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What's the link between cosmic rays and climate change?

What the science says...

Select a level... Basic Intermediate Advanced

Cosmic ray counts have increased over the past 50 years, so if they do influence global temperatures, they are having a cooling effect.

Climate Myth...

It's cosmic rays

"When the Sun is active, its magnetic field is better at shielding us against the cosmic rays coming from outer space, before they reach our planet. 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)

At a glance

Space may often be regarded as dark, cold, empty and lifeless but there is plenty going on out there, including the streams of high-energy particles that whizz around at close to the speed of light. These are galactic cosmic rays, discovered by Austrian-American physicist Victor Hess in 1912. Galactic cosmic rays is a catch-all term that includes high-energy particles with sources ranging from the Sun to remnants of ancient supernovae – exploded stars – in other galaxies.

When cosmic rays hit the top of our atmosphere, a highly crowded environment compared to deep space, they interact with the atoms up there producing showers of charged particles known as ions. The ions then head on down towards the surface, where they make up just over ten percent of our typical yearly radiation dose. That's approximately equivalent to three chest x-rays.

The Solar wind protects Earth from cosmic rays and Earth's strong magnetic field in turn shields us from both. In this respect we are fortunate: if you want to find out what happens to a planet that has lost its strong magnetic field, go and take a look at Mars. As a result of these planetary defences, the amount of cosmic rays reaching the lower atmosphere and surface of Earth is minimised.

Direct recording of the cosmic ray flux has been possible since the beginning of the satellite era, since the satellites can carry particle detectors. We therefore have over a half-century worth of data on the changes in the intensity of the flux.

The idea that changes in the cosmic ray flux could drive the observed global warming has a small but determined number of fans. In short, their hypothesis suggests that the ions produced by cosmic rays can 'seed' clouds. That means more cloudiness - and clouds reflect sunlight, reducing the energy reaching Earth's surface. So, it imagines, if there are fewer cosmic rays reaching Earth, there will be fewer clouds, more sunlight reaching the Earth's surface, and thus more global warming. In a sense, this is a variant of the “It's the Sun” argument, because the cosmic ray flux falls when the Sun is in the active phase of its 11-year sunspot cycle and the Solar wind is typically stronger.

In 2017, the Cosmics Leaving Outdoor Droplets (CLOUD) experiment reported in. It had been created to test the link between cosmic rays and climate and was specifically looking for any connection between ions resulting from cosmic rays and cloud-seeding. The CLOUD experiment succeeded in unlocking many of the mysteries of cloud formation and growth in our atmosphere. That greatly improved our understanding of human influences on climate. In particular the study concluded that the effect of changes in cosmic ray flux intensity on the cloud condensation process is small. To quote its authors, it is, "unlikely to be comparable to the effect of large variations in natural primary aerosol emissions" - things like volcanic eruptions, wildfires and so on. So no, cosmic rays do not have much of an effect at all.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!

Further details

It was at one time hypothesised that galactic cosmic rays (GCRs) may play a part in helping form clouds. A leading proponent of this idea was Danish scientist Henrik Svensmark. If this hypothesis were correct, an increase in the GCR flux, creating an increase in cloud condensation nuclei, would lead to more cloud cover in our lower atmosphere, reflecting more sunlight and resulting in a global cooling effect. Conversely, a decrease in GCR flux would lead to a reduction in cloudiness, warming the planet by letting more sunlight through.

People look at new hypotheses in order to test them. In order to calculate the maximum possible role of GCRs in recent warming, global temperatures have been compared to variations in the GCR flux, as measured by particle detectors aboard satellites and by neutron monitors at the Earth's surface. We'll take a look at some of these studies, for there are many, mostly reaching the same conclusion but with improvements in methodology through time, as always tends to occur in scientific research.

A 2003 paper observed that while there was some correlation between GCR levels and temperature prior to 1970, the correlation breaks down sharply after that point. The analysis concluded that "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" (Krivova & Solanki 2003).

Krivova & Solanki (2003) 

Figure 1: Reconstructed cosmic radiation (solid line before 1952) and directly observed cosmic radiation (solid line after 1952) compared to global temperature (dotted line). All curves have been smoothed by an 11 year running mean (Krivova & Solanki 2003).

Another analysis from the 2000s scrutinises the link between GCRs and cloud cover and finds several discrepancies. As GCR flux shows greater variation in magnitude in high latitudes, one would expect larger changes in cloud cover in polar regions. This, the authors found, was not observed. They also examined the aftermath of the nuclear reactor accident at Chernobyl: the thinking was that if the GCR hypothesis was correct then since the Chernobyl site was a strong source of ionising radiation, some effect on cloud formation might be expected. They found none (Sloan & Wolfendale 2008).

The chance to soundly test the Svensmark hypothesis came up again in a particularly extended Solar minimum (between solar cycles 23 and 24, 2008-2010). This minimum was associated with a record high level of GCR flux, but at the same time, there was a record low level of cloudiness in the lower atmosphere – the bottom ~10 kilometres of the atmosphere where most of the weather occurs. If the GCR/cloud seeding idea was correct, the reverse should have been the case (Agee et al. 2012; fig. 2). Also in 2012, an important review paper, covering the past 35 years of research, concluded, “it is clear that there is no robust evidence of a widespread link between the cosmic ray flux and clouds.” (Laken et al. 2012).

GCR vs. Temp

Figure 2: Annual average GCR counts per minute (blue - note that numbers decrease going up the left vertical axis, because lower GCRs should mean higher temperatures) from the Neutron Monitor Database vs. annual average global surface temperature (red, right vertical axis) from NOAA NCDC, both with second order polynomial fits.

More recently, the Cosmics Leaving Outdoor Droplets (CLOUD) experiment, created to systematically test the link between GCRs and climate, reported in. It had been specifically looking for any connection between ions resulting from GCRs and aerosol nucleation and thus cloud condensation nuclei and cloud formation. The CLOUD experiment succeeded in unlocking many of the mysteries of nucleation and cloud growth in our atmosphere, greatly improving our understanding of human influences on climate. In particular the study concluded that the effect of changes in GCR flux intensity on the cloud condensation process is small and “unlikely to be comparable to the effect of large variations in natural primary aerosol emissions” - things like volcanic eruptions, wildfires etc (Gordon et al. 2017).

This story illustrates nicely how science proceeds. Someone thinks up a hypothesis and it is repeatedly put to the test and is found to be wanting. In turn that leads to further research and important discoveries, providing progressively better understanding into the details of how certain processes work – atmospheric ones in this case. In recent years, Svensmark has been associated with the likes of the Global Warming Policy Foundation, the Heartland Institute and other such organisations who prefer their own version of reality (details at DeSmog). Meanwhile, the science has moved on and left him behind.

Update June 17, 2023 - Based on feedback received, added a concluding paragraph to the at-a-glance section.

Last updated on 18 June 2023 by John Mason. View Archives

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Argument Feedback

Please use this form to let us know about suggested updates to this rebuttal.

Further reading

A team of scientists from 17 countries have found the most likely origin of galactic cosmic rays - the centres of distant galaxies (Active Galactic Nuclei) powered by supermassive black holes. This discovery is not particularly pertinent to the global warming debate but it is cool :-)

Further viewing

This video published on Nov. 17, 2019 by "Have a think" provides some more and current explanations of why GCRs do not play a role in current global warming.



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Comments 76 to 92 out of 92:

  1. I was wondering if someone with a stronger background in physics than I could help place this new discovery into the broader context of the scientific knowledge of climate change. I can't say I agree with Dr. Lu's assertion that CFCs are the sole cause, and that CO2 can be ruled out, but that degree of correlation within Antarctica certainly does present a strong argument.

    Could it be possible that the link between CFCs and cosmic rays does indeed play a strong role in determining Antarctic temperatures, even if the role in the global climate system is less pronounced?

  2. DMCarey, as I was trying to answer that same question, I discovered other commenters in other threads here at Skeptical Science already had answered.  (What a team!) 

    This is merely Lu recycling the same claims he has been making for years. His claims have been proven wrong repeatedly. RealClimate has a short critique with a link to a peer-reviewed critique.

    And see the It's CFCs entry here at Skeptical Science.

  3. Tom,

    Thanks for the quick reply! The answer is much appreciated.

    uWaterloo is my alma mater, making it kind of disappointing to realize there is a professor there continuing to assert claims when faced with evidence that it's incorrect

  4. I am a bit confused by this page, as the basic and advanced versions seem to contradict each other. From the former:

    "Cosmic ray counts have increased over the past 50 years, so if they do influence global temperatures, they are having a cooling effect."

    And from the latter:

    "Cosmic ray flux on Earth has been monitored since the mid-20th century, and has shown no significant trend over that period."

    So my questions are whether this is, as it appears, a contradiction, and if so, which one's correct and can the one that's incorrect be changed?

  5. jsmith @79, if you read further into the advanced version, you will find it later refers to a record high GCR flux; after which it shows the same diagram used in the basic version, showing the same decline in inverted neutrino flux.  The key point is that while GCRs have increased over time, the increase is not statistically significant.  Consequently there is no contradiction between the advanced version and the basic version, nor internal inconsistency in the advanced version. 

  6. Here's the latest "knock down evidence" against AGW theory from the skeptic camp. Have you guys seen this one yet? I fail to see this as overwhelming evidence that cosmic rays are the main driver of the recent warming, but I'm just a layperson so maybe I'm missing something. Anyone care to comment on this? Thanks!

  7. I like the way you write this, "The body of scientific research has determined that GCRs are actually not very effective at seeding clouds."

    'not very effective'  so it's not a 'myth'

    don't say it's a myth and then admit that it's not a myth in the first paragraph of your editorial!  That's called a fallacy of logic, something you people seem to excel at.


    [Rob P] - All caps edited out - please note the comments policy that you agreed to adhere to when commenting here.

    As for logic: note that the rebuttal points out that GCR's have increased in recent decades -which should have seeded more clouds and induced a cooling effect. Instead the Earth has warmed dramatically. The bottom graphic is very unintuitive though.

  8. qikplay... The myth would be that GCR are responsible for warming of the past 50 years. That GCR are "not very effective" at seeding clouds suggests that they are, in fact, not responsible for recent warming.

  9. OK, sorry for the rude all caps shit..

    BUT (whoops) You don't say something is a 'myth' then admit that it's not a myth in the first paragraph of your commentary! what are you thinking.. it's not a myth, rather its extent a bone of contension between you and other scientists, pundits etc..

    you don't say something doesn't exist, oh but actually it exists just not that much.. big difference there and talk about being misleading perhaps you should take this off your 'myths' section lol feeling stupid?


    and the reason its not responsible for the recent warming is that there is recent cooling like snow in calgary in august, snow in hawaii in july, polar vortex in long do you think you can keep up this sham that the mini-ice age isn't really happening? (snip)


    [RH] Please be more careful. I'm going to drop out of commenting here and just moderate. You really need to go carefully read through the commenting policy before continuing to post. 

  10. It's even worse than Rob suggests. The hypothesis is that GCRs seed clouds and that the resulting cloud cover modulation is a forcing, i.e. responsible for the current warming. Not only there is still no clear evidence for GCRs actually being a significant factor in nebulosity, but the recent GCR count shows an increase, which would mean more cloud and a cooling effect. This whole idea that GCRs influence the climate is a joke, coming from people so desperate to distract attention that they will grasp at the most feeble of straws. It does not deserve any attention whatsoever.

  11. no clear evidence for GCRs actually being a significant factor

    Yes, but that's a far cry from 'doesn't exist' dont you think? 


    [RH] Your concern has been addressed already, saying that GCRs are responsible for global warming is the myth. You're going to have to find a way to accept that and move on. Repeating the same error is considered sloganeering is not allowed here.

  12. Qikplay, your lists of anecdotal blurbs is not even funny. Have you even tried to figure what the global temperatures have been so far this year? And last year, the warmest on record? With the immense majority of glaciers receding and loosing mass all over the world? It seems that your participation here is another thing not deserving of any attention. It seems the snow in Calgary has not prevented the region from enacting a fire ban. And what was the wildfire season like this year in Canada again? Do you honestly think that, on a website where scientific evidence is discussed, you rantings would have a chance to sway anyone? An ice age eh? Illustrated by a Arctic sea ice once again below average by more than 2 standard deviations? Makes perfect sense right?

    Per environement Canada, the long term trend 1948-2013 for winter temperatures is +3.2 degrees C. The annual average has increased by 1.6 degrees over the past 67 years. Some ice age that is. Personally I think that moderators summarily delete such obvious nonsense as your last post.

  13.   wtach from 30minutes


    [RH] I think you need to watch this video that shows how Durkin fraudulently altered the materials, to the point where even skeptics complained.

    [TD] Also watch the video by Peter Sinclair, on that Durkin's fake documentary and in particular his fakery regarding the Sun and cosmic rays.

  14. can you comment on the correlation between the sun and climate and the graph they show that shows the correlation.


    [RH] The correlation was faked by Durkin.

    [TD] Also, read the SkS post "It's the Sun"--the Basic tabbed pane, then watch the video lower on that page, then read the Intermediate one, then the Advanced one. If you want to comment further on the Sun, do so on that thread, not this one.

  15. That's it already? Down with GCRs and jumping to the next thing? How boringly typical. Two suggestions, if you want to discuss the role of the Sun:

    1-go to the appropriate thread

    2- drop the YouTube horse puckey and start with published scientific litterature.

  16. Quikplay, if you read carefully, you will see that the myth is that "It is cosmic rays" that is causing the current warming, or more correctly, it is a paucity of cosmic rays that cause the warming.  There is no claim that it is a myth that cosmic rays exist.  Nor is there any claim that it is a myth that cloud extent effects global temperatures.  Nor is there any claim that it is a myth that cosmic rays seed clouds.

    As to your anecdotes, yes it snowed in July on Hawaii at 13,000 feet.  At that altitude, with the normal lapse rates temperatures are 26 C less than surface temperatures due to altitude.  As it happens, the temperature in Hawaii at sea level on the day of the snow (July 17th) was a 90 F (32 C) maximum, and 79 F (26 C) minimum, 2 and 5 F above average respectively.  Noting the average July minimum temperature, it is evident that snow in July on the mountain peaks is a rarity primarilly due to lack of thunderstorms early in the day to lift the humidity that high.

    As to Calgary, on average it snows in August in Calgary every ten years or so.  And you want to count that as evidence of a "mini-ice age"?  As somebody just said, "lol feeling stupid [much]?" 

    Meanwhile you are ignoring the massive, and extended heat wave in the state of Washington, the heat wave in  the heat wave in Pakistan that killed 2000 people, and the heat wave in India which caused the deaths of 2,500 people, as well as the heat waves in Europe, and China.  In fact, you ignore all the evidence that show 2015 to be the hottest year todate by a large margin, which along with a significant El Nino is causing predictions 2015 will be the warmest year on record:

    So please, no more demonstrations of your complete lack of reading comprehension (ie, your persistent and obtuse misidentification of the myth); and no more cherry picking.

  17. Elsewhere Bi5h0p presents an argument that is off topic there, and on topic here.  Specifically they say:

    "So, if the Sun has such a major impact on the Earth's weather, how much more does our own galactic weather have on our Sun and it's solar system? It's reasonable to hypothesize that galactic weather could have a much greater effect on the solar system, as a whole, during certain galactic weather events. Our solar system is travelling through an interstellar medium, the density and energy of which may vary greatly - and for extended periods of time. This could also explain any other planetary changes which have been, or may have been observed as every object in our solar system could be impacted by such events."

    In support of this, they link to a conservative "news" site that is stong on pseudoscience, and in particular to a 2012 article that claims that:

    1)  Two professors have discovered new particles reaching Earth from galactic center; and

    2)  That some unknown particle from the Sun causes variations in the rate of nuclear decay.

    With regard to (1) it is hard to comment.  At the time of publication of the article, the professor's work has been "submitted to the peer-reviewed American Physical Society journal Physical Review" as of 2012, but of which I can find no sign three years later.  Because I cannot find a source paper, all I an say is that nothing in the report from "beforeitsnews" implies either new particles, or new energy intensities.  Indeed, at most it seems to imply that the professors have better localized the source of already observed cosmic rays.

    With regard to (2), the report is of actual peer reviewed papers that have not been consistently confirmed by later observations.  That is, it is still possible that there is no such effect.  Further, it is presently conjectured that if the effect is real, it is caused by neutrinos rather than as yet unobserved (and untheorized) mystery particles.

    With regard to climate, if real, the effect only applies to beta particle decay (ie, the conversion of protons to neutrons by the emission of a neutrino and an electron, or of neutrons to protons by the emission of a neutrino and a positron).  As such, it has minimal imact, if any, on geophysical heat, which is primarilly based on alpha particle decay.  Further, even if it did, any such impact would be long delayed and difuse due to the time it takes for heat to rise through the mantle and crust.  Finally, and most importantly, newly discovered does not mean recently started.  If the ambiguous support for this phenomenon turns out to be accurate, that only means that an effect that has been in existence for the enirety of the Earth's existence will have been newly discovered.  Ergo, it implies no change in heatflow, and hence no change in climate.  

    You will notice that neither (1) nor (2) have any bearing on "galactic weather".  Nevertheless I did find websites discussing the above phenomenon which also drew attention to a NASA press release drawing attention to a newly discovered interstellar magnetic field.  The magnetic field is associated with the local interstellar cloud, and when the Sun exits the local interstellar cloud, this could result in a different strength of the interstellar magnetic field, and hence a change in the number of galactic cosmic rays reaching the Earth.  As the news release says:

    "The fact that the Fluff is strongly magnetized means that other clouds in the galactic neighborhood could be, too. Eventually, the solar system will run into some of them, and their strong magnetic fields could compress the heliosphere even more than it is compressed now. Additional compression could allow more cosmic rays to reach the inner solar system, possibly affecting terrestrial climate and the ability of astronauts to travel safely through space. On the other hand, astronauts wouldn't have to travel so far because interstellar space would be closer than ever. These events would play out on time scales of tens to hundreds of thousands of years, which is how long it takes for the solar system to move from one cloud to the next."

    (My emphasis)

    Completely ignoring the highlighted statement, the pseudoscientific sites trying to sell this phenomenon as a cause of recent climate change suggest the Sun has only just recently entered the local cloud, perhaps encouraged by the illustration below.

    They have paid not attention, however, to the relative distances involved.  A recent mapping of the structure and velocities of the local cloud shows that the most recent time in which the Sun could have entered the local cloud (based on relative velocity and the lower bound estimate of the closest cloud surface) was ten thousand years ago.  Even if we allow that cosmic rays effect climate (and it is very dubious that they have a major effect, as detailed in the OP above), this change occured 10 or more thousand years ago, and is certainly not the cause of the rise in temperature in the 20th century.

    In sum, the evidence Bi5h0p relies upon is (at best) a beat up of far more mundane facts, presented breathlessly, inaccurately, and treated as certainties despite the highly qualified nature of the actual reports.  This tissue of distortion, misrepresentations on uncertain basis is then presented as better than the very well established facts of climate science.

  18. A new paper published in the Journal of Atmospheric and Solar-Terrestrial Physics in August 2016 finds:

    "There is a significant correlation only between cosmic ray (CR) intensity (and sunspot number (SSN)) and the cloud cover of the types cirrus and stratus. This effect is mainly confined to the CR intensity minimum during the epoch around 1990, when the SSN was at its maximum.This fact, together with the present study of the correlation of LSCC with our measured CR intensity, shows that there is no firm evidence for a significant contribution of CR induced ionization to the local (or, indeed, Global) cloud cover.

    Pressure effects are the preferred cause of the cloud cover changes. A consequence is that [b]there is no evidence favouring a contribution of CR to the Global Warming problem.[/b] Our analysis shows that the LS data are consistent with the Gas Laws for a stable mass of atmosphere."

    Relevance of long term time – Series of atmospheric parameters at a mountain observatory to models for climate change

  19. Elsewhere Echo_Alpha_Zulu is arguing that cosmic rays " more of a role in climate than anything else".  He attributes that view to unnamed "CERN scientists", and provides no links or citations so we can confirm that that is indeed what "CERN scientists" are saying.  Curiously Echo_Alpha_Zulu says, "I am a real scientist I study the data itself. I dont rely on some 'Expert' to interpret the data for me".  Despite this claim, he provided no relevant evidence with regard to cosmic rays, instead rellying on the authority of "experts" who are carefully kept of page and uncited.

    Echo_Alpha_Zulu may consider that characterization unfair, given that he linked to this graph, which is a truncated version of Figure 1 from Kirkby (2008):


    However, that graph shows nothing interesting because, the temperature proxies do not agree among themselves about the temperature pattern over the last 1000 years, let alone with the cosmic ray proxies.

    That lack of correlation can be seen in modern records where, if the theory had any substance, the more accurate records should make the connection obvious.  Instead, taking the montly values of the  OULU neutron record and the Berkeley Earth Land Ocean Temperature Index, a regression analysis shows a positive trend of 7.4 (+/- 6) x 10^-5 C/(Count/Min).  That is the opposite of the negative trend predicted by the theory.  Worse, the correlation is just 0.097 with an R^2 of 0.009 indicating cosmic rays to be a negligible causal factor with regard to global temperatures, if relevant at all.

    It becomes a little more interesting when we look at the timeseries of the BEST LOTI and the inverted OULU Neutron count:

      Here we see that where there may have been some slight justification for the theory in data up to circa1995 (Regression: -1.9 (+/-0.47) x 10^-4; correlation: -0.388; R^2: 0.15), thereafter temperature continues to increase steadilly while the inverted cosmic ray count plummets.  The complete breakdown of the relationship post 1995 shows the weak statistical relationship apparent beforehand to have been largely coincidental.

    A simple linear regression is not the only test that could be applied to the data, but no theory which claims cosmic rays " more of a role in climate than anything else" survives the data shown.  At best, the relationship is that found by Tsonis et al (2015), who write:

    "Our results suggest weak to moderate coupling between CR and year-to-year changes of GT. They resonate with the physical and chemical evidence emerging from laboratory studies suggesting a theoretical dynamic link between galactic CR and GT. However, we find that the realized effect is modest at best, and only recoverable when the secular trend in GT is removed (by first-differencing). Thus, it is important to stress that they do not suggest that CR influences can explain global warming and should not be misinterpreted as being in conflict with the IPCC. Indeed, the opposite is true: we show specifically that CR cannot explain secular warming, a trend that the consensus attributes to anthropogenic forcing. Nonetheless, the results verify the presence of a nontraditional forcing in the climate system, an effect that represents another interesting piece of the puzzle in our understanding of factors influencing climate variability." 

    (My emphasis)

  20. It may be useful to add that the CERN group has long since dropped the argument that cosmic rays affect climate. Their latest paper (with Kirkby a co-author) in Science summarizes (abstract):

    "... A considerable fraction of nucleation involves ions, but the relatively weak dependence on ion concentrations indicates that for the processes studied, variations in cosmic ray intensity do not appreciably affect climate through nucleation in the present-day atmosphere."

    ... and that position has been in place for some time.

  21. December 2016 paper in Science: "Nearly all nucleation involves either ammonia or biogenic organic compounds. Furthermore, in the present-day atmosphere, cosmic ray intensity cannot meaningfully affect climate via nucleation."

  22. Reviewing some of the papers linked in the advanced version of this article, I could not find the quote attributed. Quoting the article:

    In the CERN CLOUD experiments, Almeida et al. (2013) found

    "ionising radiation such as the cosmic radiation that bombards the atmosphere from space has negligible influence on the formation rates of these particular aerosols [that form clouds]"

    That quote appears nowhere in the paper at the link provided (which is the full version of the paper). Rather, the paper concludes that there are significant uncertainties regarding the matter assessed.

    If I've read it right, it would be well to correct the OP.


    [PS] Looks to me like the quote came from the press release accompanying the paper. However the abstract "The ion-induced contribution is generally small, reflecting the high stability of sulphuric acid–dimethylamine clusters and indicating that galactic cosmic rays exert only a small influence on their formation, except at low overall formation rates." hardly contradicts that.

  23. Thanks for the reply PS.

    If the quote is not at the source linked, then an additional link should be added to lead interested readers in the right direction.

    I read the paper. It's discussing a sub-component of cloud formation. These remarks are in the concluding paragraphs:

    The Intergovernmental Panel on Climate Change (IPCC) considers that the increased amount of aerosol in the atmosphere from human activities constitutes the largest present uncertainty in climate radiative forcing2 and projected climate change this century. The results reported here show that the uncertainty is even greater than previously thought, because extremely low amine emissions—which have substantial anthropogenic sources and have not hitherto been considered by the IPCC—have a large influence on the nucleation of sulphuric acid particles.

    The study is focussed on amines in cloud nucleation. It does not quantify whether low concentrations are abundant or not, but it does point out significant uncertainty regarding their influence.

    I'm not sure that this paper corroborates the general contentions made here about GCR/cloud formation after reading the whole paper for comprehension.

  24. From the article you linked:

    The CLOUD result adds another significant measurement in understanding the climate. But it does not rule out a role for cosmic radiation, not does it offer a quick fix for global warming.

  25. "However, the hypothesis is also disproven just by examining the data."

    how is Mr. Svensmark's cloud driven climate change a hypothesis when he tested, concluded with results to back his theory...


    [JH] Please read the Advanced version of the rebuttal article.

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