There’s some interesting information of the six month trend of neutrons being detected globally that I want to bring to discussion, but first I thought that a primer on cosmic rays, neutrons, and their interaction with the atmosphere might be helpful to the many layman readers here. – Anthony
Cosmic rays are energetic particles that originate in space and our sun and collide with particles as they zip through our atmosphere. While they come from all directions in space, and the origination of many of these cosmic rays is unknown, they has recently been shown that a larger percentage emanate from specific deep space sources. Cosmic rays were originally discovered because of the ionization they produce in our atmosphere. They cause ionization trails in the atmosphere much like you see in a simple science project called a cloud chamber, shown below:
Using the Wilson cloud chamber, in 1927, Dimitr Skobelzyn photographed the first ghostly tracks left by cosmic rays.
In the past, we have often referred to cosmic rays as “galactic cosmic rays” or GCR’s, because we did not know where they originated. Now scientists have determined that the sun discharges a significant amount of these high-energy particles. “Solar Cosmic Rays” (SCR’s – cosmic rays from the sun) originate in the sun’s chromosphere. Most solar cosmic ray events correlate relatively well with solar flares. However, they tend to be at much lower energies than their galactic cousins.
Because Earth’s atmosphere also reacts much like the ionization trail effect seen in the Wilson cloud chamber, scientists such as Svensmark have postulated that galactic cosmic rays can affect the earth by causing changes in weather and possibly long term climate. Moving at close to the speed of light, these nuclear fragments smash into air molecules hard enough to knock electrons loose. This well-documented process creates negatively and positively chargedions.
Like the cloud trails seen in the Wilson cloud chamber, cosmic ray ionization trails in our atmosphere can act as cloud seeds. Some studies suggest that ions play a central role in creating aerosols. Aerosols are minute but important atmospheric particles that can serve as the cores of growing cloud droplets. Aerosols can cause clouds to form in the upper atmosphere, after the particles collide with other atmospheric particles in the troposphere and conglomerate into larger particles.
Aerosols: Many atmospheric aerosols are liquid droplets containing dissolved sea salt from sea spray, sulfuric acid (H2SO4), organic molecules from trees and plants, and other compounds. Over agricultural and urban areas, dust and soot are common aerosols Soot particles emanate from incomplete combustion of fuels such coal, wood, oil, jet fuel, and kerosene. Soot consists chiefly of amorphous carbon and tar like substances that cause it to adhere to surfaces. Both liquid and solid aerosols help clouds develop by encouraging the condensation of water vapor, which does not occur readily without an original seed particle of some sort in the air.
A cosmic ray, especially a high energy one from deep space, can cause an entire family tree of smaller particles and ionization trails. See this animation below created by the Cosmus group at the University of Chicago.
The process of a cosmic ray particle colliding with particles in our atmosphere and disintegrating into smaller pions, muons, and the like, is called a cosmic ray shower. These particles can be measured on the Earth’s surface by neutron monitors.
Click on figure to view a diagram of a cosmic ray shower
Neutron Monitors. Ground-based neutron monitors detect variations in the approximately 500 Mev to 20 GeV portion of the primary cosmic ray spectrum.
(Note: 1 Mega electron Volt = 1.60217646 × 10-13 joules)
This class of cosmic ray detector is more sensitive in the approximate 500 Mev to 4 GeV portion of the cosmic ray spectrum than are cosmic ray muon detectors. The portion of the cosmic ray spectrum that reaches the Earth’s atmosphere is controlled by the geomagnetic cutoff which varies from a minimum (theoretically zero) at the magnetic poles to a vertical cosmic ray cutoff of about 15 GV (ranging from 13 to 17) in the equatorial regions. (Note: GV is a unit of magnetic rigidity. Magnetic rigidity is a particle’s momentum per unit charge. It is the relevant quantity for characterizing a cosmic ray’s ability to penetrate Earth’s magnetic field.).
The primary cosmic ray particles interact with the atmosphere and generate secondaries, some of which will reach the surface of the Earth.
When the secondary cosmic rays interact in the monitor, (actually in lead surrounding the counters) they cause nuclear disintegrations, or “stars”. These stars are composed of charged fragments and neutrons typically in the energy range of tens to hundreds of MeV (million electron-volts), even up to GeV energies. As a result of these high energy nuclear interactions, there will be more secondary fragments generated than incident particles and hence there is a multiplier effect for the counters. The neutrons are moderated and then counted using Boron tri-fluoride (BF3) proportional counters which are efficient thermal neutron detectors; hence the name neutron monitor.
The original design by Simpson is often designated as an IGY neutron monitor. From that link:
John A. Simpson, at the University of Chicago, invented and developed the neutron monitor over the years 1948-50 and found that the Earth’s magnetic field could be used as a spectrometer to allow measurements of the cosmic ray spectrum down to low primary energies. The magnetic latitude of a particular neutron monitor determines the lowest magnetic rigidity of a primary that can reach the monitor, the so-called “cut-off rigidity”. The station’s altitude determines the amount of absorbing atmosphere above the station and hence the amount of absorption of the secondary cosmic rays (the higher the station, the higher the counting rate). By using a combination of lead (to produce local interactions), paraffin or polyethylene (to moderate or slow down the neutron component) and multiple slow-neutron counters, Simpson greatly increased the counting rate in his monitor design.
The worldwide network neutron monitors that have since been established gather data that have shown there is a correlation between periodic solar activity and the earthly neutron count. For example:
This plot shows data from the Climax, Colorado neutron monitor operated by the University of Chicago. The cosmic rays show an inverse relationship to the sunspot cycle because Sun’s magnetic field is stronger during sunspot maximum and shields the Earth from cosmic rays.
Right now we are near the solar minimum, but neutron counts are still increasing. The current science says that if we had passed solar minimum, neutron counts should be decreasing.
Michael Roynane writes today:
The Bartol Research Institute of the University of Delaware manages five real-time neutron monitors, at widely dispersed locations, all of which indicate that over the last six months cosmic rays are increasing. This would not support the hypothesis that we are past solar minimum and suggests that solar minimum has not yet been reached.
Links to the Bartol Research Institute of the University of Delaware:
http://neutronm.bartol.udel.edu/
http://neutronm.bartol.udel.edu/main.html#stations
Newark, DE Neutron Monitor
![[image]](https://i0.wp.com/neutronm.bartol.udel.edu/~pyle/theplot2.gif)
McMurdo Neutron Monitor
![[image]](https://i0.wp.com/neutronm.bartol.udel.edu/~pyle/themcplot2.gif)
Thule Neutron Monitor
![[image]](https://i0.wp.com/neutronm.bartol.udel.edu/~pyle/thethplot2.gif)
Fort Smith Neutron Monitor
![[image]](https://i0.wp.com/neutronm.bartol.udel.edu/~pyle/thefsplot2.gif)
Inuvik Neutron Monitor
![[image]](https://i0.wp.com/neutronm.bartol.udel.edu/~pyle/theinplot2.gif)
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Robert Bateman (22:07:46) :
We know from literary records that the 1790’s were brutally cold. Much writing and no secret.
That it was cold has no bearing on the Sunspot Number.
SC4 probably had a 2nd peak halfway down, in the position you have as a flat line (black).
There is no good evidence for that. On the contrary, the newly digitized Staudacher drawings [ http://www.leif.org/research/Staudacher-1.pdf http://www.leif.org/research/Staudacher-2.pdf ] show clearly that there is no ‘lost cycle’. Gilpin’s measurements of the diurnal variation of the Declination in London http://www.leif.org/research/Gilpin.png likewise show that there is increase in the SSN in the 1790s.
The problem I have with your statement is the word ‘probably’. Available data show otherwise as I have just shown, so why ‘probably’?:
http://www.leif.org/research/Sunspot%20Number%20Data%201775-1802.png
The resistance you are getting is the tendency of old works once remodeled is to be forgotten and discarded.
Read the introduction in http://www.leif.org/research/IAGA2008LS-final.pdf The final sentence says: “We argue that all efforts must be expended to preserve and digitize these national and scientific treasure troves”.
It is by harnessing the forgotten treasures that we improve the historical record. The resistance I’m getting is that many people do not want the record improved, if the old record matches their pet theories better.
Ninderthana (01:36:14) wrote: “Rodger Carr, Haven’t you ever wondered why Leif Svalgaard spend so much time on excellent blogs like this trying to put out spot fires…”
As I have never viewed Leif’s comments that way, Ninderthana, I cannot agree with the general negative thrust of your posting; but I fully endorse your positive comments.
Where Leif (in your words) “shuts down” a discussion this is because there is sound science and agreement on the subject/question raised and therefore there is no valid reason to spend time chewing on it. We can all waste time through basic ignorance (of which I am the sad holder of records), and I am always grateful when Anthony, Leif, or others with knowledge, shunt me back onto the mainline with basic facts.
When it comes to speculation and new insights I have always found such people open and eager to explore.
Robert Bateman (22:07:46) :
Gilpin’s measurements of the diurnal variation of the Declination in London http://www.leif.org/research/Gilpin.png likewise show that there is NO increase in the SSN in the 1790s.
grrrr.
March 16 already, and not a sunspot in sight.
We’re headed for yet another almost spotless month.
Sigh…
Leif Svalgaard (02:47:08) :
That it was cold has no bearing on the Sunspot Number.
And you are entitled to your beliief. Not everyone shares it, and the relation of climate to SSN is not a settled issue by any means. I’ll give you an example at the end.
Where we differ, Leif, is in the view of importance of the original vs the iterpretation. The record is the data, and the record was made by very earnest observers. Interpretation of an observers work and the esteem to which they honestly performed thier observations is intertwined.
Eddy himself bore witness to the dedication he found.
This I find remarkable since it was his original mission to disprove.
The early observers had no varying opinions of the day to bias thier observations. It was them and nobody else.
Sir William Herschell observed and noted the lack of sunpots and the price of wheat at the time. Opinion starts after the fact and varies.
When I observed and reported back to you the poor contrast of several recent sunspots, it was because I had to really work at spotting them, not because I had a preconceived notion that they were of poor contrast.
I highly encourage anyone with opportunity and a good small modern refractor to do the same. Observe while you have the chance. Down the road, when the
sunspots go back to thier original state, you will have the record or you will have the opinion of the record, but you will not be able to observe the past.
E.M.Smith (21:32:03) :
I think that many of the tools / indicators developed for tracking stocks could probably be of some benefit in climate analysis.
Absolutely. The averages conceal the important details.
e.g.
1. Most of the warming experienced since 1978 is confined to high latitudes in both hemispheres and it is related to an increase in winter minima.
2. Antarctica is cooling in summer and warming in winter.
3. The increase in the temperature of the atmosphere is absolutely confined to the levels below 700hPa where the air is in contact with a warming ocean. Most of the latent heat of condensation is released lower than the 700hPa level. Above 700hPa there is no upward trend at all.
4. There has been no increase in surface temperatures in the mid latitudes of the northern hemisphere where the complaints of global warming predominantly comes from.
I grow plants. Growth is maximal at about 25°C. A day that varies between 20 and 30°C is more favourable to a plant than one which varies between 0°C and 50°C.
Why should we worry about an increase in winter temperatures in climates that are icy during winter. Are we afraid of having a longer growing season?
Robert Bateman (03:52:32) :
Where we differ, Leif, is in the view of importance of the original vs the iterpretation. The record is the data, and the record was made by very earnest observers.
I don’t think we communicate. The original data is king. The only issue is its calibration [not interpretation]. Suppose you unearth a carefully kept notebook with daily temperatures taken at a monastery in the 1500s using a thermometer of their own design and invention. Clearly such a record is a treasure. Only problem is that we do not know its scale. When an entry in the notebook reads ’25’, what is that on a scale we know, in Fahrenheit, or Celsius, or Reamur, or Kelvin? If we could somehow establish a link between their scale and ours, the notebook data would be a scientific treasure; if not the data is next to worthless.
This is what the issue is. Not if they were earnest, careful, honest, meticulous, trusty, etc. So, how do we go about establishing the scale? Imagine, now, that in the notebook it also stated each year when the ice broke on the nearby river and when the cherry trees blossomed. By watching the river and the cherry trees today we can get a fix on the unknown scale of the readings in the notebook.
The diurnal variation of the geomagnetic field is our river ice and cherry trees. This was well-known to Rudolf Wolf and he used that fact to great effect which made it possible for him to calibrate his Wolf Number across different observers and times. As Wolf unearthed geomagnetic data from the past he was able to recalibrate his original list and to improve its accuracy. See the table on page 10 of http://www.leif.org/research/Napa%20Solar%20Cycle%2024.pdf that shows an early version of his table and the corrections he made in recalibration.
My work is simply an application of the same principle. It is like noting that in the beginning of the notebook the river ice broke at a reading of 10, but all the sudden halfway through it breaks at 14 for the rest of the notebook. Clearly, a discontinuous change of the measurement technique must have happened. By adding 4 to the earlier readings we bring the earlier data on the same scale as the later and the data becomes valuable. Without the correction, the data is useless, or worse since based on the uncorrected data we are lead to falsely conclude that a change of the climate has taken place.
By correcting the data and using them today, 500 years later, in a meaningful way is to show the highest respect for the early observers, and as I said in the conclusion in http://www.leif.org/research/ISSC06-xx-Svalgaard.pdf
“By constructing indices that are directly related to separate physical conditions in Geospace we bring investigations of the long-term behavior of these conditions onto a firm physical basis and remove much of the speculative character of our inferences about Space Climate. At the same time we are able to bring the historical record to bear on the issues of Space Climate in ways our predecessors could not dream of, but would certainly much appreciate and delight in.”
Robert Bateman (03:52:32) :
“That it was cold has no bearing on the Sunspot Number.”
And you are entitled to your belief. Not everyone shares it, and the relation of climate to SSN is not a settled issue by any means.
Again we are not communicating. What I meant, of course, [but expressed badly] was that one should not use one’s belief to judge the quality of the sunspot number record.
That said, if it were firmly established that there is a tight correlation between temperature and SSN, so that without fail one is a measure of the other, then one could use one as a proxy for the other if direct measurements are lacking. This is, however, not the case here.
Pierre Gosselin (03:42:19) :
March 16 already, and not a sunspot in sight.
We’re headed for yet another almost spotless month.
Sigh…
upper [thus SC24] left quadrant of http://sohowww.nascom.nasa.gov/data/realtime/mdi_igr/1024/latest.html
hurry before it dies…
Robert Bateman (22:07:46) :
We know from literary records that the 1790’s were brutally cold. Much writing and no secret.
The cosmic ray proxy record, e.g. 14C, shows that solar activity then was very high, perhaps even higher than today: http://www.leif.org/research/14C.png
This is compatible with the large diurnal variation of the Declination at that time, showing a clear correlation between high solar activity and brutal cold, so if that was your intent by your statement, I apologize for misinterpreting it.
Of course, correlation [and for a couple of decades only] is not causation, so perhaps we shouldn’t read too much into the brutal cold at that time.
Peter Taylor (03:22:17) : Sorry for catching up with this discussion so late. There are some gems here, including sterling service from Leif as usual.
Peter says:
“we ought to be more interested in what is happening in the Arctic and in particular the North Atlantic, than some global mean – this region is acutely sensitive to what the sun is up to and to cloud patterns. The area between Iceland and Norway is crucial – what happens here feeds back to the whole Northern Hemisphere.”
Never a truer word spoken. You may find some points of interest and agreement with your basic thesis at http://climatechange1.wordpress.com
Free University of Berlin started looking at the relationship between solar influences and temperature above 200hPa into the stratosphere a long time ago. and in particular the temperature in the stratosphere over the Arctic. Karen Labitzke and Harry Van Loon did a lot of good work on tracing the solar influence. Unfortunately, in comparing solar minima with solar maxima we are often comparing two La Ninas. Hence little difference. But weak solar cycles bring a strong La Nina dominance.
Although global temperatures may decline by only one tenth of one degree over the next ten years the high latitudes of the northern hemisphere should see all of the gain of the last 30 years erased. That’s about 5°C in terms of winter sea surface temperature. Look forward to more winters like the last two.
The stratosphere at 10hPa above the poles is cooling reflecting a stronger polar vortex in both hemispheres. That in turn seems to be related to weakening solar activity, both in terms of ionizing short wave radiation and the solar wind. The result is a denser atmosphere above the poles. That should in turn relate to relatively weaker muon counts at high latitudes by comparison with lower latitude stations. That sentence is in there for the sake of relevance. Perhaps the people counting cosmic rays could check the changing ratios.
Winter warming in the Arctic stratosphere is strongly correlated with warming in tropical waters. A cool Arctic is associated with diminished energy input into the tropics. That in turn relates to a cooler upper troposphere (less ozone) and more high altitude cloud.
erlhapp (05:07:05) :
The stratosphere at 10hPa above the poles is cooling reflecting a stronger polar vortex in both hemispheres. That in turn seems to be related to weakening solar activity, both in terms of ionizing short wave radiation and the solar wind. The result is a denser atmosphere above the poles.
What is a ‘denser’ atmosphere? And where is it ‘denser’? At the surface? You should use terms that are in the usual nomenclature.
erlhapp (05:07:05) :
Winter warming in the Arctic stratosphere is strongly correlated with warming in tropical waters. A cool Arctic is associated with diminished energy input into the tropics.
I think you state this backwards. How about: “warming or cooling of the tropics results in warming or cooling of the Arctic and [you say] the Stratosphere”?
Leif – Does Mike Lockwood agree with your interpretation of the date – i.e. that his Nature paper with Wild and Stamper on the ‘doubling of the sun’s coronal magnetic field during the past 100 years, (nature, june 3, 1999)? And then there is Solanki, Usoskin. Kromer, Schuessler and Beer in 2004 in Nature 28 October 2004 ‘unusual activity of the sun during recent decades compared to the previous 11,000 years’.
I know that IPCC prefer Muscheler’s interpretation – ‘how unusual is today’s solar activity’ (Nature 436, 2005) but Usoskin counters that Muscheler’s methodology is unverifiable.
It is hard for non-specialists to get a handle on who might be right, unless the original authors of the ‘unusual sun’ capitulate in the peer reviewed lit.
Thus far, I am of an open mind. Oceanographers have shown that the 11yr cycle affects sea surface temperatures and apparently by more than the 0.1% TSI variation would credit – so there does appear to be an amplifier.
But if the sun’s magnetic status (coronal field) was not much lower in the Maunder Minimum, how do you account for the c-14 and be-10 data? Internal distribution? Can you point me to any papers on that?
Much appreciate, as always, your perspective on things and thanks Anthony for maintaining the quality of this thread.
Leif : should read interpretation of the ‘data’ !
Peter Taylor (05:51:40) :
Does Mike Lockwood agree with your interpretation of the date – i.e. that his Nature paper with Wild and Stamper on the ‘doubling of the sun’s coronal magnetic field during the past 100 years, (nature, june 3, 1999)? […]
It is hard for non-specialists to get a handle on who might be right, unless the original authors of the ‘unusual sun’ capitulate in the peer reviewed lit.
It is very rare to see ‘capitulation’ in the literature. The closest one usually gets is a new paper with new and better data, which then carries an implicit capitulation. In Rouillard, A. P., M. Lockwood, and I. Finch, Centennial changes in the solar wind speed and in the
open solar flux, J. Geophys. Res., 112(5), A05103,
doi:10.1029/2006JA012130, 2007, they acknowledge that the aa-index must be corrected and derive a new list of HMF field strengths which Alex Rouillard has been so kind to send me [their Figure in the paper is so small as to be unreadable]. I have plotted their values and mine for comparison in Figure 10 of http://www.leif.org/research/AGU%20Fall%202008%20SH24A-01.pdf which we presented at the last AGU meeting. The point for 1901 is simply in error [Rouillard, personal communication].
The [now superseded] 1999 data was the basis for Solanki’s reconstruction of the open flux [and ultimately for Usoskin’s claim, rooted in a fit to the open flux]. We take care of that in:
http://www.leif.org/research/Consensus-I.pdf
But if the sun’s magnetic status (coronal field) was not much lower in the Maunder Minimum, how do you account for the c-14 and be-10 data? Internal distribution? Can you point me to any papers on that?
In http://www.leif.org/research/TSI%20From%20McCracken%20HMF.pdf I point you to papers on 10Be by McCracken and Beer, also on page 2 you can find a plot of HMF B calculated by them [their plot in their paper is too small to be readable]. You can see that B during 1630-1690 was almost as large as during 1900-1950. In our opinion [as spelled out in the link], they have a calibration problem around 1950, but since Lockwood et al. now agree with us [or at least their latest data does] that B during 1900-1950 is not much different from B 1950-now, B during 1630-1690 was also not much different according to McCracken.
The fallout from all this still has to settle, but there is a growing consensus that the famous ‘doubling’ which I may be originally the first [ page 2 of http://www.leif.org/research/GC31B-0351-F2007.pdf ] to claim [incorrect, as we now know] never happened.
In fact, the IMF B right now is just where it was 108 years ago.
Leif Svalgaard (05:42:14) :
“I think you state this backwards. How about: “warming or cooling of the tropics results in warming or cooling of the Arctic and [you say] the Stratosphere”?
I am not implying that warming in the Arctic causes warming in the tropics. I am simply noting the association. Nor would I asset that warming in the tropics is related in a causal way with short term warming in the Arctic stratosphere.
I assert that the collapse of the Arctic vortex is related to a relatively low density in the stratosphere/mesosphere above the pole. Hence, the enhanced muon count that is associated with sudden stratospheric warmings. In my view it is the collapse of the vortex that enables the warming. The lack of re-establishment of the vortex after the warming of mid January 2009 is a matter of considerable interest. Good parallels occurred in January-April 1987, 1994 and 1996, all La Nina years. After the La Nina of 1987 came the substantial El Nino of 1998. September 1986 marked the end of solar cycle 21.
What I in fact am saying is that we should look to the influence of the sun on the stratosphere and mesosphere as the all important link in the chain of causation behind sudden stratospheric warmings in the Arctic and the associated warming of the ocean in the tropics.
The radical element in the argument is the association of warming in these two very different two locations, one in the full field of the sun and the other wrapped up in Arctic night, and the lack of any reference to planetary waves.
The speculate on the solar mechanism that could be common to both phenomena at http://climatechange1.wordpress.com
Leif,
“In fact, the IMF B right now is just where it was 108 years ago.”
Good to know that.
And was the atmosphere at that time just as compact as it is, or has been until recently? And is there any sign in terms of increasing satellite drag that there is a change underway. And will that change manifest first in any particular place, like for instance over the equator?
Leif
What is a ‘denser’ atmosphere? And where is it ‘denser’? At the surface? You should use terms that are in the usual nomenclature.
A denser atmosphere would contain more particles per cubic metre. It should relate to higher surface pressure. I speak of the total column and in particular that part of it above 100hPa.
erlhapp (07:09:13) :
A denser atmosphere would contain more particles per cubic metre. It should relate to higher surface pressure. I speak of the total column and in particular that part of it above 100hPa.
Since the total number of molecules in the atmosphere is constant, the atmosphere cannot be denser overall. It can be denser somewhere and thinner somewhere else, so the surface pressure should be larger somewhere [region A] and smaller somewhere else [region B], meaning that the difference [delta A,B] between average pressures between regions A and B should be a measure of importance to you. This difference is known for many decades.
erlhapp (06:59:07) :
And was the atmosphere at that time just as compact as it is, or has been until recently?
New word: ‘compact’. Assuming it means ‘dense’, as per my earlier posting, the atmosphere as such [with your definition of ‘dense’] cannot be more ‘compact’ as a whole. So where is it more compact? Where are regions A and B?
Leif – regarding your comment from yesterday. It would make no sense to “adjust” the effective SSN (SSNe) we calculate for the earth-sun distance. That parameter is a measure of the state of the global ionosphere, to be used to drive specific ionospheric models that require an SSN input. SSNe is only indirectly a measure of solar output, and it’s purpose has little to do with tracking the solar output. My research interests are the ionosphere and the rest of the near-earth space environment. I obviously care about the solar output, since it is a major driver to the system I do care about, but only as a driver and not a research topic in and of itself. As such, I care more about the flux at the earth than the flux at 1AU. For folks wanting to track the sun’s state, the 10.7cm flux adjusted to 1AU is probably as good as any.
Sorry about the response delay, but I visit this list irregularly.
Jim (08:25:03) :
As such, I care more about the flux at the earth than the flux at 1AU. For folks wanting to track the sun’s state, the 10.7cm flux adjusted to 1AU is probably as good as any.
Yes, of course, that is so. For the sun one must use the corrected F10.7 flux. It is just amazing how hard it is to get that across.
That said, if it were firmly established that there is a tight correlation between temperature and SSN, so that without fail one is a measure of the other, then one could use one as a proxy for the other if direct measurements are lacking. This is, however, not the case here.
Diode
Of course, correlation [and for a couple of decades only] is not causation, so perhaps we shouldn’t read too much into the brutal cold at that time.
If we only look at one specfic time where it has happened, yes. If there are other times in history where it has been repeated, then there are things to be dug into further. I believe the literary works indicate postive for there being other such instances. If the C14 leads to an opposite indication by proxy of sunspot activity, there has to be a reason why. Who knows, the C14 may only be half of the story of the proxy.