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Taking Cosmic Rays for a spin

Filed under: — gavin @ 16 October 2006 - (Español)

In 1859, John Tyndall’s laboratory experiments showed that water vapour and carbon dioxide absorb infra-red radiation and that they could therefore affect the climate of the Earth. As soon as his paper was published (1861) in the Proceedings of the Royal Society, he put out a press release for the London newspapers explaining that this result implied that all past climate changes were now understood and all future climate changes could be predicted simply from a knowledge of the concentrations of these ‘greenhouse’ gases…

Fast forward to 2006: Svensmark and colleagues’ laboratory experiments show that highly ionizing radiation can create ultra-small aerosol particles. As soon as the paper is published in the Proceedings of the Royal Society, they put out a press release for the world’s newspapers explaining that this result implied that all past climate changes were now understood and all future climate changes could be predicted simply from a knowledge of the intensity of these ‘cosmic rays’….

History repeating itself? Well, not exactly. Tyndall actually restricted himself to describing his experiments and simply linking it to the work of Fourier a few decades earlier. It took more than another century before the credible quantitative estimates of these effects and their influence on past and possibly future climate were made, along with good enough observations of the gases to know that they have (and continue) to change significantly. However, Svensmark and colleagues, not wanting to wait for the credible quantitative results to come in, instead short circuited all of that tedious follow-up work, scaling up to realistic conditions, theoretical and modelling studies demonstrating that their effect was indeed viable, and simply declared in their press materials that the team had ‘discovered that cosmic rays play a big part in the everyday weather’ and ‘brings to a climax a scientific quest that has lasted two centuries’. Nobel prizes all round then.

Alas! if only it were that simple….

(In explaining why it isn’t, I should first apologise for the third solar related posting in as many weeks. I realise that most people are not that interested and so after this one, I promise a moratorium for a month or so!)

Svensmark’s paper itself is indeed of some interest. Aerosol processes are among the most uncertain, and most studied, aspects of climate and these experiments (they bombarded a clean mixture of water, SO2, O3 and air with high energy UV and saw small H2SO4 droplets form) might be useful in adding to that field. One could quibble with the use of the high-energy UV (which never penetrates to the lower troposphere), and the high concentrations of SO2 and O3, but by far the biggest problems lie in the study’s relevance to the real world atmospheric conditions.

The working hypothesis of the cosmic ray crowd is that the (weak) correlations between low clouds and cosmic rays are causal (i.e. a cosmic ray increase – due to a solar magnetic field weakening – causes low clouds to increase, cooling the planet). The ‘spin’ on this new paper is that this has been demonstrated, and is significant, and furthermore, is responsible for the 20th Century rise in global temperatures. But let’s look carefully at what is required in this logic:

First, the particles observed in these experiments are orders of magnitude too small to be Cloud Condensation Nuclei (CCN). In the press release, this is why they talk about the ‘building blocks’ of CCN, however, aggrandisation of these small particles is in no sense guaranteed (Missing step #1). Secondly, the focus is on low clouds over the ocean. However, over the ocean, there are huge numbers of condensation nuclei related to sea salt particles. Thus to show that the cosmic ray mechanism is important, you need to show that it increases CCN even in the presence of lots of other CCN (Missing step #2). Next, even if more CCN were made, you would need to show that this actually changed cloud cover (or optical thickness etc.) (Missing step #3). And given that change in cloud properties, you would need to show that it had a significant effect on radiative forcing – which despite their hand waving, is not at all well quantified (even the sign!) (Missing step #4). Finally, to show that cosmic rays were actually responsible for some part of the recent warming you would need to show that there was actually a decreasing trend in cosmic rays over recent decades – which is tricky, because there hasn’t been (see the figure) (Missing step #5). All of this will require significant work and there are certainly no guarantees that all the steps can be verified (which they have been for the greenhouse gas hypothesis) – especially the last! However, they would seem essential to justifying the claims in the press releases.

Will these results be a spur to future research? Possibly. But the ridiculous spin put on this paper is liable to continue to put off mainstream scientists from pursuing it. It’s as though Svensmark and co. want to enhance the field of solar-terrestrial research’s bad reputation for agenda-driven science.

Unsurprisingly, this paper was trumpeted throughout contrarian circles last week and was received uncritically (with one honorable exception in the ‘climatesceptics’ discussion group), even by people who normally spend their time decrying science-by-press-release. (A word to the wise, consistency goes a long way to establishing credibility…).

At RealClimate, we’ve often criticised press releases that we felt gave misleading impressions of the underlying work and lead to confused, and sometimes erroneous, headlines, but this example is by far the most blatant extrapolation-beyond-reasonableness that we’ve seen. If this group wants to be taken seriously and interact constructively with the rest of the community (which is the only way the ‘missing steps’ will get sufficient attention), they have to act in a serious manner, be honest about the problems and caveats, and resist the temptation to speculate beyond what is justified. The kind of antics seen in this case may play well for the peanut gallery, but they won’t impress the critics.

121 Responses to “Taking Cosmic Rays for a spin”

  1. 51
    muller.charles says:

    “Looking for clouds where there shouldn’t be any is perhaps the only way to demonstrate Cosmic Ray effects.”
    On long term trends, you may be right. But on short term influence, you can also observe the correlation with Forbush decreases (Todd 2001, Harrison 2006).

  2. 52
    Raimund Muscheler says:

    Hi Gavin,

    you write that:

    “the problem in the long term (pre-1950) is that we don’t have any cosmic ray records from then and the proxies (14C, 10Be from Greenland and 10Be from Antarctica) all give different trends”

    10Be from Greenland and Antartica agree quite well for the period before 1950 AD. The main disagreement comes from the period after 1950 AD. 10Be from the South Pole increases and 10Be from Southern Greenland decreases. So both records exhibit disagreement with the neutron monitor data. These differences have led to the different conclusions about the solar activity in the past (see ).

    However, the long-term (pre-1950) changes in 10Be from Greenland and Antarctica agree quite well. The changes are also supported by the 14C data.

    [Response:Thanks! - gavin]

  3. 53
    Jay Furneaux says:

    It might be worth noting that this experiment is to be expanded upon at the CERN particle accelerator using, its claimed, â??clean airâ?? etc.
    It has gathered quite a collection of institutions as multi-disciplinary partners.

    CLOUD proposal


  4. 54
    James says:

    Re #39, #42, 49, etc. Two questions.

    First, there are a number of factors (some obvious even to a casual observer like me) that could have affected climate on a 500 My timescale. Continental movement has already been mentioned. IIRC there’s also evidence for significant changes in atmospheric composition & pressure, possible long-term orbital variations, etc. But what no one seems to be asking is whether the temporal resolution of measurements over this period is fine enough to track the effects of CO2 on the decade to century timescale that is of practical interest re GW?

    Second question: In the 100 Ky timescale for which there is high resolution data, AFAIK there’s no instance of (and no mechanism for!) significant CO2 being added to a stable climate, previous to the modern anthropogenic CO2. So for instance you might have a climate warming that releases dissolved CO2 from the oceans, and that CO2 might further drive the climate. But isn’t claiming that CO2 lags change in this period a fallacious argument, since there’s no instance of an increase absent a such a change?

    FTM, doesn’t the historical record in fact suggest that we ought to expect additional natural CO2 to be released as the Earth warms in response to the anthropogenic CO2?

  5. 55
    Peer says:

    Re:2 Sulfate VS Ions from outer space

    “UPDATE: It occured to the old hare that he needs to use a hammer.

    * Everyone accepts that cosmic rays are the principal source of ions in the lower atmosphere. The ion density is around 1000/cm3.
    * Everyone accepts that there will be nucleation around the ions because of electrostatic forces

    The Svensmark et al. paper simply restated the obvious. But the real questions are:

    * Is the availability of ions the limiting factor in forming cloud condensation nuclei or is the availability of other species limiting.
    * Are there other ways of forming cloud condensation nuclei (CCN) besides around ions and if so (it is so) what is the relative importance of each type of CCN and what are the characteristics of the CCNs.

    And, I think the figure at the end from a Mexico study pretty well shows that under normal conditions SO2 is limiting for forming small aerosols.”

    But one of the most convinient if true is the following Qestion.

    * Do negative charged air increase the optical thickness of SO2 induced clouds/smog/fog/local dimming under an hot mexican sun ?

  6. 56
    Rick says:

    Havn’t I read that there are differences in the warming pattern which should be expected (and has been predicted) from solar contra greenhouse gas forcing? For example GHG forcing is expected to cause night time, winter, high latitude warming..? Have these factors been overlooked with all this talk of….calibration of NOAA-14 (and NOAA 16 – from 2001) is performed directly against the NOAA-9 values, not with respect to overlapping satellites..!!etc..
    A short summary of the two warming patterns expected would be very much appreciated by us laymen….anyone?

  7. 57
    chris says:

    Re #54

    I agree with you, especially on point #2. From my amateurish viewpoint it’s rather obvious that in pre-anthropogenic times, changes in CO2 levels were driven by temperature changes (as a rule) and that these presumably fed-forward to “reset” the ambient temperature to a new equilibrium (resulting from the forcing – solar most likely – that increased both the temperature and the CO2, or decreased these as the case may be). The CO2 released under these conditions contributed rather minimally to temperature levels and certainly so in relation to the very large increases in CO2 from anthropogenic originsthat we’re seeing now. That seems to apply at least through the glacial/interglacial cycles.

    Of course significant changes in CO2 might arise within a stable climate due to catastrophic effects. Thus the end-Cretaceous period with hugely increased atmospheric CO2 levels were (I think) a result of either/and/or the dinosaur-killing impact that occurred in a limestone rich sediment that released massive amounts of CO2…and the ginormous volcanic eruptions that produced the Deccan Traps in India and released enough lava to cover the entire USA to a depth of more than 1 kilometre (if it had actually been released in what was to be the USA rather than in what was to be India!).

    Your last point is also correct. In fact on the second thread on this blog Dr. Scafetta is pursuing a related point..that solar influences are responsible for some of the enhanced 20th century CO2. But I would have thought the evidence from the glacial history would indicate that warming-induced CO2 levels from non-fossil fuel reservoirs are small. We have raised CO2 levels from around 280 ppm to 385 ppm with an increase in temperature of around 0.7 oC plus perhaps 0.2 oC (if we were to remove the cooling from aerosols) plus perhaps 0.5 oC (the warming still “in the pipeline”)..say 1.5 oC all together to come, but more relevantly only 0.7 oC actually extant. But the 180 to 280 ppm glacial to interglacial rise in CO2 is associated with around a 6 oC change in temperature (Is that about the right value of a post glacial temperature rise?). So clearly the bulk of the post glacial warming is from direct solar influences with a relatively minor part from solar-induced recruitment of CO2 from natural reservoirs. And the contribution to 20th century CO2 levels resulting from recruitment from reservoirs due to solar and/or anthropogenic warming feedbacks must be rather small (no more than 10-15 ppm or so if we were to scale with respect to the glacial-interglacial transition. The experts would be able to make these “calculations” more precisely than me!)

    On the other hand, an anthropogenic CO2 -induced release of carbon and methane from tundra and deep sea clathrates etc. might eventually fed-forward in a rather non-linear (catastrophic!) manner at some point!

  8. 58
    Onar Ã?m says:

    Re #49

    “Thus you will never find a good correlation of one factor at all times.”

    That’s actually not true. Cosmic rays/solar activity give excellent correlations at all times and at all time scales. (ranging from days such as the recently cited Forbush events to hundreds of millions of years such as the work by Shaviv cited above) This is evidence that cosmic rays are a formidable factor in climate, so great that it can even overshadow the effects of continents on ocean circulation.

  9. 59
    Urs Neu says:

    Re 58

    I have never seen excellent correlations for cosmic rays and solar over all time scales. There are claims of such correlations, but they are far from convincing. Reconstructions are so different and have such high uncertainties especially on the multimillion year time scale, that it is no problem to show either a match or a mismatch of the same parameters by choosing specific data set, tuning the data (within the frame of the uncertainties) and making enough assumptions.

  10. 60
    Pat Neuman says:

    re: 56.

    In reply to 56, The warming trends in looking at numerous 100 year temperature plots from northern and high elevation climate stations … i.e. warming trends in annual mean and minimum temperature averages, winter monthly means and minimums and especially winter minimum temperatures and dewpoints …

    Climate warming is being driven by the accumulation of greenhouse gases in the atmosphere – no visible effects from other things like changes in solar radiation or the levels of cosmic rays. Greenhouse gas emissions are completely overwhelming all other changes in forcing in driving global warming.

    There are other articles recently put out with spin to downplay greenhouse warming, most recent included links below. As I said in calling Senator Dayton’s office yesterday, the articles below are not accurate – all just smokescreen attempts to mislead the US public into voting against any political parties that may show support for reducing greenhouse gas emissions. So far the only party that has shown any strong support for reducing US greenhouse gas emissions has been the Green Party, but some people may think that one or the other of the major parties actually supports action to reduce CO2 emissions. Neither major party supports reducing emissions by using fewer products, building smaller homes, having fewer children and, above all, traveling only when needed.

    Three recent Antropogenic (AGW) skeptic articles, below:

    U.S. Commission Environment and Public Works
    Majority Press Release
    Decorated Scientist Defects From Belief in Global Warming â?? Caps Year
    of Vindication for Skeptics
    October 17, 2006
    Washington DC – On
    Decorated Scientist Defects From Belief in Global Warming â?? Caps Year
    of Vindication for Skeptics
    # # # # #

    Open Kyoto to debate – Sixty scientists call on Harper to revisit the
    science of global warming
    Published: Thursday, April 06, 2006
    An open letter to Prime Minister Stephen Harper:
    National Post
    Part of the network
    Sixty scientists call on Harper to revisit the science of global
    # # # # #

    Debra J. Saunders: Many take global warming on faith
    Debra J. Saunders, San Francisco Chronicle
    published: October 19, 2006

    Three recent AGW skeptic articles, above.

  11. 61
    Crocodile Hunter says:

    Speaking of spin, where did all the hurricanes go?

  12. 62
    Dan says:

    re: 61. A developing El Nino in the Pacific effectively limited Atlantic hurricane development due to increased wind shear. And yet, despite the El Nino, we are now at the average climatological number of storms for the year. Amazing! During an El Nino season, we expect far below normal numbers of storms. And yet we still had an average year. Clearly, as the peer-reviewed studies have indicated, the base-line for storms has been raised due to climate change. With the El Nino developing, this should have turned out as a below normal season. It wasn’t.

  13. 63
    Crocodile Hunter says:

    re 62: Newton’s third law of climatology: for every climate explanation, there’s an equal and opposite explanation.

  14. 64
    Dan says:

    re: 63. Nothing “opposite” there. It is a simple, accurate scientific explanation that fits perfectly with the current studies about hurricanes and climate change.

  15. 65

    Re #63 Newton’s laws do not concern climatology because they describe linear systems. The climate is a non-linear dynamic (chaotic) system, for which the First Law rule is that that every law has an exception. The exceptions to this law are Newton’s Laws :-)

    [Response: Ummm... Newton's laws are the basis for the Navier Stokes equations which are highly non-linear. And chaotic dynamics in weather are a purely classical phenomenon - no special relatively there! - gavin]

  16. 66
    Leonard Evens says:

    Re 65:

    Let me echo Gavin. Newton’s equations are linear only if the forces are linear, which is seldom the case. In many circumstances one can use linear approximations within certain narrow ranges, but in many applications that is not feasible. A classical example is celestial mechanics. Most of chaotic dynamical systems is done starting with Newton’s laws, and is entirely classical.

    People should be careful about throwing around words that they don’t understand.

  17. 67
    an old federal regulator says:

    Re 62: But did El Nino form early enough and was it strong enough to have a significant effect on the hurricane season this year? Also, some scientists think the AMO is entering its positive (warm) phase – so, we would have expected an above average year based on that alone without the climate change signal. (Yes, I know, some scientists think the AMO is bogus.) I’m not disputing that climate change is occurring or that it’s a likely factor in hurricane formation. There’s ample evidence of climate change. But is the connection between El Nino, climate change and this year’s Atlantic hurricane season solid or is it more speculative?

  18. 68
    L. David Cooke says:

    In Reference to Original Post:

    Dear Dr. Schmidt;

    Just a request for clarification of the statement “One could quibble with the use of the high-energy UV (which never penetrates to the lower troposphere)”, what high-energy UV are you referring, UV-A, B or C EM energy, or could it be the energy insolation at altitude? I only mention it as this as the lack of presence of these frequencies seems inconsistant with general knowledge wrt terrestrial UV shielding requirements. Even if you are not being frequency specific and are speaking of energy content, is there not a recent change in the levels wrt the recent apparent Stratospheric Ozone reduction?

    Do we have any non-Labratory radiant energy measurement of the energy levels or changes of the energy levels/frequency at or above the 250mb altitude range with which to refute the study? (I reviewed the site and did not see any at altitude, only terrestrial readings and those were not high enough in resolution (through 2004) to be of much use.) I have not seen any measures in the TOA readings on any of the satellites that Dr. Scafetta was using in his Duke University studies either. (Any chance the next gen MODIS or EOS birds will have an experiment included to measure high “Q” (resolution) cloud top spectral (EMR) reflections?)

    I just mention this in passing as the energy levels required for the formation of the nitric tri-hydrates in the polar regions would appear to require a significant input of photonic energy to form in the presence of the PSCs (in the 16 to 24 km range)would it not? Also, if I understand correctly, this chemical phenomena is fairly recent or was this only due to a lack of measuring it until around 2003?

    Dave Cooke

  19. 69
    Ike Solem says:

    Around 1910 people thought that CO2 increases wouldn’t warm the planet for two reasons – (1) experimental setups showed that the infrared window was already saturated with respect to CO2 and H2O- adding more wouldn’t make a difference, and (2) it was assumed that the ocean would rapidly absorb any excess CO2 produced by fossil fuels.

    Gilbert Plass showed that the initial experiments were flawed – cold air at lower pressure behaved differently than at sea level (every spectroscopist knows that if you want sharper, tighter absorption bands you put the sample in liquid nitrogen, for example). (Charles Keeling’s measurements showed that the CO2 was not all going into the oceans)

    It seems that there are similar flaws in the connections between experiments described in this paper and the global climate system

    If you want a little background on cosmic rays and the magnetic fields of the Earth and the Sun: (Cosmic rays) (Solar magnetic field)
    If you look at the second link, you’ll see a graph of the sun’s solar activity; according to the ‘cosmic ray theory’ you should see ‘cool cloudy summers’ peaking around 2001 and warming peaking around 2006. Well… that doesn’t seem to fit!

    Another site worth looking at is
    However if you follow the link to ‘cosmic rays and the atmosphere’ they have a link titled “Influence of Cosmic Rays on Earth’s Climate” which takes you right to Svensmark’s page:

    It’s probably nothing more nefarious than trying to drum up attention for SLAC-related research. High energy physicists seem to live in a bit of a bubble, but that’s going a bit overboard. Stanford – tut, tut, tut.

    The main gem at the authors web site is this:
    “Estimated effect of the increase of CO2 (1750-present): 1.5 W/m2
    Estimated effect of doubling of CO2: 4 W/m2
    Radiative effect of clouds (cooling): 17-35 W/m2″

    Plus, the ‘references’ link only includes the author’s own work! That’s not how the references section is supposed to work…

    And from the author’s press release:
    “William Herschel, a famous astronomer in England, suggested in 1801 that the price of wheat was high when there were few sunspots. That link is now explained â�� a shortage of sunspots implies more cosmic rays and cloudy, cool summers. The recent discovery by our team in Copenhagen of the chemical mechanism of cosmic-ray action on cloud formation thus brings to a climax a scientific quest that has lasted two centuries.”

    Before the Nobels are passed out, perhaps it is worth considering the thorny issue of clouds – to briefly recap:

    (1) Clouds cool the Earth by reflecting incoming sunlight.
    (2) Clouds (and water vapor) warm Earth by absorbing heat emitted from the surface and reradiating it in all directions
    (3) Cloud behavior is itself changed by the warming or cooling of Earth.

    You might find these abstracts worth a brief perusal:
    Recent Trends in Arctic Surface, Cloud, and Radiation Properties from Space

    Why it matters: Cosmic ray fluxes are expected to be more noticeable at the poles (Aurora Borealis) due to the shape of Earth’s magnetic field, but polar climate appears to be dominated by the large-scale circulation.
    Rapid Formation of Sulfuric Acid Particles at Near-Atmospheric Conditions

    Why it matters: “The results demonstrate that under laboratory conditions similar to the atmosphere, particle formation occurs at atmospheric H2SO4 concentration levels.” This indicates that no ‘cosmic ray forcing’ is needed to form cloud condensation nuclei.
    Evidence for Large Decadal Variability in the Tropical Mean Radiative Energy Budget

    Why it matters: “We present new evidence from a compilation of over two decades of accurate satellite data that the top-of-atmosphere (TOA) tropical radiative energy budget is much more dynamic and variable than previously thought.” So – where does Svensmark get the 17-35 W/m2 radiative cooling number for clouds?
    The Complex Interaction of Aerosols and Clouds

    This last one is just more on how complex clouds are, particularly when the equally complex issue of aerosols is included.

    As gavin points out in his comment,
    “… Calculations of ‘Cloud radiative forcing’ (which is a specific kind of diagnostic – Cess et al definition) are not the same as the ‘radiative forcing’ in the sense of CO2. It is actually quite difficult to work that out and depends enormously on what kind of environment the extra clouds/aerosols are in (this is one of the big ‘missing steps’).”

    To summarize, this extrapolation of an isolated experimental result to the global planetery system is unjustified (conceptually similar to the c.1900 experiments with infrared light and CO2)

  20. 70
    Dan says:

    re: 67. Yes it formed early enough. Remember that even though the “official” start of the hurricane season is June 1st, it does not really get going climatologically speaking until very late summer. Furthermore, a developing El Nino itself can affect Atlantic hurricane season; it does not have to be peaking. Obviously it is too early for any peer-reviewed papers to come out on this season since it is not officially over. But the El Nino influence on this season has been discussed on NOAA sites.

  21. 71
    Crocodile Hunter says:

    Re 63: My “3rd law” remark was facetious but it has a serious side.

    At some point the scientists have to own their predictions. Post-hoc revisions of every prediction that doesn’t turn out the way you thought it would undermines your credibility. Economists are famous for it, but then that’s a big part of why their’s is the “dismal” science.

    Post-hoc explanations suffer from “early stopping”: you stop digging when you have found a sufficient explanation, but who is to say you’ve incorporated all the relevant phenomena?

  22. 72

    The lack of a trend in “cosmic ray flux” is presumably based on neutron monitors. What it suggests to me is that the wrong particle is being monitored in this connection. The lack of charge on neutrons implies that they are not involved in ionisation processes in the atmosphere.

    A more direct measure is the sunspot count over 400 years – – the obvious and evident (I don’t want to use the word correlation) similarity with global temperature trends beg the question of a causal relationship.

    The AAstar index – – again is suggestive of trends that reflect changes in global temperatures over the last century. As the theory involves magnetic modulation of the cosmic ray flux, the magnetic record (available over a relatively long period) may be more relevant than neutron monitoring.

    Let’s look at it from a different angle. It is known that there are climate trends that operate over a period of decades. These are powerful climate signals that impact ecologies and temperatures globally. These cycles were first discerned in 1996 in artic fisheries and since in sardine and anchovy abundances in Monterey Bay and in Australian rainfall and flood records. The cycles have been traced back in tree and coral proxies for 400 years – and so are undoubtedly a natural phenomenon that cannot be associated with rises in greenhouse gases.

    Australia now has quite good flood records going back more than 100 years. It has been known for some time that Australia experiences decades long periods of extended drought and, alternatively, decades long periods of flooding. These periods coincide with the temperature record of the last century. The period of rising temperature to the mid 1940′s saw drought, to 1975 was a wet period and then dry again to well now.

    Recent flood analysis suggests that the phenomenon is a result of modulation of both the frequency and intensity of La Nina and El Nino events in the El Nino Southern Oscillation.

    The possible phase reversal of the Pacific Decadal Oscillation since 1998 provides a robustly testable hypothesis. A “cool phase” would result in fewer and less intense El Nino episodes and a consequent fall in the trend line of global temperatures over the coming decades – depending on the relative strength of GHG and the natural background climate cycle climate forcing.

    The decline in solar activity, the decline in temperature since 1998, the slowing of the Great Solar Conveyor Belt (a long range predictor of sunspots), the increase in clouds in recent years may all be connected. There must be a stage at which the accumulation of “coincidence” becomes convincing.

    The cosmic ray flux theory appears to have considerable explanatory power for climate variations over timescales ranging from decades to millennium. If this is not the answer, one will need to be found before anthropogenic influences can be convincingly disentangled from the very powerful background variations.

  23. 73
    Grant says:

    Re: #72

    The lack of a trend in “cosmic ray flux” is presumably based on neutron monitors…

    A more direct measure is the sunspot count over 400 years

    I know very little about how cosmic ray flux is measured. But I do know that neutrons from space are cosmic rays, sunspots are not. You might therefore make a case that sunspot count as a proxy for cosmic ray flux is more meaningful, but to claim that a proxy (sunspot count) is a more “direct” measure than measurement of *actual cosmic rays* seems rather absurd.

    … the obvious and evident (I don’t want to use the word correlation) similarity with global temperature trends beg the question of a causal relationship.

    Some of the purported similarities are by no means quite so “obvious.” An extremely enlightening paper on this topic can be found here:

    … the decline in temperature since 1998…

    What decline in temperature is that? It doesn’t appear in either the GISS or HADCRU temperature time series — or any other that I’m aware of. In fact, according to GISS, 2005 was the hottest year ever recorded. Using either GISS or HADCRU temperatures, the difference between 1998 and 2005 is not statistically signficant.

  24. 74
    Urs Neu says:

    Re 72

    When we talk about no trend in cosmic ray flux this is related to the measurements starting in the 1950ies. The claimed effect of GHG is also mainly after 1950. If you have a closer look at the sunspots you will detect that there is no trend neither in sunspots nor in the aa index nor in direct cosmic ray flux since 1950. However, the temperature trend since 1950 is quite large. So how do you explain this rise without GHGs?
    Nobody claims that GHGs are the reason of all the temperature trend for the last 400 years.

  25. 75
    Tom Fiddaman says:

    Re 72

    Neutrality is irrelevant; ionization occurs due to collisions. The source cosmic rays are a mix of particles, mainly protons, and the measured neutrons are secondary.

  26. 76
    Charlie T says:

    Re 74 ‘So how do you explain this rise without GHGs?’

    Urs, to play devils advocate; De Laat and Maurellis ‘Industrial CO2 emissions as a proxy for anthropogenic influence on
    lower tropospheric temperature trends’

    If the economic signatures that DL&M found in temperature series are genuine (and not simply artifacts of, say, the north south split in economic activity) then solar plus aerosol plus direct anthropogenic could be quite a powerfull combination?

  27. 77
    James says:

    Re #72, among others. I’m having a bit of a conceptual problem in understanding why sunspots are a valid proxy for cosmic ray rates. The CalTech site on cosmic rays linked in #69 says

    “The term “cosmic rays” usually refers to galactic cosmic rays, which originate in sources outside the solar system, distributed throughout our Milky Way galaxy.”

    That certainly seems to imply that most cosmic rays originate outside the solar system. So could we have some numbers, please? What fraction of cosmic rays actually come from the sun? What is the variation between high and low solar rates?

    Furthermore, if I remember my general astronomy correctly, the solar particle flux increases dramatically during solar flares. Flares sometimes hit Earth, with measureable effects such as more widespread aurorae, disruptions to radio & electric power grids, etc. Do we also see increased cloudiness at these times? If not, doesn’t that weigh heavily against any cosmic ray connection to climate?

  28. 78

    Wow – this is an active site. At comment No. 72 – I expected that no one
    wuld read it.

    The temperature decline since 1998 – it is perhaps more accurate to say that there was no increase in temperature.

    The difference between 1998 and 2005 is statistically insignificant. One argument goes that 1998 was affected by a strong El Nino whereas 2005 wasn’t and so should be considered the warmer year. The trend line of temperature increase since 1998 is not statistically different from 0.

    If we look only at observed climate phenomenon. What I know most about is flood forecasting in Australia. Australia has quite good flood records going back more than 100 years. It has been known for some time that Australia experiences decades long periods of extended drought and, alternatively, decades long periods of flooding. These periods coincide with the temperature record of the last century. The period of rising temperature to the mid 1940′s saw drought, the period to 1975 was a wet period and then dry again to – well – now. The decline in temperature between 1945 and 1975 indicates that this is a powerful phenomenon with the potential to swamp the GHG signal.

    Recent flood analysis suggests that the phenomenon is a result of long term modulation of both the frequency and intensity La Nina and El Nino events in the El Nino Southern Oscillation.

    The connection between more frequent and more intense El Nino and global temperature is obvious.

    The decades long cyclic climate variation is in principle predictable based on a negative trend of the Pacific Decadal Oscillation (PDO)index. Other empirical evidence supports the idea of a phase shift in the PDO since 1998 – although I am still waiting for a hard rain to fall.

    The connection of solar magnetism to climate is an intriguing idea at this stage.

    The idea seems worth pursuing as a possible explanation for the observed phenomenon – phenomenon that were never adequately explained by GHG forcing alone.

    I am by no means endorsing continued increase in GHG’s in the atmosphere. Even with a moderation of the GHG climate signal, there are still serious problems with that course of action. We may, at best, buy some time.

    In the response to my post – I feel I have recieved some of the respect due to a serious commentator – beats being ignored. Thank you anyone who is interested.

  29. 79

    Just a quick addendum on cosmic rays – the idea is that solar magnetism modulates cosmic rays. Not 100% convinced but intriguing nonetheless.

  30. 80
    gary says:

    Re #73 What decline in temperature is that?

    Perhaps he googled “Did Global Warming Stop In 1998?”

    Some folks are interpreting data to show either zero increase, or even a slight decrease in global temperatures since 1998.

  31. 81

    Re #77 and “I’m having a bit of a conceptual problem in understanding why sunspots are a valid proxy for cosmic ray rates. The CalTech site on cosmic rays linked in #69 says ‘The term “cosmic rays” usually refers to galactic cosmic rays, which originate in sources outside the solar system, distributed throughout our Milky Way galaxy’.”

    The sources of the cosmic rays are interstellar, the strength of the Earth’s magnetic field determines whether they get through to Earth’s surface or not, and the latter is partly affected by solar activity.


  32. 82
    Steve Hemphill says:

    I think it’s apparent that cosmic rays (leading to muons – charged particles, not neutrons anyway) can’t explain the changes of the very late 1900′s. However, a couple of bigger questions are:
    1. Can they affect, or bias, cloud formation?
    2. Is this discussion really about the MWP, with the truly global proxy of C14 production? If that is the case, what are we doing to science by denying it?

    Does this need a lot more study or not?

  33. 83
    Mike Bauer says:

    I see “The Economist” magazine is printing a favorable blurb about how a new experiment will shown how comic rays alter climate…. see it online at

    I wish the economist allowed user feedback/posts … I’d direct people here.

  34. 84
    James says:

    Re #81: “The sources of the cosmic rays are interstellar, the strength of the Earth’s magnetic field determines whether they get through to Earth’s surface or not, and the latter is partly affected by solar activity.”

    Thanks for the clarification. Still leaves me with a couple of questions, though. First, whether there is any correlation between solar flares and clouds, which it seems there ought to be if the theory is correct.

    Second, the Earth’s magnetic field periodically reverses itself. Presumably there is a period (which I seem to recall reading might be on the order of centuries) in which the field is close to zero, and thus exerts no protective effect. These periods ought to be extraordinarily cloudy, shouldn’t they? If comparatively minor changes produce observed global warming, shouldn’t the larger changes of the reversal periods have produced even greater climate change? Is there any geological record of this?

  35. 85
    David B. Benson says:

    James, I too would like a fairly definitive answer to your last question. Unfortunately, I doubt that the climate prozy records are sensitive enough to leave mush trace of an event lasting only ‘a few centuries’. Hope somebody can show I am wrong about this…

  36. 86

    Gavin, Your statement that “Finally, to show that cosmic rays were actually responsible for some part of the recent warming you would need to show that there was actually a decreasing trend in cosmic rays over recent decades” ignores the climate commitment studies that show that surface temperature takes decades to equilibrate to a new level of forcing, and sea level can take a thousand years or more. A cosmic ray reduction from the first part of the century, that is sustained without any further trend in the latter part of the century could explain some part of the recent warming. The argument that you put forward here and also use in “How not to attribute climate change”, that an increasing trend in solar activity or a decreasing trend in cosmic rays in the most recent decades is required is not in accord with the climate commitment literature.

  37. 87
    John Lederer says:

    Is it assumed all variations in GCR energy and frequency at the edge of the earth’s atmosphere are the result of solar effects?

    [Response: On the short (up to millenia?) timescale, I think so. On longer scales you cna invoke modulation by the suns orbit in the galaxy - William]

  38. 88
    C. W. Magee says:

    Our weekly seminat here at ANU may be topical:

    Jan Veizer (Ottawa-Carleton Geoscience Center, University of Ottawa)


    4:00 pm, Thursday 2nd November
    Jaeger Seminar Room, RSES

    The observed temperature increase of ~ 0.6C over the last century has been attributed (IPCC) by ~ 2/3 to greenhouse gases (GHG) and ~ 1/3 to an increase in solar irradiance (TSI). Such relative attribution reflected the general consensus that no credible amplifier to muted changes in TSI was known. Recently, however, a spate of empirical observations demonstrates that sun-climate connections are apparent in a plethora of high-fidelity climate indicators, suggesting that “solar influence on climate is greater than would be anticipated from radiative forcing estimates” (Hadley Centre technical note 62). The most likely amplification candidates are high-energy particles such as cosmic rays and solar protons, via their potential role in cloud formation. Juxtaposition of empirical records of paleoclimate with proxies for atmospheric CO2 levels vs. celestial (solar and cosmic rays) intensities, across a hierarchy of time scales, indeed favours a reversal of the relative impact of the above climate “drivers”, the last few decades being the focal point of the ongoing controversy. In the above scenario, the celestially modulated planetary energy balance drives the hydrological cycle, with the carbon cycle “piggy-backing” on the water cycle “thermostat”.

    [Response: "and ~ 1/3 to an increase in solar irradiance (TSI)" is wishful thinking. I don't remember that from the TAR. Sadly its site is down now so I can't check - William]

  39. 89
    L. David Cooke says:

    Comment Related to #88


    I believe the reference is the 2007 draft based on what seems to have leaked out so far. Anyway, I wonder if there might be a point here that has been missed. We keep talking about earth being the black body and absorbing the lions share of the incoming radiative solar energy. We have discussed aerosols and water vapor to death and found all to be lacking. The numbers attributed to GHG seem in some sectors to be in question especially in light of the very recent data of the last nine months.

    My question, What if the incoming radiative energy was not all absorbed and reradiated by a terrestrial source. What if the aerosols were to participate in absorbing the incoming radiated solar energy and via convective process to transfer some of the energy to the surrounding air. What if instead of a sperical radiative black body with a diameter of 7726 miles miles you have a black body with a 7926 mile diameter and an average density of 1.48 instead of 1.5? What happens if the aerosol counts of very small aerosols were to increase dramatically, either as hold overs of very small volcanic dust, Kuwaiti oil field fires, forest fires, and possibly now, additional cosmic particles in an era of apparent weakened planetary magnetic field? What happens if the water content of the atmosphere were to increase from an average of say 30% to an average of 50% in addition to the increased aersol density?

    Sorry more questions than I perhaps should be alloted. It seems I have more questions then I have publically avilable resources to pull from.

    Dave Cooke

  40. 90
    Urs Neu says:

    Re 76

    De Laat and Maurelli is one more example of a study looking for simple correlations without accounting for other influencing factors. They ignore e.g. that 1. the difference of the increase of temperature over land and the ocean will automatically produce a correlation of CO2 emissions and temperature trend since CO2 emissions are almost all over land; 2. CO2 is well mixed in the atmosphere and therefore a correlation to emissions is unlikely; 3. During the time frame they investigate, aerosol emissions have declined over the areas with most intense emissions, possibly leading to an enhanced warming. Aerosol concentrations vary much more regionally than CO2, therefore a link to regional emissions is much more likely to aerosols, not CO2.

    Moreover, they worked with data that have since been corrected (the UAH data), and the difference between surface and lower troposphere temperature trends which they discuss has more ore less vanished.

    Summary: Some outdated speculations…

  41. 91
    C. W. Magee says:

    “What happens if…”

    I think most of those things would get measured, and people would take note- esp. a vast increase in atmospheric H2O, which is under continual weather sat observation.

  42. 92
    Urs Neu says:

    Re 88

    Be aware that Jan Veizer, an emeritus professor, is a profound AGW sceptic, who disputes that there is a significant influence of CO2 on climate, who tells that water vapour is a much more important greenhouse gas, that CO2 reacts on temperature and not vice versa, and more well-known sceptics stuff.

    And remember from my comment 59: Reconstructions (of temperature, CO2, cosmic rays etc.) are so different and have such high uncertainties especially on the multimillion year time scale, that it is no problem to show either a match or a mismatch of the same parameters by choosing specific data sets, tuning the data (within the frame of the uncertainties) and making enough assumptions.

    These remarks are among others related to some work of Veizer. Be aware that much of the cosmic ray-climate connection that Jan Veizer will show, especially on the geological time scale, is the result of an awful lot of picking and tuning (see e.g.

    Unfortunately a lot of geologists (by far not all of course) ignore 1. that geological time scales and the time scales of AGW are way different; 2. that anthropogenic CO2 emissions is a factor that has not existed at the times they are looking at and thus they will logically only find natural variations; and 3. that a new developing factor is not a priori unimportant just because it hasn’t existed before.

  43. 93
    Fergus Brown says:

    Re #82 and others. A new paper from GRL. I don’t subscribe, so somebody will have to do the dirty work, The abstract is tantalising:

    GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L21802, doi:10.1029/2006GL027820, 2006

    Different response of clouds to solar input

    Mirela Voiculescu

    Department of Physics, â??Dunarea de Josâ?? University of Galati, Galati, Romania

    Ilya G. Usoskin

    Sodankylä Geophysical Observatory, (Oulu Unit), Oulu, Finland

    Kalevi Mursula

    Department of Physical Science, University of Oulu, Oulu, Finland

    There is evidence that solar activity variations can affect the cloud cover at Earth. However, it is still unclear which solar driver plays the most important role in the cloud formation. Here we use partial correlations to distinguish between the effects of two solar drivers (cosmic rays and the UV irradiance) and the mutual relations between clouds at different altitudes. We find that the solar influence on cloud cover is not uniquely defined by one solar driver, but both seem to play a role depending on the climatic conditions and altitude. In particular, low clouds are mostly affected by UV irradiance over oceans and dry continental areas and by cosmic rays over some mid-high latitude oceanic areas and moist lands with high aerosol concentration. High clouds respond more strongly to cosmic ray variations, especially over oceans and moist continental areas. These results provide observational constraints on related climate models.

    Received 9 August 2006; accepted 27 September 2006; published 1 November 2006.


  44. 94
    Erich J. Knight says:

    Percentage of low clouds due to Cosmic Rays:

    WOW…….What a great thread!

    I started several threads, in various science forums, titled ” Lightning Comes from Space” citing Joe Dwyer’s work at FIT on runaway cascade initiation of CG lightning from his observations of X-Rays and Y-Rays.

    Dwyer’s paper:

    Looks like I’ll have to update them with ” Clouds Come from Space Too”

    It will be interesting when we know what exact % of cloud cover is created by CRs.

    If it is high, One of my greatest fears is the Republicans trying to use it to obfuscate the dangers of Green house gases.

    Here are the best numbers I’ve found for the % of low clouds due to Cosmic Rays:

    â??â?¦ cosmic rays. These high-energy particles originate in outer space and in solar flares, and can have a small but significant effect on the weather, increasing the chances of an overcast day by nearly 20 per cent.
    Giles Harrison and David Stephenson from the University of Reading, UK, examined 50 years of solar radiation measurements from sites all over the country, enabling them to calculate daily changes in cloudiness. By comparing this data with neutron counts – a measure of cosmic ray activity – for the same period, the scientists have shown an unambiguous link between cosmic rays and clouds (Proceedings of the Royal Society A, DOI: 10.1098/rspa.2005.1628).
    “The odds of a cloudy day increase by around 20 per cent when the cosmic ray flux is high,” says Harrison, amounting to a few extra days of cloudiness per year.â??

    Thanks for your explanations
    Erich J. Knight

  45. 95
    Steve Hemphill says:

    re 92 #2,

    This is also misattributed by those who link CO2 with temperature. A deep, basic, unproven attribution.

    What if CR’s modify cloudiness and CO2 amplifies convection, increasing albedo? It is within the range of the uncertainty.

  46. 96
    Urs Neu says:

    Re 95

    Just two things: 1. The link of CO2 to temperature is not based on reconstructions on the geological time scale, but on solid physics. 2. There is no need to change the frequencies of the ice age cycles for CO2 in order to get a fit to the temperature cycle. However, you have to adjust the frequency of million year cosmic rays cycle considerably to get a match to the temperature.
    The cosmic ray-climate link very often needs artificial adjusting of data to get the match, the CO2-climate link does not.

  47. 97

    Re #95 and “This is also misattributed by those who link CO2 with temperature. A deep, basic, unproven attribution.
    What if CR’s modify cloudiness and CO2 amplifies convection, increasing albedo? It is within the range of the uncertainty.”

    The attribution of temperature rise to CO2 is not “unproven” at all, it is basic radiation physics. Joseph Fourier speculated on the greenhouse effect in 1824, John Tyndall demonstrated that CO2 absorbs infrared light in 1859, Svante Arrhenius made the first quantitative estimate of global warming under increased CO2 in 1896. The effect of atmospheric CO2 on surface temperatures is so well demonstrated that you would have to be grossly ignorant of radiation physics to deny it.

    And how, precisely, does convection increase the planet’s albedo?

  48. 98
    Erich J. Knight says:

    The current Nature has a couple studies, a little off topic concerning sun forcing of climate …….but these measurements do provide an Earth magnetic field history 800,000 years ago and implies stability of geodynamo processes on billion-year timescales.

  49. 99
    William Astley says:

    The criticism of Svensmark and colleagues’ search for a solar forcing mechanism is perhaps unfair, as there is significant Palaeoclimatic proxy data that links concurrent changes in cosmogenic isotopes (solar forcing evidence) with ice core and other proxy evidence of rapid climatic changes. There is a smoking gun, so to speak. If the smoking gun data is accepted, the question then becomes how the sun likely causes rapid climatic change events, not if the sun causes rapid climatic change events.

    For example the paper: “The role of solar forcing upon climate change” Published 1999.

    “A number of those Holocene climate cooling phases… most likely of a global nature (eg Magney, 1993; van Geel et al, 1996; Alley et al 1997; Stager & Mayewski, 1997) … the cooling phases seem to be part of a millennial-scale climatic cycle operating independent of the glacial-interglacial cycles (which are) forced (perhaps paced) by orbit variations.”

    “… we show here evidence that the variation in solar activity is a cause for the millennial scale climate change.”

    Last 40 kyrs
    Figure 2 in paper. (From data last 40 kyrs)… “conclude that solar forcing of climate, as indicated by high BE10 values, coincided with cold phases of Dansgaar-Oeschger events as shown in O16 records”

    Recent Solar Event
    “Maunder Minimum (1645-1715) “…coincides with one of the coldest phases of the Little Ice Age… (van Geel et al 1998b)

    “Mayewski et al (1997) showed a 1450 yr periodicity in C14 … from tree rings and …from glaciochemicial series (NaCl & Dust) from the GISP2 ice core … believed to reflect changes in polar atmospheric circulation..”

  50. 100
    William Astley says:

    In follow-up to comment 99, that there is significant Palaeoclimatic evidence that links concurrent changes in cosmogenic isotopes (solar forcing evidence) with ice core and other proxy evidence of rapid climatic changes, the following is a paper that discusses the Younger Dryas and Solar Forcing.

    “Reduced solar activity as a trigger for the start of the Younger Dryas?”

    From the paper, “Estimates for the start of the YD all demonstrate a strong and rapid rise of C14 (Cosmogenic isotope that increases when there is decreased solar activity that hence allows increased galactic cosmic rays GCR to strike and interact with the atmosphere.) This change is the largest increase of atmospheric C14 known from the late glacial period and Holocene records.”

    The paper also provides evidence that challenges Broecker’s hypothesis that a sudden stoppage of the thermohaline conveyor, caused the YP. (The paper address the question as to what could have stopped the THC. Also noted has evidence from ocean core data that the THC did not change during the YD.)

    “The main late glacial meltwater pulse found by Fairbanks (1989) is dated 14ka BP, thus at least 1000yrs before the start of the YD (Bard et al., 1996). Maybe, regional meltwater pulses, occurring near locations of the NADW formation, could have perturbed the THC. However, ocean records near the mouth of the St. Lawrence river suggest the opposite, giving evidence of a reduced meltwater outflow from the Laurentide Ice sheet near the start of the YD (de Vernal et al.,1996) Also, the initial drainage of the Baltic ice lake occurred a few hundred years after the start of the YD (Boden et al.,1996). In any case, ice rafting can be excluded as the trigger, since ocean cooling started before the ice rafting occurred (Bond, 1995). Moreover, the ice sheets in N. America, Scandinavia and Iceland fluctuated coherently, thus implying that ice rafting was triggered by climate and not vice versa (Fronval et al., 1995; Bond and Lotti, 1995).

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