley series) is not statistically significant. -mike]

  3. 103
    nicola scafetta says:

    ciao, Rasmus and Gavin. How are you? I hope well.

    [Response: Fine - We are ready for an exciting debate! -rasmus]

    I see that Rasmus has once again written an interesting article on our research. I sincerely suggest Rasmus to be more relaxed when he writes something. I do not undestand why it is not possible to the writers of this web site to give a fair and calm reading of a paper and only after then to write an interesting and useful critique.

    The arguments made by Rasmus are quite wrong on several grounds:

    A) He claims that I did wrong calculations because in his opinion our evaluation of the warming from 1900 to 2005 of 0.8K is too small. Well, around 1900 the average temperature anomaly was -0.3K and around 2005 the average was 0.5K. The sum is 0.8K, right? Rasmus is considering the extreme of the fluctuations seen in the temperature, instead of looking at some mean value.

    [Response: When discussing long-term changes for series with year-to-year variations, you need to do a proper trend-analysis, rather than just pick a single year. Just look at your graph, and you see that it's not representative for the development. -rasmus]

    B) The issue of the cooling between 1940 to 1970. Rasmus claim that our paper is wrong because I do not recover 100% of this cooling. Well, first, as some readers above have noticed, this is a problem also for the GCMs guys because these models such as the GISS one fail to reproducing this cooling too. The GCMs guy claim that this cooling was cause by an increase of aerosol in the athmosphere (not well documented, actually). Fine. So, why this cannot be true also for our study? I have never claimed that the Sun explains 100% of the patterns seen in the temperature record since 1900. So, Rasmus argument is quite unfair, as the readers can easily undestand.

    Observed global mean T and corresponding results from GISS GCM - tests ignoring GHG.Observed global mean T and corresponding results from GISS GCM - tests ignoring TSI.

    [Response: The problem with this paper is that it claims both a dominant role for the sun in addition to a long relaxation time. That combination doesn't work when looking at the temperature evolution, as most (almost all) of the solar activity changes happened before 1950. About your comment that the GISS model fails to reproduce the levelling off: Actually, the levelling off/cooling period is quite well reproduced by the GISS-model (see above Figures and FAQ 8.1 Figure 1 on p. 600 from the IPCC WG1 AR4). I don't think that you are up to date! You are right that there are considerable uncertainties associated with aerosols, and aerosols should also be one of the factors of your study. Likewise, so should GHGs. But do you really believe that the relaxation time for these forcings are much shorter than for solar forcing? After all, the alleged effect from aerosols appear to produce quite rapid changes compared to the long time scales you claim to be at work. And are you admitting that aerosols have a much stronger effect masking a solar signal? -rasmus]

    However, there might be another explanation I wrote in the paper, that Rasmus in his impetus has missed again. In fact, I used the TSI proxy reconstructions by Lean. These reconstructions reproduce the secular solar trend with the geomagnetic and smooth sunspot record. These records pick around 1960. However, other solar observables, such as the solar cycle length picks in the 1940s and then decrease untill the 1970s. Perhaps, the sun followed this proxy better, as assumed by Hoyt and Schatten in ther TSI reconstruction and picked in the 1940s when there was a temperature maximum is observed. This might explain the 1940-1970 cooling with a solar decrease that is only partially recovered when I use the Lean’s reconstruction. So, I believe that this issue about the correct TSI reconstruction, which is not solved yet, merits a deeper study. However, this is said in our paper and in the previous papers, and also several times in this web-site in response to Rasmus. Rasmus always repeats the same point and never listen!

    Figure 2 from Benestad (2005)

    [Response: Actually, the solar cycle length (SCL) really doesn't 'peak' in the 1940s - look at the figure on the left (Fig 2 from Benestad (2005)). Only a traditional method of estimating SCL directly from the Wolf sunspot number (not recommended as it involves high degree of uncertainty) yields anything that can be interpreted as a 'dip' around 1940 (when you invert it a 'dip' becomes a 'peak'). Or perhaps you are referring to those filtered curves by Friis-Christensen & Lassen (1991) which since have been discredited? But even if you were to use SCL and it did peak in 1940, a hypothetical solar response would, according to your work, be delayed. But it's a bit dodgy to throw in different indices to the equation without a clear physical understanding for why they should be more appropriate than the others. Also, it's interesting to note that there are discrepancies between the different solar proxies - beit TSI, SCL, aa/ak indices, sunpot number, 10.7 cm flux, or magnetic components. It's always possible to do a 'curve-fit' by selecting a suitable time relaxation after searching for a curve that looks a bit similar - and voila! There is a nice fit in the end! But that's not science. Science is about being critical. If you claim there is a relaxation time and a peak in the response, then you imply that the level of solar activity must have dropped quite a bit since some time before 1940. As far as I know, this has not happened. I suspect that if you use Hoyt and Schatten in ther TSI reconstruction instead of Lean TSI, then you don't need any relaxation time, as this would provide a poor fit (the peak would still be delayed). I suggest a read up on Karl Popper. About me not listening - well the fact that I write this post means that I do take some interest in your work and that I do read your papers. The reason why I repeat some points is because you don't learn from our discussions or because you do not convince that the way you do it is correct. I did hope that you put more care in stitching together different series and that you eventually learn that because you find spectral power near 11 years in a time series, it doesn't prove that it's caused by the solar cycle. -rasmus]

    C) the issue between ACRIM and PMOD. I believe that Rasmus is not really understanding the difference between the two. In a few words, both claim to be composites of the TSI satellite data however there is a significant difference. Why is it so? The reason is that ACRIM uses the satellite data as they are published by the experimental groups while PMOD assumes that ACRIM1 and NIMBUS7 data are corrupted and alters them in such a way that the resulting composite looks similar to the TSI proxy reconstruction by Lean. The problem is that the experimental groups which are responsible of both ACRIM1 and NIMBUS7 data do not agree with the PMOD group about the necessity of these corrections. Thus, ACRIM represents the satellite data and is the real composite, while PMOD is a theoretical composite that fits well the TSI proxy reconstructions (that might be wrong!).

    [Response: This is the version I have heard: 'There is reason to doubt that the ACRIM composite is correct - during the 'ACRIM gap', you need to use another source of irradiance data to fill in. Willson using one, Lean+Frohlich use another. The proxy records - 10.7 radio flux, cosmic rays etc all correlate with L+F's choice - not Willson's. But it could still be that there really is an incoherence between the other solar indices at solar min and irradiance - in which case there is no information available prior to the direct measurements that is useful! One final issues is that the nature of the 'trend' even in the ACRIM composite is pretty diffuse. It does not come from any statistical regression, but was simply the difference between the two solar min. With the latest solar min below even the first in all records, there is no sense in which the Willson analysis shows an upward trend. The problem with the SW composites is that a) their Lean + ACRIM record is just made up - Lean's reconstruction is from a model that is tuned to the PMOD composite, not ACRIM - and so there is no real idea of how ACRIM would really effect the reconstruction or the errors, b) as you point out, they have a single factor analysis that will fold any power (from noise, volcanoes, GHG trends) into their assessment of the 'solar' terms.' ]

    In my opinion both composites are important for a study like mine because there might be the possibility that the Earth climate might contain mechanisms sensitive to the pattern observed in PMOD and other mechanisms sensitive to the pattern observed in ACRIM. So perhaps, a more correct result would be some how between the two curves I get.

    [Response: It's a fact that ACRIM differs from the TSI-construction in the period they overlap (otherwise, there would be no point to change the series). This is a clue! Either the ACRIM is wrong or the TSI-construction, and by stitching them together you get an inhomogeneous series which invalidates trend analysis. -rasmus]

    I hope this helps the readers of this forum. Those interested in another different forum on our work can read this:

    http://www.climateaudit.org/?p=2451

    (Rasmus and Gavin, please do not erase the link above, climateaudit links to your web site, it would be kind if you link their)

    [Response: I won't censor your link, but I will dare to be somewhat sarcastic and say that the link is indeed enlightening (not). -rasmus]

    ciao, ciao,
    nicola

    PS: about the F grade Rasmus gave me, I just let the readers notice that it is not fair to be at the same time the accuser and the judge. Rasmus likes to be both. Let Rasmus be the accuser, but let the readers of the debate be the judge, OK?

    [Response: You are right, the readers should judge the material for themselves. -rasmus]

    Merry Christmas to all!!!!

    [Response: Same to you!]

  4. 104
    tamino says:

    Re: #102 (Charles Muller)

    So, the “proof” that there’s no quasi-200 yr solar cycles is… that too many scientists find this cycle when filtering their data ? Hard for me to understand your point, because witjout more precise critics of proxy analysis, this kind of “prior assumption suspicion” may be adressed to any research in any field of climate science

    First of all, a quasi-200 yr cycle is not a periodic cycle; it’s a variation which happens on a timescale of around 200 years, but is not strictly periodic, its period and amplitude may both be highly variable, it may lose phase coherence altogether, and the fluctuation may be intermittent or even temporary, disappearing for long stretches of time or even forever. I meant just what I said: I remain highly skeptical that solar minima occur every 200 years, which is what William Astley claimed.

    I did not make a “prior assumption of suspicion.” As I already stated, I have actually analyzed much of this data, and reviewed published works. Many analysts have claimed “periods” which are at best pseudoperiods, at worst nothing but noise. For example, the best C14 data of which I’m aware is the INTCAL98 data, for which a large number of authors have claimed a very large number of periods. But when I run the numbers the vast majority of the claimed periods (including that near 200 years) are consistent with psuedoperiodic fluctuation or with nothing more than the spectral signature of red noise. The data are most definitely NOT consistent with a truly periodic phenomenon with period anywhere near 200 yr.

    There may indeed be a roughly 200-yr pseudoperiodic behavior in solar output, but the data I’ve seen indicate that it’s still an open question. And in my opinion, the claim that “solar minima occur every 200 years” is utter nonsense.

  5. 105
    William Astley says:

    In reply to Ray Lambury’s comment:

    “Thus, any decrease in solar forcing will buy at most a temporary reprieve (and probably a return to complacency) before the end of the Minimum brings the return of warming with a vengeance. That CO2 is responsible for most of the current warming is really inescapable.”

    Ray you are missing the points. GWG warming is over estimated if solar warming is significantly under estimate. Also I see the problem as eminent global cooling not warming which is consistent with paleoclimatic record. Interglacial periods end abruptly and there is clear unrefutable evidence of periodic abrupt climate changes. Have you ever thought about the glacial portion of the cycle?

    It seems the solar modulation of planetary cloud cover has not been taken into account. i.e. The GWG calculations assume all of the 20th century warming is due to GWG?

    This paper shows that the solar changes which modulate cloud cover correlate with the observed 20 th century temperature changes for the entire period in question.

    http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76..969G.pdf

    “We show that the index commonly used for quantifying long-term changes in solar activity, the sunspot number, accounts for only one part of solar activity and using this index leads to the underestimation of the role of solar activity in the global warming in the recent decades. A more suitable index is the geomagnetic activity which reflects all solar activity, and it is highly correlated to global temperature variations in the whole period for which we have data.”

    In Figure 6 the long-term variations in global temperature are compared to the long-term variations in geomagnetic activity as expressed by the ak-index (Nevanlinna and Kataja 2003). The correlation between the two quantities is 0.85 with p

    [Response: I'm a bit skeptical to the figures in that paper - how are the curves smoothed? (they remind me a bit of the work of Svensmark, Friis-Christensen & Lassen). It's also typical - when one index doesn't work, a new one is thrown in. The authors use the ak-index for which they claim describes the geomagnetic field. But it's the interplanetary magnetic field (IMF) - or the magnetic field spanning the solar system - which has been proposed to be important for shielding most of the GCR. The geomagnetic field has little to do with the solar activity, but more to do with earth's crustcore (sorry, got the words mixed up!). It is not clear then why the ak-index should be superior to other indeces. My GRL paper on solar proxies like the aa-index, sunspot number, SCL, and GCR suggest that these have not changed appreciably since the 1950s. also see the posts on 'Comsoclimatology' , and about the spin on GCR, and lack of similar long-term variations between GCR and T. -rasmus]

  6. 106
    Timo Hämeranta says:

    Many thanks Nicola Scafetta to participate in this discussion (# 103)!

    I forward the readers of this blog to read also ClimateAudit at http://www.climateaudit.org/?p=2451

    and

    Reference Frame at http://motls.blogspot.com/2007/11/scafetta-west-climate-phenomenology.html

    Nicola Scafetta’s comment on the way this blog is run is a good impetus for all readers to read Science Editorial today:

    Sykes, Kathy, 2007. The Quality of Public Dialogue. Science Editorial Vol. 318, No 5855, p. 1349, November 30, 2007

    Extract:

    “…But these dialogues must be of a high standard; otherwise, time is wasted, the public lose trust in science, and bad policy decisions result. So, what constitutes good dialogue?

    Public dialogue is valuable when it helps policy-makers hear the views of people who have no prior or vested interest. It can challenge assumptions, explore long-term impacts, generate ideas, tease out the nature of public concerns before polarized positions emerge, and help broaden consideration of the issues. Dialogue is not about the public making decisions about science policy; that is for policy-makers. Neither is it formal public consultation, nor is it an open platform for debates that can polarize participants or be hijacked by lobby groups or stakeholders (although their perspectives are important to consider)….”

    Well, you surely have yr views whether RealClimate is or not run by “people who have no prior or vested interest” and whether this blog is or not “an open platform for debates that can polarize participants or be hijacked by lobby groups or stakeholders…”

    [Response: But the pages of those links that you provide DO NOT hold a dialogue of high standard. They rather serve to provide ad hominem attacks. The latter, among other things, calls RC a 'propagandistic blog designed to politicize science, a kind of blog that refers to all politically inconvenient scientific results as the "industry-funded misinformation"'. Not much scientific reasoning there. No documentation no proof. Just childish statements taken out of the air. ClimateAudit publishes statements such as '[people at] RealClimate are not scientists at all. They are priests of a mystery cult.’. Or this thing about the ‘penalty box’. Again, childish, and that blog is in a similar category as the former. You surely have yr views whether these sites are or not run by “people who have no prior or vested interest, to use your oewn words? I can assure you that I have neither experienced that RC has been hijacked by lobby groups, stake holders, and that we are open to different views (this is but one example). But perhaps by insisting that we link to those trashy sites, you are trying to hijack our blog? -rasmus]

  7. 107
    Ray Ladbury says:

    William Astley, your post #105 demonstrates a common misconception among skeptics–namely that if we can just find some other factor that contributes to climate change, then we can forget about CO2. Unfortunately, CO2 forcing is constrained by several independent lines of evidence. There isn’t much wiggle room without having to scrap the whole theory of climate–and since this theory has yielded pretty good qualitative and in many cases quantitative agreement, we have to assume it’s a pretty good theory in its basics. The degree of constraint is much less wrt aerosols, clouds, etc., so these parameters could drift a bit in future models. So if your modulation of cloud cover is correct, the most likely other forcing affected would be aerosols, not CO2, and our problem doesn’t go away. Unfortunately, climate models are not Chinese menus where you pick one from column A and one from column B.
    Moreover, there are reasons to doubt that a cloud modulation mechanism really works–it’s a neat trick to suppress cloud formation during the day when it promotes warming, but not at night when it promotes cooling, for instance. Looking for correlations in data unguided by physics (or using physics a posteriori to explain the correlations) is a fraught proposition–as medical studies demonstrate abundantly. I’ve seen four-sigma signals emerge in channels where they have to be garbage.

  8. 108
    Ray Ladbury says:

    Timo, I wonder why you consider Motl anything but a court jester wrt climate. He has no relevant expertise and merely demonstrates that smart people can be very wrong when they venture outside their narrow realm of expertise. I wonder if you consult him on matters of plumbing and electrical work to your house as well. I also wonder why we are talking about “public debate” wrt the science of climate change. The public really doesn’t get a vote on the science.
    Climate audit has also made itself increasingly irrelevant by continuing to ignore the science. Many on that board are still questioning WHETHER the planet is warming. The level of scientific literacy there is pretty apalling.
    Where the public need to weigh in is wrt what we do about the threat we face. As long as a segment of that public continue to waste time by debating established facts, they disenfranchise themselves from the process of coming up with solutions. In effect, we need the loons on the right to cancel out the loons on the left so the center can make real progress.

  9. 109
    Hank Roberts says:

    Any public forum needs a killfile. Usenet had threaded reading and killfiles that could remove both individual posters (uniquely identifiable) and entire threads, at each reader’s individual choice.

    One thing we know about all of us — it’s hard to ignore distraction, hard to remain focused on a discussion, unless we can truly not see the attempts to derail and insult and confuse the conversation. Being human means being easily trolled. We rise to bait, even with the best self control.

    This is why we don’t do important work in hostile crowds, except on the Web that’s hard to avoid, while we are still lacking Usenet’s capable tools for talking only among those willing and able to contribute toward making progress in understanding the topic.

    “Don’t criticize what you can’t understand” is advice rarely taken.

  10. 110
    William Astley says:

    In reply to Ramus’ comment:

    “It is not clear then why the ak-index should be superior to other indices.”

    The ak index (which measures the affect of the solar wind on the geomagnetic field) is used rather than aa as the 20th century 1991 to 2007 reduction in planetary cloud cover is due to electroscavenging not due to decreasing levels of GCR. The electroscavenging is caused by high speed solar wind bursts, from coronal holes. The coronal holes move to the solar equator at the end of solar cycles 21, 22, 23. As noted in Georgieva, Bianchi, and Kirov’s in their 2005 published paper the aa index and a simple count of sunspots does not correlate with the change in planetary temperature, 1992 to 2001. The problem is the aa index or a simple sunspot count does not measure the parameter which causes electroscavenging.

    http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76..969G.pdf

    The electroscavenging mechanism at the end of the solar cycle removes the extra ion cloud forming ions including extra ions that are produced at the end of the solar cycle by the increase in GCR. As you state the heliosphere is reduced at the end of the solar cycle, hence GCR increases. The electroscavenging mechanism explains why there is less cloud modulation variance from solar cycle peak to solar cycle minimum for cycle 21, 22, 23.

    Palle’s earthshine and satellite data and analysis supports the reduction in planetary cloud, 1992 to 2001. Palle notes in his satellite paper that the reduction in cloud cover is consistent with Tinsley’s electroscavenging mechanism. (Electroscavenging reduces cloud cover at specific latitudes. Palle found the reduction in cloud cover occurred at the latitudes as predicted by Tinsley.)

    The following is Palle’s earth shine paper that notes the change in planetary albedo is an observed 7.5 W/m^2 which supports a large solar impact on 20 th century temperature.

    http://solar.njit.edu/preprints/palle1266.pdf

    Our simulations suggest a surface average forcing at the top of the atmosphere, coming only from changes in the albedo from 1994/1995 to 1999/2001, of 2.7 +/- 1.4 W/m^2 (Palle et al., 2003), while observations give 7.5 -/+ 2.4 W/m^2. The Intergovernmental Panel on Climate Change (IPCC, 1995) argues for a comparably sized 2.4 W/m^2 increase in forcing, which is attributed to greenhouse gas forcing since 1850.

    The analysis concerning electroscavenging occurred in the last 5 years. Here is a paper written (1998) before the electroscavenging mechanism was known or at least the authors of the 1998 paper appear to be not aware of it. The authors of this 1998 paper expect the solar influence on climate should be greater than observed based on the aa index.

    http://adsabs.harvard.edu/abs/1998GeoRL..25.1035C

    Nevertheless, the general similarity in the time-variation of Earth’s surface temperature and the low-frequency or secular component of the aa index over the last ~120 years supports other studies that indicate a more significant role for solar variability in climate change on decadal and century time-scales than has previously been supposed. The most recent aa data for the current solar minimum suggest that the long-term component of solar forcing will level off or decline during the coming solar cycle.

  11. 111

    In # 98 Raypierre responds:["Response: Not to defend S&W, which is really quite full of nonsense, but I think you are misconstruing their argument in this instance. I believe they are making a statement about estimating climate sensitivity to solar forcing by using the pre-industrial fluctuations; they are not arguing for a direct lagged effect of solar forcing 250 years ago. If a climate reconstruction like Moberg’s, with a lot of variability, were right, you’d need a high sensitivity to solar forcing in order to account for it. Then, take that high sensitivity into the post-industrial era, and you get a lot of solar response then, part of which correlates with the observed temperature."..........]

    Thank you for the clarification. I thought I must be reading too much into it. It was admittedly a painstaking slog, reading through and trying to comprehend a number of aspects of the paper.Now I can go over it again with a better understanding of the underlying principles. I still feel,though, that models are very useful tools, but can sometimes be misused and/or abused and deserve close scrutiny. I’ll leave it to more authoritative and trained minds,in this discipline, to judge whether it’s true,or not, in this case.

  12. 112
    Charles Muller says:

    #102 (Mike answer, and broader questions)

    Thank you for the precision, Mike, but I’m still perplex on the issue. I try to explain the point as I undestand it, but please correct all the wrong assertions.

    1. Direct measures of TSI by satellite began only in 1980 (cycle 21 > cycle 23). We’ve two main compostites – PMOD by Frohlich et Locwood, ACRIM by Willson et Mordvinov. Because of a satellite problem and data gap, they differ slightly.

    2. Estimates of long term solar varibility (secular to millenia) are based on previous measures (like 10,7 radio flux, aa index), historical data (sunspot numbers, observed radius) or cosmogonic isotopes (C14, Be10, Cl36, Ti44, etc.).

    3. Quality of long term solar variability reconstructions depends of the quality / reliability of proxies. The only way to evaluate that is to develop a solar model (eg SATIRE of Solanki team) based on 1980-present precise measurements, and to observe how TSI variation in a cycle (or between cycles) correlates with magnetic / cosmogenic / historical variations. From such a model, it is possible to re-estimate more precisely the solar variability of past 100, 1000 or 10,000 yrs.

    ***

    From these three points (if correct), my questions :

    - Are reconstructions like Crowley 2000 still valuable today (I suppose, because Mike used it in his 2005 paper) ? More broadly, which are the supposed better reconstructions (that is better fit with instrumetal measure of TSI since 1980)?

    - On Crowley 2000 reconstruction, what is the correct evaluation for the trend and its significativity? An example : the 1910-1939 mean is 0,218 W/m2, the 1940-1969 mean is 0,269 W/m2 and the 1970-1999 mean is 0,322 W/m2. So, these 30yrs mean give an increasing trend, even the second half of the Century (contrary to the supposed “no trend” since 1960 RC often quotes). Of course, the trend is small… but anyway, everybody agrees now that solar TSI trends are weak since 1750 or 1900 (cf. the 0,12 W/m2 for 1750-present solar forcing in AR4 IPCC, adn the table 2.10 for the different reconstructions from Maunder minimum to present minima). It is precisely because the TSI trend seems weaker than previousley assessed that scientists look for indirect effects of solar forcing on climate. No ?

    ***

    #104 Urs : thank you for your precision, and I agree with them. I don’t know if William Astley had in mind a strict 200 years cyclicity. I read in some papers (Solanki if I recall correctly) that solar activity should decrease in this century after XXth C maximum, but without any precision on the timing of this decrease and without any allusion to a “grand minimum” of Maunder-type.

  13. 113
    William Astley says:

    In response to Ray Ladbury’s comment.

    “William.., your post #105 demonstrates a common misconception among skeptics–namely that if we can just find some other factor that contributes to climate change, then we can forget about CO2. …Unfortunately, climate models are not Chinese menus where you pick one from column A and one from column B.”

    1) I unequivocally support conservation and responsible development. Please do not me names.

    2) There is evidence throughout the glacial periods and the last interglacial period of abrupt cooling, which is also climate change. Solar modulation of cloud cover and change in TSI would explain the past abrupt cooling. There are a number of papers that support the solar modulation of cloud hypothesis. I am interested in all scientific research concerning climate change not just GWG.

    3) Do you have any comments re: Palle’s earthshine data and analysis concerning planetary cloud cover. (see my comment 110.)

    4) I thought the climate models have an acknowledged problem with modeling cloud cover. I do not understand your comment concerning Chinese menus and climate models. The two seem to be unrelated.

  14. 114
    Urs Neu says:

    Re 82 (Robert)
    Solanki and Krivova made one clear assumption (that all global temperature variability form 1860-1970 is explained by solar variability) which, although very unlikely, allows a clear interpretation of the results.
    The SW paper mixes such a number of assumptions, which are unlikely and some of them physically questionable, that a meaningful interpretation of the result is impossible.
    I do not reject a paper because of its results but because of the way the results are achieved.

  15. 115

    William Astley writes:

    [[ GWG warming is over estimated if solar warming is significantly under estimate.]]

    Nope. You’re missing a basic principle here. The radiative forcing of one is not affected by the radiative forcing of another. They are each computed from first principles. Neither is the residual for the other.

  16. 116
    Charles Muller says:

    #106 Rasmus Comment

    It seems the ak index have been proposed by Nevanlinna, H. and Ketola, A., 1993. Do you know (or somebody here) the difference with aa index ?

    On this Finnish URL, I just find the precision : The Ak(Hel) index measuring the geomagnetic activity was created by Nevanlinna and Ketola (1993). It has been adjusted with the aa index to form the longest uniform index of global geomagnetic activity, extending over the last 14 solar cycles (Nevanlinna and Kataja, 1993).
    http://www.oulu.fi/~spaceweb/textbook/indices.html

    ***

    You say : The geomagnetic field has little to do with the solar activity, but more to do with earth’s crust.

    For an oppositive view (geomagnetic index as proxy of solar activity), see Le Mouel et al. 2005 :
    http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V61-4FV9MMT-1&_user=10&_coverDate=04%2F15%2F2005&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=e35256660478dac919c7311ee59cbe84

    And Courtillot 2007 (I leave this one because raypierre should comment it in his part II of Chevaliers de la Terre Plate – you know, the nice piece from Les Chevaliers du Soleil Calme :D)

  17. 117
    Charles Muller says:

    Two other questions :

    - is there an ftp access for Wang, Lean and Shelley 2005 reconstruction data (latest update of Lean 1995 and Lean 2000) ?

    - Nicola (if you read), did you try the same work with Fligge 2000, Krivova 2003 or Foster 2004 solar reconstructions, a bi more pronounced than Wang et Lean, and if so did you find the same solar signal ?

  18. 118
    Ray Ladbury says:

    William, I’m not sure which Palle study you mean, as 110 is not one of your comments. However, I am somewhat familiar with Palle’s work. First, it’s not uncontroversial, and even if it is confirmed, there are question about how important it might be. One problem is that clouds both reflect and insulate. The two effects tend to cancel out–hence my comment about getting clouds to form only at night is a neat trick. Again, keep in mind that just finding another heat source won’t absolve CO2. You also have to show how so many different lines of evidence supporting current estimates of CO2 forcing could be wrong.

  19. 119
    Alexander Harvey says:

    Gavin Your:

    “Arrggh! The whole point of the ‘mainstream’ view is that you are not going to get very far with simple one-factor correlations. It doesn’t work for solar, and it doesn’t work for CO2 either – too many of the forcings are correlated. You absolutely need to use all major forcings before you can do an attribution. When you do that, GHGs are very likely responsible for the rise in recent decades.”

    Gavin please excuse me if I elaborate:

    What we risk is the tyranny of non-orthogonal functions competing for first position.

    If (just being impartial) TSI is the primary driver and correlates well with the temperature record we need to consider just how well it compares with other forcings. There is a temptation to take your preferred function, ascertain its correlation, calculate the optimal multiplier of this function, subtract the explained element from the temperature record and say: “whatever is left is all that competing functions can explain”.

    As you say. No! If the candidate functions are correlated you simply cannot do that.

    For simplicity we can begin with just two competing functions A and B.

    If they are non-orthogonal, (their dot product is not zero), then one can proceed by constructing two new functions (A+B) and (A-B) which are orthogonal (where A and B are normalised i.e their mean = 0 and their variance = 1).

    Do this and the (A-B) vector discriminates between the relative contribution of A and B.

    Do the calculations and optimal values for the contributions of A and B emerge.

    If having done this the remaining unexplained variance is zero you can stop.

    If it is not zero the optimal values are not the absolute result. Other functions will have to be investigated and the are also likely not to be orthogonal to the original functions. New orthogonal functions will have to be generated, new dot products found, new calculations made and new optimal allocations amongst the candidate functions found.

    This has to continue until all residual variance is removed or a declaration of noise is made.

    To assume that a single function can be considered by itself is only valid if the residual variance is then zero or can confidently determined as noise.

    I hope that you agree and I have not made more or less of your comment than you intended.

    Best Wishes

    Alexander Harvey

  20. 120

    William Astley (#112) wrote:

    1) I unequivocally support conservation and responsible development. Please do not me names.

    If one refers to you as a “skeptic,” that is actually at worse a neutral term, and I suspect an inaccurate one. But it is generally what they prefer.

    William Astley (#112) wrote:

    2) There is evidence throughout the glacial periods and the last interglacial period of abrupt cooling, which is also climate change. Solar modulation of cloud cover and change in TSI would explain the past abrupt cooling. There are a number of papers that support the solar modulation of cloud hypothesis. I am interested in all scientific research concerning climate change not just GWG.

    Abrupt climate change resulting in drastic cooling?

    Local abrupt climate change. Bipolar seasaw. Greenland suddenly warms by ten degrees Celsius or more within a matter of decades while Antarctica undergoes somewhat slower warming. Heinrich events. Can’t be explained by solar variability per se since it has effects which are in opposite directions in the two hemispheres. It would appear to be due to change in the modality of the ocean where ocean circulation flips between two modes.

    The only way the models were able to get Greenland to warm like that was with bipolarity — and strong paleoclimate evidence shows that this is exactly what is happening. In essence, the models predicted the bipolarity, and that prediction was a success.

    Beyond such local events, what we see in the paleoclimate record on a global scale is sudden warming followed by a gradual cooling that takes about a hundred thousand years. Orbital variation is getting amplified by the albedo effect and the reduced capacity of the ocean to retain carbon dioxide. But the albedo effect wouldn’t explain the asymetry between sudden warming and gradual cooling. The role of carbon dioxide does given that it is only gradually reabsorbed and mineralized by the climate system.

    But this isn’t why we know that carbon dioxide plays such a role. The forcing due to carbon dioxide is the result of its spectral properties which are virtually derivable from first principles — quantum mechanics — and the distribution of carbon dioxide in the atmospheric column — which is well known. But the extent to which this gets amplified by various feedbacks in the climate system (roughly by a factor of three) is more uncertain — although now we have roughly half a million years of paleoclimate evidence (and other evidence) which puts it at about 3 Celsius per doubling.

    Thus for example, when one tries to make the climate system more sensitive to solar insulation by raising the climate sensitivity to forcing, one also makes it more sensitive to variation in levels of carbon dioxide. Not much that can be done there. Additionally even if one were to find some other mechanism, one would still be left with the problem of explaining why carbon dioxide does not have the effect upon the climate system that it does — given its spectral properties and distribution within the atmospheric column.

    William Astley (#112) wrote:

    3) Do you have any comments re: Palle’s earthshine data and analysis concerning planetary cloud cover. (see my comment 110.)

    I don’t know much about it as of yet, not enough to say its the typical shoddy science coming out of the skeptics corner.

    William Astley (#112) wrote:

    4) I thought the climate models have an acknowledged problem with modeling cloud cover. I do not understand your comment concerning Chinese menus and climate models. The two seem to be unrelated.

    Increased cloud cover raising the albedo with warming would be a negative feedback. Decreased cloud cover (where the cloud cover has its own greenhouse effect) with warming would be a negative feedback. But increased cloud cover with warming raising the cloud-associated greenhouse effect would be a positive feedback. Likewise, decreased cloud cover with warming lowering the albedo would be a positive feedback.

    The questions are: (a) which effect of clouds is stronger – the greenhouse effect or albedo effect?; and, (b) does warming increase or decrease cloud cover? And while Christy for example dances around the following issue, here it is: cloud cover is going to be a function of forcing, whether it is solar forcing or carbon dioxide forcing. So for those who would explain why carbon dioxide doesn’t have the effect that it does by means of negative feedback, the same thing will apply to forcing by solar insulation.

    Finally, with regard to the “Chinese menu” comment, it means essentially that there are multiple forcings and these will be amplified the essentially the same way by the climate system. And one does not get rid of the role of carbon dioxide simply by associating a greater climate sensitivity to solar variability. And at a more basic level, it means that we aren’t facing a choice between solar variablity models vs. enhanced greenhouse models. Both solar variability and the effects of greenhouse gases are a part of climate models, and they have been from the beginning.

    We explain the trend in twentieth century temperatures by means of both, although relative to 1880, for all but one year (1881), best estimates are that well-mixed greenhouse gases (mainly carbon dioxide, methane and nitrous oxide) have had a greater forcing than solar insulation. But the evidence suggests that now just carbon dioxide considered by itself (due to its accumulation in the atmosphere, with roughly 2 kilograms per square meter of anthropogenic carbon dioxide directly above your head) has had a greater forcing relative to 1880 than solar variaibility, and has since the late 1970s.

    As such, when you stated:

    It seems the solar modulation of planetary cloud cover has not been taken into account. i.e. The GWG calculations assume all of the 20th century warming is due to GWG?

    William Astley, 105

    … the second sentence indicates that you really do not know what you are talking about, and furthermore suggests that you have fallen for politically-motivated propaganda that is part of a concerted attack upon climate science. This might also help to explain why you didn’t know about the bipolarity of Heinrich events: the people that you have been listening to would appear to be cherry-picking the evidence, presenting only the evidence which tends to support their views and ignore the evidence which demonstrates that their arguments don’t hold water.

  21. 121
    tamino says:

    Re: #120 (Timothy Chase)

    Orbital variation is getting amplified by the albedo effect and the reduced capacity of the ocean to retain carbon dioxide. But the albedo effect wouldn’t explain the asymetry between sudden warming and gradual cooling.

    I was under the impression that the chief reason for the asymmetry in glacial cycles (deglaciation faster than glaciation) is that the accumulation of ice sheets is necessarily slow (one snowflake at a time) while wasting of ice sheets can happen much faster, including both mechanically (big chunks break off) and and thermodynamically.

    Who’s the resident ice age expert at RC?

  22. 122
    William Astley says:

    Hello Charles,

    In reply to your comment 112:
    “I don’t know if William …had in mind a strict 200 years cyclicity.”

    The solar Maunder like minimums do appear to follow a 200 year cycle. (Hence it is fairly easy to predict a Maunder Minimum, but difficult to predict the magnitude of each solar cycle. One is a chaotic process the other is due to a cyclic interruption.) The characteristics/features of the specific Maunder minimum appear to depend on chaotic processes or what state the sun has at the time of interruption. i.e. A Maunder minimum is a cycle interruption as opposed to a slow down. (See below for details.)

    The following is what I could find out concerning the solar magnetic field generation mechanism and what causes a Maunder minimum. Solar observations support Gene Parker’s hypothesis that the sunspot magnetic field is generated at the tacholine, the region of the sun where there is a change from the radiative zone to the convection zone. The magnetic fields generated at the tacholine rise through the convection zone to the solar surface, where they are removed by the solar magnetic cycle. A large sunspot has a measured magnetic field strength of around 3000 gauss, as compared to the earth’s magnetic field strength of 0.5 gauss. Theoretical calculations indicate that a magnetic field of up to 100,000 gauss can be generated at the tacholine.

    In the normal solar cycle the magnetic fields generated at the tacholine rise to the surface before reaching a 100,000 gauss. The past solar cycle is hypothesized to act as a seed for the next cycle. If the magnetic field generation at the tacholine is interrupted, the past solar cycle no longer interacts at the tacholine. Hence, solar models of the normal solar cycle which use features of the past solar cycle for normal solar cycle predictions are not useful to predict the length and severity of the deep solar magnetic minimum.

    This is one of a number of papers I found that predict a Maunder type minimum. Of course time will tell, however the Maunder minimums have in the past been cyclical.

    http://adsabs.harvard.edu/abs/2003SPD….34.0603S

    “Long-range (my comment: solar forecasts)….vary greatly in their methods. They range from examining planetary orbits, to spectral analyses ….to artificial intelligence methods, to simply using general statistical techniques. Rather than concentrate on statistical…. methods, we discuss a class of methods which appears to have a “physical basis.” Not only does it have a physical basis, but this basis is rooted in both “basic” physics (dynamo theory), but also solar physics … “

    “My colleagues and I have …expanded the prediction methods using “solar dynamo precursor” methods, …These methods are now based upon an understanding of the Sun’s dynamo processes- to explain a connection between how the Sun’s fields are generated and how the Sun broadcasts its future activity levels to Earth. This has led to better monitoring of the Sun’s dynamo fields and is leading to more accurate prediction techniques. Related to the Sun’s polar and toroidal magnetic fields, we explain how these methods work, past predictions, the current cycle, and predictions of future of solar activity levels for the next few solar cycles.”

    “The surprising result of these long-range predictions is a rapid decline in solar activity, starting with cycle #24. If this trend continues, we may see the Sun heading towards a “Maunder” type of solar activity minimum – an extensive period of reduced levels of solar activity. “

  23. 123
    nicola scafetta says:

    Rasmus,
    just a little reply.

    A) about the solar cycle. For “peak” I was intending the possible effect of the solar cycle length pattern on the TSI patter. To be more precise, the idea is that when the solar cycle length is small TSI is high, so the two things are neg-correlated. In your figure it is evident that during the 40s the solar cycle length was at a minimum, thus TSI (according this hyothesis) was at a maximum. I hope this helps.

    B) About ACRIM and PMOD: unfortunately, the story you know is quite confusing. It is not for arrogance but I have a direct knowledge of this issue because I regularly meet Willson of the ACRIM group and I have met Frolich and personally discussed with him and while he was discussing with Willson. My story is the correct one. PMOD alters the satellites data before 1980 and during the ACRIM gap. That is, they alter both ACRIM1 data and NIMBUS7 data. Willson says that Frolich has altered the ACRIM1 data without even contacting him and discussing the matter with him.

    During the ACRIM gap PMOD claims that they are using NIMBUS7 as you can see in their web-site, but indeed they are using an altered version of it to fit a proxy model.

    From 1978 to 1980 both Nimbus/7 and ACRIM1 show a decrease, PMOD alters both in such a way to make to appear that the TSI is increasing during that period. During the ACRIM gap (1988-1991) Nimbus7 shows an increase, PMOD alters it in such a way to obtain a decrease during the same period.

    This is a statement from Willson:
    **
    The PMOD composite was constructed to agree with the linear regression solar proxy model of Judith Lean and took considerable liberties with the satellite TSI database to accomplish it. Frohlich and lean modified the results of the Nimbus7/ERB and ACRIM1 experiments published by their science teams to agree better with Lean’s model. In the case of ACRIM1 this was in direct contradiction with the (published) satellite performance issues and observations and without any consultation with the science team.

    To construct a multi-decadal composite it is necessary to relate the ACRIM1 and ACRIM2 results across the two year gap between them. There are two choices to do this and they give quite different results. The highest quality ‘ACRIM gap’ comparative database is the Nimbus7/ERB which produces a TSI composite demonstrating significant upward trending during solar cycles 21 – 23, then a return to cycle 21 levels approaching cycle 24. The other ‘gap’ database, the ERBS/ERBE, clearly inferior to the Nimbus7/ERB in calibration, precision and sample rate, produces no significant TSI composite trend when used to bridge the ‘gap’.

    The difference between Nimbus7/ERB and ERBS/ERBE results during the ‘gap’ is caused by uncorrected degradation of the ERBS/ERBE sensors. Nevertheless Frohlich and Lean chose the ERBS/ERBE connection to relate the ACRIM experiments. The resulting PMOD composite shows no significant trend and agrees better with the predictions of Lean’s proxy model than if they had used the Nimbus7/ERB comparisons. This facilitates their conclusions about solar trending and climate change but does not represent the most objective use of the extant TSI satellite database.

    **

    Rasmus, note that PMOD uses ERBS/ERBE just to cross calibrate ACRIM1 and ACRIM2, not to fill the ACRIM gap, where they must use Nimbus7. The problem is that when ERBS/ERBE is used NIMBUS7 does not match with ACRIM1 and ACRIM2 anymore. Thus, PMOD has decided to solve the problem by altering NIMBUS7 data!

    Hoping that this helps you to update your story!

    To #115

    Charles, I believe you can find those data in internet, if not, email me. About the other solar reconstructions, according to the method I adopted in the paper they would give more or less the same result if you use the same temperature data. In fact I am assuming that the climate sensitivity to solar change is such that it fits the data during the preindustrial period. This means that if the trend in the TSI data is larger the sensitivity is smaller.

  24. 124
    tamino says:

    Re: #122 (William Astley)

    The prediction of Schatten & Tobiska to which you refer uses an entirely new prediction method which has never been tested. The track record of new prediction methods of solar activity is poor, to be generous. You say you found “a number of papers … that predict a Maunder type minimum.” There are vastly more papers which predict otherwise. For you to claim that we’re necessarily headed for another Maunder-like minimum (and it’s clear to everybody that’s your meaning) is nothing more than wishful thinking on your part.

    Your further statement that “The solar Maunder like minimums do appear to follow a 200 year cycle” is absolute rubbish. We’ve only seen one of them — two if you count the Dalton minimum as “Maunder-like” — and to conclude from this that they’re cyclic is the fantasy of an overactive imagination declaring as fact what you wish to be true. I have indeed studied the proxy data, which not only fail to support a genuine periodicity, they actually contradict it. As I said before, there may or may not be pseudoperiodic behavior on that time scale, but claims of genuine periodicity are contradicted by the available evidence.

    It’s seems that you simply won’t listen to reason on this matter.

  25. 125
    Ray Ladbury says:

    William, have you looked at Solanki’s paper on sunspot maxima and minima whose link was kindly provided by Timo? It looks pretty good and has some comments on whether there is any real periodicity in solar magnetic activity. He also points out that the minima/maxima have an interesting distribution of durations and amplitudes. I reproduce the link here:
    http://cc.oulu.fi/~usoskin/personal/aa7704-07.pdf

  26. 126
    Ken Rushton says:

    It’s “hold onto your parkas” time in Mid and Eastern Canada and the US midwest – the unfrozen, relatively warm patch of Arctic ocean seems to have encouraged a massive (larger than I’ve seen in 10+ years, anyway) influx of Pacific air, see here.

    If this plays out like it has in past years, this will act like a carooming billard ball, and knock a big cascade of polar air over those areas (the actual dynamics look a tad more complex; but its a good sound bite). Judging from the size of the “billard ball”, it’s going to be stronger (Eg. 2-3 times) than usual.

    Also see animated and this IR movie. It’s happened before, just not this strongly.

    Ken.

  27. 127

    Tamino (121) wrote:

    I was under the impression that the chief reason for the asymmetry in glacial cycles (deglaciation faster than glaciation) is that the accumulation of ice sheets is necessarily slow (one snowflake at a time) while wasting of ice sheets can happen much faster, including both mechanically (big chunks break off) and and thermodynamically.

    Actually I believe we are both right — and thank you for the reminder.

    The build-up of icesheets is a slow process, but so is the clearing of carbon dioxide from the atmosphere. Each are slow feedbacks that quite literally take tens of millenia to fully react to decreased forcing. Carbon dioxide on the order of 100,000 years (roughly the length between ice ages), and according to a paper by Hansen, at least in the case of Greenland’s icesheet, if it goes, it will take 30,000 years to be reform.

    And they are slow feedbacks to increased forcing (solar insolation due to the orbit of the earth, an impulse of anthropogenic greenhouse gases, the release of methane, Siberian supervolcanoes, etc.) but considerably faster than they are in the other direction. The $64,000.00 question is:

    How much faster?

  28. 128

    #125, This Jet stream was made after several North Pacific intense North Pole bound cyclones, surely influenced by the record thin ice Arctic Ocean. The air is of course warmer in a great chunk of the Arctic, especially over the thin ice.

    I am quite impressed with Rasmus patience, and also very pleased of Scaletta entering a debate. Although the acronyms used at times make it a difficult
    read.

    There is also an important point to make, when the majority of scientists say
    that solar activity has remained steady since 1950, the minority saying otherwise must show compelling data backing this up. Reading solar constant graphs, my favorite, SARR TSI since 1978, I can see what the majority are saying quite well

    http://science.nasa.gov/headlines/y2003/images/solcon/beat_lg.gif

    Direct reliable measurements show a remarkable cycle, when during the late 70′s the solar peaked while it was much cooler than recently. Same sun,
    but greater recent warming, someone needs to come up with a sensational explanation as to why Solar is responsible for 1998-2007 warming.

  29. 129

    Correction to 126

    I noticed there is a problem with what I said. The level of carbon dioxide will reach equilibrium only asymptotically. So after 100,000 years I believe you are talking about 5% being left. Slowest part of the process is mineralization.

    So where does this leave us? Well, the actual answer as to which drives the cycles would appear to be not so much a little of each, but… it depends…

    Ice-driven CO2 feedback on ice volume
    W. F. Ruddiman
    Clim. Past, 2, 43-55, 2006
    http://www.clim-past.net/2/43/2006/cp-2-43-2006.html

    … presumably. But prior to this paper at least, it was thought that ice took a back seat. Based on bubbles.

  30. 130

    Re: William Astley (#122)

    The high resolution Be-10 records, e.g. the work of Jurg Beer and colleagues at Dye-3, show unequivocally that the solar magnetic cycle continued during the Maunder minimum.

    Even in the absense of visible sunspots, there is a very obvious 11-year cycle in Be-10 production. This implies that the solar magnetic field continued its pattern of reversals uninterrupted. The relatively high flux of Be-10 implies that the intensity of the solar field was significantly reduced, but it was certainly neither absent nor static.

    Also, I would like to again state my agreement with tamino. Proxy records show a pattern of solar behavior that is episodic, but not periodic. The apparent pattern of ~200 year cycles in major minimum is not a persistent long-term feature of the data and so should not be used to draw any sort of a strong conclusion about the future.

  31. 131
    Aaron Lewis says:

    Re 125
    NEAT! However, looking at surface sea temps ( http://www.osdpd.noaa.gov/PSB/EPS/SST/contour.html ) and the brightness temperature of various levels of the atmosphere (http://pm-esip.msfc.nasa.gov/amsu/index.phtml?12 ) it is hard to believe that a patch of Arctic water could trigger the northward movement of so much warm, moist air. Perhaps other factors also contribute?

  32. 132
    Charles Muller says:

    #127
    Wayne : Same sun, but greater recent warming, someone needs to come up with a sensational explanation as to why Solar is responsible for 1998-2007 warming.

    For the moment, we need to explain the 1977-2001 warming. Because there’s no trend on surface or low troposphere for 2001-2007 (according to HadCru, RSS and UAH). (2001-2007 are of course warmer than 1996-1990 mean, 0,4 K approx., but nothing like a global acceleration of surface warming for these most recent years)

    Cycles 21 and 22 were very similar (unfortunately for solar researchers). It seems cycle 23 has been quite different and we may hope cycle 24 will be even more, so as to better observe and understand the physics of cyclic variations. The ideal situation (for the present debate) would be of course a very quiet cycle 24.

  33. 133
    Alexander Harvey says:

    rasmus, your:

    “This is probably because the relaxation time response has been increased between the two panels and is greater than 10 in the lower panel. The presence of a trend should not affect the amplitude of the higher frequency in such a simple linear system (see my reproduction above).”

    Spot on! It has been increased by two thirds from 10 to ~16.7

    I suspect this is a genuine mistake as if it had been left at 10 the secular trend reaches 80% of final value by t=50 as indicated in the text whereas the graph has it at only 70% leaving 30% of the warming to occur in the t > 50 period not 20% as stated.

    Even if a mistake it is misleading and … it is a mistake that had to wait for you to pick it up.

    Best Wishes

    Alexander Harvey

  34. 134

    Charles Muller (#131) wrote:

    For the moment, we need to explain the 1977-2001 warming. Because there’s no trend on surface or low troposphere for 2001-2007 (according to HadCru, RSS and UAH). (2001-2007 are of course warmer than 1996-1990 mean, 0,4 K approx., but nothing like a global acceleration of surface warming for these most recent years)

    I myself have three questions.

    First, why do you consider six years to constitute a trend? Typically, given the internal variability due to Southern Oscillation, the North Atlantic Oscillation and Pacific Decadal Oscillation, etc. a climatologist would require in the neighborhood of at least 15 years before they would consider it a trend.

    Second, would you consider the three years or so to constitute a trend? Looking at the temperature records for all these indicies, I see a “flat trend” of two or three years between 1980 and 1985. In fact, I see a cooling “trend” of perhaps a couple of years.

    Third, why do you dismiss the role of carbon dioxide that the vast majority of climatologists regard as being responsible for the trend from 1979-2001, or for that matter, the role of anthropogenic greenhouse gases from 1882 to the present day?

    Come to think of it, the last of these brings to mind a few more questions.

    Do you believe that it doesn’t absorb infrared radiation? Do you believe that it doesn’t emit backradiation? Do you believe that rising levels of carbon dioxide have no effect upon the atmosphere’s opacity to infrared radiation?

    Do you believe that climatologists are mistaken with respect to the distribution of carbon dioxide in the atmospheric column? Or do you believe that levels of carbon dioxide haven’t been rising throughout the 20th Century?

    Are what climatologists would normally regard as facts simply dismissed when you find them unpalatable?

  35. 135

    #131, Charles, this apparent +0.4 K has made remarkable transformations in the Arctic. Temperature increase in the Northern Hemisphere’s polar region was much more stronger, not explained by very reliable solar measurements, nor by any oscillation which have occurred many times in the past without giving the same results. What was observed was a gradual consistent heat boost despite oscillations, especially the Arctic Oscillation. From reliable solar constant measurements
    we can clearly see that the sun had not contributed extra heat as measured on the ground and in the atmosphere, what is left can be explained by a change in atmospheric chemistry though. For the solar causation guys, the question to ask: where is the extra heat coming from between 1977-2007?

  36. 136
    Jim Galasyn says:

    Re solar periodicities in 123, it’s widely understood that the sun’s dynamics are accurately described by a dynamo. It’s well known that dynamos typically exhibit nonlinear “chaotic” oscillations, as well as quasi-periodic oscillations. Whether the sun’s dynamics are currently in a quasi-periodic or chaotic regime is debatable, but for my money, I’d bet on chaotic oscillations.

  37. 137
    Steve Reynolds says:

    rasmus> Not much scientific reasoning there. No documentation no proof. Just childish statements taken out of the air. ClimateAudit publishes statements such as ‘[people at] RealClimate are not scientists at all. They are priests of a mystery cult.’.

    I did a search to find the statement that you quote. It appears to be from an ordinary commenter, not someone affiliated with the site.

    Would you want RC to be judged by the worst comments that you let through?

    [Response: Yes. Moderation of comment threads to remove namecalling and innuendo is part of what keeps serious conversation going. Similar comments here have been, and will continue to be, rejected. - gavin]

  38. 138
    Charles Muller says:

    Timothy

    First, why do you consider six years to constitute a trend? Typically, given the internal variability due to Southern Oscillation, the North Atlantic Oscillation and Pacific Decadal Oscillation, etc. a climatologist would require in the neighborhood of at least 15 years before they would consider it a trend.

    Seven years rather than six, Hadley Center have announced 2007 would be the sixth warmest year, similar to 2006. I agree with you, 7 yrs does NOT constitute a significative trend (and 30 yrs is better than 15 yrs for that purpose). The same is true for many other domains (five years of GRACE measure on Greenland, for example, usually presented as an alarming trend in ice meting, but you will agree with me that such a short measure is not very significative)

    But here, I was answering to Wayne 127, that is correlation or anticorrelation between Ts and Fs for 1998-2007 (he chose this period). So, I just precised the absence of recent trend, after 2001. As cycle 23 was weaker than two previous one, recent years are not a good argument for an insensitivity to solar variations, rather the opposite.

    You’re right for intrinsic variability. I suspect the huge warming of 1977-2006 period to be in part due to such a variability, not very well constrained by models presently.

    A question for you : if there’s no more trend on surface temperature for 2001-2010, would you consider that as significant ? Or more precisely, how many years of Ts stagnation would be necessary to revise our evaluation of transient climate response to CO2 forcing ?

    Second, would you consider the three years or so to constitute a trend? Looking at the temperature records for all these indicies, I see a “flat trend” of two or three years between 1980 and 1985. In fact, I see a cooling “trend” of perhaps a couple of years.

    No, of course.

    Third, why do you dismiss the role of carbon dioxide that the vast majority of climatologists regard as being responsible for the trend from 1979-2001, or for that matter, the role of anthropogenic greenhouse gases from 1882 to the present day?

    The role of CO2 in warming, no, there’s no physical reason to dismiss it. But attribution-detection of this warming, yes. In fact, I don’t dismiss it, I simply consider there are still too much uncertainties in models (eg aerosol, clouds, etc.), too noisy signals in climatologies, too low level of understanding of different forcings (including solar one we discuss here) for giving a great confidence to AD exercise, so to CO2 role in surface trends. I’m quite sure modern GW is in part anthropic, but I wouldn’t bet on a 40, 60, 80%… responsability of GHGs forcing.

    Do you believe that it doesn’t absorb infrared radiation? Do you believe that it doesn’t emit backradiation? Do you believe that rising levels of carbon dioxide have no effect upon the atmosphere’s opacity to infrared radiation?

    No, no, no… :D We all know that CO2 forcing in itself have a weak effect on Ts, approx 1 K for 2xCO2 or 3,7 W/m2 (IPCC AR4 best estimates). The problem is not IR absorption-emission, rather correct evaluation of water vapor and clouds feedbacks to an IR forcing.

    As Lindzen, I observe that the present 85% of CO2 doubling gave a 0,76 K response in Ts ; but contrary to Lindzen, we should recall it’s a climate transient response, not an equilibirum state. But even for CTR, a 85% of 2xCO2 would give a 1,0 – 2,2 K Ts response in the 20 IPCC models (see table 8.2), so we’re still far from that (and far more if solar forcing play a non negligible role in the 0,76 K observed trend). Fortunately, we could always fill the gap with aerosols…

  39. 139
    Ray Ladbury says:

    The discussion with William Astley on heliomagnetic activity as a contributor to climate has brought up the ideas of periodicity and quasi-periodicity. At the risk of gross oversimplification, I’ll look at what we mean by these terms:
    Periodicity occurs for states that are stable ans oscillate about some equilibrium position. We don’t expect either the geodynamo or heliodynamo to be truly periodic, since they have 2 metastable states with roughly equal energies–the dipiles pointing to either pole. Because the dipole state are energetically favorable, it takes energy–a fluctuation of the energy in the heliodynamo–to push it out of one state. The fluctuations happen continually, but large fluctuations are rarer. Because the expected time between fluctuations of a given size has some expected value, the heliodynamo will exhibit a quasi-periodicity about this mean. Once the dipole decays, you get a period of instability with energy going into the higher multipoles until the system stabilizes back in one of the energetically favorable dipole states. The geodynamo behaves similarly, albeit with a much longer period due to the relatively slow circulation of the outer core liquid iron and the impedance provided by the solid inner core.
    So it is a mistake to expect one solar cycle to look like the last, or one “Magnetic Minimum” to behave similarly. We expect a distribution of magnitudes and “periodicities”. So I think Usoskin and Solanki are on the right track.

  40. 140
    Steve Reynolds says:

    gavin> Yes. Moderation of comment threads to remove namecalling and innuendo is part of what keeps serious conversation going. Similar comments here have been, and will continue to be, rejected.

    post 18> Odds are they’re being rewarded for their tireless contributions somehow, along with the editors of the crappy journals where their discharges are deposited.

    It looks to me like there is ‘namecalling and innuendo’ right here in this thread.

    raypierre even appears to continue the innuendo in his response.

    [Response: Thanks for bringing that to my attention. It's been edited. We don't catch everything, but feel free to email if you think comments have strayed. - gavin]

  41. 141
    Ray Ladbury says:

    Ain’t it funny how you have brilliant insights just as you hit the post button. An analogy that may help (and yes, it is an analogy only):
    We’re all familiar with the concept of a 100-year flood. The fact that such events occur ROUGHLY every 100 years does not cause anyone to suggest that weather is periodic. It is just that the conditions necessary for such an extreme event only come into being ROUGHLY every 100 years. Extreme events tend to follow a Poisson distribution and vary about the Poisson mean.

    This is one reason why having a physical understanding of the processes in your system is critical–it keeps you from making mistakes in characterizing its dynamical behavior.

  42. 142

    Charles Muller (#137) wrote:

    Seven years rather than six, Hadley Center have announced 2007 would be the sixth warmest year, similar to 2006.

    Well if you accept the short-term predictions of the Hadley Center, then I suppose you know what is in store for next year and the following decade. I on the otherhand wasn’t counting 2007 since we still have a month or so left.

    I agree with you, 7 yrs does NOT constitute a significative trend (and 30 yrs is better than 15 yrs for that purpose).

    Not for temperatures – given the oceanic oscillations.

    The same is true for many other domains (five years of GRACE measure on Greenland, for example, usually presented as an alarming trend in ice meting, but you will agree with me that such a short measure is not very significative)

    There I would have to disagree — unless you have reason to believe that the doubling of the rate of glacial water discharge or the tripling of glacial quakes in a decade is unrelated to the past decade being the warmest in well over a century’s time. I assume you believe that heat melts ice?

    But here, I was answering to Wayne 127, that is correlation or anticorrelation between Ts and Fs for 1998-2007 (he chose this period). So, I just precised the absence of recent trend, after 2001.

    By choosing so short a period, he was actually being generous.

    You’re right for intrinsic variability. I suspect the huge warming of 1977-2006 period to be in part due to such a variability, not very well constrained by models presently.

    Internal variability helps in the case of 1998 — a particularly strong El Nino in that year. But it would not seem to help with 2005 — which was a cool solar year. But in any case, Hadley seems to believe that they are getting a better handle on internal variability — now that they are specifically taking it into account.

    A question for you : if there’s no more trend on surface temperature for 2001-2010, would you consider that as significant ?

    I would consider the laws of physics more significant. Given the models, there might be a 5-10% chance of surface temperatures being flat for a decade. But I would have to give up Aristotle for Descartes to worry about the former.

    Or more precisely, how many years of Ts stagnation would be necessary to revise our evaluation of transient climate response to CO2 forcing?

    Well, if you are speaking of the transient climate response to CO2 forcing, I suppose about the same as an equal forcing due to solar insulation.

    The role of CO2 in warming, no, there’s no physical reason to dismiss it. But attribution-detection of this warming, yes. In fact, I don’t dismiss it, I simply consider there are still too much uncertainties in models (eg aerosol, clouds, etc.), too noisy signals in climatologies, too low level of understanding of different forcings (including solar one we discuss here) for giving a great confidence to AD exercise, so to CO2 role in surface trends. I’m quite sure modern GW is in part anthropic, but I wouldn’t bet on a 40, 60, 80%… responsability of GHGs forcing.

    Some forcings are more uncertain than others. The forcing due to greenhouse gases is well understood. The forcing due to solar insulation is well understood. Forcings due to aerosols and feedbacks due to clouds are less well understood — but our understanding is improving. So is our understanding of climate sensitivity to forcing.

    We all know that CO2 forcing in itself have a weak effect on Ts, approx 1 K for 2xCO2

    I believe that is 1.2 K. Which leaves perhaps 1.7 K to be explained in terms of feedback.

    … or 3,7 W/m2 (IPCC AR4 best estimates). The problem is not IR absorption-emission, rather correct evaluation of water vapor and clouds feedbacks to an IR forcing.

    This would seem to apply equally to solar insulation.

    As Lindzen, I observe that the present 85% of CO2 doubling gave a 0,76 K response in Ts ; but contrary to Lindzen, we should recall it’s a climate transient response, not an equilibirum state.

    Such honesty is genuinely appreciated.

    But even for CTR, a 85% of 2xCO2 would give a 1,0 – 2,2 K Ts response in the 20 IPCC models (see table 8.2), so we’re still far from that…

    We aren’t that close to a doubling of CO2 either. 378 ppm vs. 560.

    (and far more if solar forcing play a non negligible role in the 0,76 K observed trend).

    Forcing due to solar insulation has no effect upon our estimates of forcing due to CO2 — the latter is simply a matter of physics, not some sort of statistical residual.

    Fortunately, we could always fill the gap with aerosols…

    Not if they are flat, like solar insulation since 1950. But I believe we were discussing electron-scavenging solar winds and geomagnetic fields — and I do find Rube Goldberg devices amusing. :-)

  43. 143
    Charles Muller says:

    Timothy #141

    The forcing due to solar insulation is well understood
    Precisely not. IPCC AR4 still attributes a “low level of scientific understanding” (even lower than aerosols).

    We aren’t that close to a doubling of CO2 either. 378 ppm vs. 560.
    The addition of anthropogenic forcing (in the IPCC AR4) 1750-present give a 3,17W/m2 forcing, so 85% of 3,7W/m2 (TOA).

    Forcing due to solar insulation has no effect upon our estimates of forcing due to CO2
    Of course. But I guess the problem lies with sensitivity rather than forcing. If there are indirect effects of solar forcing (because of UV spectral forcing and strato-tropo-ocean coupling, or because of GCR and nebulosity, or anything else), this would mean that AOGCMs uncorrectly simulate modern GW (or paleoclimates). And uncorrectly project for 2100. The more you attribute to solar factor for 1750-present warming, the less climate is supposed to be sensitive to GHGs factor (imagine, quite absurdly, that just 10% of the modern warming is due to GHGs ; it would be difficult to maintain an equilibrium sensitivity of 0,75 K/W/m2 for 2xCO2 ; the same is true, less absurdly, if GHGs account for 50% rather than 80% of modern warming).

    So in my opinion, if S&W are OK, it would imply that modern climate has not the same sentivity to 1 W/m2 TSI forcing and to 1 W/m2 CO2 forcing. Models presently conclude to the opposite. But if models do not correctly implement all the physical effects of total / spectral solar forcing, their conclusions are precisely not valid. We are stil far from that, because there is no decisive (physical) demonstration of indirect solar effects on climate.

  44. 144
    Charles Muller says:

    (#142 Precision in my previous post : the sum of positive anthropogenic forcing give 3,17W/m2. Of course, aerosols are supposed to mask the “real” transient response).

  45. 145
    Ray Ladbury says:

    Again, Charles, you are viewing climate like a Chinese restaurant menu, which, unfortunately, it is not. Forcing due to CO2 is one of the better understood aspects of the models. So if some other forcer pops its head up, it is unlikely CO2 forcing that would change in our understanding of climate, but rather some other, more uncertain forcing, such as aerosols, clouds, etc. This means that aerosols or other factors could be masking the full extent of CO2 forcing. The thing is that most other forcers actually act for relatively short times–aerosols for months, water vapor for days, CH4 for ~10 yrs. CO2 keeps on giving for thousands of years. During that period TSI will wax and wane. We will have periods of volcanism and quiescence. Forests will grow and die. Through it all, the CO2 we add will keep things just a wee bit warmer than they would otherwise be. That, of course presumes that the positive feedbacks do not kick things up a notch.
    If you manage to show the models are wrong, it is very likely that the new models show even more warming than the current batch. The uncertainties are skewed toward greater warming.

  46. 146
    William Astley says:

    In reply to Ray Ladbury’s comment:

    “William, have you looked at Solanki’s paper on sunspot maxima and minima whose link was kindly provided by Timo?… I reproduce the link here:”

    http://cc.oulu.fi/~usoskin/personal/aa7704-07.pdf

    Thanks Ray. This paper provides an overview of the solar maximum and minimum over the last 11,000 years. I have heard that the 20th century level of solar activity is the highest in 11,000 years. Usoskin, Solanki, and Kovaltsov’s paper puts that in perspective. (See figure 3 in the above linked paper.) This paper finds no repeated periodicity of “Maunder Minimums” except for the 2000 year cycle. (P.S. I support Tamino’s comment that solar periodicity can not be used to predict that cycle 24 will be a minimum.)

    Based on the Usoskin et al’s data and definition, in the last 11,000 years the sun has had 27 grand minimums which lasted from 20 to 160 years. The sun has spent 1880 years in grand minimum, 16.8% of the 11,000 year period.

    The sun in currently in a grand maximum, which Solanski’s defines as a smoothed sunspot number (see paper for details) greater than 50. According to the authors, the sun has had 19 great maximum in the 11,000 years and has spent 1000 years or 9% of the 11,000 year in grand maximum.

    In reply to Robert Rohde’s comment:

    “The high resolution Be-10 records, e.g. the work of Jurg Beer and colleagues at Dye-3, show unequivocally that the solar magnetic cycle continued during the Maunder minimum.”

    Yes. It will be interesting to see what is happening in a “Maunder Mininum”, if a cycle can be observed with modern instruments. I would expect there are minimums and deep minimums.

    In reply to Charles Muller:

    The following is a detailed explanation of Georgieva and Kirov’s, reasoning as to why to use the ak parameter as opposed to aa. The parameter ak, I believe measures significant change in the geomagnetic field which correlates with the solar wind strength. (i.e. The geomagnetic field is reacting to the solar wind.)

    http://arxiv.org/pdf/physics/0703187

    “Since the beginning of the 20th century, the correlation in the 11-year solar cycle between the sunspot number and geomagnetic aa-index has been decreasing, while the lag between the two has been increasing. We show how this can be used as a proxy for the Sun’s meridional circulation, and investigate the long-term changes in the meridional circulation and their role for solar activity and terrestrial climate.”

  47. 147

    I had written in 141:

    Some forcings are more uncertain than others. The forcing due to greenhouse gases is well understood. The forcing due to solar insulation is well understood. Forcings due to aerosols and feedbacks due to clouds are less well understood — but our understanding is improving. So is our understanding of climate sensitivity to forcing.

    In 142 Charles Muller responds:

    Precisely not. IPCC AR4 still attributes a “low level of scientific understanding” (even lower than aerosols).

    Judging from:

    FAQ 2.1, Figure 2. Summary of the principal components of the radiative forcing of climate change
    Chapter 2: Changes in Atmospheric Constituents and in Radiative Forcing
    Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, pg 136
    http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/AR4_WG1_ch02.pdf

    … it would appear that the range of uncertainty ascribed by the IPCC to forcing by solar insulation/irradiance relative to 1750 (or roughly the start of the industrial age) is actually smaller than that ascribed to any other factor — save stratospheric ozone and stratospheric water vapor. That is, unless you are thinking in terms of percentages. It is afterall a rather small forcing. Compared to other positive forcings, their estimate would seem to be just after stratospheric water vapor and black carbon on snow — the smallest of the positive forcings. And it would appear that tropospheric ozone plays a far greater role.

    *

    I had written in 141:

    Forcing due to solar insulation has no effect upon our estimates of forcing due to CO2 — the latter is simply a matter of physics, not some sort of statistical residual.

    In 142 Charles Muller responds:

    Of course. But I guess the problem lies with sensitivity rather than forcing. If there are indirect effects of solar forcing (because of UV spectral forcing and strato-tropo-ocean coupling, or because of GCR and nebulosity, or anything else), this would mean that AOGCMs uncorrectly simulate modern GW (or paleoclimates).

    You do like to throw a great many things together. Reminds me of a stew. Not much for clarity. However, given what I have just cited, “UV spectral forcing” wouldn’t seem to be the cause of much uncertainty.

    “strato-tropo-ocean” coupling? Now you seem to be tying yourself in knots. “GCR and nebulosity” ? Galactic Cosmic Rays?– not much of a trend there, I’m afraid. Nebulosity?– I believe you might have to clarify a bit here. “… or anything else” – nice escape clause. Sounds like the refuge of a radical skeptic: since we don’t know everything, we can’t claim to know anything. “… this would mean that AOGCMs uncorrectly simulate modern GW (or paleoclimates).” They seem to be doing rather well at simulating both, although there are still some details to work out.

    In any case, it helps to make distinctions — particularly when they involve different causal mechanisms. That is, assuming you prefer clarity over confusion.

    *

    In 142 Charles Muller states:

    The more you attribute to solar factor for 1750-present warming, the less climate is supposed to be sensitive to GHGs factor (imagine, quite absurdly, that just 10% of the modern warming is due to GHGs ; it would be difficult to maintain an equilibrium sensitivity of 0,75 K/W/m2 for 2xCO2 ; the same is true, less absurdly, if GHGs account for 50% rather than 80% of modern warming).

    And uncorrectly project for 2100. The more you attribute to solar factor for 1750-present warming, the less climate is supposed to be sensitive to GHGs factor (imagine, quite absurdly, that just 10% of the modern warming is due to GHGs ; it would be difficult to maintain an equilibrium sensitivity of 0,75 K/W/m2 for 2xCO2 ; the same is true, less absurdly, if GHGs account for 50% rather than 80% of modern warming).

    As I stated in 141:

    Forcing due to solar insulation has no effect upon our estimates of forcing due to CO2 — the latter is simply a matter of physics, not some sort of statistical residual.

    The forcing due to carbon dioxide and the forcing due to solar insulation are independently known. Comes down to physics. Up to this point at least you have agreed. Climate sensitivity to carbon dioxide? Given the past 460,000 years of paleoclimate records, I believe that is around 2.9 K per doubling.

    Of course if you have anything else of interest to you — at least regarding climatology — feel free to bring it up.

  48. 148

    PS

    In my last post, I had written:

    The forcing due to carbon dioxide and the forcing due to solar insulation are independently known. Comes down to physics. Up to this point at least you have agreed.

    This included a link — to an anchor. Unfortunately the anchor was stripped out.

    But what I was linking to was where I had stated:

    Forcing due to solar insulation has no effect upon our estimates of forcing due to CO2 — the latter is simply a matter of physics, not some sort of statistical residual.

    … and Charles Muller had responded:

    Of course. But I guess the problem lies with sensitivity rather than forcing.

    It’s a pity: anchors would have been one more way to keep things in context.

  49. 149

    Charles: “But if models do not correctly implement all the physical effects of total / spectral solar forcing” . Care to elaborate? Are TSI’s incomplete?

  50. 150
    Timothy Chase says:

    William Astley (#145) wrote:

    In reply to Charles Muller:

    The following is a detailed explanation of Georgieva and Kirov’s, reasoning as to why to use the ak parameter as opposed to aa. The parameter ak, I believe measures significant change in the geomagnetic field which correlates with the solar wind strength. (i.e. The geomagnetic field is reacting to the solar wind.)

    http://arxiv.org/pdf/physics/0703187

    Good. Perhaps it will help me with an issue that I found earlier.

    Previously you (#105) wrote:

    This paper shows that the solar changes which modulate cloud cover correlate with the observed 20 th century temperature changes for the entire period in question.

    [Once again about global warming and solar activity
    K. Georgieva, C. Bianchi and B. Kirov, unpublished? not peer reviewed? - 2005]
    http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76..969G.pdf

    “We show that the index commonly used for quantifying long-term changes in solar activity, the sunspot number, accounts for only one part of solar activity and using this index leads to the underestimation of the role of solar activity in the global warming in the recent decades. A more suitable index is the geomagnetic activity which reflects all solar activity, and it is highly correlated to global temperature variations in the whole period for which we have data.”

    In Figure 6 the long-term variations in global temperature are compared to the long-term variations in geomagnetic activity as expressed by the ak-index (Nevanlinna and Kataja 2003). The correlation between the two quantities is 0.85 with p

    Rasmus responded inline in part: “Response: I’m a bit skeptical to the figures in that paper – how are the curves smoothed? (they remind me a bit of the work of Svensmark, Friis-Christensen & Lassen).”

    The smoothing is cause for concern, but I believe the following may be closer to the mark: “It’s also typical – when one index doesn’t work, a new one is thrown in.”

    I looked up the Ak index:

    Ak index. A daily index of geomagnetic activity for a specific station or network of stations (represented generically here by k) derived as the average of the eight 3-hourly ak indexes in a Universal Time day.

    Collection of Geomagnetic indices and like
    Väinö K. Lehtoranta 16.11.1997
    http://www.sci.fi/~fmbb/astro/indices.htm

    Is this what they mean by the Ak index?

    I haven’t had any luck finding anything else by this name associated with geomagnetic activity. But if so, what specific station or network of stations are they using? Given a large enough number of stations, one could easily select just those stations that would let you fit just about any curve you might wish — including the Dow Jones.

    But now looking at the paper you have just referenced:

    To extend the data record back by two more cycles, we use ak-index of geomagnetic activity, analogous to aa-index but derived from only one observatory (Helsinki) and highly correlated to aa-index in the period when the two overlap (Nevanlinna and Kataja, 1993). The mean annual values of ak are available online at (http://www.ava.fmi.fi/MAGN/K-index/ak-aa_index).

    The long-term changes in solar meridional circulation as the cause for the long-term changes in the correlation between solar and geomagnetic activity
    K.Georgieva and B.Kirov
    (unpublished? not peer reviewed? – 2006), pg. 7
    http://arxiv.org/ftp/physics/papers/0703/0703187.pdf

    Selecting one station is a better. Reduces the number of combinations. Helsinki might also make some sense in terms of their theory since it is farther north.

    But lets look at the description of the series itself:

    The files Hels_D_K1844-80_06 and Hels_H_K1844-97_05 contain geomagnetic activity indices derived from observations carried out in the Helsinki magnetic observatory. The first file is based on observations of the declination (D) from July 1, 1844 to June 30, 1880. The second file is based on the horizontal component (H) valid from July 1, 1844 to May 31, 1897. There are several gaps in the data series. Both files contain eight 3-hour K-values for each day and the daily activity index Ak. The first K-value in each row corresponds to the interval 0…3 in UT.

    http://www.ava.fmi.fi/MAGN/K-index/readme.html

    Still sounds like curve-fitting. At least two curves — with “several gaps.”

    PS

    Thank you for bringing us back (or at least closer) to the topic of the post.


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