Could cosmic rays be causing global warming?

It's cosmic rays

"In 1996 we discovered a surprising influence of the Sun – its impact on Earth’s cloud cover. High-energy accelerated particles coming from exploded stars, the cosmic rays, help to form clouds. By regulating the Earth’s cloud cover, the Sun can turn the temperature up and down. As the Sun’s magnetism doubled in strength during the 20th century, this natural mechanism may be responsible for a large part of global warming seen then." (Henrik Svensmark)

Comments 1 to 22:

1. Wondering Aloud at 04:54 AM on 15 November, 2007
   I always thought this hypothesis seemed unlikely, but...
   
   What about the last 10 years of global not warming? Why does CO2 get an 800 year wrong direction lag and the sun has to be exactly in step to be a viable hypothesis?
   Response: The point is that because the sun has correlated so closely with temperature in the past, when the correlation ended in the 1970's, it's reasonable to conclude some other forcing imposed itself on the climate. Re the CO2 lag, the ice core records actually confirm the amplifying effect of atmospheric CO2. As for the last 10 years of global not warming, you'll find the warming rate is the same over the last 10 years as over the last 30 years.
2. Den siste mohikanen at 02:10 AM on 3 January, 2008
   First, the Harrison paper of 2006 state
   
   "...Furthermore, during sudden transient reductions in cosmic rays (e.g. Forbush events), simultaneous decreases occur in the diffuse fraction, showing that the diffuse radiation changes are unambiguously due to cosmic rays."
   
   http://www.cosis.net/abstracts/EGU06/07661/EGU06-J-07661.pdf
   
   Hence, it is pointless to argue that cosmic rays do not affect cloudiness. The correlation is there on a timescale of hours to decades, and as others have shown, on centennial to billion of years. The mechanism might not be what Svensmark has proposed but it doesn't change the basic fact if he is wrong about that.
   
   Secondly, your argument is nonsensical, as what Svensmark and other argue is not that cosmic rays can account for all climate influences. But if he is right - and evidence is piling up that he is - two things follows.
   
   1) the parametrisation in current GCMs are wrong as they fit past temperatures without taking this effect in consideration. Hence they are not reliable as tools for forecasts.
   
   2) climate sensitivity is overestimated by earlier attempts such as Hansens, as one major forcing was not considered when calculating those sensitivity values.
   
   What "sceptics" such as me claim is that there is precious little evidence to support the higher estimates on future temperatures as presented by UN (IPCC). And quite a bit of evidence against it. Emission scenarios is, well, rather extravagant, as they include projections of emissions many times higher than todays in year 2100 in spite of our likelhood to develop good alternatives to the ever more pricier fossile fuel (current trends are cutting the cost of renewables at half each decade). Climate scenarios based on these extravagant emission scenarios is then calculated with GCMs that are likely overestimating the response to a particular forcing. In general I would say sceptics accept that the climate warms when we add CO2 to the atmosphere, but we believe its effect will be muted by the climate systems rather than enhanced.
   
   I also want to add that I recognise all other environmental (and geopolitical) problems associated with burning fossile fuel and find that a compelling reason to put higher efforts in developing alternatives.
3. Den siste mohikanen at 08:03 AM on 14 March, 2008
   Sir, you state that
   "The point is that because the sun has correlated so closely with temperature in the past, when the correlation ended in the 1970's, it's reasonable to conclude some other forcing imposed itself on the climate. Re the CO2 lag, the ice core records actually confirm the amplifying effect of atmospheric CO2. As for the last 10 years of global not warming, you'll find the warming rate is the same over the last 10 years as over the last 30 years."
   
   For sure, neither the sun nor CO2 nor the two together make up for the only climate forcing. So your argument is a bit weak by itself, but even if we assume that all the unexplained difference is due to CO2, that doesn't give as much room for IPCCs +6°C forecast that you seem to imply.
   
   If all the difference from Krivova et al graph is attributed to CO2 that means that burning half of our known reserves of oil and gas has yielded us less than 0,3°C in temperature change. Some may be in the pipeline but several degrees? The climatic response time would need to be many hundreds of years for that to be possible, which clearly is not the case with TSI & cosmic ray forcings.
   
   I would also think that the discussion would be less confusing if we started to define what kind of cosmic rays we are discussing. If I remember correctly Laut is using low energy CR but what Svensmark and others claim is that it is cosmic rays of a certain energy (around 10 GeV) that makes the difference: only these energies create the secondary particles needed for the ionisation over low altitudes far from land. Sometimes the CR of high and low energies follow eachother, other times they won't; hence we should clearly state what kind of cosmic rays we are refering to.
4. Robert S at 18:40 PM on 19 April, 2008
   Here are a few new studies in favor of the climate-GCR link:
   
   http://aps.arxiv.org/ftp/arxiv/papers/0803/0803.2765.pdf
   
   http://aps.arxiv.org/ftp/arxiv/papers/0803/0803.2766.pdf
   
   GCRs are certainly a fascinating aspect of climate.
5. Mizimi at 07:49 AM on 16 November, 2008
   It is suggested that high level cloud formation is not affected because of the differences between ice crystals (high level)and vapour ( low level).
   There is a strong correlation between CR's and low level cloud referred to in this paper...
   
   http://www.solarstorms.org/CloudCover.html cosmic ray/low cloud cover.
   
   "The correlation of low cloud factor and cosmic ray flux is unexpected as the maximum degree of ionization by cosmic rays occurs in the altitude range 12-15km, i.e. close to or above the tropopause. The altitude ranges covered by clouds of different type are: 0-3.2 km for the low clouds, 3.2-6.5 km for the mid-level clouds and 6.5-16 km for the high clouds. Thus any cosmic ray induced cloud effect would be expected to be stronger for high rather than low cloud layers (Kernthaler et al. 1999; Jorgensen and Hansen, 2000). An explanation may lie in the fact that, as the neutron detectors are located at ground level, the measured flux is more representative of lower than higher regions of the atmosphere. Also, we suspect that the physical state of the cloud droplets may play a significant role in the cosmic ray-cloud interaction. It has been pointed out before that the physics of ice and liquid clouds may differ (Gierens and Ponater, 1999). By analysing different low cloud types separately we found that clouds in a liquid phase account for almost all the variability during the observed period, leaving the ice clouds constant in time, except at the poles where a slight increasing trend for some of the ice cloud types is found. Thus the greater sensitivity of low cloud to cosmic rays may result from the preponderance of liquid phase cloud types at lower altitudes (less than 6-7 km). "
6. Mizimi at 05:49 AM on 17 December, 2008
   A thought: cosmic rays are essentially protons, alpha and beta particles (90%,9%,1%) and since it is well known that both alpha and beta particles cause condensation trails in cloud chambers thro' ionisation, does it not follow that in appropriate atmospheric conditions they would cause condensation nuclei to form?
   And that the extent of such formation would depend on the quantity and energy levels of these particles?
   Also, is the ratio of particles always the same or is there variation which would allow for increased/decreased cloud formation regardless of the overall level of CR's?
7. NewYorkJ at 15:04 PM on 27 May, 2009
   More recent studies:
   
   http://www.sciencedaily.com/releases/2008/12/081217075138.htm
   
   http://www.sciencedaily.com/releases/2009/05/090511122425.htm
8. George Curzon at 01:25 AM on 30 May, 2009
   The point is how much heat arrives on the surface of the earth for what duration. If you leave water in a pot on the stove, and do with the the heat control a mock-up of the suns behaviour over the past 1100 years, the water will get hottest when you turn the heat up and leave it up.
   The water will not get hot hot when you give irregular bursts of heat, then turn it down again, or no heat.
   That temperatures continue to rise when sunspots level off is analogous to the water continuing to heat when you leave the stove turned on.
   Perhaps a pig on a spit might be a sizzling analogy for some.
   Until our planet reaches the temperature of the surface of the sun as it would be at this solar radius, we are going to continue heating up. Hopefully, sunspots will drop off before then.
   The 'exact' set interacting mechanisms of cloud formation would be interesting to know, and must affect the amount of the suns energy arriving at what the oil-well-country-occupying military types refer to as 'ground zero', eh?
9. ekogaia at 08:14 AM on 30 November, 2009
   I am sure the global warming denialists are going to climb onto the bandwagon that cosmic rays are found to influence tree ring growth - http://news.bbc.co.uk/earth/hi/earth_news/newsid_8311000/8311373.stm - and then try to tie that to proof that cosmic rays are responsible for climate change.
   What really amuses me about climate change denialists is the fact that they postulate all of these other reasons for climate change, like cosmic rays, water in the atmosphere, and so on, and then state that there is no climate change, or at least that it is not anthropogenic. What a great cop out so that life can continue as normal. And so it goes........
10. Mizimi at 06:26 AM on 31 December, 2009
    "The bottom line is even if these difficulties can be resolved and the causality link between cosmic rays and cloud formation is proven, all they'll find is the cloud formation 50 years ago is similar to now and has had little to no impact on the last 30 years of long term global warming."
    
    Not so; as I posted somewhere else on this site there are 2 factors here - cosmic radiation and water vapour. If CR remains essentially the same you can still increase cloud formation if WV concentration increases.
    Temperature rises from CO2 increases are 'amplified' by increased WV according to AGW hypothesis - which is confirmed to be ocurring in the lower troposhere by direct measurement.
    Work by the Danes has shown that CR's act more like a catalyst in that single particles can cause many nucleation events, so the effect becomes SO2/WV dependant if CR level is constant.
    There is a link to the website of the Danish Technical University on the page "Do cosmic rays cause clouds?" (#40)
    "Set loose by cosmic rays passing through the atmosphere, the electrons attach themselves to fragile clusters of sulphuric acid and water molecules. Their electric charges stabilize the clusters while more molecules join them. When the molecular clusters are big enough, the electrons can leave them in a stable state, and go off to encourage other clusters to grow.
    
    In other words, the electrons act as catalysts, which promote chemical action while remaining unchanged themselves. A single electron can make many attempts to grow clusters, even though it will fail if it leaves too soon. "
11. Alexandre at 10:23 AM on 1 January, 2010
    Recently I watched a lecture by Dr. Richard Alley, at the AGU (link below). He mentions a "Muschler et al. 2005" paper, with a very neat graph showing a distinct spike in cosmic rays during the Laschamp event some 40 thousand years ago, with no corresponding change in temperature at the same time.
    
    I could not find the paper, though. Could anyone help?
    
    (relevant part at 42:10 min)
    http://www.agu.org/meetings/fm09/lectures/lecture_videos/A23A.shtml
12. Tom Dayton at 03:30 AM on 2 January, 2010
    Mizimi, it doesn’t matter what the purported mechanism of GCRs’ effect is--water vapor, cloud formation, or anything else.
    
    Once the changes in GCR level stopped (i.e., GCR level became constant), the resulting energy imbalance of the Earth must “immediately” have started to shrink as the Earth “immediately” started to heat and therefore radiate more to match the new, now constant, level of GCR--regardless of whether the GCR effect occurs via some additional mechanisms involving water vapor, and regardless of whether the higher level of GCR amplifies the effect of increased water vapor.
    
    But the Earth’s energy imbalance has not been shrinking. It has continued to grow, which means the cause of the imbalance has continued to grow, which means the cause cannot still be GCR, because GCR has been constant for half a century. It is impossible for the effect to lag this long.
    
    This is the same reason the effect of solar radiance’s increase up to the 1950s cannot lag this long. The same argument applies to any factor once it stops changing.
13. djb95054 at 06:35 AM on 16 January, 2010
    Possible error in this article...
    
    I try always to verify quotes from original sources in order to eliminate the possibility of misattribution. In this article, there is a quote referenced from a Max Planck article here: http://www.mps.mpg.de/dokumente/publikationen/solanki/r47.pdf (Krivova 2003).
    
    The quote is "between 1970 and 1985 the cosmic ray flux, although still behaving similarly to the temperature, in fact lags it and cannot be the cause of its rise. Thus changes in the cosmic ray flux cannot be responsible for more than 15% of the temperature increase".
    
    The above referenced .pdf file is a scan and is therefore not searchable for this quote. I have attempted to read the entire article (a daunting task for a non-scientist like myself) and cannot locate the referenced quote. A Google search finds only additional references to this .pdf and this article.
    
    Is the above quote actually in the referenced article? If so, I'm blind and didn't see it. If not, where does this quote come from?
    Response: The quote is on page 281 of that paper, beneath the graph I reference above.
14. djb95054 at 08:51 AM on 17 January, 2010
    Thanks! I now see the quote (and will have my eyes checked).
15. Alexandre at 01:08 AM on 2 February, 2010
    Here's the graph I mentioned above about the Laschamp event:
    
    http://ossfoundation.us/projects/environment/global-warming/myths/images/galactic-cosmic-rays/LaschampAnomaly.jpg/view
    
    I presume it comes from this paper:
    
    Muscheler et al. 2005
    "Geomagnetic field intensity during the last 60,000 years based on 10Be and 36Cl from the Summit ice cores and 14C"
    
    http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VBC-4FTS349-2&_user=10&_coverDate=09%2F30%2F2005&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1188611081&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=d7767a216035551c2353da3f1cd38838
    
    The graph looks pretty strinking to me.
    
    John, do you think it would be worth adding this to a future update on this argument?
16. Turboblocke at 04:10 AM on 21 February, 2010
    BTW hope you don't mind me asking here, but someone claims that the Twomey effect is wrong for dealing with clouds and that "Mie scattering" is more appropriate. Anyone know anything about this?
17. Riccardo at 04:50 AM on 21 February, 2010
    Turboblocke,
    there's something missing in the claim you're reporting. Twomey effect and Mie scattering are two different things.
18. Turboblocke at 21:29 PM on 21 February, 2010
    Riccardo, this is what he says,"Reportedly, the models significantly over-predict temperature rise for a given level of CO2 and have to be corrected by an assumed aerosol cooling from the 'Twomey Effect': the apparently greater brightness ['diffuse albedo'] of clouds with smaller droplets. Twomey's explanation, greater surface area gives greater 'reflectivity', is wrong physics but plausible: I saw it recently in NASA literature so it appears to be taught in climate science as if it were a fact.
    
    The correct physics is 'Mie scattering'. Smaller droplets do lead to earlier onset of diffuse radiation. However, unless the measurement is done exactly coaxially with the sun's illumination, the backscattered contribution to the energy loss to space is not quantified. ...
    So, the satellites don't measure true albedo. The physicists know all about Mie scattering. One paper points out that there is no 'albedo' difference between southern and northern hemispheres when it is known that the aerosol concentration is much higher in the north."
    
    It isn't a subject I'm competent in, so I don't know if what he says makes sense.
19. Riccardo at 07:31 AM on 22 February, 2010
    Turboblocke,
    you friend is making some confusion between Mie scattering and Twomey Effect. The latter appears to be interpreted as the explanation of the dependece of clouds albedo on droplet size. I assume this is correct.
    Twomey (e.g. Twomey 1977, J. Atmos. Sci. 54, 1149) did infact apply Mie scattering (with some aproximations) to clouds and not what your friend said ("greater surface area gives greater 'reflectivity'". What your friend appears to be missing is that as far as clouds are concerned one need to consider that:
    1) the total mass of water is kept constant, so smaller drops means larger concentration.
    2) in real clouds the droplet size is much larger than the wavelength of light (several microns and more vs rougly half a micron)
    3) most of the clouds (low and medium level clouds) are optically thick and therefore single scattering aproximation breaks down. This means that the polar distribution of the scattered intensity varies only slowly, almost flat indeed. This contradicts the claim that "satellites don't measure true albedo".
    
    I'd like to add a few other comments on his claims.
    "models significantly over-predict temperature rise for a given level of CO2 and have to be corrected by an assumed aerosol cooling".
    Yes, if you give incorrect input to the models you'll get garbage for sure. Indeed, no one denies (i hope) that pollution from aerosol (sulfides in particular) has increased till roughly the '60s. Why the models should not consider this given that they do have an effect on climate?
    
    "One paper points out that there is no 'albedo' difference between southern and northern hemispheres when it is known that the aerosol concentration is much higher in the north."
    This is really a miopic point of view. Is albedo determined just by aerosol? No for sure. You have clouds, oceans, ice and several types of land. It is surprisingly enough that the mean albedo turns out to be almost equal in the two emisphere.
20. Turboblocke at 22:15 PM on 27 February, 2010
    Thanks Riccardo. BTW he's not a friend, just another blog scientist.
21. muoncounter at 13:13 PM on 20 March, 2010
    I'm brand new to this forum and a bit intimidated by some very good-looking and well-researched science in these posts.
    
    I've been involved in cosmic ray research for several years and have followed the recent cosmic rays-cause-climate-change brouhaha with some skepticism. Perhaps I can clear up a few subtleties of the argument that seem important to this thread.
    
    First of all, its best to define terms: nearly all cosmic rays (CRs) detected at the surface of the earth are of solar origin, the result of collisions between primary particles (mostly protons in the solar wind) and nuclei in the upper atmosphere. The energy of these collisions throw off a chain of secondary particle interactions; what we routinely see are the muons and neutrons.
    
    On the other hand, the primary particles of Galactic Cosmic Rays (GCRs) are protons and heavier nuclei (up to Fe) from distant stars.
    
    Now then:
    
    At #3, there's a mention of CR energies and that only CRs of 10GeV or more produce secondary particles. Here is the standard chart of the CR energy spectrum, presented as measured particle flux vs. energy. Note that there are lots of 10 GeV CRs; what excites CR researchers these days are events around the "knee" -- 10^6 GeV or more.
    
    But it is well known that secondary particles (mostly muons) are generated by lower energy primary particles. We can even stop these muons with appropriate detectors.
    
    At #6, alpha particles don't get that far. As the decay scheme suggests, if any of these secondary particles are potential cloud-formers, betas (aka e- and e+) are the most likely culprits.
    
    At #12 there's a mention of GCR flux and the statement that GCR flux is now constant. This is where it gets complicated: during low periods in the solar cycle, we observe more GCRs. GCR flux is hardly constant.
    NASA recently found the GCR level to be 19% higher than previous records. This article proposes several mechanisms for this apparent paradox, not the least of which is the weakened solar magnetic field.
    
    The 10Be ice core data is mentioned in #15: for the last 500 years shown here, there seems to be about a 100 year cycle to 10Be peaks. Some of these peaks are coincident with low sunspot numbers (which is true of the 2009 GCR high-sunspot low). Problem is those peaks aren't very wide, so it seems that concluding much about causality or a 6 month lag or lead at this scale is a bit chicken and egg.
    
    Here's another science thread on this topic from last year.
    
    Finally, CERN's CLOUD project would be a controlled study of cloud formation by ionizing particles. No data yet.
22. Mikemcc at 00:28 AM on 5 April, 2010
    There's a new paper out Kulmala et al (Atmos. Chem. Phys., 10, 1885–1898, 2010), it's available on line here:
    
    http://www.atmos-chem-phys.net/10/1885/2010/acp-10-1885-2010.pdf
    
    The telling part in the conclusions is:
    
    "Our results do not support the idea that the ions produced by galactic cosmic rays would be a major factor behind secondary aerosol production and the related aerosol-cloud interactions."

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