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Galactic cosmic rays: Backing the wrong horse

Posted on 24 September 2011 by muoncounter

The popular press is still pushing the preliminary CERN CLOUD results as proof that galactic cosmic rays (GCRs) are a major influence on climate. We've already had an excellent rebuttal here on SkS, featuring Jasper Kirkby's own words urging a more sober interpretation of his preliminary results.  Yet those who do not fully understand the science are willing to bet that they have proof positive of the GCR-climate connection.  Here is another look at the science of cosmic rays, in which we find out that's not a very good bet.

In horse racing, there's a payout for the 1st, 2nd and 3rd place finishers.  All the other horses in the race finish 'out of the money.'  One way to go broke very quickly is to repeatedly back the wrong horse.

 

 

 

Let's Check the Odds

The GCR-climate connection is based on well known science:  cosmic rays do indeed contribute to ionization of the earth's  atmosphere (known as CRII, for cosmic ray induced ionization).  Whether CRII leads to enhanced cloud formation is the basic conjecture that GCR supporters want to establish.  They must then show that GCR-induced clouds (if any such exist) in turn produce observable climatic effects. 

If this is to be a horse a race, we must examine the field of entrants and study their track records.  The full family of particles observed when an energetic primary GCR particle enters the atmosphere is illustrated below.

-- source

The CERN CLOUD experiment uses a positive pion beam of 3.5 GeV energy, a relatively middle-of-the-road energy on the spectrum of GCRs.  Thus CLOUD backs only one horse in this race: the right-most interaction, pions (π) decay to muons (µ) and neutrinos (ν); note that this interaction does not produce neutrons and is thus invisible to neutron monitors around the world.  What of all the other particle interactions on the diagram above?  Which horse is the favorite in this race?

Picking a Favorite

Cosmic ray particles sourced by the sun are  known as Solar Energetic Particles (SEPs) -- these are typically fast-moving solar wind protons.  The energy associated with SEPs runs as high as 5 GeV, equivalent to a flux of  3x10-6 to 2x10-5 W/m2.  Those on the lower end tend to penetrate only the upper atmosphere; these are the events that can lead to Forbush Decreases (FDs).  Even higher energy SEPs can lead to significant increases in particle count rates at the earth's surface known as Ground Level Enhancements (GLEs).  These events produce the additional particles shown in the illustration above; we do indeed see these events on neutron monitors. 

The image below is a composite of neutron monitor records, illustrating the distinction between the appearance of FDs and GLEs.  FDs have been observed as precursors to GLEs.  In this example, the count rate multiple is approximately 25%, so the GLE is not particularly energetic.

FD and GLE

-- source

Usoskin et al 2009 investigated ionization by GLEs (emphasis added):

"There is a strong correlation between the GLE magnitude (in Neutron Monitor %) and the ionization effect in the stratosphere ... – all strong GLEs led to a more than 10% enhancement of CRII in the polar region. There is still some weak relation in the upper troposphere ... – all strong GLEs lead to a slight positive ionization effect.  ...

SEP play a role in the ionization only in the upper-middle polar atmosphere. In all other regions the ionization is suppressed due to the accompanying Forbush decrease. ... There is no ionization effect at mid- or low-latitudes, even for the strongest events. It is clear ... that there is no straightforward relation between the strength of GLE (as measured by neutron monitors) and the ionization effect in polar atmosphere. The net atmospheric ionization effect is defined by an interplay between the SEP event itself and a Forbush decrease, which often accompanies it."

That last statement is key to understanding just how difficult it is to establish a cosmic ray-climate connection:  Not all cosmic ray increases ionize the atmosphere.  This horse race went from a walk in the park to a long, slow steeplechase on a very muddy field.

Jumping the Ionization Hurdle

Many GLEs originate as X-class solar flares and are thus relatively rare.  The neutron monitor at  Oulu, Finland observed  55 GLEs during the 50 year period 1960-2010. The neutron count rate increased by more than 10% in only 21 of these recorded GLEs.  One of the largest occurred on 20 Jan 2005, as reported by a number of authors.  From Bieber et al 2005,

"Within a 6-minute span on January 20, 2005, the count rate registered by a neutron monitor at the sea level station of McMurdo, Antarctica increased by a factor of 30, while the rate at the high-altitude (2820 m) site of South Pole increased by a factor of 56."

Inuvik and Fort Smith, Canada reported count rate multiples of 4-5; at Oulu the increase was 269%.   High multiples of the background count rate persisted for several hours.  Per Moraal et al 2008, the protons in this GLE contained a spectrum of energies from ~1.5 - 5 GeV; they also reported that the GLE was composed of at least 3 distinct pulses of particles arriving at the surface of the earth (the first of which caused a Forbush Decrease).  Mironova et al 2011 looked at ionization due to this GLE (emphasis added):  

"The very high level of neutron monitor count rate increase implies that the ionization of the polar atmosphere was dramatically increased during the event ... the calculated ionization due  to the SEP event of 20 January started dominating over the GCR ionization already at 10-km altitude and reached its maximum at about 30 km altitude.  In particular, the CRAC:CRII model calculations suggest that the SEP event produced additional ionization in the polar atmosphere in the altitude range 12–23 km, with the number of ions being greater by a factor of 3–30 than the averaged GCR-induced daily ionization in January 2005." 

Mironova also looked for atmospheric effects due to this GLE (emphasis added):

"We would like also to emphasize that the observed atmospheric effect for this extreme GLE event was barely significant. No clear atmospheric effect was found beyond statistical fluctuations for the weaker SEP event of 17 January 2005, which is a typical SEP event. This implies that only extremely hard-spectrum (high energy) GLE/SEP events can produce a noticeable direct effect on aerosols in the polar low-middle stratosphere."

Thus one of the strongest known GLEs, producing much more ionization than the typical GCR, had no direct affect on the weather - and the sum of many such events will have no connection to climate

In this horse race, until the CLOUD experiment can clear the ionization hurdle by investigating the complex relationship between FDs and higher energy GLEs, it will continue to be tripped by this hurdle and always finish out of the money. Those who've put their money on CERN CLOUD finding a GCR-climate connection are backing the wrong horse.  

 

 

 

Note:  Revised 9/24/2011

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Comments 51 to 100 out of 121:

  1. Eric, you're making suggestions that GCRs drive deglaciation and the Younger Dryas, yet these are not supported by evidence or your references. What is your support for GCRs being necessary for deglaciation in our current geographic configuration? Why, when this configuration has lasted throughout the Quaternary, are glaciations and deglaciations timed with orbital forcing? An again, why does any noticed correlation necessitate a causal connection?

    Your assertion about GCRs and the Younger Dryas is unsupported by the Hughen et al 2004 article from which you take your graph:
    "Peaks in 14C are also reconstructed at 40 and 29 cal. ka B.P. and previously reported at 12 cal. ka B.P. (13), coincident with Heinrich events H4, H3, and H0 (Younger Dryas), respectively (35). These events may also have been associated with unusually large perturbations in ocean ventilation and sea-ice cover explaining “anomalously” elevated 14C at those times
    (23, 36)."

    The main hypothesis is that the radiocarbon plateaux are driven by oceanic circulation changes (Hughen et al 2000 is ref 13 in the above quote). There is also doubt about the Cariaco radiocarbon spike - Muscheler et al 2008 suggest that upper ocean changes in the Cariaco basin itself influence the record.
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  2. Eric#48: The last sentence of the Laken abstract sounds like the standard qualifier, YMMV, to me. What significance do you see in it?

    "A control knob need not be overwhelming and instant and this GCR link would be offset by oceanic cycles and other weather."

    If this so-called control knob is so easily offset, then why maintain that it is a 'control' of any kind? At best, it is a fine tuner. But you cannot suggest that a GCR-cloud mechanism, if real, has some sort of lag. Ionization and cloud condensation either makes clouds or it doesn't.

    "A large decrease in GCR flux appears necessary for deglaciation"

    Again, where is the evidence for this declarative statement?

    The YD is not without its own complexities, as reported by Hughen et al 2000:

    the Younger Dryas 14C anomaly, which is by far the largest of the last 15,000 years, is not matched in amplitude by corresponding atmospheric 10Be concentration estimates. Thus, available 10Be data do not support the interpretation of the Younger Dryas 14C anomaly as solely or mostly due to increased production.

    In order to promote the speculative GCR-climate connection into a 'control knob,' you'll need a lot more evidence, a mechanism and most critically, an explanation for the climatological non-event at the Laschamp GCR peak.
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  3. Tom, thanks for the comment. Yes, GCR's + or - do not result in positive forcing sufficient to exit the snowball state. GCR is definitely not the control knob, but one of several. The main theory seems to be cooling from high GCR's. It seems to me a more precise theory is that high GCR's retard or preclude warming by other means. Looking at the earth's magnetic reversals, http://upload.wikimedia.org/wikipedia/en/c/c0/Geomagnetic_polarity_0-169_Ma.svg in a very rough sense, more reversals (with coincident weakening) allows more GCR and more cooling. Obviously earth's reversals are a small part of the modulation of GCR so not a strong connection.

    I was unaware of the complexities of Be10 and I am sure there are some for C14 as well. The correlation of low Be10 measurements with higher rainfall could explain some of the Mercurio chart and is worth looking into further.
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  4. Thanks for the clarification Sphaerica. CO2 being "not a control knob" for preindustrial has a couple exceptions that Tom pointed out on the other thread. There are times when it was in the past along with methane.

    Muoncounter and skywatcher, I agree that YD is not strong evidence, but more study is needed to determine the causes which AFAICT remain unknown. Another bit of evidence for a GCR knob is LIA cooling although it coincides with decreased TSI as well. I don't think the Laschamp event is a good test of GCR impact since we were in a glacial state which was probably a somewhat stable state.
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  5. Because of the importance of C14 to dating, the isotope and its interactions have been very closely studied for a long time. Be10 is nowhere near as well understood and I have colleagues working on hard on it.

    If GCR is important to YD, then why is it decoupled between hemispheres? For the corresponding SH events, you have ACR (Antarctic cold reversal) started before YD and finishing as YD gets going.

    This is fascinating area of study but the collected evidence from both hemispheres I think supports the idea that these events, associated with deglaciation, have there origin in ice sheet dynamics and interactions with the THC rather than some external forcing.
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  6. Eric#53: "in a very rough sense, more reversals (with coincident weakening) allows more GCR and more cooling."

    A geomagnetic reversal includes a period of time (decades? hundreds of years?) when the field is of very low intensity. If the GCR story is to be believed, these must be times of high GCR flux, cloud formation and significant cooling. However, Lee and Kodama 2009:

    report high-precision records of a magnetic reversal event at the Paleocene-Eocene thermal maximum (PETM), a cataclysmic global warming event initiated at 55.0 Ma.

    But that's the earth's magnetic field; GCR orthodoxy involves solar output - those FDs that are supposed to be harbingers of fewer clouds. Is there a connection between geomagnetic reversals and the solar wind?
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  7. Scaddenp, the difference between hemispheres reduces one of the explanations of the C14 spikes (suggested in 51 and 52). The GCR effects could vary depending on the amount of ocean versus land, but I have no information for or against that idea.

    Muoncounter no possible connection between magnetic reversals and solar inputs that I can imagine. The PETM magnetic reversal was isolated and probably just coincidence (see the chart in my post 53. Certainly the link from magnetic field reversals to climate is going to be very tenuous due to the rather short duration of the change as you point out.
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  8. Hmm, why would cooling start in SH and then end as NH goes cold? (Actually not an uncommon pattern). I think other explanation other than GCR remain a great deal more plausible. Also, the real question of interest, is whether the forces at play in these events could be still impacting modern climate. Very difficult to find evidence for that.
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  9. Eric #54, not only is there not strong evidence for a YD/GCR link, there is no evidence for a YD/GCR link. Your saying so does not count as evidence. We have a very plausible mechanism in place for the observed changes of C14 and of regional cooling, in the form of changes in oceanic ventilation driving changes in delta C14. Changes in oceanic circulation conveniently also help explain the see-saw effects between SH and NH cold periods (noted by scaddenp in #55). Why invent a cause that as yet has no connecting driving mechanism, and fails to explain all the evidence?

    The failure to explain the Laschamp anomaly is still not a help to your thinking. Why would it have no effect during a glacial phase? And you certainly cannot have any timelag (your #48), given that the few proposed (yet not demonstrated) mechanisms for a GCR-climate connection require it to be immediate.
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  10. scaddenp, except for perhaps a partial explanation for the LIA, I have not found convincing evidence of a cosmic ray effect on modern climate (i.e. late 20th century warming)

    skywatcher, conditions are different enough during glaciation to have a no GAT response to a large influx of cosmic rays and other coincidental effects. Life which can be killed off by possible coincidental solar flares would be different and restricted; there would be much drier air for less cloud formation; and there would be a lot more dust prior the event for nuclei so the event would not add much.
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  11. Hi Eric @60 I found this very interesting
    On infrequent occasions when the Platteville, Colorado,
    10-MW radio transmitter matched the F region peak plasma frequency, intence localized sporadic E layers occured at low altitudes (95 km) Here is the link to the full artical
    http://www.ngdc.noaa.gov/stp/IONO/Dynasonde/images/HeatPrecip.pdf I started here, got me interested when looking at charged particals (free electrom formation) Ionespheric Heating http://www.ngdc.noaa.gov/stp/IONO/Dynasonde/SpEatHeating.htm
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  12. jmorpuss, thanks for the links. Lots of interesting effects measured by the Dynasonde but I'm not sure how much energy is involved.
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  13. Eric #60, I thought you were better than that. You've provided no supporting evidence (and I suspect there is none) for any of the statements in #60 (yes, the LGM was dusty, but not insensitive to climate change). "Life which can be killed off by possible coincidental solar flares..." Pull the other one, Eric, this is a rubbish climastrological statement. The world might end on December 21st too.

    jmorpuss, does your link actually have any relevance to the OP?
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  14. Eric#6: "there would be much drier air for less cloud formation;"

    Glacial stages cannot be dry - accumulated precipitation (albeit frozen) is a requirement for firn/glacial ice advance. In addition, much of the globe wasn't ice-covered. I don't think your 'we won't see GCR evidence during glacial stages' idea has much support.
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  15. Another stake in the heart of the GCR-climate connection:
    Love et al 2011 Are secular correlations between sunspots, geomagnetic activity, and global temperature significant?

    We examine the statistical significance of cross-correlations between sunspot number, geomagnetic activity, and global surface temperature for the years 1868–2008, solar cycles 11–23. ... Treated data show an expected statistically-significant correlation between sunspot number and geomagnetic activity, ... , but correlations between global temperature and sunspot number (geomagnetic activity) are not significant. In other words, straightforward analysis does not support widely-cited suggestions that these data record a prominent role for solar-terrestrial interaction in global climate change.

    That statistical significance thing is a bother, no?
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  16. skywatcher, if what I say is purely speculation I will try to caveat appropriately it (e.g. "I don't have evidence in front of me, but I think...") Irregardless I should have supported #60 a little more. Dust is an important feedback in glacial periods although not well understood and quantified (e.g. http://www.sciencedirect.com/science/article/pii/S0277379111002861 and (for Muoncounter) the air is drier during glacial periods http://earth.geology.yale.edu/~wb98/papers/Boos2011_LGMthermoscaling_090711.pdf although with latitudinal variation. Ice sheet build up does not require more precip, just precip over the ice sheet. The dust is the result of the predominately drier climate. The dust makes cosmic rays somewhat moot.

    Skywatcher, yes, my solar flare idea is somewhat spurious, only supported by the increased probability due to lack of a protective magnetic field. But it is not a valid reason as to why the explain the Laschamp anomaly did not produce a climate change, I should not have brought it up. The lack of climate change rests sufficiently on the fact that the glacial climate is dry. How would more clouds form in a dry atmosphere (and stable tropical atmosphere, see Boos paper)?
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  17. Eric#66: "the air is drier during glacial periods"

    And yet it must have rained:

    Lake Bonneville was a large, ancient lake that existed from about 32 to 14 thousand years ago. ... At its largest, Lake Bonneville was about 325 miles long, 135 miles wide, and had a maximum depth of over 1,000 feet. ... Its relatively fresh water was derived from direct precipitation, rivers, streams, and water from melting glaciers. During the time of Lake Bonneville, the climate was somewhat wetter and colder than now.
    -- source
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  18. Eric, you don't have to convince me that LGM conditions tend to be drier. What you have to convince me of is a connection between cosmic rays and climate, of which there is no observational or experimental evidence! To justify your statement in #60 about when GCRs could and could not affect climate, you'd have to have a mechanism by which they affect climate. Otherwise you're playing word games and wasting time with wild speculation. What is the mechanism (as I asked in #46 with reference to the article on SkS showing what is required by the GCR speculations)?

    Also worth noting that the Laschamp anomaly (graph in #29) covers both colder and warmer conditions according to delta-18O, so discussions about dustiness of the atmosphere are pretty spurious.
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  19. #67, muoncounter, I believe they are talking about the local climate.
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  20. Skywatcher, I owe you an answer...
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  21. skywatcher the GCR's my top plot in 38 show upward spikes (inverted show depicted as downwards) without much response during glacial periods. Although scaddenp points out above that the Be10 proxy may not be not well understood. The necessary conditions for an interglacial appear to be consistently low GCRs for some period of time. I don't think any of the temperature spikes in #29 during the Laschamp event show fall into the interglacial category. I don't know why high cosmic rays precluded any warming at all during that event. In general I don't think there are any control knobs that are that exact, CO2 and TSI included. For one thing all but TSI have a saturation effect. The CO2 also tracks because it is an amplifier (as well as a control knob in relatively cold conditions). The other exogenous control knobs cannot also be amplifiers by definition.

    The biggest unresolved question IMO is how the electric field and other cosmic ray effects shown to act on the order of minutes on clouds by Lockwood, Harrison and others could have anything to do with a causal effect over 1000's of years. That is particularly problematic when the effects vary by latitude, there is no worldwide effect. A possible mechanism is the low GCR environment with "fewer low clouds" (very crude I realize) allows more solar ocean heating which warms over longer time periods.
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  22. Hi again Eric @71 It is generally understood that the inner and outer Van Allen belts result from different processes. The inner belt, consisting mainly of energetic protons, is the product of the decay of so-called "albedo" neutrons which are themselves the result of cosmic ray collisions in the upper atmosphere. The outer belt consists mainly of electrons. They are injected from the geomagnetic tail following geomagnetic storms, and are subsequently energized though wave-particle interactions.
    http://en.wikipedia.org/wiki/Van_Allen_radiation_belt
    I don't know whether you have looked at this process If not it may help.
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  23. "The necessary conditions for an interglacial appear to be consistently low GCRs for some period of time."

    Am I to understand that you think the driver for interglacial/glacial is GCR flux instead of the existing milankovich theory? ie we are in a glacial until GCR values drop?
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  24. Wouldn't it be more correct to say that the necessary condition for Eric's necessary condition is that GCRs have a demonstrable impact on climate? or even on just the weather?

    Neither of those have been substantiated as of yet - and there is considerable evidence to the contrary: Dragic's disappointingly scant results, Pierce on aerosol nucleation (at RC) and Love et al's lack of statistical significance.
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  25. Skywatcher - you say "We have a very plausible mechanism in place for the observed changes of C14 and of regional cooling, in the form of changes in oceanic ventilation driving changes in delta C14". Do you have reference for this please? I'm interested in isotope variation by swamp methane (eg Petrenko) cf ocean ventilation.
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  26. scaddenp - The plausible mechanism is that of disruption of North Atlantic ocean circulation by a freshwater pulse, leading to a reduction in the exchange between ocean and atmosphere of C14, causing the plateau. The bipolar seesaw (Broecker 1998) of Antarctic warming at the time is strong evidence for ocean circulation changes, rather than an overarching global cause (solar/GCR/impact (impact discussed by RC here and in internal links). For ocean ventilation, references might be the Hughen ones linked in my #51, or Keigwin and Schlegel 2002, but there are dissenting voices, suggesting a much more mixed ventilation/other cause (e.g. Marchal et al 2000. A few references on the YD in this NOAA perspective article too. Wally Broecker on his flood hypothesis provides a very balanced discussion of the distinctiveness and of possible problems with a flood hypothesis. It may even be the last Heinrich event (see the refs via this Wiki page).

    What is clear about the YD: It's abrupt, and apparently a very unusual event during deglaciation. It is most pronounced around the Atlantic. It's not global, and abundant evidence exists for a 'seesaw' between NH and SH, suggesting changes in global oceanic heat transport via the Atlantic. Whether the trigger is massive flood, other freshwater discharge, ice sheet dynamics, or some other cause, the ocean circulation is altered, and there seems reasonable evidence that this drives the delta C14 changes. It's not a closed book, however, but there is no evidence that GCRs triggered it!
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  27. muoncounter, that's reasonable but it is difficult to discern effects in noisy measurements. My engineering approach would be to describe one or more models of potential physics (e.g. some aspect of clouds), what input measurements are made and how they map to the model (e.g. proxy measurements), and what the model outputs are (e.g. types of cloud cover over various areas) and how those can be mapped to real world measurements (e.g. satellite measurements). I don't think it is possible to map a model output to GAT in a short or medium term, there is too much short term variation from other factors. My cloud cover example should be the easiest one and even that is hard in step 3 (obtaining suitable measurements and determining the mapping).

    I think that in the Dragic et al paper the diurnal temperature range link is rather diffuse. But your critique of the delay seem unwarranted since the cosmic ray created particles take time to grow (days seems reasonable). As Pierce points how, the higher the initial nucleation rate, the slower the growth rate. So a higher event (7% vs 5%) may be more detectable because there is more lag. Love (above) may be in the worst measurement regime namely decade timescales containing numerous natural cycles.
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  28. Eric, did you read sphaerica's response to your #38 in #39? I'm not going to be in a hurry to trust that graph in #38 at all. The necessary conditions for an interglacial are suitable orbital forcing - or do you think Milankovitch was wrong and the pacemaker pattern of 100k, 41k and 26kyr cycles is entirely coincidental? CO2 only a 'control knob in cold conditions'? That's a new one - source please. The saturation effect only means that there is a reduction in forcing per tonne of atmospheric CO2 as you increase, not that there is a ceiling above which there is no forcing. For the same reason, methane is much more powerful a GHG - the spectral line is less saturated. The rest of your post is conjecture - can you provide sources (e.g. Lockwood and demonstrated effects). The biggest unresolved question is what is the mechanism by which GCRs can affect climate, don't you think?
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  29. {#78 is in response to #71 BTW}
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  30. Thanks skywatcher. I guess I am in the mixed camp. When temp goes down it seem to me that many other aspects of carbon cycle are also changed (eg vegetation uptake, swamp venting). Be10 looks to be a better indicator of GCR in the long run.
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  31. Eric:

    My main criticism of Dragic's result was the fact that in a 41 year database, they can show only 35 events producing an identifiable change in temperatures. At less than 1 per year, that's not much to hang a hat, let alone a theory, on.
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  32. #80, I agree that other aspects of the carbon cycle would change too. I'd hang my hat on the primary trigger being a disruption of circulation in the Atlantic, but this would surely then drive changes in other parts of the carbon cycle as unglaciated parts of Europe and America cooled. Presumably Be10 is a better indicator as there is less exchange between ocean and atmosphere? Not sure on chemistry for Be, but clearly C14 record is complicated by the 2-way exchange of CO2 between ocean and atmosphere, hence its use in seeing ocean circulation change.
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  33. skywatcher (#78), I agree with your assessment of the Shaviv graphic (lower graphic in #38) and I answered in #40. The pacemaker question is important and GCR coincides somewhat with Milankovitch as explained by Mercurio. CO2's control knob works best in cold conditions like the present or colder. My source is simply the logarithmic curve that we all have seen. There is no ceiling like you say but a gradual switch from CO2 causation to temperature causation in the amplification effect. I will elaborate more on a CO2 control knob thread if you want me to.

    Back on topic, my conjecture about the cosmic ray mechanism is that it shows up in the long term (e.g. upper graphic in #38) so therefore must act through the oceans which are really the only plausible long term actor. I would expect that given a particular rate of overturning, a very subtle warming of SST's would be possible (on average) in a low GCR (lowered cloudiness) regime which over time would warm all ocean layers and aid a flip out of glacial into interglacial. Of course the coincidental increase in TSI is important and may well be the only necessary factor or the main factor. It's not easy to determine.
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  34. muoncounter, I agree, 35 events is meaningless for modern climate analysis. The other problem is that they are going in the other direction from what I am, they are showing events to cooling. I am postulating that the lack of events causes warming over the very long run (100 to 1000 years or more as shown in the top graphic in #39).
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  35. Be10 is complicated because climate affects deposition rates.
    With C14, you have a calibrated production curve going back 4000+ years thanks to tree ring data but then issues after that. Be10 is also used to date how long rock exposed (Be10 production from cosmic ray hitting O2 in SiO2). As I understand, you are nowhere near being able to infer flux from this because of timescale issues but this doesnt have deposition rate issue so could be used to supplement ice core data in future.
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  36. Eric,
    You've given yourself a difficult task. If 'the lack of events causes warming,' you'll need a signal to trace. Unfortunately for that, low GCR flux rates correspond to the highs of the solar cycle (see the graphs here, specifically figs 1 and 4 for the years 2000-2004 - peak of cycle 23).

    So if solar activity peaks -> TSI in any way, wouldn't any GCR-induced warming be swamped by the coincident uptick in solar forcing? If so, you'll have a hard time pinning any warming directly to the lack of GCRs.

    I always find it difficult to prove anything by demonstrating a lack of evidence, but I know others in the community who don't hesitate to do so. There certainly isn't any basis for saying that you shouldn't give it a try.
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  37. Not to mention the unproven link between clouds/weather and GCR...

    I notice mercurio 2002 has single cite and no followup by mercurio either. Guess we are not the only ones unconvinced.
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  38. Muoncounter, yes the two effects are parsimonious and TSI is a clear cut forcing while GCR was not a detectable forcing in the historic and paleo events where it can be singled out. My personal theory of climate is that equilibrium is impossible due to factors like the rotation of the earth. Therefore climate is determined mostly by the balance of forcing and energy flows but partly by the feedbacks. GCR is a potential modulator of the fast feedback.

    Scaddenp, There is evidence for the weather link (in 35 cases in 41 years as muoncounter pointed out), but not evidence for a climate link other than the top graph in #39 and similar which all coincide with and can be explained by TSI.
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  39. Eric, Mercurio's discussion of cosmic rays and the glacial-interglacial cycle is unsupported speculation on his part. That is is un-peer reviewed, and ignored speaks to the wildly speculative nature of the content. Muoncounter at #41 has other valid criticisms.

    On your conjecture - you appear to be using a high;y-criticised graph from #38 which has lags/errors of tens of millions of years in order to support a conjecture about oceanic circulation and glacial cycles. Do you think it's plausible for the oceans to work on a timescale as slow as millions of years? Even a few tens of thousands of years is stretching credulity a bit. Nonetheless, a graph covering 500 million years can't hope to support your argument for the glacial-interglacial cycle. So again, what's the mechanism?
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  40. skywatcher sorry I mixed up the two charts together in #38. The top chart is Mercurio and the bottom is Shaviv. I agree the Shaviv chart (500 million years) is probably flawed. It is about the spiral arms of the galaxy and there are subsequent papers demonstrating that Shaviv had the wrong timing (I linked to one in #40). I am only using Mercuirio for my conjecturing. The biggest weakness of the correlation in Mercuirio is that low GCR coincides with higher TSI.
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  41. Scaddenp, here is that single cite of Mercurio http://earthscience.ucr.edu/docs/chapter2.pdf This author explains that there are various possible explanations for PDO: small variations in TSI influencing SST and winds, cloud cover and GCR. But the author appears to favor an internal mechanism: 'spin rate of the gyre". I don't know how such an influence on PDO would translate into a tendency towards interglacial states.
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  42. Paper in press in GRL titled "Solar irradiance, cosmic rays and cloudiness over daily timescales". From the conclusions:

    "we found no widespread detectable changes in cloud cover at any tropospheric level within a 20 day period of the solar forcing clearly associated with solar activity changes."

    For solar activity they mean TSI, F10.7 flux and GCR.
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    Moderator Response: [muon] Fixed link. Noted that paper here.
  43. Riccardo, from their abstract "...focusing on the largest TSI increases and decreases (the latter occurring in both the presence and absence of appreciable GCR reductions)..."


    Do the authors understand that TSI decreases coincide with GCR increases (not reductions)?

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  44. Do you really think that professionals publishing in GRL do not know what they do at this very trivial level? Read the paper and try harder.
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  45. the paper is password protected.
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  46. So don't presume they do not understand, assume that much more likely it's you.
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  47. Reading through benlaken.com, there's a bit more about the paper: "In Laken et al. (2011) the use of FD events as a basis for testing is evaluated, and it is found that this method does not necessarily isolate the effects of GCR variations effectively, as associated changes in total solar irradiance (TSI) emissions and an often protracted difference between the onset of FD events and the date of maximum reduction can potentially hamper analysis."

    Dr. Laken obviously knows his field and I should not imply otherwise.
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  48. 91, Eric,

    I'm not sure what the purpose of that Mecurio "cite" is. The author is presenting a simple overview of modern climate in that section, and basically says "there's this thing called PDO" and "these people all proposed different mechanisms for its cause" (one of them being Mecurio).

    As such, it makes no actual use of content of the paper, and puts no weight whatsoever on the conclusion. I suspect that if I'd written an e-mail to the author saying that Eurasian Leprechaun Farts cause the PDO, he might have cited my e-mail as well. He was just looking for a list of different proposed causes to demonstrate that no one actually knows.

    It's a "throwaway" cite with no bearing on climate change and giving no veracity to an un-peer reviewed, un-published and otherwise ignored paper.

    You can't discuss that Mecurio paper and claim to be discussing science. It's like discussing any number of self-published crackpot theories out there. They aren't worth anyone's time.

    Stick to meaningful and robust (or at least published!) papers. Don't assume that because a paper has a published format and some letters after the author's name that that means it's (a) good science and (b) true.
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  49. Erik
    you really badly quoted from Ben Laken site, hope it's unintentional.

    Dr. Laken whas reviewing the litterature and found that FD events "not necessarily isolate the effects of GCR variations effectively". Their new paper address exactly this and found that "However, the analysis presented in this work shows that following careful isolation of TSI and GCR variations, neither is found to be significantly associated with changes in cloud cover."

    Hopefully next time you'll carefully read before questioning the understanding (no less!) of reputable scientists.
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  50. Riccardo, please understand I was not misquoting or intentionally "badly" quoting. All I did was quote the full summary of the 2011 from his web site. There is nothing more and nothing less on that paper than what I quoted.
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