Guest Post by Willis Eschenbach
In a recent interchange over at Joanne Nova’s always interesting blog, I’d said that the slow changes in the sun have little effect on temperature. Someone asked me, well, what about the cold temperatures during the Maunder and Dalton sunspot minima? And I thought … hey, what about them? I realized that like everyone else, up until now I’ve just accepted the idea of cold temperatures being a result of the solar minima as an article of faith … but I’d never actually looked at the data. And in any case, I thought, what temperature data would we have for the Maunder sunspot minimum, which lasted from 1645 to 1715? So … I went back to the original sources, which as always is a very interesting ride, and I learned a lot.
It turns out that this strong association of sunspot minima and temperature is a fairly recent development. Modern interest in the Maunder sunspot minimum was sparked by John Eddy’s 1976 publication of a paper in Science entitled “The Maunder Minimum”. In that paper, Eddy briefly discusses the question of the relationship between the Maunder sunspot minimum and the global temperature, viz:
The coincidence of Maunder’s “prolonged solar minimum” with the coldest excursion of the “Little Ice Age” has been noted by many who have looked at the possible relations between the sun and terrestrial climate (73). A lasting tree-ring anomaly which spans the same period has been cited as evidence of a concurrent drought in the American Southwest (68, 74). There is also a nearly 1 : 1 agreement in sense and time between major excursions in world temperature (as best they are known) and the earlier excursions of the envelope of solar behavior in the record of 14C, particularly when a 14C lag time is allowed for: the Sporer Minimum of the 16th century is coincident with the other severe temperature dip of the Little Ice Age, and the Grand Maximum coincides with the “medieval Climatic Optimum” of the 11th through 13th centuries (75, 76). These coincidences suggest a possible relationship between the overall envelope of the curve of solar activity and terrestrial climate in which the 11-year solar cycle may be effectively filtered out or simply unrelated to the problem. The mechanism of this solar effect on climate may be the simple one of ponderous long-term changes of small amount in the total radiative output of the sun, or solar constant. These long-term drifts in solar radiation may modulate the envelope of the solar cycle through the solar dynamo to produce the observed long-term trends in solar activity. The continuity, or phase, of the 11-year cycle would be independent of this slow, radiative change, but the amplitude could be controlled by it. According to this interpretation, the cyclic coming and going of sunspots would have little effect on the output of solar radiation, or presumably on weather, but the long-term envelope of sunspot activity carries the indelible signature of slow changes in solar radiation which surely affect our climate (77). [see paper for references]
Now, I have to confess, that all struck me as very weak, with more “suggest” and “maybe” and “could” than I prefer in my science. So I thought I’d look to see where he was getting the temperature data to support his claims. It turns out that he was basing his opinion of the temperature during the Maunder minimum on a climate index from H. H. Lamb, viz:
The Little Ice Age lasted roughly from 1430 to 1850 … if we take H. H. Lamb’s index of Paris London Winter Severity as a global indicator.
After some searching, I found the noted climatologist H. H. Lamb’s England winter severity index in his 1965 paper The Early Medieval Warm Epoch And Its Sequel. He doesn’t give the values for his index, but I digitized his graph. Here are Lamb’s results, showing the winter severity in England. Lower values mean more severe winters.
So let me pose you a small puzzle. Knowing that Eddy is basing his claims about a cold Maunder minimum on Lamb’s winter severity index … where in Lamb’s winter severity index would you say that we would find the Maunder and Dalton minima? …
Figure 1. H.H. Lamb’s index of winter severity in England.
As you can see, there is a reasonable variety in the severity of the winters in England. However, it is not immediately apparent just where in there we might find the Maunder and Dalton minima, although there are several clear possibilities. So to move the discussion along, let me reveal where they are:
Figure 2. As in Figure 1, but with the dates of the Maunder and Dalton minima added.
As we might expect, the Maunder minimum is the coldest part of the record. The Dalton minimum is also cold, but not as cold as the Maunder minimum, again as we’d expect. Both of them have warmer periods both before and after the minima, illustrating the effect of the sun on the … on the … hang on … hmmm, that doesn’t look right … let me check my figures …
…
…
…
… uh-oh
…
…
Well, imagine that. I forgot to divide by the square root of minus one, so I got the dates kinda mixed up, and I put both the Maunder and the Dalton 220 years early … here are the actual dates of the solar minima shown in Lamb’s winter severity index.
Figure 3. H.H. Lamb’s England winter severity index, 1100-1950, overlaid with the actual dates of the four solar minima ascribed to that period. Values are decadal averages 1100-1110,1110-1120, etc., and are centered on the decade.
As you can see …
• The cooling during the Wolf minimum is indistinguishable from the two immediately previous episodes of cooling, none of which get much below the overall average.
• The temperature during the Sporer minimum is warmer than the temperature before and after the minimum.
• The coldest and second coldest decades in the record were not associated with solar minima.
• The fastest cooling in the record, from the 1425 decade to the 1435 decade, also was not associated with a solar minimum.
• Contrary to what we’d expect, the Maunder minimum warmed from start to finish.
• The Dalton minimum is unremarkable in any manner other than being warmer than the decade before the start and the decade after the end of the minimum. Oh, and like the Maunder, it also warmed steadily over the period of the minimum.
Urk … that’s what Eddy based his claims on. Not impressed.
Let me digress with a bit of history. I began this solar expedition over a decade ago thinking, along with many others, that as they say, “It’s the sun, stupid!”. I, and many other people, took it as an unquestioned and unexamined “fact” that the small variations of the sun, both the 11-year cycles and the solar minima, had a discernible effect on the temperature. As a result, I spent endless hours investigating things like the barycentric movement of the sun. I went so far as to write a spreadsheet to calculate the barycentric movement for any period of history, and compared those results to the temperatures.
But the more I looked, the less I found. So I started looking at the various papers claiming that the 11-year cycle was visible in various climate datasets … still nothing. To date, I’ve written up and posted the results of my search for the 11-year cycle in global sea levels, the Central England Temperature record, sea surface temperatures, tropospheric temperatures, global surface temperatures, rainfall amounts, the Armagh Observatory temperatures, the Armagh Observatory daily temperature ranges, river flows, individual tidal stations, solar wind, the 10Beryllium ice core data, and some others I’ve forgotten … nothing.
Not one of them shows any significant 11-year cycle.
And now, for the first time I’m looking at temperature effects of the solar minima … and I’m in the same boat. The more I look, the less I find.
However, we do have some actual observational evidence for the time period of the most recent of the minima, the Dalton minimum, because the Berkeley Earth temperature record goes back to 1750. And while the record is fragmentary and based on a small number of stations, it’s the best we have, and it is likely quite good for comparison of nearby decades. In any case, here are those results:
Figure 4. The Berkeley Earth land temperature anomaly data, along with the Dalton minimum.
Once again, the data absolutely doesn’t support the idea of the sun ruling the temperature. IF the sun indeed caused the variations during the Dalton minimum, it first made the temperature rise, then fall, then rise again to where it started … sorry, but that doesn’t look anything like what we’d expect. For example, if the low spot around 1815 is caused by low solar input, then why does the temperature start rising then, and rise steadily until the end of the Dalton minimum, while the solar input is not rising at all?
So once again, I can’t find evidence to support the theory. As a result, I will throw the question open to the adherents of the theory … what, in your estimation, is the one best piece of temperature evidence that shows that the solar minima cause cold spells?
Now, a few caveats. First, I want to enlist your knowledge and wisdom in the search, so please just give me your one best shot. I’m not interested in someone dumping the results of a google search for “Maunder” on my desk. I want to know what YOU think is the very best evidence that solar minima cause global cooling.
Next, don’t bother saying “the Little Ice Age is the best evidence”. Yes, the Maunder occurred during the Little Ice Age (LIA). But the Lamb index says that the temperature warmed from the start of the Maunder until the end. Neither the Maunder’s location, which was quite late in the LIA, nor the warming Lamb shows from the start to the end of the Maunder, support the idea that the sun caused the LIA cooling.
Next, please don’t fall into the trap of considering climate model results as data. The problem, as I have shown in a number of posts, is that the global temperature outputs of the modern crop of climate models are nothing but linear transforms of their inputs. And since the models include solar variations among their inputs, those solar variations will indeed appear in the model outputs. If you think that is evidence for solar forcing of temperature … well, this is not the thread for you. So no climate model results, please.
So … what do you think is the one very best piece of evidence that the solar minima actually do affect the temperature, the evidence that you’d stand behind and defend?
My regards to you all,
w.
[UPDATE] In the comments, someone said that the Central England Temperature record shows the cooling effects of the solar minima … I’m not finding it:
As you can see, there is very little support for the “solar minima cause cool temperatures” hypothesis in the CET. Just as in the Lamb winter severity data and the Berkeley Earth data, during both the Dalton and Maunder minima we see the temperature WARMING for the last part of the solar minimum. IF the cause is in fact a solar slump … then why would the earth warm up while the sun is still slumping? And in particular, in the CET the Dalton minimum ends up quite a bit warmer than it started … how on earth does this support the “solar slump” claim, that at the end of the Dalton minimum it’s warmer than at the start?
The Usual Request: I know this almost never happens, but if you disagree with something that I or someone else has said, please have the common courtesy to QUOTE THEIR EXACT WORDS that you disagree with. This prevents much confusion and misunderstanding.
Data: Eddy’s paper, The Maunder Minimum
Lamb’s paper, The Early Medieval Warm Epoch And Its Sequel
Berkeley Earth, land temperature anomalies
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Reblogged this on The Next Grand Minimum and commented:
See Willis’ Challenge at the bottom of the post. This is a very challenging analysis.
A dispassionate observer might have the impression that he thought ‘science’ meant: disagreeing for the joy of being disagreeable.
Willis Mosher Pamela
You all seem happy to ignore the solar activity – climate connection referred to in my earlier comment.
“Check Figs 8 and 9 at
http://climatesense-norpag.blogspot.com/2013/10/commonsense-climate-science-and.html
Here are some quotes.
“Furthermore Fig 8 shows that the cosmic ray intensity time series derived from the 10Be data is the most useful proxy relating solar activity to temperature and climate. – see Fig 3 CD from Steinhilber
http://www.pnas.org/content/early/2012/03/30/1118965109.full.pdf
NOTE !! the connection between solar “activity” and climate is poorly understood and highly controversial. Solar ” activity” encompasses changes in solar magnetic field strength, IMF, CRF, TSI ,EUV,solar wind density and velocity, CMEs, proton events etc. The idea of using the neutron count as a useful proxy for changing solar activity and temperature forecasting is agnostic as to the physical mechanisms involved……..
The trends in the neutron count over the last few solar cycles strengthens the forecast of coming cooling made from projecting the PDO and Millennial cycle temperature trends The decline in solar activity from 1990 (Cycle 22) to the present (Cycle 24) is obvious……..
Fig9
It has been estimated that there is about a 12 year lag between the cosmic ray flux and the temperature data. see Fig3 in Usoskin et al
http://adsabs.harvard.edu/full/2005ESASP.560…19U.
With that in mind it is reasonable to correlate the cycle 22 low in the neutron count (high solar activity and SSN) with the peak in the SST trend in about 2003 and project forward the possible general temperature decline in the coming decades in step with the decline in solar activity in cycles 23 and 24.
The value of the Steinhilber interpretations is indicated in the following link posted earlier by Sturgishooper
http://www.sciencedirect.com/science/article/pii/S0012821X12004748
“This suggests that studies which assimilate bipolar composite 10Be records in solar or cosmic ray
intensity reconstructions (e.g. Steinhilber et al., 2012), or variants,
such as the leading principal component of multiple records (e.g.
Muscheler et al., 2007b) are less likely to introduce spurious
climate-related signals than those assimilating 10Be records from
individual sites (e.g. Bard et al., 2000; Vonmoos et al., 2006;
Shapiro et al., 2011). Using multiple 10Be records in addition to
cosmogenic 14C (from tree rings), which has a very different
geochemical behaviour to 10Be, can help to further decouple the
climate signal from the 10Be record (e.g. Muscheler et al., 2007b;
Usoskin et al., 2009; Steinhilber et al., 2012”
lsvalgaard says:
“Solar activity now is on par was it was during 12-14, but the climate is not.”
I am not surprised, there was far less global warming in the 19th century so the global mean temp base line was lower, and the worst cold in this cycle will straddle the second half of SC24 and the first half of SC25, from 2016 to 2024, much like 1807 to 1817 in SC’s 5 & 6.
But something seem to happen in the 1980s….
=============
the two graphs diverge with the fall of the soviet union when thousands of weather stations across Russia went permanently off line. Remove a lot of cold stations and the potential exists to create an artificial warming, that cannot be explained by any other mechanism except CO2, because they only looked for CO2.
Ulric Lyons says:
June 24, 2014 at 6:57 am
I am not surprised, there was far less global warming in the 19th century
Even if solar activity was nearly the same in the 19th century as in the 20th. So clearly the Sun is not involved. As you say: not surprising.
the CET clearly shows that during the latter part of both the Maunder and Dalton minima the temperatures warmed steadily
============
This only makes sense. During the latter part of the Maunder and Dalton minima, the minima was ending. Thus temperatures warmed. This would indicate the minimal follows a curve (sin/cos), not a step function (on/off).
Steven Mosher said:
“If you point to a purely local record ( like CET) then you’ve havent made the case.”
CET tracks the NAO really well, that’s not local, and the NAO tracks the short term solar variability far better than any global mean that is hugely damped, and with major negative feedbacks in the form of oceanic modes working in opposition to the solar signal.
KDK says:
“It says: ERBE WFOV Edition3 Revision1 Monthly Means of TOA Fluxes, Solar Incidence, and Albedo (20N – 20S)”
… as does the legend on the graph as well as the linked provided under “…that is detailed here:”
“Mount Pinatubo erupted on June 15, 1991. It’s at 15°08’30″N so it is in the defined tropics band.
But then global temperatures dropped about 0.5°C for a bit. Your graph shows a bump, temperatures had a brief upward pulse. But longer term there was cooling, to about 2000 where the graph ends.”
My graph shows a “bump” because it’s temperature of the lower stratosphere ( TLS ) . Today you have learnt that volcanoes have the opposite effect on the stratosphere. They then take what looks like a definitive step down. That part is covered in more detail here:
http://climategrog.wordpress.com/?attachment_id=902
“However as Eschenbach showed in Volcanic Disruptions in 2012, for global temperatures there was a quick recovery from the cooling.”
And one of the main reasons for that recovery is what I showed here. Changes in the transparency of the stratosphere leading to an additional 2 W/m2 making it into the tropical lower climate system.
If volcanoes cause a _temporary_ cooling of the extra-tropical regions, someone ought to be explaining why it warms up again. The orthodoxy pretend this is due to AGW. What I have shown here is that it is far too closely linked to aerosol density and the timing of volcanic eruptions.
Had you bothered to follow the link below the graph you would have got the full story, in all it’s technical detail:
http://climategrog.wordpress.com/?attachment_id=884
So I have provided evidence if you could be bothered to read it before sounding off.
Thanks Willis, interesting as always. I’m very late to this party and was too lazy to read all 304 previous posts. However, here is my 2 cents worth.
1) We receive 98+% of our energy from the Sun so it is the probable cause.
2) Our orbit and tilt vary over time, providing additional variability in energy input.
3) Earth’s climate is dominated by negative feedbacks as evidenced by Earth’s relatively stable climate over millions of years.
4) Deep ocean currents have a tremendous impact on Earth’s climate as evidenced by the change three million years ago when volcanic activity in Central America connected NA & SA, changing those currents and leading to our current glacial/interglacial cycles.
Therefore, there are multiple drivers and multiple negative feedbacks that keep Earth’s climate relatively stable. Plus/minus 5K over ~300K mean Earth average temperature is very stable! You are looking for multiple harmonics in an extremely complex and dynamic system.
In conclusion, it is obviously the Sun. Take away the energy from the Sun, and we begin to freeze in 8+ minutes. However, that is only the primary driver and minor fluctuations in that primary driver are hidden by Earth’s dynamic systems responses. We simply don’t know enough to separate all the harmonics to see the true impact of minor variations in the Sun’s influence to determine the true impact of the Sun Spot cycles.
Bill
Why are you guys arguing about sun spot records and temperature records…..like any of them are factual? ( and no, I won’t quote anything)
Willis,
I can create a temperature graph using random numbers, where the amplitude of the peaks drop exponentially over time from +/- 4.0 to +/- 0.5 from 1700 to 2020. If I then filter this data set (by decade say) I will see significant peaks and troughs (the period being a function of filter length) where amplitude is a function of “noise”. This will produce hot and cold periods early on with amplitudes exceeding 1.0 degrees, but only small hot and cold periods later on with amplitudes less than 0.1 (not worthy of a LIA or MWP). All of this is caused by noise in the data and has nothing to do with solar activity. I can then correlate my fictitious graph with sun spot count and remarkably will find some correlation because the Maunder and Dalton Minimums correspond with the oldest parts of my data set. Also in the Figure 4 data set the time period at the Dalton Minimum corresponds exactly with an increase in noise of the temperature record, exactly where we would expect a major peak or trough to occur due to filtering alone. I have an Excel spread sheet showing this. The code is below:
assignfile(txt,’noise.txt’);
rewrite(txt);
for i := 1700 to 2020 do
begin
y:=(random(800)-400)/100.0; {generate a random time series from +/- 4.0 deg}
y:=y*exp(-(i-1700)/150); {make it exponentially decrease with TC = 150 yrs}
y:=y+(i-1700)/500; {add a linear trend for fun}
writeln(txt,i:10,y:10:4);
end;
closefile(txt); {now put that in Excel and filter}
Note that y first holds the random error (+/- 4 deg peak to peak).
Then y is scaled to decrease exponentially with a time constant of 150 years. This better matches the noise I see in the temperature record (Fig. 4).
Finally, I add a simple linear trend of approx. 0.2 deg / century to give an apparent (CAGW) trend upward.
If you want my data just ask Anthony for my email address and I’ll send you the code (Pascal) as well. But it’s pretty simple. You can see you get a couple of LIA’s and MWP’s with every run, earliest on in the data record.
If multi-decade changes in solar output are mostly manifested on earth as regional effects over time and translated to other heating and cooling factors and systems, including poorly described and monitored ones, then the story is incomplete rather than closed.
lsvalgaard says:
June 24, 2014 at 7:02 am
Ulric Lyons says:
June 24, 2014 at 6:57 am
“I am not surprised, there was far less global warming in the 19th century”
“Even if solar activity was nearly the same in the 19th century as in the 20th. So clearly the Sun is not involved. As you say: not surprising.”
To say, “So clearly the Sun is not involved.” is clearly an extreme over statement. As has been pointed out by other comments in this, and many other posts, temperature is undoubtedly a result of a complex mutivariate mix of causal variables, evidently nolinear, which may, indeed, be actually a chaotic mix. This does not mean that the Sun is “not involved”. Nor does it mean that its effect can be estimated in the linear fasion you regularly quote as 0.2 degrees or whatever. Better to simply say that its overall effect, in combination with the other variables with which it interacts, which magnify or reduce its effect, is presently not known.
Jim G says:
June 24, 2014 at 7:26 am
“Even if solar activity was nearly the same in the 19th century as in the 20th. So clearly the Sun is not involved. As you say: not surprising.”
To say, “So clearly the Sun is not involved.” is clearly an extreme over statement.
It should be clear that what was meant was ‘in a major way’. There is no doubt that the Sun is involved at the 0.1 degree level, but that is not what the issue is.
Better to simply say that its overall effect, in combination with the other variables with which it interacts, which magnify or reduce its effect, is presently not known.
That is an extreme under statement. If not known, then the null-hypothesis must be that there is no major influence.
Hi Willis, Always a pleasure to absorp your writings. My best shot would be the increase/decrease in the rotation speed of the earth as measured by IERS. See this link: http://hpiers.obspm.fr/eop-pc/earthor/ut1lod/lod-1623.html. The reason (for me) is the link between the sun’s magnetic regime (reverse of the sun-spot regime, see the notch of david evans) and the rotation speed of the earth designated as LOD (length of day). The more active the sun’s magnetic field the slower the LOD and vice versa. A higher earth rotation speed may spread the colder air and water layers in ways different from a lower earth rotation speed; colder meaning more dense and hence (my opinion) more equitorial distribution under higher rotation speed conditions. In combination with your emerging atmospheric phenomena driven by temperature resulting cloud cover and distribution it may, I said may generate further insight.
The Sun is the major player providing radiation: consider it ROCK
Major Volcanic Activity severely blocks solar radiation: consider it PAPER
PAPER COVERS ROCK Sometimes – Significantly Lowering Earth’s Temperatures
The Sun is not the only player in the Earth’s Climate Game
I believe that the discussion has degraded to the level of how many angels can dance on the head of a pin. We cant know even assuming they exist. That pretty sums up our knowledge of the climate. It changes and we really dont know why so arguing about what level of co2 or sunspots it takes to change the weather seems pointless.
lsvalgaard says:
June 24, 2014 at 7:36 am
Again, non-linear. Not known means just that, not that there is NO effect. Why is it so difficult to admit that we just have not yet figured out the relationships?
Leif would you care to comment on this quote from my 6:51 am post.
“Furthermore Fig 8 shows that the cosmic ray intensity time series derived from the 10Be data is the most useful proxy relating solar activity to temperature and climate. – see Fig 3 CD from Steinhilber
http://www.pnas.org/content/early/2012/03/30/1118965109.full.pdf
NOTE !! the connection between solar “activity” and climate is poorly understood and highly controversial. Solar ” activity” encompasses changes in solar magnetic field strength, IMF, CRF, TSI ,EUV,solar wind density and velocity, CMEs, proton events etc. The idea of using the neutron count as a useful proxy for changing solar activity and temperature forecasting is agnostic as to the physical mechanisms involved……..
The trends in the neutron count over the last few solar cycles strengthens the forecast of coming cooling made from projecting the PDO and Millennial cycle temperature trends The decline in solar activity from 1990 (Cycle 22) to the present (Cycle 24) is obvious……..:
(you might like to read the whole 6:51 comment and check the science direct link before replying)
Jim G says:
June 24, 2014 at 7:43 am
Again, non-linear. Not known means just that, not that there is NO effect.
It means that there is no evidence for an effect.
Why is it so difficult to admit that we just have not yet figured out the relationships?
Tell that to the sun-enthusiasts who invoke the stupid mantra ‘it’s the Sun, stupid’. If there is no evidence it is no surprise that we haven’t figured anything out, in which case the null-hypothesis stands.
Sturgis, the 1257-58 eruption is approximately twice the size of Tambora. You are not presenting yourself very well here. The 1257-58 event is considered to be the largest explosive volcanic event in the past 7000 years. All ice cores with records that extend through that time span demonstrate this signal as clearly being of greater magnitude than Tambora. While your thesis can be whatever you want it to be, at least get your facts straight. What is more concerning however, is that in my opinion it is evident from your comments you must be choosing not to.
“Estimates of its stratospheric sulfate load are around eight- and two-times greater than those of Krakatau in A.D. 1883 and Tambora in A.D. 1815, respectively (6), ranking it among the most significant volcanic events of the Holocene (7).”
http://www.pnas.org/content/110/42/16742.full
Dr Norman Page says:
June 24, 2014 at 7:46 am
Leif would you care to comment on this quote from my 6:51 am post.
“Furthermore Fig 8 shows that the cosmic ray intensity time series derived from the 10Be data is the most useful proxy relating solar activity to temperature and climate.
There is much evidence that the cosmic ray record is heavily influenced by the climate [if you need references it just shows that you are not current with the literature], so the ‘usefulness’ is highly dubious, in fact there is a fair amount of circular reasoning involved.
Willis wrote,”As you can see, there is very little support for the “solar minima cause cool temperatures” hypothesis in the CET.”
The graph you posted shows the Maunder Minimum as the coldest period in the graph. Take Leif Svalgaard’s presentation slide 31, bottom graph, “Total absolute magnetic fluxes on the Sun”. Place that graph over the CET graph, and there is what I would consider to be reasonable correlation. About as correlated as I would expect if the sun has some impact on temperature but with other things going on like changes in ENSO cycles and etc.
The problem here is that you are saying that there is no support or very little support for solar minima causing cool temperatures. I believe this statement is not correct. The correct statement is that there appears to be some correlation. Correlation is not causation. So, more research is needed to determine how solar minima cause temperature changes and to what degree it causes them (if it does).
Willis wrote, “…during both the Dalton and Maunder minima we see the temperature WARMING for the last half of the solar minimum. If the cause is in fact a solar slump … then why would it warm while the sun is still slumping?”
The answer is that determining the actual changes in heat in the oceans and on land is very difficult even today. Even today, the analysis is not very accurate. Locations on land are influenced by multidecadal changes in the PDO, AMO, NAO, AO and etc. If various of those cycles are in the “positive” mode, and there was a small change in the sun, it might take 20 years or more to see any major impact and that impact would vary depending on the location. Second, no one really knows what impact the sun has and what mechanism(s) are most responsible. For example, is it changes in ultraviolet radiation from the sun or is it galactic cosmic rays that have the most impact? How do they impact climate and how long does it take for the impact to be seen? The answers to those questions are unknown.
That said, your analysis is very interesting as always and I remain a Willis fan :). It also started a good discussion. Thanks for posting it.
lsvalgaard says:
June 24, 2014 at 7:47 am
Jim G says:
June 24, 2014 at 7:43 am
Again, non-linear. Not known means just that, not that there is NO effect.
“It means that there is no evidence for an effect.”
Unless one continues to think in single variable linear terms, there is also no evidence for your 0.1 degree estimate of solar involvement.