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Why the continued interest?

Filed under: — rasmus @ 9 October 2009

I believe the idea that galactic cosmic rays (GCR) play a role for the present global warming is unlikely to fade soon, despite a growing number of scientific arguments that normally would falsify a hypothesis and lay it dead (see links here and here). Despite all the arguments against the role of GCR, there was a solicited talk about ‘cosmoclimatology’ at the European Meteorological Society’s (EMS) annual meeting in Toulouse. Henrik Svensmark is further invited by the Norwegian Academy of Science and Letters (NASL) to provide an introduction to their seminar on climate. So why is the GCR-hypothesis still perceived as an interesting explanation?

My impression from the solicited talk, is that the confidence in the GCR hypothesis now rests on two points that were made explicit in the presentation, and that we have not adequately addressed here. So, here they are:

Point I: When I asked Svensmark why he presented a curve describing low cloud-cover from the ISCCP – used for correlation study with GCR (link) – that differed from the curves presented at the ISCCP web site (link), he informed me that he used a corrected version that has been published. Nevertheless, the ‘correction’ of the curve is controversial, and the ISCCP team is clearly not convinced, despite the likelihood of instrumental degradation.

Good practice would then be to present all the curves that cannot be ruled out because of errors. When asked why he didn’t present the other cures too, he said that he only wanted to show the one curve. Not a very convincing answer, and not very reassuring.

Point II involves a ‘remarkable’ correlation, meant to demonstrate a link between high GCR flux and cold conditions. This analysis is based on a comparison between band-pass filtered ice-rafted debris from iceberg drifts (Bond, 2001) and Carbon-14 (a cosmogenic isotope) over the last 12,000 years (e.g. after the most recent ice age).

The relationship between temperature and drifting icebergs, however, is complicated and not so straight forward. Icebergs are formed when chunks of ice break off glaciers and icesheets – a process known as ‘calving’.

On the one hand, icesheets and glaciers grow when the accumulation of precipitation at below freezing temperatures (snow) exceeds the summertime melting. Very low temperatures, tend to be associated with low precipitation, however. One the other hand, iceberg calving does not require very low temperatures (as long as the ice is present), but is favoured by reduced friction at the base of ice caps, resulting in a faster flow towards the sea. Melt water can lubricate the ice sheets and hence affect the ice flow.

Once the icesheets have calved and produced icebergs, they will drift according to the winds and ocean currents. The most influential ocean currents for iceberg drift in the North Atlantic include the East Greenland Current EGC), which follows the east coast of Greenland and flows from northeast to southwest, the West Greenland current (WGC) into the Labrador Sea, and the Labrador current (LC), a coastal current following along the perimeter of the Labrador sea basin in an anti-clockwise fashion.

North Atlantic ocean current systems Many of the cores used to study the ice-rafted debris were from locations away from these currents. It is not clear whether anomalous cold conditions produced more southerly winds and ocean currents. However, many of the core locations are associated with a surface flow from the south in the present climate, so it is possible that the icebergs transported by the EGC, WGC, and LC end up in the North Atlantic current. One explanation is that the icebergs got caught in the warm currents from the south, and melted on their way north, but that does not necessary imply cold conditions in that region, as these warm ocean currents provide a heat transport and the melting of icebergs suggest higher temperatures.

Cold conditions favour the formation of sea-ice, which have very different characteristics to icebergs. Sea-ice forms when the sea surface freezes, and can affect the ocean circulation through their effect on salinity. However, sea-ice does not create debris of rocks and minerals, as the icebergs do when the bottom of the sliding icesheets scrape the rocks.

It is plausible that very cold conditions can produce thick sea-ice that will lock icebergs in place near their sources in the Labrador sea and along the east coast of Greenland, but seasonal variations in the sea-ice may also imply open water in the summer. Nevertheless, very cold conditions may not necessarily favour the production of icebergs, as freezing temperatures will prevent the formation of melt water acting as lubrication and the accumulation of ice is expected to be less due to lower precipitation.

In summary, the ‘remarkable’ correlation does not seem to support the hypothesis that high flux of GCR produces a very cold climate. The question is rather whether the ocean and atmospheric circulation were influenced by the level of solar activity and associated changes in the total solar irradiation (TSI) – without involving GCR. After all, GCR is affected by the level of solar activity through its influence of the inter-planetary magnetic field, and anti-correlated with the sunspots.

When taken in the context of the global warming, there are other problematic issues such as the lack of trend in GCR (here and here), stronger warming during nighttime than daytime, large unknowns regarding the physical mechanisms involved in the growth of ultra-small molecule clusters to much larger cloud condensation nuclei (here and here), and questionable data handling and statistical analysis (here). In addition, it is difficult to statistically distinguish between the apparent response to solar forcing in the observations and GCM which do not take GCRs into account (link to a recent paper by Gavin and myself), implying that GCRs are not needed to explain past global temperature trends.

So what makes the GCR-hypothesis so convincing that warrants a solicited talk at the EMS annual meeting and an invited presentation at the NASL? Is the support based on the attention in media, or does it have a scientific basis?

I want a response from the community still supporting the GCR hypothesis, explaining why they find it convincing after all these misgivings. The spirit of science is about discussing different ideas and challenge unconvincing points of view. So far, I feel that many of these issues have gone unheeded outside the climate research community. Perhaps an improved dialogue between various research communities can help resolving these issues – the counter-arguments and GCR hypothesis represent a paradox that should be sorted out if the science is to progress. Either the supporters of the GCR hypothesis should convincingly explain why these misgivings are unfounded or irrelevant, or the GCR hypothesis should be buried. However, I feel that there is a lack of dialogue and willingness to listen, so I think that progress is not likely to happen regarding a commonly accepted solution on the GCR hypothesis.

Update: According to a recent (October 16) news relsease from the International Ice Charting Working Group (IICWG), over 1,200 icebergs drifted into the trans-Atlantic shipping lanes in 2009, making the iceberg season in the North Atlantic the eleventh most severe since the tragic loss of the RMS Titanic in 1912.

P.S. So far in 2009, three articles have been published in the arXhive on GCR and clouds (here, here, here). It is possible that such articles are more accessible to communities other than climate research, and hence enhances the awareness about the controversy surrounding the GCR-hypothesis.

506 Responses to “Why the continued interest?”

  1. 51


    And do we have any real handle on what changing the amount of UV might do to the climate?

    Yes, we can run it through a climate model.

    There is little effect on most of the climate system since pretty much all the far-UV (7% of TSI) gets absorbed by oxygen and ozone in the ozone layer. Not no effect, but not enough for UV variation to matter very much.

  2. 52
    Bengt A says:

    Svensmarks latest paper isn’t about GCR versus CO2. It’s not about global cooling or warming. It’s about GCRs impact on earths atmosphere. My understanding of this is as follows:

    The proposed mechanism (for a Forbush decrease) is that a sudden increased strength of the Interplanetary Magnetic Field (IMF) shields cosmic rays (GCR) from entering earths atmosphere. The reduced amount of GCR causes a reduction in the production of ultrafine aerosols (1). The missing aerosols would eventually have grown into Cloud Condensation Nucleis (CCN), thus in a few days time the reduction of aerosols will cause a reduction of CCN. With fewer CCN in the atmosphere water vapor will condensate into larger droplets compared to if there would have been more CCNs around. Larger droplets translates into quicker build up of drops that are big enough for rainfall to start. So the rain falls and dries out clouds (2).

    In Svensmarks latest paper there are some nice graphs indicating that (1) and (2) is a reality. If you don’t agree with that it would be interesting to hear why.

  3. 53
    Sekerob says:

    Re Thomas #47,

    Given the ever increasing number of reported skin cancer cases, I think there is compelling reason to seriously address the ozone depleting causes of CFC’s (NASA uses them quite abundantly still I think to have read recently) and their replacements who are because of volume found to be acting in the same even more devastating fashion… ozone depletion resumed in the last 2 years. No, it’s not GCR’s induced 3rd party effect doing that as was predicted by some Japanese scientist recently [discussed also here or at Open Mind I think]. It’s direct reaction to sources released from ground level… by Homo Sapiens Sapiens… bromides and what not.

    By product of Ozone restoration in the stratosphere… it’s got a cooling effect as well to down below…. a knife cutting on 2 sides, somewhat mitigating CO2/CH4 greenhouse effects as by product.

  4. 54
    Hank Roberts says:

    sekerob — citations needed.

    > resumed in the last 2 years
    This assumes it stopped — why do you think this?
    > direct reaction to sources released from ground
    Nope; lag time

    > NASA uses them quite abundantly still I think to have read recently
    Maybe some, but not ‘abundantly’–compared to baseline, no chance. Check whether you were reading it; there are sites attacking NASA because it studies climate, and for screwier reasons.

  5. 55
    Mark says:

    “Svensmarks latest paper isn’t about GCR versus CO2. It’s not about global cooling or warming. It’s about GCRs impact on earths atmosphere.”

    GCR is used to explain the warming trend (when it is deigned to be recognised) and delay AGW.

    And plenty has been looked at and it says “very little effect on climate”. So why keep pushing?

    Hence the thread.

    “In Svensmarks latest paper there are some nice graphs indicating that (1) and (2) is a reality.”

    Go right back to Rasmus’ conversation. It’s right at the top of the thread. Read this:

    “Good practice would then be to present all the curves that cannot be ruled out because of errors. When asked why he didn’t present the other cures too, he said that he only wanted to show the one curve. Not a very convincing answer, and not very reassuring.”

    If he’s picking what he’s showing you, then there’s no proof of (1) and (2) being real at all, unless he can answer the quesions:

    1) Does this concordance continue with the other possible graphs?
    2) Why did you pick just that one?

    You know. Like a real skeptic.

  6. 56
    chris says:

    re #52

    re your comment:

    In Svensmarks latest paper there are some nice graphs indicating that (1) and (2) is a reality. If you don’t agree with that it would be interesting to hear why.

    Svensmark’s data don’t show that (your nice description of a hypothesis) is a reality at all. If we take the data at face value we can say that for an average of 5 very strong Forbush events, that some atmospheric metrics show a delayed (between 5 and 9 days) response (Figure 1).

    That may or may not indicate there is a causal relationship along the lines you suggest, Bengt. One of the problems with drawing this conclusion is that an independent study of Forbush events came to a rather different conclusion [***]. There is a lot of overlap in the two studies; Svensmark analyzed 26 events; Kristjansson 22 events, with 13 events being common to both studies. Of the 5 strongest events that Svensmark averaged into his Figure 1, all of these were in Kristjansson’s analysis. Kristjansson made a detailed analysis of the strongest event (31 October 2003) and came to a completely different conclusion than Svensmark. Kristjansson found that analyzing the 6 strongest events (corresponding to the same 5 in Svensmark’s figure 1 + 1 other) resulted in weak correlations with atmospheric parameters, but if a delay of several days was allowed for cloud-relsted effects to develop, any weak correlations were lost and even became anti-correlated. And so on…

    So there’s clearly a problem. If a tentative conclusion arises only from one particular set of analyses then one would want this descrepancy to be resolved before any confidence can be ascribed to whether a hypothesis is consistent with the data.

    More generally, I think we all recognize that there hasn’t been any trend in the GCR count during the past 50 years (e.g. [*****]), and so whether or not variations in the CRF does have a small effect on the properties on climate-relevant atmospheric properties, the issue is not relevant to the very marked warming of this period.


    [***] Kristjansson JE et al. (2008) Cosmic rays, cloud condensation nuclei and clouds – a reassessment using MODIS data Atmos. Chem. Phys. 8, 7373-7387

    Abstract: The response of clouds to sudden decreases in the flux of galactic cosmic rays (GCR) – Forbush decrease events – has been investigated using cloud products from the space-borne MODIS instrument, which has been in operation since 2000. By focusing on pristine Southern Hemisphere ocean regions we examine areas where we believe that a cosmic ray signal should be easier to detect than elsewhere. While previous studies have mainly considered cloud cover, the high spatial and spectral resolution of MODIS allows for a more thorough study of microphysical parameters such as cloud droplet size, cloud water content and cloud optical depth, in addition to cloud cover. Averaging the results from the 22 Forbush decrease events that were considered, no statistically significant correlations were found between any of the four cloud parameters and GCR, when autocorrelations were taken into account. Splitting the area of study into six domains, all of them have a negative correlation between GCR and cloud droplet size, in agreement with a cosmic ray – cloud coupling, but in only one of the domains (eastern Atlantic Ocean) was the correlation statistically significant. Conversely, cloud optical depth is mostly negatively correlated with GCR, and in the eastern Atlantic Ocean domain that correlation is statistically significant. For cloud cover and liquid water path, the correlations with GCR are weaker, with large variations between the different domains. When only the six Forbush decrease events with the largest amplitude (more than 10% decrease) were studied, the correlations fit the hypothesis slightly better, with 16 out of 24 correlations having the expected sign, although many of the correlations are quite weak. Introducing a time lag of a few days for clouds to respond to the cosmic ray signal the correlations tend to become weaker and even to change sign.

  7. 57
    Matti Virtanen says:

    There are some skeptical remarks in this thread about the CLOUD (not CLOUDS) experiment at Cern. It is strange that someone would want to oppose this research project, a good description of which was recently given by Jasper Kirkby: – In the beginning of the lecture he says he does not know the answers. How’s that for an attitude in science?

  8. 58
    Bengt A says:

    Mark #55

    Surely you understand that this paper I’m trying to discuss isn’t about finding a trend? So why keep on arguing that it doesn’t show a trend? This paper is about trying to understand how GCR interacts with the atmosphere.

    Chris #56

    There’s a difference in methodologies between Svensmark and Kristijansson and the resulting discrepancies are discussed in Svensmarks paper. Svensmark chooses to study the strongest Forbush decreases and he uses three different indicators which all show a response to Forbush decreases. That can’t be purely coincidental, can it? Referring to Science daily Kristijansson finds Svensmarks results “astonishing”.

    I’m not arguing for a casual relationship between GCR and global warming from this paper. I’m just trying to answer Rasmus question why there’s still interest for Svensmarks research.

  9. 59
    Eli Rabett says:

    Bengt the basic problem is that the atmosphere is pretty much completely chock full of really small aerosols and ions. The rate limiting step appears to be how many of them grow into CCNs. In that case having more ions or nanodust really is not going to make much of a difference.

    Someone told Eli a bunch of weeks ago that they tossed Svensmark out of the CERN experiment. Is that true?

  10. 60
    Ray Ladbury says:

    Matti Virtanen, A confession that we don’t know the answers is a typical response in science, but I would contend that it is also wrong to understate what we do know or to fail to assess how significant our lack of knowledge might be wrt a subject of interest like climate change.

    A lot of us would absolutely love to know whether GCR have an effect on climate. It would be one less unknown source of noise. What we object to is the appeal to this unknown to explain an unknown when in fact we have a perfectly adequate explanation in terms of a known physical mechanism–the greenhouse effect.

  11. 61
    chris says:

    re #57

    Matti, I mentioned the CERN CLOUD study in my post #6 and also suggested that I had no problem with research in this area. However I do have a problem with the misrepresentation of the science by some of the individuals involved.

    You link us to a talk by Jasper Kirkby. You seem impressed that “in the beginning of of the lecture he says he does not know the answers”. That doesn’t seem that impressive to me – after all that’s the whole point of doing science. What’s less impressive is the misrepresentation of science in the talk that follows. Here’s a few things that stand out from just the first 20 minutes (I might listen to the rest later):

    Kirkby goes out of his way to pretend that CO2 and solar irradiance effects have been insignificant in temperature change from the Maunder minimum to mid 20th century. In order to insinuate a role for the CRF, he misrepresents two bits of science:

    First he states that anthropogenic CO2 can have had no effect before the 20th century. In fact there’s little doubt that the rise in CO2 from 280 ppm (pre-industrial) to nearly 300 ppm by 1900 (and around 310 ppm by mid 20th century) was anthropogenic. Taking the mid range of climate sensitivity (3 oC of warming per doubling of CO2) it’s easy to calculate that the pre-20th century anthropogenic warming contribution was likely 0.25-0.3 oC (that’s what we expect), and nearly 0.5 oC by mid-20th century.

    He then shows a solar irradiance (TSI) reconstruction of Judith Lean’s (Lean 2002), and asserts that this shows that the TSI change between the Little Ice Age (LIA) and today is “a few hundreds of a degree”.

    Never mind that Lean 2002 only reconstructs TSI back to 1840, and that the data Kirkby shows looks more like a solar irradiance reconstruction that Lean published in 2005 in which she and her collaborators explicitly considered irradiance changes since the Maunder Minimum:

    Y.-M. Wang, J. L. Lean and N. R. Sheeley, Jr. Modeling the Sun’s Magnetic Field and Irradiance since 1713 Astrophysical J. 625 522-538

    Lean’s analysis in fact yields a TSI contribution to surface temperature of 0.14-0.2 oC (not Kirkby’s “a few hundreds of a degree”).

    In other words it’s straightforward to understand the warming since the LIA of around 0.6 oC to mid 20th century according to the (rather extreme possibly) temperature reconstruction Kirkby used (Moberg’s), as a combination of an anthropogenic warming (up to 0.5 oC), TSI (0.14-0.2 oC) as well as a small contribution from volcanic activity that suppressed temperatures during the LIA (around 0.1 oC), with perhaps some countering of all of this by anthropogenic aerosols.

    In other words Kirkby’s insinuation of a lack of CO2 and solar contribution and a (ah-ha!) role for CRF in the LIA to mid 20th century warming is entirely bogus.

    I won’t go through the others in so much detail, but you’re welcome to ask for clarification:

    a. His insinuation that the MWP had a major CRF contribution is bogus

    b. The 500 MYR so-called CRF variation (according to movement of the solar system through the spiral arms of the galaxy) with temperature is likely bogus.

    c. He pretends that there is no relationship between temperature on the Phanerozoic time scale and CO2 concentrations by ignoring the actual CO2 proxy data and showing an (otherwise excellent) model of long term CO2 levels. When the actual paleoproxy CO2 data is compared with paleotemperature data there is a rather strong link between earth temperature and CO2 levels in the deep past; e.g.:

    DL Royer (2007) CO2-forced climate thresholds during the Phanerozoic Geochim. Cosmochim. Acta v. 70/23, p. 5665–5675


  12. 62
    Brian Dodge says:

    “Low solar activity and poorer shielding against cosmic rays result in increased cloud cover and hence a cooling. As the Sun’s magnetism doubled in strength during the 20th century, this natural mechanism may be responsible for a large part of global warming seen then.” Translation approved by Henrik Svensmark @

    Is there a “Leibigs Law” that applies to cloud formation – e.g., can lack of – water vapor, or sulfate aerosols, or charged particles – limit cloud formation?

  13. 63
    Steve Fish says:


    Bengt A (~58 — 10 October 2009 @ 3:46 PM}:

    I understand your “finding a trend” problem (re Mark ~ 55) with the specific paper, but it is reasonable to evaluate Svensmark’s research in light of his high profile public statements. For example- “we are advising our friends to enjoy global warming while it lasts” and “In fact global warming has stopped and a cooling is beginning. …” It appears that he has a preconceived goal for his research that doesn’t include the physics of CO2.

    As for the different methodologies problem (as per Chris ~56), when the research is not supported by a reasonable replication it raises major questions. Claiming that different methods makes the competing research inapplicable is only reasonable when one makes a cogent argument regarding which methods are appropriate, and then this contention can then be tested with subsequent research. It is most damaging to Svensmark’s argument that he did not respond to Rasmus’ question about specific methods, as stated in the OP.

    If you want the answer to Rasmus’ question regarding continuing lack of interest in Svensmark’s research, he will first have to respond to reasonable criticism.


  14. 64
    Mark says:

    “Surely you understand that this paper I’m trying to discuss isn’t about finding a trend?”

    What does that have to do with Rasmus’ question.

    Please go and read the text at the top of the thread. It tells you what the thread is about. You haven’t read it yet, obviously.

  15. 65
    Mark says:

    PS what IS it about finding, then? That charged atomic particles are CCN’s? Well, I think they knew that already, since that’s how they found charged particle tracks before they had computers.

    And when you say “correlation”, surely YOU are going on about a trend.

  16. 66
    Bengt A says:

    Eli Rabett #59

    If the atmosphere is “chock full of really small aerosols and ions” then why is it that you can see ship tracks and airplane contrails?

    Steve #63

    It’s seems reasoneble to me that you’re upset by Svensmarks opinion piece where some of his claims have weak support by science, and I’m not prepared to defend every word Svensmark has ever written or said. But to me you all just seem so eager to ditch Svensmark that you don’t see the findings within his scientific papers.

    I think it would be more correct to say that Svensmark tried to replicate Kristijanssons work, and not the other way around. And to put it frankly, and I don’t think Kristijansson will agree with this, Svensmark did a better job. He used more indicators, as the AERONET network for aerosols that Kristijansson didn’t include. Kristijansson exclusively used the MODIS data. Svensmark used only the strongest Forbush decreases which translates into better signal-noise ratio compared to Kristijansson.

    Let me just ask one question about this paper – the AERONET aerosol network shows a very clear response to Forbush decreases. Is there something wrong with this measurement? Is there something wrong with the selection of stations or selection of wavelengths or what’s the problem? Someone has to come up with some serious flaws otherwise we have to consider this as an important scientific finding.

  17. 67

    #58 Bengt A

    The paper may be about how GCR’s interact with the atmosphere, but what Rasmus has pointed out, is that he did not weigh all the data objectively and the graph he did use was in question. The old adage correlation does not equal causation has not been abandoned.

    Favoring a particular graph may be a personal preference but it is still a cherry pick.

    Also, what is important here is the fact that once again Svensmark exceeds the general claims of the paper when talking about the paper by inferring that his findings are “remarkable”. Given the context, it becomes and thus contributes to the red herring museum of silly climate claims and inferences.

    For Christy to maintain credibility in his statements, he has to ignore climate sensitivity and latitudinal shift as well as basic economics and resource capacity tied to infrastructure.

    For Pielke Sr. too, I think probably the same. Cherry picking seems to be their modus operandi.

    Svensmark has to keep ignoring the bulk of climate science and relative context such as forcing through layers of atmosphere as well as the cumulative effects of Co2 as infrared climbs through the columns, and feedbacks… well, not a lot of integrity there.

    In reality, he may actually have something interesting, but how relevant to AGW?. GCR’s probably do affect clouds… But as far as forcing relative to AGW, it’s still in the noise. There are some valid questions if ones goal is to determine the resulting changes…

    Would be great if he can tease out the signal and add it to the body of science to further separate the signal from the noise between natural variation and AGW forcing… but to claim or infer that GCR’s are responsible for the current warming signal would be something similar to saying that as a locomotive comes down a hill with 300 loaded railcars, the inertial force is mainly attributed to the lack of pebbles on the track.

    Svensmark has a history of public assertions and claims that exceed the scope of the science though, so listening to him and giving him credence in that respect is a fools errand.

    Would really be great if Svensmark would stop claiming how remarkable his work is in the context of AGW when in reality he has proven nothing of significance in that respect, when weighed in context.

    When it comes to what is causing the warming, Svensmark needs to explain the attribution of the forcing that is causing the heating. GHG’s and associated effects do fit the bill as models and observations clearly indicate. So GCR’s may have an effect, but that is only a part of the bigger picture. Until he can show that his GCR’s account for 3.6 W/m2 of increased forcing, I’m afraid he’s going to remain in the darkness of his perspective on this one.

    So, can he show that GCR’s give us +3.6W/m2 of forcing? Well, I’m not going to hold my breath on that one.

  18. 68
    Ray Ladbury says:

    Bengt A, Contrails have nearly immediate effect–no 5-9 day delay. It’s a totally different realm of aerosol size. What is lacking is any evidence we have a dearth of aerosols that agglomerate to become CCN on the proposed timescale.

  19. 69
    CM says:

    Bengt, don’t imagine that people are just ignoring Svensmark’s science because they’re upset about that op-ed of his. Noone (maybe #20) even mentioned it before you did. I hadn’t heard of it, but I had read six articles of Svensmark’s, as well as the hype in ‘Cosmoclimatology’, ‘The Chilling Stars’, and some press releases, so the op-ed didn’t shock me.

    But it was impressing how Svensmark cited the recent misreported remarks of Mojib Latif to
    a) take an alleged cooling prediction (based on ocean circulation patterns) from a climate model that ignores GCRs,
    b) present it as validation for his GCR theory, and
    c) suggest climate models that ignore GCRs will be shown to have failed because they did not predict a cooling.
    That’s chutzpah!

    Speaking of which, I think it’s a stretch to cast Svensmark et al. 2009 as trying to “replicate” Kristjanson et al. 2008. You’re usually interested in seeing if you can replicate a study that rejects the null hypothesis, not a study that doesn’t. And “no significant GCR/cloud link” remains very much the null hypothesis. It’s Svensmark who’s got something to prove.

  20. 70
    Bengt A says:

    John #67

    I don’t get this. Why does Svensmark have to come up with the number of 3.6 W/m2 of forcing? He’s trying to establish a plausible mechanism for GCRs interaction with the atmosphere. That is what he does. Would be interesting to visit that “red herring museum of silly climate claims and inferences” of yours! Is it AGW-skeptic only or does it include silly pro-AGW claims as well?

    Ray #68

    Airplanes and GCRs impact on the atmosphere clearly are two different things. I agree with that. I was just trying to make the point that adding ions/aerosols can have an effect on cloudiness

    No, there’s no evidence for the whole chain of events as suggested of Svensmark. But the SKY experiment in Copenhagen revealed some information about the possible initial steps (se abstract below). Hopefully the CLOUD project at CERN will give us some more information about this.

    Abstract from Svensmark et al (2007)
    Experimental studies of aerosol nucleation in air, containing trace amounts of ozone, sulphur dioxide and water vapour at concentrations relevant for the Earth’s atmosphere, are reported. The production of new aerosol particles is found to be proportional to the negative ion density and yields nucleation rates of the order of 0.1–1 cmK3 sK1. This suggests that the ions are active in generating an atmospheric reservoir of small thermodynamically stable clusters, which are important for nucleation processes in the atmosphere and ultimately for cloud formation.

  21. 71
    Matti Virtanen says:

    Re 61. Chris. Thanks for the reply (“bogus. bogus, bogus”). Whether one likes it or not, the experiment at CERN seems to be going ahead, and in a couple of years we may read the results. Will they settle the question about the relative strengths of natural and anthropogenic warming? Probably not, because many “skeptics” will only be convinced by temperature data. Will the experiment shed light on how cosmic rays affect the formation of cloud condensation nuclei? Probably yes, but how, that we don’t know until we know.

  22. 72
    Mark says:

    Oh, aye, that reminds me, Ray. Wasn’t there a few days delay for the effect to look convincing? Despite these particles being a few light-seconds away and travelling at near light speed.

    Just delayed so as to make some short perturbation look good.

    Was it Svensmark’s paper too?

  23. 73
    Mark says:

    “If the atmosphere is “chock full of really small aerosols and ions” then why is it that you can see ship tracks and airplane contrails?”

    You do know that combustion creates water too, don’t you?

    [Response: Contrails are related to direct water vapour emissions (and enhanced by associated aerosols) but ship tracks are almost exclusively driven by sulphate emissions, not water vapour. – gavin]

  24. 74
    David B. Benson says:

    Brian Dodge (62) — Water vapor at saturation + CCN –> clouds. Need both.

  25. 75

    # Bengt A

    I’m confident you would like to only discuss the one paper, but I am a generalist, so I tend to put everything I see into perspective with other things. I think myopia is inherently dangerous when examining systems, especially systems such as climate which are composed of multiple interacting systems.

    So concentrating on a single paper, or a single system, or a single idea is pretty darn silly from that perspective. There are some videos on youtube listed at the bottom of this page:

    In the videos, it is claimed that when Svensmark and his team presented their findings to the IPCC and they were rejected, and they were disappointed.

    “Bert Bolin thought it was irresponsible of us to say that something else other than Co2 could be the main driver for climate.”

    The video also claims that:

    “most of the people today think that most of the climate change is because of co2, but this is wrong, most of the warming of the 21st century is because of the sun”

    Svensmark claims “the climate is a result of the clouds”. That’s a pretty bold statement, don’t you think. In fact, based on the compendium of the science, downright arrogant.

    So yes, if he is going to push the above claim and go along with the notion that climate is a result of clouds, and 21st century climate is because of the sun, not co2, then he has to explain how we get 3.6W/m2 of forcing (from the effects he is asserting are the culprit), which happens to be the mean assessment of the forcing above natural cycle for the 21st century, generally speaking.

    You can call me silly all day long if you wish, but your going to have to bring some substance if you really want to put me in my place. I’ve got Svensmarks words and others in the video claiming and inferring that Co2 is not such a big deal. Well Co2 is a big deal. You can argue semantics all day if you want, but in the end, you will lose that argument.

    Or can you prove Svensmark and his team are not asserting the things they have stated in the video?

  26. 76

    #70 Bengt A

    Could you give me some examples for silly pro-AGW claims? I don’t get out much.

  27. 77
    Thomas says:

    I wanted to discuss foundational memes, and how they may be affecting the way skeptics think. First, as someone with training in Astrophysics, with an interest in energy technology, one of my foundational memes is that perpetual motion machines are impossible. If someone proposes that they have invented one, I don’t need to understand the details of the thing, I know that they have missed something fundamental in their analysis. Therefore I would consider it to be a collosal waste of my time for him to demand that I read/understand his papers in detail, and make detailed arguments about the correctness of each step in his train of thought in order to have the right to assert my opinion.

    Now, let us say you meet a technically adept person, but that he fully subscribe to the meme “God created this planet to be under his control, any suggestion that anything man does can affect the global climate is more than wrong, it is pure arrogance”. Now, if he held this meme as a central tenant of philosophy, in the same way that I hold that because of the laws of thermodynamics prove that anything which purports to be a perpetual motion machine is wrong, how would I view climate science? Clearly I would be convinced that climate scientists had completely missed something fundamental. I wouldn’t feel that I had to understand any of their arguments in detail, for their results violate a fundamental theorem of how the universe works. Therefore, I might simply search elsewhere for alternative explanations. It would also be impossible to convince him otherwise based upon your arguments concerning how the science works, in detail. For, he would be certain that you are missing something fundamental, and all your detailed models simply serve to obscure this fact. That avenue for becoming convinced of your science, is simply closed to him. In order for him to be “converted”, his foundational worldview has to be challenged and overcome. It is only by this direct confrontation of his “priors”, that he could be convinced.

    Now, look at an argument between this hypothetetical individual, and a climate scientist, as seen by a member of the general public (or a journalist). Both of these people, are using technical argumentation far beyond my ability to evaluate. I am forced to fallback on other methods to determine who is likely to be right. If I were honest, I would just have to conclude “opinions on the shape of the earth differ”. Perhaps the only way forward is to expose the foundational myths on which convinced skeptics thinking is based upon.

  28. 78
    Ricki (Australia) says:

    Can you guys please comment on the recent paper by Tripati et al and the relationship to other proxy temperature reconstructions. Does this latest paper confirm our current understanding of the on-set of the ice ages and the relationship to CO2 and what are the implications for the coming decades of cliamte change?

  29. 79
    Mark says:

    : Contrails are related to direct water vapour emissions (and enhanced by associated aerosols) but ship tracks are almost exclusively driven by sulphate emissions, not water vapour. – gavin

    OH, Aye, remember now: those contrails were from piston engines.

  30. 80
    CM says:

    Mark, re “trend”:
    the recent Svensmark paper Bengt is discussing is about aerosol and cloud response to sudden falls in GCR intensity (Forbush decreases – FD), not trends over time.

    Re #72 (“light speed”), no, I remember that remark from a previous thread. It was certainly not Svensmark’s suggestion.

    Bengt, re #66,

    Svensmark did a better job. He used more indicators, as the AERONET network for aerosols that Kristijansson didn’t include. Kristijansson exclusively used the MODIS data. Svensmark used only the strongest Forbush decreases which translates into better signal-noise ratio compared to Kristijansson.

    Kristjánsson et al. did not look at aerosols, did they? Only at cloud parameters. So there was no call for them to use AERONET data. Kristjánsson too tried using only the strongest FDs.

    (The experts here can perhaps speak to the different choices of cloud parameters in the two studies, and whether it makes any difference that Kristjánsson got them all from MODIS while Svensmark used a different data source for each parameter.)

  31. 81
    Bengt A says:

    John #76

    I’m not calling you silly and I have no intention to put you in your place. But I find it hard to defend every You tube video of Svensmark. I’m just trying to answer Rasmus question in his opening post “Why the continued interest” by referring to Svensmarks two most recent scientific papers . I’m still interested to hear what the flaws are with these papers.

  32. 82
    mauri pelto says:

    This initial post considers the role of melt water and iceberg production and temperature and iceberg production. High iceberg production is prompted by two different processes: 1) a calving retreat, where glacier volume is shed by calving. 2) Advancing glaciers with positive mass balances delivering more ice to the glacier front. The role of melt water lubrication provided from the surface has been demonstrated to be limited in Greenland as reviewed-
    The melt water needed to sustain rapid flow is generally basal melt water and warm basal conditions. Note the rapid flow of Antarctic Ice Streams that lack surface melting. The connection between more melt water and more icebergs may exist at a point in time such as the last decade, but it is not the main causal agent.

  33. 83
    bushy says:

    To address the initial post. The reason the theory requires further investigation is the undoubted correlation between solar cycles and climate shift. Because TSI can probably be ruled out as the primary causative agent some other mechanism must be in play. The GCR theory therefore remains the strongest alternative. The experiments at Cern will be followed with great interest I think.

    [Response: “undoubted”? Actually, it is very much doubted at least if you are talking about any recent shifts. -gavin]

  34. 84
    Mark says:

    “But I find it hard to defend every You tube video of Svensmark. ”

    However, you’re trying to do so by ignoring them.

    “He isn’t doing this to avoid CO2 being the cause”

    (as long as we ignore any statements where he says he is)

  35. 85

    #81 Bengt A

    Just for the record, I don’t mind being put in my place (corrected). As to the the flaws Svensmarks papers, I thought Rasmus did a good job above. And others in the thread have already outlined many of the issues. Maybe just review the thread and look up Svensmark in other RC items and review the discussions.

    Generally there are some flaws in his lack of consideration of time spans regarding residence and CCN’s to effects (hope that is close), as has been pointed out. I don’t recall the details but you can find the discussions. Beyond that is, the assertions he makes extend beyond the scope of his papers ability to support the assertions, and then claiming loosely in an obtuse fashion that because he writes papers… his assertions are somehow profound or remarkable and by extrapolation and therefore disrupt the scientific consensus on global warming, thus showing GCR’s…

    Plato would have had a ball with all the shadows he is casting.

  36. 86
    Mark says:

    “Re #72 (”light speed”), no, I remember that remark from a previous thread. It was certainly not Svensmark’s suggestion.”

    OK, it could easily have been another “paper” trying to make CO2 a non-issue.

  37. 87
    Hank Roberts says:

    google finds it in several threads here “light speed”

  38. 88
    RichardC says:

    58 Bengt said, “I’m not arguing for a casual relationship between GCR and global warming from this paper. I’m just trying to answer Rasmus question why there’s still interest for Svensmarks research.”

    But without a purported significant link between GCR and global warming, there would be no significant interest in Svensmark’s research. The reason for continued interest is that people tend to jump from “a possible [small] effect” to “most likely the primary driver” when it suits their preconceptions.

  39. 89
    Hank Roberts says:

    Proceedings of the TAC-Conference, June 26 to 29, 2006, Oxford, UK
    Contrails, contrail cirrus, and ship tracks
    K. Gierens*
    DLR-Institut für Physik der Atmosphäre Oberpfaffenhofen, Germany

    ABSTRACT: The following text is an enlarged version of the conference tutorial lecture on contrails, contrail cirrus, and ship tracks….

  40. 90
    chris says:

    re #71
    Yes indeed Matti, they did get their experiment funded. To my mind they’ve been a tad dishonest since some of the misrepresentations of the science in Kirkby’s lecture were also in their funding application(s) (and in a rather dismal review that Kirkby published a few years ago), and some of the supporting documentation for their CLOUD proposal is somewhat dodgy too:

    e.g. “The changes in global cloud coverage are thought to be responsible for the observed global warming. Therefore experimental investigation of these processes are very important” (from a supporting letter from the vice-president of the Russian Academy of Sciences)

    Still, maybe there’s little point in being “po-faced” about this. Perhaps this odd group of CRF advocates are disciples of the Paul Feyerabend school (“anything goes”!), and it doesn’t really matter if they misrepresent the science wildly in order to get funding and attention. We’ll see what they come up with when they actually publish this stuff. My feeling is that while they should obtain some useful data on gamma-ray-induced condensate formation under controlled conditions, this is unlikely to have much impact on pinning down events in the real world since competition from other endogenous and man-made nucleation species, and air transport processes (surely relevant for a phenomenon with an apparent 5-9 day post-cosmic-ray-impact delay!), and so on, can’t necessarily be translated to a chamber connected to a particle accelerator.

    In this respect their acronym “Cosmics Leaving OUtdoor Droplets” is a tad inaccurate since it’s not an “outdoors”y experiment at all….it’s an indoorsy experiment!

  41. 91
    Josephine M says:

    As far as I can tell, there is no disputes that cloud cover was
    – low for the period of suspected AGW (~ 1980-2000)
    – high for the period of flat temperatures (~ 2000-2009)
    and this change correlates to solar activity changes.
    Is that not reasonable prima facie support for Svensmark?

    [Response: Not when you realize that these correlations are made with data that are i) not homogeneous in time, and ii) have been ‘corrected’ by svensmark in ways that make absolutely no sense in order to preserve his correlations. -gavin]

  42. 92
    chris says:

    re #83

    The reason the theory requires further investigation is the undoubted correlation between solar cycles and climate shift. Because TSI can probably be ruled out as the primary causative agent some other mechanism must be in play. The GCR theory therefore remains the strongest alternative.

    Your post is unsupported assertion Bushy and a bit of a non-sequitur. Which “undoubted correlation between solar cycle and climate shift” are you referring to specifically? Climate variations for the last 1000 years very likely have some solar contributions but these can be understood in relation to TSI variations (with other contributions like volcanic activity, ocean heat transport variability and anthropogenic greenhouse gas contributions), and don’t need introduction of contributions for which their isn’t any evidence.

    And as far as I’m aware we don’t have a good handle on TSI for solar activity before around 400 years ago. So I don’t think we can assert that TSI variations weren’t responsible for solar-related climate inputs before the MWP (for example), if we don’t know what the TSI was for those periods!

    It’s helpful to address some of the substantial science on this subject (e.g attributions of climate variation during the Holocene if that’s what you’re referring to). As well as TSI variations, one should take into account orbital forcing, volcanic activity, ocean heat transport variations (which might be linked to TSI-variations), greenhouse gas variaions etc. A good review on this subject has recently been published:

    [**] Wanner H et al. (2008) Mid- to Late Holocene climate change: an overview Quaternary Sci. Rev. 27, 1791-1828

  43. 93
    Martin Vermeer says:

    Thomas #77, thoughtful comment.

    Did you notice though the fundamental difference between the two ‘foundational memes’? Conservation of energy can be proven false on its own terms. Just build one of those devices, success guaranteed. Actually it isn’t even foundational enough for physicists themselves not to doubt it, as happened when apparently beta decay violated it. Not all that implausible given that weak interactions violate conservation of parity, strangeness, …
    As for the ‘God created this planet…’Ã’ foundational meme, the only way to prove it false on its own terms would be for Him to come to Earth and point out ‘hey, you wanted to be root… it’s your job now’ ;-)
    But yeah, judging who is right and who is wrong without the relevant expert knowledge is tricky — and yet something done all the time by politicians and ordinary folk alike.

    There are ways. Michael Tobis touches upon this in

  44. 94
    Phil. Felton says:

    Mark says:
    12 October 2009 at 3:07 AM
    : Contrails are related to direct water vapour emissions (and enhanced by associated aerosols) but ship tracks are almost exclusively driven by sulphate emissions, not water vapour. – gavin

    OH, Aye, remember now: those contrails were from piston engines.

    These all were. ;-)

  45. 95
    Mark says:

    $ Stands up for the theme music for “Battle Of Britain” $


    Was taught about a tephigram once. There’s a line there (dot dash, I think) marked contrails. Except the contrails don’t form there any more: the height of contrail formation was calculated on 1950’s planes and nobody cared enough about contrails on a tephigram to change it.

    Given that contrails act like Svensmark’s GCR CCN and that they’ve moved quite a distance further up, should he not get a ballpark figure of the effect to expect by looking at the change in temperatures due to the rising height of contrails?

  46. 96
    Mark says:

    “First, as someone with training in Astrophysics”

    Well that should give you a good start.

    Photometry of stars is used to work out the temperature profile of our sun and the composition of the stars including our sun.

    This is done by looking at the absorption lines of the spectrum.

    Despite these being 100% opaque to the centre of the star, we can tell if the star contains 1% He, 2% He, 3% He… likewise Oxygen, Carbon, Beryllium, and all the other metals (from an astrophysicists’ meaning of “metals”.

    So even though it’s 100% opaque, we can tell the difference between 1% He and 2%.

    If the effect of a line spectrum absorber stopped due to the application of Beers law that those who deny AGW is a problem, then this would be impossible.

    As an astrophysicist/astronomer you should know this is incorrect.

    Do like I do:

    I don’t understand much of the AGW science (either pro or anti CO2), but I let what I do know guide be as to which one I think is true.

    And the denialist use of Beers Law is wrong. I know this because I’ve searched for Helum Rich stars myself in my Astrophysics lab and worked out the He content (and by accident included Bellatrix, a Helium poor star, but turned it to our favour by pointing out that this helium poor star was a great example of how you can see the differences in the spectral classification and the peak temperature colour).

    So I don’t understand the mixing layer physics, or the North Atlantic Gyre’s effect.

    But I DO undestand what goes on in astronomy.

    And that is consistent with what the pro AGW science says and inconsistent with the anti AGW science being proposed.

  47. 97
    Mark says:

    “- high for the period of flat temperatures (~ 2000-2009)”

    If by “flat” you mean “rising”.

  48. 98

    It is just: ABC

    Anything But Carbon

    We are witnessing a twisted, contorted search for an ABC cause for global warming.

    Human action is a huge factor in climate models, now it is human thinking.

    Thanks for all that you do.

  49. 99
    Mr Henderson says:

    Just to support Hank Roberts (#21). This site is supposed to be about climate science, not psychology. What does the motivation of the deniers matter? Just prove them wrong and leave it at that.

  50. 100
    Hank Roberts says:

    Wonderful site, Phil.

    Aside, from the TAC Conference link I gave above:

    “Not all ships produce tracks. Ships powered by Diesel units that emit high concentrations of accumulation mode aerosol can produce ship tracks. Ships that produce few particles (e.g. nuclear ships) or particles too small for activation as cloud drops (even if in high concentration) do not pro- duce ship tracks. The most likely, if not the only, cause of the formation of ship tracks is the direct emission of cloud condensation nuclei from the stack of a Diesel powered ship…. The type of fuel burned seems to be more important than the type of ship engine in determining whether a ship will produce a track or not.”

    I wonder — though diesel-electric locomotives burn a lot less fuel at a time than a large ship, has anyone looked for train, er, tracks in the clouds?