Cosmic Rays too Wimpy to Influence Climate


People looking for new ways to explain climate change on Earth have sometimes turned to cosmic rays, showers of atomic nuclei that emanate from the Sun and other sources in the cosmos. 

But new research, in press in the journal Geophysical Research Letters, says cosmic rays are puny compared to other climatic influences, including greenhouse gases — and not likely to impact Earth’s climate much.


Jeffrey Pierce and Peter Adams of Carnegie Mellon University in Pittsburgh, Pennsylvania, point out that cycles in numerous climate phenomena, including tropospheric and stratospheric temperatures, sea-surface temperatures, sea-level pressure, and low level cloud cover have been observed to correlate with the 11-year solar cycle.

However, variation in the Sun’s brightness alone isn’t enough to explain the effects and scientists have speculated for years that cosmic rays could fill the gap.

For example, Henrick Svensmark, a solar researcher at the Danish Space Research Institute, has proposed numerous times, most recently in 2007, that solar cosmic rays can seed clouds on Earth – and he’s seen indications that periods of intense cosmic ray bombardment have yeilded stormy weather patterns in the past.

Others have disagreed.

“Dust and aerosols give us much quicker ways of producing clouds than cosmic rays,” said Mike Lockwood, a solar terrestrial physicist at Southampton University in the UK. “It could be real, but I think it will be very limited in scope.”

To address the debate, Pierce and Adams ran computer simulations using cosmic-ray fluctuations common over the 11-year solar cycle.

“In our simulations, changes in [cloud condensation nuclei concentrations] from changes in cosmic rays during a solar cycle are two orders of magnitude too small to account for the observed changes in cloud properties,” they write, “consequently, we conclude that the hypothesized effect is too small to play a significant role in current climate change.”

The results have met a mixed reception so far with other experts, according to an article in this week’s issue of the journal Science:  Jan Kazil of the University of Colorado at Boulder has reported results from a different set of models, confirming that cosmic rays’ influence is similarly weak. But at least one researcher — Fangqun Yu of the University at Albany in New York — has questioned the soundness of Pierce and Adams’ simulations.

And so, the debate isn’t over yet …

Sources: The original paper (available for registered AGU users here) and a news article in the May 1 issue of the journal Science. See links to some of Svensmark’s papers here.

27 Replies to “Cosmic Rays too Wimpy to Influence Climate”

  1. True, however, I do have concern should there be a SN about 500LY away causing the Suns’ protective heliosphere to be pushed into the inner Solar System perhaps causing far more UltraHighEnergyCosmicRays(the CR with the energy of a baseball fastball) to hit the Earths’ atmosphere and many will survive to the surface hitting humans and affect their DNA, estimates says perhaps 1% of the human population will get cancer that
    does not start from a certain spot, but affects the whole body, the person perish within 1 month-these are the ‘bolt from the blue’ cancer that has no occurence in family history nor in a cancerous environment.. I believe many out there heard of people who died from whole body cancer of ‘mysterious’ cause and died fast, this is the only good thing about it, the demise is quick , The number of humans I talk about is about 6,500,000 people.

  2. Addendum, The number should there be a close SN should be 65,000,000 or 1% or the Earths’ population.
    about 6,500,000 cancerous ‘bolt from the blue’ occurs every year

  3. @star-grazer west coast: I think that most UHECRs originate much further away than galactic supernovae; they’re from the jets associated with active galactic nuclei (AGNs) such as that in M87 or CygA. And in any case, they are so rare that an increase of even a thousand-fold would likely have but a trivial effect on mutation rates.

    A nearby supernova would likely produce copious quantities of cosmic rays with energies up to ~a PeV (which is ~a thousand times more energetic than the best our terrestrial particle accelerators can do), with most of the increased DNA damage being cased by considerably less energetic ones (say, GeV to TeV).

  4. Nereid – You’re right. It doesn’t require the heavt UHECR to do damage- the lesser energetic ones are nasty enough.!!!! Thank you for the info.

  5. I am glad to see this matter put to rest. Of course global warming types will keep hawking this as a source, just creationist keep hammering old discredited ideas.

    The cosmic ray tracks, artistically portrayed above contain a lot of information. Those particle sprays contain information about particle physics up to 10^9GeV. The problem is how to we detect it all. The information is there, but we can’t so far read it.

    Lawrence B. Crowell

  6. @ Lawrence B. Crowell, Thanks for the clarification of your earlier comments. I somehow couldn’t picture you in the ‘anti-global warming’ camp, as you seem to be a rational person who can interpret current scientific information and know the scientific consensus on the global warming issue. Anyway, you bring up a good point and maybe this research may sway some policy makers as to the reality of the situation.

  7. If you are familiar at all with the research that the Danish Space Institute did on this subject, you are aware that they came up with a hypothesis, conducted physical experiments that confirmed their hypothesis, and published their data and experiments so that anyone questioning it could repeat them for themselves. When I was in school this was called science. Are you going to believe physical reality or a computer simulation????

  8. conducted physical experiments that confirmed their hypothesis, and published their data and experiments

    [citation needed]

  9. I’ve read of studies of possible vast increase of cosmic rays up to ~a PeV as indicated by
    Nereid due to very close SN like the one that created the Vela nebula and a few others. Most likely high number of deaths were caused by ‘bolt from the blue’ whole body cancers that killed a person within 30 days. I’ve read NO account of CR causing global-warming or cooling-I was born and raised in the US, and where did this ‘hypoto’ (I refuse to write the whole thing lol) junk come from!??
    I can understand our Suns’ energy output can be affected should it go through the densest part of the spiral arms, however, humans will be in serious danger being too close to too many of the ‘big heavyweight’ stars anyway!!!!

  10. I think the question should be whether cosmic ray showers induce ion trails that initiate lightning strikes. THEN, what effect do those lightning generated shock waves have as they propogate outward in dense cloud structures?

  11. Aqua Says- I have to agree with you.Unfortundately, Ann had to post this article whether it made sense to her or not.
    . I;ve read articles some time back,something about it made no difference to the climates dispite high or low CR counts. In the event that a very distant object is affecting our weather, that would be the least of our worries!!!! It would probably mean our atmosphere is being torned apart!!!

  12. Henrik Svensmark (along with Nigel Calder) have written a book detailing their research; it also contains many references to other works. The book is called “The chilling stars” I read it recently; it is worth reading with an open but critical mind. A good read (I have no connection with this book whatsoever).

  13. S.E.Cycloid Says:
    Thank you for the title-besides your suggested book-I’m also getting ‘Death from the Sky’ by Philip Plait . It took me 3 hours to read ‘Physics of the Impossible’ by Michio Kaku. These books are so relatively cheap being paperbacks, I usually give them to the libraries when finished. I have to check what ‘The chilling stars’ have to say, I will be open but always critical minded, if I have doubts, I always check other sources dealing with the same subject matter. S.E.Cyclold, it is true there are 2 sides to every story, but some tries to inject a 3rd-4th etc for whatever reason. Like some of the subject matters in
    ‘Physics of the Impossible’ , many things will remain impossible but I do have an open mind, but will start to think of smashing all weaknesses in the ‘fortress hypothesis’ of someones ideas- if the ‘fortress’ remains standing, then someone does have revolutionary facts, however, practically all ‘fortresses’ were breached, and I exterminated everything inside lol. You get the idea!!!!!!!

  14. Henrick Svensmark’s research, which came out around 2006-7 or so, ran into trouble back then as I recall. The problem is that I am far from being a climate scientist, so I have to go with what is being published in the mainstream on the subject. I will say that it largely makes more sense than the “alth-theories.”

    For cosmic rays to be a major driver in the climate picture they would have to deposit some appreciable fraction of a watt/meter of energy ot the Earth. They don’t have anywhere near this flux. Further, there would have to be some mechanism for why cosmic radiation has a variation with time and data to support that conclusion. There is none on either account.

    My sense is similar with solar variation hypotheses. There is no data to support a variation in solar irradiance that would drive a warming of the planet. The Ulysses probes and other space based solar observatories have recorded nothing of that sort.

    The CO_2 warming mechanism remains as the dominant source corroborated by data at this time. Denialisms and counter claims are a matter of political smoke screens than honest research. These are of course a disservice, and we risk not fully addressing this problem as a result.

    Global warming is really just an extension of a problem identified 50 years ago by Rachael Carlson in her “Silent Spring.” We humans are extracting resources and energy and by corollary dumping entropy on the biosphere at a rate far faster than natural systems can adjust, replensish or absorbe these changes.

    Lawrence B. Crowell

  15. Professor Wang at the University of Albany has been charged with massaging data to attack the Urban Heat Island effect in two seminal papers, and the University has failed to make the results of its investigation known as Prof. Wang has refused to turn over his source data. This behavior casts a pall on all University of Albany research in my view.

  16. groupguy
    The effects and feelings of the Urban Heat Island is known to anyone with a pulse-the only ones who don’t know about the UHI are those who never left the very rural areas and those without a pulse. The UHI effect is so extreme in some metro areas, NOAA had to move the thermometers out further, sometimes several times, even then, the minimum temperatures is higher then when the term UHI was not generally known. I can’t figure out why that Professor Wang is trying to disprove something known for decades

  17. Mr. Crowell, you have not understood the CR theory if you suggest that the CR must contribute an “appreciable fraction of a watt/meter.” The CR are proposed as having an amplifying effect through their influence on low cloud cover. I suggest reading Jasper Kirkby’s proposal paper for CERN. Notice that CERN is spending a lot of money to do the research on this and replicate Svensmark’s own work. ( Notice too that Ms. Minard seems to be a bit schizophrenic: the title leads us to believe the theory is dead; her own conclusion states, “so the debate goes on.” Ms. Mindard may not be a careful writer, may be simply trying to sensationalize, or may be a victim of her editor’s desire to sensationalize. The CR – climate link’s death has been exaggerated before. Here is a recent defense:

  18. Lawrence B. Crowell, who keeps pointing out that he’s not a climate scientist, just gave me the best simple explanation for global warming I’ve seen so far:
    “We humans are … dumping entropy on the biosphere at a rate far faster than natural systems can adjust, replensish or absorbe these changes.”
    Woah, could it really be that obvious?!

  19. Readers interested in published work on ‘cosmoclimatology’ by Henrik Svensmark and the controversial nature of his claims might want to check his Wiki page here: . I found it to be a good overview of his work on this topic with many links to peer-reviewed, published work on both sides of this issue. Links to CERN’s proposed CLOUD experiment can also be found here. While mention is made of ongoing research on this particular topic, nothing I’ve read on this seems very convincing, so I await independent confirmation of his results, preferably by multiple research efforts, confirming his theory of ‘cosmoclimatology’.

  20. BTW, the proposed CERN CLOUD experiment proposals date from around 2000 to 2006. Another CERN CLOUD page was last updated in 2008. Maybe CERN has had a change of heart in pursuing this experiment, especially given the numerous refutations of this theory based on physics alone and also the current funding problems due to the global economy. This theory may not be ‘dead’, but it’s facing an uphill battle for acceptance by the mainstream astrophysical community, not to mention other associated sciences.

  21. Jon Hanford
    Your link to Svensmark at May4th2009 at .925am had this
    ‘During the last 100 years cosmic rays became scarcer because unusually vigorous action by the Sun batted away many of them. Fewer cosmic rays meant fewer clouds–and a warmer world’
    My career I finished is not into astrophysics, nor any of the applied higher degree Space Science decipals,nor any Earth Science degrees, just Info Technology as a Network Administrator-very unrelated but just a serious amateur astronomer and .love to research about Earth Sciences.
    The statement ‘ During the —– to me, if the Sun is more active, there is a slight increase in Earths’ temperature, yet, Svenmark says
    because of fewer clouds due to less CR means even warmer?!?!?!? Such a statement tells me should the Sun goes through some periodic normal cooling, does it mean the CR will increase causing the Earths’ temperature to drop like a rock?
    I’m sorry, I do not buy that hypoto… as I think Svenmark is just trying to sell a book or conjouring up a very unusual hypothesis in order to get funding.
    I have nearly 300GB (no duplicates but another 300GB backup) of climatology,meteorology data and storm and unusual weathers from many US and many other cities in the world dating back over 100 years, the fact of the matter is, the weather is warming up!!!!!!!
    CO2 is a very important factor
    Urban sprawl is another factor
    Simply put. I love to research!!!! lol

  22. As a sort of erratum I meant to say watt/meter^2 — I forgot the squared.

    As for references, I would suggest going to a library which carries the AAS “Science” and look at some of the short review articles there, and if you deign to read them some of the professional articles on climate science. The evidence supporting global warming is literally snowballing. You might also look at some of these youtube clips which debunk some anti-global warming media statements

    As for cloud seeding by cosmic rays, it must be pointed out that this involves the cosmic rays depositing energy in water vapor. There is still insufficient energy to accomplish this. The hypothesis is very questionable.

  23. At the most,I am a low level environmentalist or most likely, not at all- however, GLOBAL WARMING IS FOR REAL!!!! It is unfortunate most of my fellow Americans do not believe it. What should really open your eyes and mind is, 70% of our petroleum is IMPORTED!!! This will eventually become a very serious national security issue!!! Many Americans are under the impression Saudi Arabia is the country of the 1970s’- wrong-Saudi Arabia now has 4 times the population and increasing rapidly and their requirements for petroleum and to run expensive desalination
    plants will soon cause their exports to drop 50-75% in the next few years, dispite increasing production. Saudi Arabian pipelines are subject to terrorize actions all the time!!. The US will soon have to compete with India and China for remaining Saudi exports. Most of the other exporting petroleum nations are quite unstable/unfriendly to America. The next thing to think about is economics, I believe after a few years of hardship and expenses, the US economy will recover, however, unless this incredible import of petroleum continues, the next economic crisis, America will NOT recover and will start a decline to 2th rate, your kids will inherit America in economic decline. Military power is tied to economic power- remember what happened to the Soviet Union!!!! Today, because Russia is petroleum independent, their economy is slowly but surely improving, they can ween themselves off petroleum as their technology
    for alternate cleaner fuels becomes feastible for mass production.
    In the US, there is a strip of land north to south about the 100W longitude about 5-10 degrees wide called the western great plains, lightly inhabited-the climate is semi- arid at best, the winds nears 20mph(32KPH) and during the Spring and Fall, has the most violent, dramatic weather in the world(most of the residents are not proud of this fact!!!!!)
    This area is ideal for Wind Power, the amount of power has the potential to be in the hundreds of GigaWatts of power-it is true from time to time a monster tornado about 1,5miles or 2500meters on the ground with winds to 300mph (490KPH) will place some windmills into history, but there will still be much redundancy. Hybrid cars and better outdoor lighting will lessen our energy needs and there are many thing that can be done without lowering the standard of living, a LOT OF THINGS.!!!! I am now 62yo, and I hope my Sons and grandkids still have a future like I enjoyed, however, I don’t know..

  24. After reading star-grazers west coast rational and passionate post on the reality of global warming and Lawrence B. Crowells’ quantitative analysis of the problem, it would seem that if CR did impact global warming appreciably, we as a civilization would have little control over the current situation. IMHO, this is not the case at all. Research like this and the refutation of the Urban Heat Island phenomena are just wrongheaded and only obfuscate and delay action on the problem at hand.

  25. I like the way that the true believers massage each other with adjectives that are meant to convince others that only one side in global climate science is rational and scientific. Very scientific of you.

    And of course we have the requisite approving reference to one of the most disastrous pop science campaigns in memory, the DDT banning hysteria of Rachael Carlson, which resulted in the miserable deaths of tens of millions of black and brown malaria victims. A future Margaret Sanger Award nominee, no doubt, for racial eugenics.

  26. OK, let me see here. There is abundant evidence that significant climatic variations correlate very well with solar cycles. But we can’t figure out why, so we will pretend that the effect does not important. This reminds me of the physicians in The Madness of King George who dismiss the significance of the King’s urine being blue because they cannot imagine how it could relate to his symptoms. This is not science, guys. When a correlation stares you in the face you try to explain it, not try to fit into your preconceived, fixed notions.

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