There is a new paper in Environmental Research Letters that give additional support to Henrik Svensmark’s cosmic ray hypothesis of climate change on Earth. The idea is basically this: the suns changing magnetic field has an influence on galactic cosmic rays, with a stronger magnetic field deflecting more cosmic rays and a weaker one allowing more into the solar system. The cosmic rays affect cloud formation on Earth by creating condensation nuclei. Here is a simplified block flowchart diagram of the process:
The authors of the the new paper have a similar but more detailed flowchart:
The new paper suggest that changes in the quantity of cloud condensation nuclei (CCN) are caused by changes in the cosmic ray flux:
The impact of solar variations on particle formation and cloud condensation nuclei (CCN), a critical step for one of the possible solar indirect climate forcing pathways, is studied here with a global aerosol model optimized for simulating detailed particle formation and growth processes. The effect of temperature change in enhancing the solar cycle CCN signal is investigated for the first time. Our global simulations indicate that a decrease in ionization rate associated with galactic cosmic ray flux change from solar minimum to solar maximum reduces annual mean nucleation rates, number concentration of condensation nuclei larger than 10 nm (CN10), and number concentrations of CCN at water supersaturation ratio of 0.8% (CCN0.8) and 0.2% (CCN0.2) in the lower troposphere by 6.8%, 1.36%, 0.74%, and 0.43%, respectively. The inclusion of 0.2C temperature increase enhances the CCN solar cycle signals by around 50%. The annual mean solar cycle CCN signals have large spatial and seasonal variations: (1) stronger in the lower troposphere where warm clouds are formed, (2) about 50% larger in the northern hemisphere than in the southern hemisphere, and (3) about a factor of two larger during the corresponding hemispheric summer seasons. The effect of solar cycle perturbation on CCN0.2 based on present study is generally higher than those reported in several previous studies, up to around one order of magnitude.
The wider variation in CCNs makes the Svenmark’s hypothesis more plausible since the effect on clouds would also be proportionately larger.
They conclude:
The measured 0.1% level of the longterm TSI variations on Earth’s climate (i.e., solar direct climatic effect) is too small to account for the apparent correlation between observed historical solar variations and climate changes, and several mechanisms amplifying the solar variation impacts have been proposed in the literature.
Here we seek to assess how much solar variation may affect CCN abundance through the impacts of GCR and temperature changes on new particle formation, using a global aerosol model (GEOSChem/APM) optimized for simulating detailed particle formation and growth processes. Based on the GEOSChem/ APM simulations, a decrease in ionization rate associated with GCR flux change from solar minimum to solar maximum reduces global mean nucleation rates CN3, CN10, CCN0.8, CCN0.4, and CCN0.2 in the lower troposphere (0–3 km) by 6.8%, 1.91%, 1.36%, 0.74%, 0.54%, and 0.43%, respectively. The inclusion of the impact of 0.2 C temperature increase enhances the CCN solar cycle signals by around 50%.
The annual mean solar cycle CCN signals have large spatial and seasonal variations, about 50% larger than in the northern hemisphere than in the southern hemisphere and about a factor of two larger during the corresponding summer seasons. The average solar cycle signals are stronger in the lower troposphere where warm clouds are formed. The regions and seasons of stronger solar signals are associated with the higher concentrations of precursor gases which increase the growth rate of nucleated particles and the probability of these nucleated particles to become CCN. The effect of solar cycle perturbation on CCN0.2 based on the present study is generally higher than those reported in several previous studies, up to one order of magnitude. Clouds play a key role in the energy budget of Earth’s surface and lower atmosphere.
Small modifications of the amount, distribution, or radiative properties of clouds can have significant impacts on the climate. To study the impacts of a 0.5%–1% change in CCN during a solar cycle on cloud albedo, precipitation, cloud lifetime, and cloud cover, a global climate model considering robust aerosol–cloud interaction processes is needed. It should be noted that 0.5%–1% change in CCN during a solar cycle shown here only considers the effect of ionization rate and temperature change on new particle formation. During a solar cycle, changes of other parameters such as UV and TSI flux may also impact chemistry and microphysics, which may influence the magnitude of the solar indirect forcing. Further research is needed to better quantify the impact of solar activities on Earth’s climate.
Note the bold in the last paragraph.
WUWT readers may recall that Dr. Roy Spencer pointed out the issue of a slight change in cloud cover in his 2010 book intro of The Great Global Warming Blunder: How Mother Nature Fooled the World’s Top Climate Scientists. He writes:
“The most obvious way for warming to be caused naturally is for small, natural fluctuations in the circulation patterns of the atmosphere and ocean to result in a 1% or 2% decrease in global cloud cover. Clouds are the Earth’s sunshade, and if cloud cover changes for any reason, you have global warming — or global cooling.”
The paper at ERL:
Effect of solar variations on particle formation and cloud condensation nuclei
Fangqun Yu and Gan Luo
The impact of solar variations on particle formation and cloud condensation nuclei (CCN), a critical step for one of the possible solar indirect climate forcing pathways, is studied here with a global aerosol model optimized for simulating detailed particle formation and growth processes. The effect of temperature change in enhancing the solar cycle CCN signal is investigated for the first time. Our global simulations indicate that a decrease in ionization rate associated with galactic cosmic ray flux change from solar minimum to solar maximum reduces annual mean nucleation rates, number concentration of condensation nuclei larger than 10 nm (CN10), and number concentrations of CCN at water supersaturation ratio of 0.8% (CCN0.8) and 0.2% (CCN0.2) in the lower troposphere by 6.8%, 1.36%, 0.74%, and 0.43%, respectively. The inclusion of 0.2 °C temperature increase enhances the CCN [cloud condensation nuclei] solar cycle signals by around 50%. The annual mean solar cycle CCN signals have large spatial and seasonal variations: (1) stronger in the lower troposphere where warm clouds are formed, (2) about 50% larger in the northern hemisphere than in the southern hemisphere, and (3) about a factor of two larger during the corresponding hemispheric summer seasons. The effect of solar cycle perturbation on CCN0.2 [cloud condensation nuclei] based on present study is generally higher than those reported in several previous studies, up to around one order of magnitude.
The paper is open access and can be downloaded here: http://iopscience.iop.org/1748-9326/9/4/045004/pdf/1748-9326_9_4_045004.pdf
h/t to The Hockey Schtick and Bishop Hill
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Cosmic ray theory debunked,
‘This one is important…the Sun doesn’t alter much, [the theory says] the Sun modulates the cosmic rays, the cosmic rays modulate the clouds, the clouds modulate the temperature, so the Sun amplified hugely… but we have reasons to believe it’s a fine tuning knob…the cosmic rays came streaming in…we had a big cosmic ray signal and the climate ignores it and it’s just about that simple, these comic rays didn’t do enough for you to see it, so it’s a fine tuning knob’. R Alley.
Tex
“The effect of GCR/solar changes to CCN will only be seen in cloud data sets for areas where CCN number is the limiting factor on cloud formation. Where there are already abundant CCN and moisture is the limiting factor, GCR/solar increases in CCN production will not manifest as increased cloud cover. ”
YES. this is something that most people dont get. One way to explain it to them is as follows.
If you already have 100% cloud cover, adding GCR won’t get you anything.
and at the other end of the spectrum, if there isnt enough moisture you wont get clouds regardless of the GCR.
Testing this, finding the conditions where the change in GCR is the factor that drives cloud product, is searching for a needle in a haystack.
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I am waiting for a study to look theoretically at the areas where CCN number is the limiting factor and then show us cloud data just for that region that supports the connection. I believe the data will show the connection clearly if or when that is done…until then, using large scale cloud sets with larger variabilities built in will make it difficult to distinguish the relatively small changes that might be occurring due to GCR
If you look at the research on ionization you will see that the change in ionization is a function of latitude and pressure level. What I did was look at every pressure level I had ( 1018,991,887,771,648,548,441) and also looked at night versus day, and looked at the data
globally, by hemisphere, by 1 degree, 5, degree, 10 degreee, 15 degree, and 30 degree latitude bands.. Thats a lot of data snooping.. and found nothing
That is not to say there isnt something small there, but nothing was detectable.
As Leif points out. Even IFF GCR caused more clouds or fewer clouds, the problem remains
No secular trend.
Meh. I’d forgotten how weak the case was for this as far as the data goes. After googling a bit and looking at Svensmark & Chistensen 97 again and the responses to it, all I can say is. Meh.
“Above comments are based on analysis of a single event starting on 7th March 2012, when Ap-index peaked over 100, 4 times during period of one week. Such events are very rare; since there was a delay about 6 days it is hard to tell if tropics cloudiness change was a causal or coincidental.”
Interesting Vuk.
I can look for that in data that has more resolution than MODIS.
what did you find in night clouds?
Leif> For example, we are currently down to the same level of solar activity as a century ago, but the climate now is not what it was back then.
I expect better than this from a scientist who knows the difference between a value and its derivative with respect to time.
When I park my car at work, the speedometer goes back down to 0, just like it is in my driveway, but I’m not in the same place. In order to get the climate back to what it was a century ago, we have to get solar activity below its average over the last century for a substantial length of time (all other things being equal).
The polar vortex is a direct hole through the atmosphere into space. That means it is the input of the coldest air(ions that recombine) on the planet.
“All that can show is that the “it’s the sun, stupid” crowd are as simplistic and incorrect as that “CO2 control knob” crowd.”
you misunderstand the “control knob” metaphor.
Go to the primary source. Alley Argues.
1. There are many knobs. C02 is just one.
2. If you want to understand Paleo, you need this knob.
In short the biggest control knob in history is c02. other things matter as well.
Of course people “popularized” this argument, dumbed it down, used it as propaganda,
but the real argument is quite different
Did anyone ever consider that the cosmic ray effect might not necessarily produce obvious clouds but simply a faint haze or aerosol effect . All we would see would be that the sky was a slightly paler blue? Again I urge interested parties to look at the Steinhilber cosmic ray intensity graphs Fig 8 at
http://climatesense-norpag.blogspot.com/2013/10/commonsense-climate-science-and.html
This shows cosmic ray highs at the various temperature minima over the last thousand years. This also fits well with the temperature data in Fig 3 at the same link
lsvaalgard: “solar activity hasn’t varied much over the past…”
Yeah, right.
http://i273.photobucket.com/albums/jj237/tolou1/Solar%20SSN/SolarSunspotNumbers2013_2_zps1dd8b9ac.png
While this is sunpot numbers they represent overall activity and solar energy transfer to earth.
Over time, the cumulated deviation from mean adds up to a meaningful difference in energy flow.
So here the incoming energy has been higher than the long term average during second half of last century, and are now starting to drop heavily….
The Diagram (Fig. 1 in the paper, 2nd in the post) is premised on Greater Solar activity begets less GCR and fewer nucleation sites.
1. The box in the upper right has both a cooler and warmer arrow. The relative magnitudes in effect are not obvious. So this is sloppy thinking at best.
2. In the same box: “The number of cloud drops” has a blue downward arrow. Is it that the number of drops decreases or that the change in the number of cloud drops (either increasing or decreasing) is a cooling effect? Sloppy.
3. The radius of cloud drops has a red (warmer) ?increasing? Arrow. Why? Is this a citreous-paribus argument that with more nucleation sites, the radius must decrease for the same amount of water in the atmosphere? I’ll by that, but the hidden assumption is there is no change in the water content of the atmosphere, a most dubious assertion. Oh, but they will get to that later.. (no they won’t)
4. Cloud Albedo: In the scenario of less GCR, there are fewer drops and increased radius. That would tend to decrease albedo which would NOT be a cooling effect.
5. For smaller number of drops, but larger radius, Precipitation does what? It is a red increasing arrow. Does rain increase or decrease? They imply that precipitation increases and is a warming effect. (it is not a blue upwards arrow). Increased precipitation is greater heat transport via convection, evaporation, heat of fusion at altitude. That is a Cooling process.
6 From the Red increasing precipitation box we go to a Blue (?cooling?) decreasing cloud cover. Say again?
What does that increased cooling rain do to cloud cover? What time of day is it? What does it do to the water content of the atmosphere? (I’d think it on balance increases it — deserts are seldom cloudy) So… probably MORE cloud cover on average, and MORE cloud cover during daylight. Probably greater variability in cloud cover over the course of the day.
That lead us to the Earth’s temperature box, which in the diagram follows two ? Decreasing? Blue ?cooling? Arrows and they show a red increasing arrow. That seems mighty confused. Cloud Albedo probably increases and is a cooling factor. The precipitation path is ambiguous, but I believe greater precipitation begets a moister atmosphere, faster water cycle and an ultimate cooling effect.
So the “Earth’s Temperature” box really should result in a net cooling that reduces the temperature increase direct from the TSI. On balance, it is a NEGATIVE Feedback.
Scrap the diagram and fix its problems. Separate the numeric change (increasing, decreasing) from its (warming, cooling) implication. And as is usually the case, it is the stuff that is missing that is the real problem.
it is a long from a droplet to climate change on a large scale, there must be other limiting factors for cloud formation, so even the mechanism is valid; there will be a long way to afterward.
ANd if you look at any correlations between solar activity and climate there can be other phenomenon at play than just increase in nucleii formation…
understand the mechanism, and quantifyi it…then make prediction and see if observations are in agreement with calculations…
Well I see the usual set of problems here.
Leif has explained to us many times, that the 0.1% solar cycle variation, that is observed, would only result in about 70 mdeg. C temperature change , IF it all manifested itself as a Stefan-Boltzmann black body rebalance; which it doesn’t. Such a variation is not detected.
Svensmark’s thesis, while likely technically correct (Wilson cloud chambers DO work), does not appear to have the magnitude of an effect to show up. It’s another “butterfly” perturbation..
All kinds of atmospheric crud cause water droplet nucleation and hence cloud formation.
A lot of rainfall arrives on earth already thriving with bacterial colony life. Bacteria make very nice nucleation sites.
All of these aerosol options are simply ways for water to condense; but how much.
I think Roy Spencer’s observation, that just small cloud cover changes cause very large energy unbalance effects.
I think that is the crux of the problem; the water cycle is a negative feedback regulation of earth’s Temperature, and it is plenty powerful enough to erase solar cycle 0.1% changes, any Svensmark effects, and CO2 as well. I have repeatedly arhued that the Frank Wentz et al paper (observations) completely explains the effect and the cause of the cloud cover changes, that Roy postulates.
Remember it is changes over climate periods (30 year) and NOT last night’s weather, that is happening.
And global cloud cover is monitored satisfactorally, by only one entity.
Mother Gaia tracks the cloud cover, continuously, continually, and exactly, and set the temperature to exactly what it is supposed to be.
We humans, have NO MEANS of correctly sampling earth cloud cover, from the point of cloud area, cloud optical density (water content), and cloud persistence time (before dissipation by precipitation). Such measurements can only be made from underneath the clouds, and no such observation network exists.
So I believe Roy Spencer called it; and Wentz et al, observed it and measured it; but Svensmark and TSI cycling, while likely happening, are simply lost in the noise after cloud feedback gets through setting the Temperature, exactly where MG says it needs to be.
I think the notion that earth lies in the Goldilocks zone, and we are so fortunate, is just human centric nonsense.
Life on planet earth evolved here in this zone; because it could; and it has adapted to flourish under the conditions we have, and it has always done so, even though the key parameters of comfort, have been grossly different in the past. It never stopped life from flourishing and adapting, in the past, and a little change here and there, won’t stop adaptation in the future.
Last night, I accidently watched a section of a preposterous PBS (send more money) marine biology program,, all about carbon dioxide, seaweed, sea urchins and sea otters; that warned of the coming catastrophy from loss of sea otters.
Hey the little furbag monsters, having eliminated the abalone, on the west coast, are now eradicationg the sea urchins as well. This is good for humans, because sea urchins devour seaweed, which only grows at a slow rate of about a foot in 24 hours, and that seaweed (they call it kelp to sound scientific; but it’s seaweed); and in turn, that seaweed gorges on CO2, and makes life on earth possible for humans.
Now they never showed any video, of any sea urchins chewing down the kelp forests; well to be fair, there was no kelp at all growing where the sea urchins live.
Now I haven’t messed with too many live sea urchins while scuba diving.
These scientists were carefully measuring the diameter of sea urchins with a caliper to measure the threat to sea weed. Just what is the measure of the diameter of a sea urchin while it is waving its spines around to defend itself from the fur coats on the hoof.
But I have seen many a dead sea urchin shell, made into a light bulb or candle container, and they seem to be made out of CO2, or limestone if you prefer.
I would think that a surfeir of sea urchins would do more to sequester CO2, than any seaweed.
Now remember that sea otters were once thought to be extinct, due to the fur trade, and I never heard of the oceans being overrun with sea urchins, and the extinction of seaweed, and global warming/ acidic oceans due to lack of sea otters.
Yes I happen to like sea otters too; and other otters as well; but I believe the decline of California sea otters, is entirely due to them eating themselves out of house and home.
Absent any significant predation, including human, these eating machines, have denuded vast areas of former shell fish, abalone, and sea urchin habitats, all along the west coast.
The marine mammal protection act has done more to destroy west coast fish stocks, than any human predation has.
But such touchy feely studies will continue to be funded by a gullible public, just like climate research. What a gig; get a degree, get a living at taxpayer expense, tour the world, and report your null results in 30 years when you are ready to retire (on a taxpayer footed pension.)
We are all being scammed.
Willis’s recent expose, on the completely ineffectual decline in ML sunlight, due to volcanoes, with nary a Temperature change in response, should be enough to set the scam alarms off.
Svensmark is interesting; even gave CERN something to do; but isn’t it just another butterfly ??
From the first box of the cartoon diagram I suggest you could also add as a hypothesis:
Lower magnetic field strength —> Fewer solar surface faculae —-> greatly diminished EUV (30-120 nm) and FUV (emission —> 120-200 nm) —> greatly diminished (nonlinear to delta TSI) ionization of O and N species, and much less ozone creation in stratosphere —> less outgoing surface IR reflectance back to atmosphere (thermal blanket effect diminished) —> climate cools.
JJ says:
April 10, 2014 at 12:07 pm
I quoted you, not Svensmark. Own your words.
I quoted Svensmark. In his papers there is no delay.
The Monster (@SumErgoMonstro) says:
April 10, 2014 at 12:24 pm
I expect better than this from a scientist who knows the difference between a value and its derivative with respect to time.
We are discussing the Svensmark mechanism, and Svensmark does not invoke any ‘lag’ or delay. His effect in immediate.
I have read from the “joes” at weatherbell that they feel low solar activity correlates well with increased high latitude blocking in the NH, hypothesized to be due to solar wind interaction with the upper atmosphere (stratosphere & above) , with that then effecting the tropospheric circulation. So, no global temp effect, just a circulation effect. Probably why Henry P saw an 11-12 yr cycle in his AK data , which would be strongly influenced by NH blocking patterns
A normal Sun with a normal magnetic field would keep the temps stable, Now weaken the magnetic field for enough time and you get a imbalance in temps to the down side due to the increase in GCR’s. At solar max you should have a low neutron count, now look at the yearly graph going back to the 60’s. I think there is a correlation with temps on the amount of time above and below the zero line. Look at where the count is now, it’s at the zero line at solar max so it cant counteract the cooling from the last minimum. I expect at the next minimum they will have to make a new graph to fit the increase in the neutron count. Just looking at that chart you can tell a lot, whether one solar max cancels out a solar min to keep temps flat. Looks like this solar max is not going to counter the last solar min so cooling will be the result.
Leif, the warming response will be immediate. Just as it would be when you turn on the burner under a pot of water. But unless you drop a few ice cubes into the pot, once you turn the burner off, the water will not cool at the same rate that it heated up. The earth is the same way. When you allow extra energy in, it will warm nearly instantaneously. However, returning to the same energy input level as 100 years ago after a period of elevated input, you will not see an immediate decline, because the energy is absorbed into the system (ocean heat, etc) and the temperature will only proceed back to the level it was 100 years ago if you have a similar period of energy input that is below what it was 100 years ago.
The CERN ‘Further information” data section that was hosted on researchpages.net appears to be in limbo as the site has deceased…
Fortunately there is a backup on archive.org
Perhaps someone could track down who is responsible for maintaining the site and get them to pay the domain fees to keep it alive?
Fixed the link for “Further Information”
Tex says:
April 10, 2014 at 1:23 pm
the temperature will only proceed back to the level it was 100 years ago if you have a similar period of energy input that is below what it was 100 years ago.
The point is that in each of the three centuries (18-20) solar activity [and cosmic rays] have behaved the same way: starting low, then increasing to a maximum mid- or late-century before falling to a low at the end of each century. The maxima and the lows have not been substantially different, so I would expect the climate also not to be substantially different unless you invoke lags of many centuries in order to de-couple climate from solar input.
The SIDC and I [with coauthors from Spain and USA] are putting final touches to a draft of our reassessment of the solar cycle. My input can be seen here http://www.leif.org/research/ISSI-Book-Section-4.pdf
skip to Figure xx12 so get the bottom line. But remember that this is work in progress. You are getting a front seat to see science at work. An earlier paper is here http://www.leif.org/research/CEAB-Cliver-et-al-2013.pdf
Cloud height, has in fact been decreasing.
http://www.sciencedaily.com/releases/2012/02/120222114358.htm
If the ratio of low to high clouds increases, there is net cooling as low clouds radiate from a warmer place in the troposphere.
I have always felt that this is evidence of a negative feedback from an increase in water vapor, which would happen in the lower troposphere.
One element that seems to be overlooked is the explosive growth response by vegetation to the increasing CO2(and warming in the 80’s/90’s) and the contribution of this to evapotranspiration.
The US Midwest during the growing season is a a perfect example of this effect with planted crops.
Consider this a regional real world outdoor laboratory. Tightly packed rows of tens of millions of acres of corn(double the density of 30 years ago) over an area the size of almost a dozen states has resulted in a noted increase in dew points(+5 F or greater in some cases) creating a more humid micro climate when corn plants are established and tapping deep soil moisture. The evapotranspiration contributes to low level moisture, which lowers the lifting condensation level needed for rising air to form clouds(causing them to be lower) and formation of convective clouds earlier in the day as well as increasing rainfall from weather systems, which in turns feeds the cycle by returning moisture to the ground/plants…….which can use it for additional evapotranpiration.
Also, the more dense vegetation vs less dense vegetation or bare ground plays a role………even in deserts that are greening up from increasing CO2.
This effect may be mostly independent of the variation in cosmic rays or it could be enhanced/suppressed by changes in GCR’s.
tolou says:
April 10, 2014 at 12:50 pm
Yeah, right.
Yeah, wrong. You are plotting obsolete data.
Or ENSO?
http://virakkraft.com/Sun-clouds-tropics.png
Steven Mosher says:
April 10, 2014 at 12:31 pm
“All that can show is that the “it’s the sun, stupid” crowd are as simplistic and incorrect as that “CO2 control knob” crowd.”
++++++++++++++++++
Nice video. One question. What was the temperature of the Earth’s core 4.6 billion years ago and how much heat was reaching the surface. No one ever seems to talk about that. Are there papers on heat transfer from the earth in geologic time?
lsvalgaard says:
April 10, 2014 at 11:56 am
JJ says:
April 10, 2014 at 11:53 am
The idea that climate forcings must act instantaneously is asinine.
Tell that to Svensmark et al.
well yes and no.
It is onservable that the suns straight insolation drives the seasons with ABOUT 6-8 week lag at my latitude. (UK) – peak ice being mid to late Feb usually., If there is any.
that is ‘instant’ in climate change terms as good as.
Surface sea temperatures take longer of course, and spreading the change round the globe takes years but everything about the cloud model shows that for land based surface readings there should be little or no lag.
Now on scafetta. To make the claim that svensmark and scafetta are dong no more than curve fitting implies that AGW proponentd are doing something more than mere curve fitting, but in reality they are not.
The chief difference between then and Svensmark and Scafetta is that they dont claim to be providing the final solution – they are pretty honest that this is a work in progress, and that whilst they both think they have seen SOMETHNG neither is quite sure what it is they have seen or how it works.
And what seems – according to the CLOUD experiments at CERN – to affect cloud formations is not just any old cosmic radiation. NO sirree bob. You appear to need a pretty deep penetrating high energy muon, and those tend to be the least affected by sun deflection, which might place the actual cause of climate change outside the solar system.
I think we would be better off without the fanbois constantly yelling from one end of the spectrum to another that such and such theory has ‘discovered the causes of climate change’ The reality is beginning to dawn that in fact its a gigantic puzzle and we have perhaps found a few pieces to fit together but the overall picture is MASSIVELY unclear.,
And that is in the end the position we must take. AS skeptics we are sure that CO2 has SOME effect: we are also pretty much of the opinion that is not the whole story and in fact its effects may be second order or lower to the point where we can ignore it. That doesn’t mean we have to explain what IS causing it though. It is enough to say ‘Carbon Dioxide?’ Not guilty’ and let science take its course.
So I would say wit Svensmark we are precisely where we should have been years ago with CO2. Does cosmic radiation flux influence earth’s climate? Almost certainly. It would be strange if it did not, The question is is not that, it is by how much and of what sort.
If you were to ask the average educated man in the street of 100 years ago ‘what affects the climate most’ he would have said ‘the sun, because summer is warmer than winter’ If you had then asked what the second most important thing is he would have said ;’the clouds, because they block sunlight’ and a cloudy day is always cooler than a clear day and warmer than a clear night, all other things being equal’.
He certainly wouldn’t have said ‘carbon dioxide’;