Solar Variations Controversy

From Dr. Judith Curry’s Climate Etc.

by Judith Curry

“The field of Sun-climate relations . . . in recent years has been corrupted by unwelcome political and financial influence as climate change sceptics have seized upon putative solar effects as an excuse for inaction on anthropogenic warming” – Lockwood (2012)

“We argue that the Sun/climate debate is one of these issues where the IPCC’s “consensus” statements were prematurely achieved through the suppression of dissenting scientific opinions.” –  Connolly et al. (2021)

The impact of solar variations on the climate is uncertain and subject to substantial debate. However, you would not infer from the IPCC assessment reports that there is debate or substantial uncertainty surrounding this issue.

The Sun goes through cycles of approximately 11 years (the Schwabe Cycle) in which solar activity goes up and down. Above the Earth’s atmosphere, the difference in Total Solar Irradiance (TSI, measured in Watts per square meter W/m2) between the 11-year maxima and minima is small, on the order of 0.1% of the total TSI, or about 1 W/m2.  A multidecadal increase in TSI should cause global warming (all else being equal); similarly, a multidecadal decrease in TSI should cause global cooling. Researchers have speculated that multi-decadal and longer changes in solar activity could be a major driver of climate change.

Exactly how TSI has changed over time has been a challenging problem to resolve. Since 1978, we have had direct measurements of TSI from satellite.  However, interpreting any multi-decadal trends in TSI requires comparisons of observations from overlapping satellites.  Substantial uncertainty exists in the TSI composites during the period from 1978 to 1992. This is mostly due to the fact that the ACRIM2 solar satellite mission was delayed because of the Space Shuttle Challenger disaster in 1986 (ACRIM2 was eventually launched in late 1991). This delay prevented this record from overlapping with the ACRIM1 record that ended in July 1989. The ACRIM-gap prevents a direct cross-calibration between the two high-quality ACRIM1 and ACRIM2 TSI records. [link]

This rather arcane issue of cross-calibration of two satellite records has profound implications. There are a number of rival composite TSI datasets, disagreeing as to whether TSI increased or decreased during the period 1986-1996.  Further, the satellite record of TSI is used for calibrating proxy models, so that past solar variations can be inferred from sunspots and cosmogenic isotope measurements.  Velasco Herrera et al. 2015 As a result, some of the datasets for past values of TSI (since 1750) have low variability, implying very low impact of solar variations on global mean surface temperature, whereas datasets with high TSI variability can explain 50-98% of the temperature variability since preindustrial times.

The IPCC AR5 adopted the low variability solar reconstructions, without discussing this controversy. The AR5 concluded that the best estimate of radiative forcing due to TSI changes for the period 1750–2011 was 0.05 W/m(medium confidence). For reference, the forcing from atmospheric greenhouse gases over the same period was 2.29 W/m2. Thus, the IPCC AR5 message was that changes in solar activity are nearly negligible compared to anthropogenic ones for forcing climate change.

The IPCC AR6 acknowledges a much larger range of estimates of changes in TSI over the last several centuries, stating that the TSI between the Maunder Minimum (1645–1715) and second half of the 20th century increased by 0.7– 2.7 W/m2, a range that includes both low and high variability TSI data sets. However, the recommended forcing dataset for the CMIP6 climate model simulations used in the AR6 averages two low variability data sets (Matthes et al. 2017).

The uncertainties and debate surrounding solar variations and their impact on climate was the topic of a ClimateDialogue, a remarkable blogospheric experiment . ClimateDialogue was the result of a request by the Dutch parliament to facilitate the scientific discussions between climate experts representing the full range of views on the subject. The Dialogue on solar variations (2014) included five distinguished scientists with extensive publication records on the topic.  One participant was in line with the IPCC AR5, thinking that solar variations are only a minor player in the Earth’s climate. Two participants argued for a larger and even dominant role for the Sun, and the other two emphasized uncertainties in our current understanding.

More recently, a review article was published in the journal Research in Astronomy and Astrophysics by Connolly et al. (2021). The article has 23 co-authors with a range of perspectives, but who were united by their agreement not to take the consensus approach of the IPCC.  Rather, the paper emphasized where dissenting scientific opinions exist as well as identifying where there is scientific agreement. The authors found that the Sun/climate debate is an issue where the IPCC’s consensus statements were prematurely achieved through the suppression of dissenting scientific opinions.

Of direct relevance to projections of 21st century climate is whether we might expect a substantial change in solar activity. On multidecadal timescales, proxy reconstructions of solar activity reveal occasional phases of unusually high or low solar activity, which are respectively called Grand Solar Minima and Maxima (Usoskin et al., 2014). Grand solar maxima occur when several solar cycles exhibit greater than average activity for decades or centuries.

Solar activity reached unusually high levels in the second half of the twentieth century, although there is disagreement among reconstructions as to whether this maximum peaked in the 1950’s or continued into the 1990’s. It has been estimated that about 20 grand maxima have occurred over the last 11 millennia (Usoskin et al. 2007), averaging one per 500 years.  During the last 11 millennia, there have been 11 grand solar minima, with intervals between them ranging from a hundred years to a few thousand years. The most recent grand minimum was the Maunder Minimum, during 1645-1715.  [link]

There are several reasons to expect lower solar activity during the 21st century, relative to the 20th century. The recently completed solar cycle 24 was the smallest sunspot cycle in 100 years and the third in a trend of diminishing sunspot cycles. Solar physicists expect cycle 25 to be even smaller than Cycle 24. Further, a grand maximum is more likely to be followed by a grand minimum than by another grand maximum (Inceoglu et al., 2016). Empirically-based projections imply a new solar minimum starting in 2002–2004 and ending in 2063–2075 (Velasco Herrera et al. 2015)  It has been estimated that there is an 8% chance of the Sun falling into a Grand Minimum during the next 40 years  (Barnard et al. 2011). However, the depth and length of a phase of low solar activity in the 21st century is largely uncertain.

If the Sun did fall into a minimum during mid 21st century of the magnitude of the Maunder Minimum, how much cooling could we expect?  Estimates from climate models and other analytical models expect the cooling to be small, ranging from 0.09 to 0.3oC (Fuelner 2010). These models assume that solar-climate interaction is limited to TSI forcing alone.  

However, there is growing evidence that other aspects of solar variability amplify the TSI forcing or are independent of TSI forcing, which are referred to as solar indirect effects. Candidate processes include: solar ultraviolet changes; energetic particle precipitation; atmospheric-electric-field effect on cloud cover; cloud changes produced by solar-modulated galactic cosmic rays; large relative changes in the magnetic field; and the strength of the solar win.  Solar indirect effects can be classified as ‘known unknowns.’  While these indirect effects are not included in the CMIP6 21st century projections, we can make some inferences based upon recent publications. Recent research suggest that solar indirect effects could amplify an anomaly in solar insolation by a factor of up to 3-7. Shaviv (2008), Scafetta (2013) Svensmark (2019).  If such an amplification factor is included, then a surface temperature decrease of up to 1oC (or even more) from a Maunder Minimum could occur.

So, what are plausible scenarios for solar-driven global temperature changes in the 21st century?  These three scenarios pretty much cover the plausible range:

  • CMIP6 Reference scenario:  approximately -0.1oC (Matthes 2017)
  • Intermediate: -0.3oC, corresponds to high Maunder minimum estimate without amplification effects (Fuelner 2010), or a weaker minimum with amplification effects
  • High: -0.6oC, a low solar scenario (which is not a Maunder Minimum) with amplification by solar indirect effects Solheim

The next 20 to 30 years of observations should reveal a lot about the role of the Sun in climate.

JC reflections

The IPCC acknowledges substantial uncertainty in changes of TSI over the last centuries, stating that the TSI between the Maunder Minimum (1645–1715) and second half of the 20th century increased by 0.7– 2.7 W/m2, a range that includes both low and high variability TSI data sets. However, the recommended forcing dataset for the CMIP6 climate model simulations used in the AR6 averages two low variability data sets (Matthes et al. 2017). 

The implications of such large uncertainty in TSI on equilibrium climate sensitivity and attribution of 20th century warming are ignored by the IPCC. If the high variability data sets are correct, this has substantial implications for estimates of climate sensitivity to CO2, and attribution of 20th century warming.  This issue can’t continue to be swept under the rug.  Other authors are not ignoring this.  Here are three recent publications for discussion:

Scafetta:  Testing the CMIP6GCM simulations versus surface temperature records from 1980-1990 to 2010-2020 [link]

Connolly et al: How much has the sun influenced Northern Hemisphere temperature trends?  An ongoing debate [link]

Girma Orssengo:  Determination of the sun-climate relationship using empirical mathematical models for climate data sets. [link

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November 23, 2021 6:22 am

It is the Sun what does it! Watching the solar cycles of the last twenty years and comparing them to the historic measurements has me worried. A Dalton or Maunder would be truly devastating for civilisation as we know it. (They) We worry about the wrong climate catastrophe. (Please, please be wrong).

Reply to  Bil
November 23, 2021 10:57 am

Why do you worry about things you don’t know and are out of your control?
Don’t worry, be happy!

Reply to  Javier
November 24, 2021 2:53 am

You are of course correct, I was being hystorical. I don’t worry, I keep smiling. It’s the hubris I laugh at.

November 23, 2021 6:23 am

Why would the sun have anything to do with it?

Reply to  Scissor
November 23, 2021 6:41 am

The sun has nothing to do with the climate just as H!tler hasn’t with WW2.
We all know that WW2 was result of a bar fight in a club in San Marino.Once those guys stopped fighting the war was over,something similar is happening with climate right now.
It’s not a bar fight but a farting co2w.

Peter Wells
Reply to  Scissor
November 23, 2021 7:15 am

A number of years ago a road agent in a small New Hampshire town published in the annual town report his records from snow plowing over the past 15 or so years. Those records showed two years of unusually high snowfall. I decided to check solar cycle records, and noticed that those two years just happened to coincide with solar cycle minimums eleven years apart.

I rather doubt that such a strong correlation would hold on a long-term regular basis. However, since I had studied solar influences for a few years, I thought it was worthy of at least some note.

Andy H
Reply to  Peter Wells
November 23, 2021 7:28 am

UK gets similar periods with droughts.

Reply to  Andy H
November 23, 2021 7:44 pm

A drought in the UK is two days without rain.

Old Woman of the North
Reply to  Peter Wells
November 24, 2021 1:41 pm

I did the same with rainfall records when we were in a drought in 1969/70 in Central Queensland. The record were from 1865 – 1968. I found that there were two eleven year cycles that followed each other. One was wetter than the other, but varied greatly. The 1890 were relatively wet and that area had a major drought 1902/3. The 1950s were very wet as were the 1970s then 1990s and 2010s. Before 1950, from 1900s it was dryer for most of that time, with normal falls but not the great floods. I was just a young farmer’s wife but had empirical data to work with.

November 23, 2021 6:41 am

I have always felt that the temperature of the tea is most governed by the height of the flame under the tea kettle and not by the brand of the tea in the tea ball.

Reply to  Shrnfr
November 23, 2021 7:34 am

And you were wrong. Because scientific investigations and computer models clearly showed that it’s not as much the hit of the flame, but levels of CO2 in air around your kettle that governs the temperature of your tea.

Reply to  Bumbum
November 23, 2021 8:57 am

Manabe’s climate model explains the effects of CO2 too well …

Reply to  John Shewchuk
November 23, 2021 9:41 am

My friends should get a Nobel Prize for precisely predicting COP26 would FLOP26. And that months in advance.
Next prediction is, with slightly more CO2, COP27 will be LUKEWARM-TEA-27.
So there!
Details of model classified….

Richard M
Reply to  John Shewchuk
November 23, 2021 6:34 pm

I doubt it. The CERES data highlighted in this paper,

Radiative Energy Flux Variation from 2001–2020
Hans-Rolf Dübal  and Fritz Vahrenholt

is clearly impossible if you assume typical CO2 forcings used in climate models. Hence, those forcings must be wrong and the models as well.

Reply to  Richard M
November 23, 2021 6:42 pm

You’re right. Getting a Nobel Prize for the worst climate model is — let’s say … naughty.

Reply to  Shrnfr
November 23, 2021 7:50 am

The co2 inside the tea regulates the temperature 🙂
Sometimes,after reaching a magical number that always ends with a zero,let’s say 350ppm the tea gets warmer on it’s own by a runaway green tea effect.

Reply to  SxyxS
November 23, 2021 8:22 am

“The co2 inside the tea regulates the temperature”

Exactly. That’s why carbonated beverages are always so hot!

Rich Davis
Reply to  TonyG
November 23, 2021 9:12 am

Sometimes I leave a bottle of carbonated beverage in the back seat of my car and when I get back, it’s very hot. The sun has nothing to do with it.

Reply to  SxyxS
November 23, 2021 9:43 am

Surely you mean this :

Reply to  Shrnfr
November 23, 2021 7:56 am

Being allergic to tea I know little about it but always assumed it started out at 100C if at sea level.

Joel O’Bryan
November 23, 2021 6:50 am

Solar physicists expect cycle 25 to be even smaller than Cycle 24. “

Well that statement is certainly wrong without a leading “Some solar physicists.”

Reply to  Joel O’Bryan
November 23, 2021 4:55 pm

As of today that is certainly wrong. SC25 has been consistently just under one standard deviation below the average for solar cycles 1-24 each month, yet still higher than SC24:

comment image

Reply to  Joel O’Bryan
November 24, 2021 3:21 pm

I agree:

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November 23, 2021 6:52 am

Direct TSI reading by satellite since 1978….that pretty much tells the story….if the Little Ice Age ended because TSI increased by 5 or 6 watts around 1850-60, we would have no idea….other than gradual warming for the next century or two…

Reply to  DMacKenzie
November 23, 2021 8:08 am

interesting, probably coincidental, is the Carrington event of 1859…We have no idea how TSI trended before or after that event, only that current variation is a fraction of a percent.

November 23, 2021 6:55 am

I would state it as grouped, multi-solar cycle periods which implies multi-decade time periods. But it’s good to know someone has considered the potential effects of grouped cycles both high and low.

The longer-term ocean cycles will continue to do their thing in the mean time, i.e. turning points on long cycles and lags compared to grouped solar cycles. It would help if all sides would admit the data limitations for comparing long ocean cycles with grouped solar cycles.

NOAA SST-NorthAtlantic GlobalMonthlyTempSince1979 With37monthRunningAverage.gif (880×481) (

Can someone plot the updated and not detrended AMO for maximum years? Free the coral data for inspection.

John Shotsky
November 23, 2021 6:59 am

The IPCC dismisses all natural climate influences. Their very charter states “investigate HUMAN-CAUSED” climate change. I’ve read it. By focusing on CO2,and claiming it is human caused, they retain their jobs, since if it was learned that CO2 doesn’t affect climate, they would have no platform.

Steve Case
Reply to  John Shotsky
November 23, 2021 9:03 am

You encouraged me to find a link for that:



2.      The role of the IPCC is to assess on a comprehensive,
objective, open and transparent basis the scientific, technical
and socio-economic information relevant to understanding the
scientific basis of risk of human-induced climate change,
its potential impacts and options for adaptation and mitigation.
IPCC reports should be neutral with respect to policy, although
they may need to deal objectively with scientific, technical and
socio-economic factors relevant to the application of particular

Bolding mine 

Charles May
Reply to  John Shotsky
November 23, 2021 9:15 am

In response to your comment, I offer this.

I analyzed the raw data using the Optimal Fourier Transform (OFT) that was developed by Dr. David Evans. I was involved in the signal analysis of rotating equipment for 35 years. I find the OFT suits my needs.

The analysis furnishes a remarkable Pearson correlation coefficient of 0.92. The data are noisy.!AkPliAI0REKhhL5VN7EKSM5fKLMlUg?e=a3sbaS

Clyde Spencer
Reply to  Charles May
November 23, 2021 10:15 am

What variables are correlated with your Pearson CC of 0.92?

Charles May
Reply to  Clyde Spencer
November 23, 2021 10:34 am

The cyclical analysis is calculated at the same time series data points as the measured data. In this instance, I am comparing the Anomaly with the output of the cyclical analysis.

Joe Campbell
Reply to  Charles May
November 23, 2021 3:24 pm

“…measured anomaly…”

Joe Campbell
Reply to  Charles May
November 23, 2021 3:21 pm

Charles: Great to see your input to the discussion. I think natural activities are THE forcing functions…

Peter Wells
Reply to  John Shotsky
November 23, 2021 11:21 am

I wonder what they will do when faced with the obvious effects of the Milankovitch cycle.

Reply to  Peter Wells
November 23, 2021 6:13 pm

Guess we’ll know in another 50,000 years.

John Tillman
November 23, 2021 6:59 am

UV flux varies much more than does TSI. It’s also qualitatively different from less energetic spectral bands, since it makes and breaks ozone.

Effects of ozone variation affect weather and climate phenomena such as ENSO, both its shorter term mode swings and longer-term relative frequency and strength thereof.

Predicting Las Niñas and Los Niños helps people on both sides of the Pacific prepare for droughts and floods, how productive fishing might be and other important considerations.

Reply to  John Tillman
November 23, 2021 7:30 am


Plus with an active Sun you have all kinds of energetic particles being blasted at the Earth which heat the troposphere, changes the global electric circuit which in turn causes changes in the number and intensity of Highs/Lows and jet stream patterns. Galactic cosmic rays decrease. There is a huge difference to the Earth between an active and quiet Sun and it will have consequences.

John Tillman
Reply to  rbabcock
November 24, 2021 3:51 pm

Yes, taking all solar effects together presents much more variation than in TSI alone, whatever that amount might actually be.

Nick Schroeder
November 23, 2021 7:05 am

The atmosphere obeys Q =U A dT where U is a complex interaction among the five primary heat transfer modes: conduction, convection, advection (wind) latent (evap/cnd) and radiation. dT is Tsurface minus Ttoa. Like the draperies pulled across a large window or patio door the albedo cools the lit side of the Earth and the thermal resistance warms the dark.

Should Q, Btu/Eng h or kJ/SI h, change dT will change and if Ttoa is constant than T surface must change. This is little different from the heat loss across the insulated walls of a house. Same if U changes, e.g. clouds, storms, winds, etc.

The Earth sees a 90 W/m^2 swing every perihelion to aphelion,
The ToA at 40 latitude sees a 700 W/m^ swing from summer to winter.
A 1% change in the 30 %/100 W/m^2 albedo, which is difficult to even measure, can impact Tsurface as much as 1 C.

These single digit computer modelled ISR changes cited in the article are meaningless noise.

Heat exchanger equations..jpg
November 23, 2021 7:10 am

The last paper posted above is mine.

My main results are the following:


Figure 1. Empirical model dS/dy for the 30 yr global mean temperature (GMT) moving trends data for the period from 1850–1880 to 1988–2018 showing the multi-decadal oscillation (MDO) in the GMT data. This figure also shows that the 30 yr GMT moving trends have been slowly decelerating since 2005 (top horizontal axis label) from the observed peak value of 0.2 °C per decade toward the minimum projected value of 0.15 °C/decade reported in IPCC (2007, SPM, p. 12).

Reply to  Girma
November 23, 2021 7:14 am


Figure 2. This normal probability plot (De Veaux et al., 2005, p. 95) shows that the residuals, without the outliers, for the model dS/dy for the 30 yr global mean temperature moving trends (Figure 1) are normally distributed, which indicates that the normal residuals vary within two-standard deviation range of ±0.003 °C/year, while the recent residuals for 2015–2018 were above normal outliers. In this normal probability plot, the standard deviation of the residuals (σ = 0.0015 °C/year) was obtained from the residual value corresponding to a normal score of z = 1 and the mean (μ = 0) from z = 0.

Reply to  Girma
November 23, 2021 7:18 am

And here is what Nate Silver wrote in his book “The Signal and the Noise, Why So Many Predictions Fail-but Some Don’t”: “The signal [Figure 1] is the truth. The noise [Figure 2] is what distracts us from the truth”.

My results clearly show that the global mean temperature for the HadCRUT4 data has a single pattern of multi-decadal oscillation of 64-year period superimposed on an accelerating secular warming trend since steady state in 1865. Also, as shown in Figure 1, the observed 30-year GMT trend is approaching the minimum trend of 1.5 oC per century predicted in IPCC (2007).

Here is the Mathematica computer code that I used to analyse the global mean temperature data:

Reply to  Girma
November 23, 2021 7:16 am

And here is what Nate Silver wrote in his book “The Signal and the Noise, Why So Many Predictions Fail-but Some Don’t”: “The signal [Figure 1] is the truth. The noise [Figure 2] is what distracts us from the truth”.

My results clearly show that the global mean temperature for the HadCRUT4 data has a single pattern of multi-decadal oscillation of 64-year period superimposed on an accelerating secular warming trend since steady state in 1865. Also, as shown in Figure 1, the observed 30-year GMT trend is approaching the minimum trend of 1.5 oC per century predicted in IPCC (2007).

Here is the Mathematica computer code that I used to analyse the global mean temperature data:

Reply to  Girma
November 23, 2021 7:20 am

Please ignore the above post

Reply to  Girma
November 23, 2021 9:12 am

Thanks Girma. It’s a very interesting analysis. Thanks also to Judith, for the excellent article!

Joel O'Bryan
Reply to  Girma
November 23, 2021 10:09 am

Your 94-yr linear GMT trend is more likely a slower sinusoidal 900yr – 1000yr wave.

The outliers in 1880-1897 (low) and in 2015-2018 (high) reflect data corruption in HADCRUT, IMO. A strong 2016 El Nino was the bush to hide the elephant behind because +0.12 ºC/decade just isn’t scary enough for the IPCC charlatans where they have to get it somehow above +0.2ºC/decade to save the alarmist scam.

Tom Abbott
Reply to  Joel O'Bryan
November 24, 2021 4:41 pm

“The outliers in 1880-1897 (low) and in 2015-2018 (high) reflect data corruption in HADCRUT, IMO.”

The corrupted temperature records should not be used as corroboration. They don’t represent reality.

Thomas Gasloli
November 23, 2021 7:19 am

It is refreshing to read an article that admits our real data in the Sun is so limited that definitive statements cannot be made. If you have only been collecting real data since ‘78 your science isn’t even in its infancy.

We know almost nothing about the sun; even less about climate. Activists need to stop demanding, and governments need to stop doing, things to change the climate.

Tom Abbott
Reply to  Thomas Gasloli
November 24, 2021 4:42 pm

This article is a good overview of the subject.

It shows that “the science” isn’t settled.

Phil Rae
November 23, 2021 7:24 am

I’ve seen lots of negative comments relating to “cyclomania” (in general) here on WUWT and particularly when it comes to the Sun’s output. However, since Milankovic doesn’t fully explain the cyclical reappearances of ice ages or changes in their frequency/duration and CO2 shows up only as a following, rather than leading, indicator of warming, in the historical record, presumably there are other factors at work.

The Sun’s cyclical behaviour (on various timescales) is certainly of interest, given its role as the dominant energy source on Earth. Perhaps the small changes in TSI are not sufficient, in and of themselves, to cause warming/cooling but it’s difficult to assume they are not at all relevant to the phenomena. Maybe the variations in TSI, when combined with Milankovic cycles and other natural processes cause changes in the types of emergent phenomena that Willis often discusses here. thereby exerting a much greater effect on climate than the 0.1% variation would otherwise imply.

Reply to  Phil Rae
November 23, 2021 8:23 am

Phil Rae said: “and CO2 shows up only as a following, rather than leading, indicator of warming”

Atmospheric carbon did not follow the temperature during the PETM and other ETM events. It’s not clear that it followed the global temperature during the Quaternary Period glacial cycles either. Despite following in the SH there is evidence that it actually lead in the NH and globally (see Shakun et al. 2012 for details). And, of course, it cannot possibly be following the temperature today since 650 GtC of it was released into the atmosphere none of which was caused by a change in temperature (see Friedlingstein et al. 2020 for details).

Phil Rae said: “Perhaps the small changes in TSI are not sufficient, in and of themselves, to cause warming/cooling but it’s difficult to assume they are not at all relevant to the phenomena.”

The Sun’s role in long term climate change is not primarily in the modulation of TSI (though that is part of it), but in the modulation of the spatial and temporal distribution of it as received by Earth.
comment image

Richard Page
Reply to  bdgwx
November 23, 2021 9:14 am

Check the expanded look at the Greenland ice cores – carbon dioxide variations clearly follow temperature variations. Just saying it must be otherwise cuts no ice I’m afraid.

Reply to  Richard Page
November 23, 2021 9:39 am

There’s no question that CO2 does (probably even more often than not) follow temperature in the ice cores. There’s also no question that CO2 will often lead the temperature as well. The lead and lag behavior depicted in the data is inline with the expectation that CO2 both responds to the temperature and temperature responds to CO2. The point…CO2 does not always follow temperature.

Reply to  Richard Page
November 23, 2021 9:43 am

…carbon dioxide variations clearly follow temperature variations. Just saying it must be otherwise cuts no ice I’m afraid.

Not sure that bdgwx is saying that. My understanding is that CO2 lags temperature rise following glacial maximums because rising temperatures, caused by orbital cycles, melt sea ice and warm oceans, meaning that CO2 only gradually escapes from the oceans and permafrosts, etc to the atmosphere. This is not to say that CO2 isn’t still a greenhouse gas that can also lead warming. The two things don’t exclude each other.

In post glacial situations CO2 lags temperature rise but it still has a warming effect – a positive feedback leading to further warming. In this present case, where we have effectively short-circuited the natural carbon cycle, CO2 is leading the warming. Both situations can be true.

Reply to  TheFinalNail
November 23, 2021 10:06 am

Exactly. Even when it lags it is still forcing the temperature. And even when it leads it is still responding to the temperature. The fact is that CO2 is both responding to and forcing temperature simultaneous just with differing timescales.

AGW is Not Science
Reply to  bdgwx
November 23, 2021 10:38 am

Sorry, but repeated episodes of reverse correlation shows the assertion of CO2 “forcing” to be nonsense. Nothing more than an assumption.

If CO2 were “forcing” temperature, then whenever the (excuse me) REAL cause of warming stopped, then what we should see, but do not see, is as long as CO2 levels continue to rise, temperature should continue to rise, at a reduced rate. That reduced rate being that CO2 “forcing” you keep insisting is there.

Instead, temperatures start to fall, while CO2 continues to rise, showing CO2 as a complete non-factor in terms of driving temperature.

Ditto for the reversal of falling temperature trends. Temperatures begin rising while CO2 levels are falling. Reverse correlation shows CO2 “drives” or “forces” absolutely nothing.

Reply to  AGW is Not Science
November 23, 2021 11:49 am

Imperfect correlation does not mean that it has no effect. It just means that it is not the only agent modulating the atmospheric temperature. Likewise, a lag relationship does not mean that CO2 does not force temperature. It just means that CO2 was not initial catalyzing agent for the temperature change.

Reply to  TheFinalNail
November 23, 2021 11:25 am

CO2 is assumed to have a warming affect. To date, nobody has been able to measure this affect.

Reply to  MarkW
November 23, 2021 11:46 am

Not only has it been measured; but it can be predicted as well. See Sherwood et al. 2020 for a comprehensive review of the warming effect.

Reply to  bdgwx
November 23, 2021 2:46 pm

I read the paper in your link. At no time did I read a sentence that said the “measured” any warming caused by CO2. Lots of the model word but nothing that said they measured something.

If you are correct that CO2 causes warming the why are there only one value for the specific heat of dry air or CO2. If IR causes warming then there would need to be a value for with and without IR.

If you are correct then why does the Shomate equation not include that?

If you are correct why is that not mentioned in the NIST data sheet!

If you are correct then why does a book on thermodynamics say the following:

Reply to  mkelly
November 23, 2021 5:32 pm

The publication has a whole section dedicated to the warming caused by increasing CO2 during various eras.

ΔT = (Ein-Eout)/Cp.M where E is energy, Cp is the specific capacity, and M is the mass of the system. IR causes warming because it carries energy. The climate system accumulates this energy so it must warm to restore the energy balance.

The Shomate equation is not inconsistent with any other thermodynamic relationship thus it does not contradict the fact that the planet must warm when it accumulates energy.

Likewise, your thermodynamic test is not inconsistent with the established laws of thermodynamics including the 1LOT which says in no uncertain terms that when you perturb the energy balance of a system such that Ein > Eout then the internal energy of the system must increase. And because no material has an infinite specific heat capacity it must respond by warming.

CO2’s behavior with respect to IR radiation and its radiative force is well understood exploited with NDIR instruments and radiative transfer models that are in widespread use in many application that you likely take advantage of in some form whether you realize it or not. We know with 100% certainty that all other things being equal increasing CO2 will cause warming. That’s not in dispute even be the most vocal skeptics. What we don’t know with certainty is how much the planet will warm but we can narrow it down to a reasonable range which the Sherwood publication describes in detail.

Anthony Banton
Reply to  Richard Page
November 23, 2021 12:50 pm

“carbon dioxide variations clearly follow temperature variations.“

Of course they do.
Those cores represent the climate in a state when it’s main driver was the Earth’s orbital eccentricity. (Re the TSI at 65 deg N graph posted by bgdwx).
Therefore the natural carbon cycle was at work in that it followed temperature.
Seas warmed, less CO2 absorbed – feed back – more warming and vice versa.
The only time CO2 will lead is when a pulse enters the atmosphere outside of the CC.
As in the PETM or over this last 150 years.
Just the usual Skeptics’ myth popping up to be whacked-a-moled… if anyone can be bothered.
Otherwise denizens have their cognitive dissonance reinforced a little more.
Which of course is the MO of WUWT.

R Taylor
Reply to  Anthony Banton
November 24, 2021 5:40 am

So when will any one of you true believers in positive feedback tell me what the IPCC uses as the sensitivity to CO2 to temperature? Hint: The IPCC has to use zero, as positive feedback would blow up their models.

Reply to  R Taylor
November 24, 2021 6:38 am

Can you post a link to the IPCC section where they say the sensitivity is zero? I’d like to see the context.

Reply to  bdgwx
November 23, 2021 2:28 pm

The precession cycle dominates – just 10,000 years ago 65N had 50W/sq.m more in July than now – enough to rip Earth out of glaciation.

The idea that minute variation in TSI of fractional watts per square metre can have any influence is so silly.

Andy H
November 23, 2021 7:34 am

Is this right:

If the Earth is rotating around the Sun-Jupiter* system and the Sun is wobbling by about 1% of the distance to the Earth then the intensity of the Sun should change by 2% over the Sun’s wobble cycle. This will be superimposed on the Earth’s seasons, shifting by about 1/11th of a cycle a year. Hot Summer and cold Winter to warm Summer and cool Winter and back again. Across the year it should be almost the same solar intensity but our weather doesn’t depend upon yearly averages.

*ignoring the rest of the planets.

Reply to  Andy H
November 23, 2021 8:00 am

The Earth-Sun distance does not change as a result of the Sun-Jupiter barycenter wobble.

Andy H
Reply to  bdgwx
November 23, 2021 8:02 am

So it is wrong. Thanks.

Reply to  Andy H
November 23, 2021 8:11 am

Correct, it is wrong. The claim was recently made by Zharkova in a publication, but found to be incorrect so the publication was retracted.

Ric Howard
Reply to  bdgwx
November 23, 2021 8:09 pm

It appears the editors retracted the article but lead author V. V. Zharkova claims the retraction was unwarranted:

An updated paper is available at:

Clyde Spencer
Reply to  Andy H
November 23, 2021 10:24 am

Why did someone downvote Andy for asking a question?

Reply to  Clyde Spencer
November 23, 2021 11:45 am

Because woke people have all the answers, but only to the questions that they want asked.

Tom in Florida
Reply to  Andy H
November 24, 2021 6:12 pm

Except that no cycles are 11 years (other than the first as estimated). That is the just about average number used.

November 23, 2021 8:11 am

How do cosmic rays tie-in with this?

The solar system does not exist in splendid isolation and cosmic rays have an influence on cloud formation.

It was cloudy this morning and pretty chilly too, then the Sun came out….

Cosmic Ray Diffusion from the Galactic Spiral Arms, Iron Meteorites, and a possible climatic connection?

I believe we are on the way out of the Orion arm

We pass through a major spiral arm about every 100 million years, taking about 10 million years to go through. During the transit, there would be a higher rate of ‘nearby’ supernova and possibly other so called ‘environmental stresses’ which could alter the climate of the Earth.

It’s a small world.

Reply to  fretslider
November 23, 2021 9:01 am

This is what Henrik Svensmark’s book “the Chilling Stars” talks about.

Reply to  fretslider
November 23, 2021 9:09 am

And a big Galaxy. But you see the Sun’s radiation is OURS, and Galactic Cosmic Rays so far not.
And not to forget – the Younger Dryas rapid freeze was caused by cometary bombardment – also not OURS as it came from out there somewhere. Its broken trail is known a Tauris stream 1 and 2 and seems to hail from Taurus which even the people of Göblekli Tepe knew..
I think we have a new flat-earth cult!

Reply to  bonbon
November 23, 2021 9:13 am

Yes it is a big galaxy – big enough to have influence. You seem to be going down the same track as the warmists – dismissing possibilities

Reply to  fretslider
November 23, 2021 9:49 am

Forgot the /sarc .
Of course I follow Shaviv and Svensmark!
Those that suddenly shift to Galactic scale or Planetary scale (Nikolov) are here hounded by ‘earther Sun worshipers which actually puts them in the Gaia camp with Greta and the Pope. Ironic indeed!

Peta of Newark
November 23, 2021 8:35 am

Never mind TSI, does the sun change colour during the 11 year cycle?

Reply to  Peta of Newark
November 23, 2021 9:20 am

Here in X-ray, it also rains on the Sun :

Reply to  bonbon
November 23, 2021 9:27 am


Jim Gorman
Reply to  Peta of Newark
November 23, 2021 10:44 am

I believe you are thinking like I am. Look at the attached image. Why the big difference in TOA and sea level energies. The atmosphere either reflecting certain wavelengths or absorbing UV and visible wavelengths. Does the sun’s spectrum vary causing absorption in the atmosphere to change or maybe what is reflected?

Does the solar wind, or magnetic fields affect clouds?

It looks multivariate to me and just looking at w/m^2 may not tell the whole story.

November 23, 2021 8:56 am

Yet another example of the climate doom finger on the scales of climate science.

Nick Schroeder
November 23, 2021 10:29 am

The popular notion that the Earth existed in some kind of divine, benign, Goldilocks thermal equilibrium until mankind’s GHGs screwed it all up with a few additional W/m^2 is an article of faith not science.

Geologic history and general observations make it rather clear that such a scenario never was, is or will be.

November 23, 2021 11:21 am

The authors found that the Sun/climate debate is an issue where the IPCC’s consensus statements were prematurely achieved through the suppression of dissenting scientific opinions.

All while insisting that your politicians spend trillions of dollars on “fighting climate change”, instead of, say, maybe finding a cure for cancer.

“Fighting climate change” is the classic implementation of Claude-Frédéric Bastiat’s broken window theory.

Ian Cooper
November 23, 2021 12:19 pm

SSC 25 is not living up to the early predictions that it would be as bad or even worse than SSC 24. Most of us aurora/solar observers are happy that is so!

Reply to  Ian Cooper
November 24, 2021 3:09 pm

For the moment I can only agree… a look at a solar flux based comparison of the two speaks for itself:

comment image

This of course doesn’t mean that it will continue all the time with that power, but a belief in SC25 being weaker than SC24 from the beginning, as often claimed, doesn’t hold water.


November 23, 2021 2:02 pm

In terms of climate, sunspots and associated TSI are trivial.

The orbital precession dominates the climate as it is an obvious signal in glaciation. Since the Panama Isthmus formed, orbital eccentricity has also become a significant contributor to glaciation with deeper, multi-precession cycles.

10,000 years ago, 55N was receiving 20W/sq.m more sunlight than now in July. That was enough to pull the land masses around the North Atlantic out of glaciation.

Earth is already 400 years into the current cycle of glaciation.

Ocean warming is better described as more heat retention due to the water cycle slowing down. The Oceans received their maximum sunlight in the present era 400 years ago. Since then the sunlight over oceans has been decreasing resulting in the water cycle slowing down with less water transfer to land and oceans retaining more heat as net evaporation is reduced.

How many climate models have predicted the observed downward trend in the global river runoff?
comment image?__blob=poster

Tom in Florida
Reply to  RickWill
November 24, 2021 6:16 pm

Do not forget obliquity, 10,000 years ago obliquity was approaching maximum at the same time NH summer solstice was at perihelion.

November 23, 2021 2:46 pm

CO2 is devoured in photosynthesis in our oceans is massive and is not liked by MSM. So much marine life requires carbon dioxide to produce calcium carbonate for shells and bones however miniscule. More CO2 results in more oxygen from the phytoplankton and more greenery plant growth = food production for human population growth. So actively reducing CO2 whilst world population is growing could prove devastating, especially for poorer nations. Malthusians promote population control and decrease. Didn’t work even in China!

November 23, 2021 5:44 pm

Here is the Abstract of my paper at
For the sun- temperature – climate connection see Figs 1 – 5
This paper begins by reviewing the relationship between CO2 and Millennial temperature cycles. CO2 levels follow temperature changes. CO2 is the dependent variable and there is no calculable consistent relationship between the two. The uncertainties and wide range of out-comes of model calculations of climate radiative forcing arise from the improbable basic assumption that anthropogenic CO2 is the major controller of global temperatures. Earth’s climate is the result of resonances and beats between the phases of cyclic processes of varying wavelengths and amplitudes. At all scales, including the scale of the solar planetary system, sub-sets of oscillating systems develop synchronous behaviors which then produce changing patterns of periodicities in time and space in the emergent data. Solar activity as represented by the Oulu cosmic ray count is here correlated with the Hadsst3 temperatures and is the main driver of global temperatures at Millennial scales. The Millennial pattern is projected forwards to 2037. Earth has just passed the peak of a Millennial cycle and will generally cool until 2680 – 2700. At the same time, and not merely coincidentally, the earth has now reached a new population peak which brought with it an associated covid pandemic, and global poverty and income disparity increases which threaten the UN’s Sustainable Development Goals. During the last major influenza epidemic world population was 1.9 billion. It is now 7.8 billion+/. The establishment science “consensus” that a modelled future increase in CO2 levels and not this actual fourfold population increase is the main threat to human civilization is clearly untenable. The cost of the proposed rapid transition to non- fossil fuels would create an unnecessary, enormously expensive. obstacle in the way of the effort to attain a modern ecologically viable sustainable global economy. We must adapt to the most likely future changes and build back smarter when losses occur.
The effect of C02 on temperature is immeasurably small. There is no CO2 caused climate crisis.
For other posts on this topic scroll down through

See - owe to Rich
November 24, 2021 2:30 am

Joel O’Bryan wrote:
“Solar physicists expect cycle 25 to be even smaller than Cycle 24. “

Well that statement is certainly wrong without a leading “Some solar physicists.”

Very true. In fact one group, Leamon et al (2020) , predicted Cycle 25 will reach a huge 233 smoothed sunspots at maximum. However, this is based on a new technique called “solar terminators” for measuring the length of a solar cycle, and a linear extrapolation of a Hilbert transform phase to predict that length. They predicted that Cycle 24 would be very short by this measure (and hence Cycle 25 strong), but their exact terminator prediction has failed to come to pass.

In fact, in my paper “Limitations in the Hilbert transform approach to locating solar cycle terminators”, , I demonstrated multiple problems with their “terminator” paper; since then they have produced a Response and I a Reply to that, which you can read in the October and November issues of Solar Physics.

If the terminator proves to be in June 2022 then the new-fangled cycle length will be 11.0 years and agree with the traditional minimum-to-minimum method (Dec. 2008-Dec. 2019). But it could still be earlier, or later, than that. (My current estimate is April 2022.) An 11.0 year length would suggest that Cycle 25 would be close to average, and significantly stronger than Cycle 24, but there is significant error in the regression between cycle length and succeeding cycle strength.

Richard Booth

See - owe to Rich
November 24, 2021 2:48 am

Regarding the attribution of 20th century warming to various factors, mentioned in “JC reflections”, my paper “On the Influence of Solar Cycle Lengths and Carbon Dioxide on Global Temperatures”, Journal of Atmospheric and Solar-Terrestrial Physics 173 (2018),
or has something to say about the warming from 1980 to 2001 (over two solar cycles).

Specifically, the solar cycle length model attributes 37% of the warming to the sun, and 63% to CO2, and a radiative forcing method attributes 33% of the warming to the sun, in good agreement.

I have to acknowledge, however, that the paper only covers the period from 1850 to the end of Cycle 23 in 2008, and the HadCRUT4 mean temperature of Cycle 24 (to end 2019) did exceed my prediction – it was doing quite well until the super El Nino of 2015/16.

Richard Booth

Reply to  See - owe to Rich
November 24, 2021 3:00 pm

Thank you for the very interesting infos in your two comments.

See - owe to Rich
Reply to  Bindidon
November 25, 2021 4:12 am

And thank you! I was beginning to think no-one was reading this far down the thread…

Gregg Eshelman
November 24, 2021 3:40 am

Oh look, math.

Anyone care to calculate the massive number 0.1% of that is? Write it out with all the numbers.

By saying it “only varies 0.1% so we can ignore it”, the people who desperately want it ignored are attempting to bury and hide just how much energy is contained in that not really tiny variance.

Reply to  Gregg Eshelman
November 24, 2021 1:05 pm

It varies by 0.1% from the peak to trough of a solar cycle.

It varies by 6.5% from perihelion to aphelion.

The keyword here is varies.

That does not mean there is long term forcing. The solar cycle is about 11 yrs so 5.5 years there is positive perturbation in forcing and for the other 5.5 years there is a negative perturbation in the forcing. The net forcing over the 11 year period is close to zero. The orbital cycle is 12 month so 6 months there is a positive perturbation is forcing and for the other 6 months there is a negative perturbation in forcing. The net forcing over the 12 month period is close to zero.

The long term forcing is a product of the grand cycles. There is still a wide range of estimates for the TSI change caused by the grand cycles. Estimates are as low as about 1 W/m2 and as high as about 4 W/m2. This represents a radiative forcing of about +0.2 W/m2 and +0.7/m2 trough to peak respectively and -0.2 W/m2 and -0.7 W/m2 peak to trough respectively. Most studies are favoring the lower end of this range now.

The 12-month orbital and 11-year solar cycles have only a negligible effect on long term climatic evolution because those cycles are so short and because the Earth has a lot of thermal inertia. It is the multi-decade grand cycles that can have a noticeable effect on long term climatic evolution. Even going with the lower 0.2 W/m2 of forcing would yield a noticeable change in the global mean temperature over several decades.

Now consider that the net anthropogenic forcing is on the order of +2.0 W/m2 or about 10x more than the more favored estimates of solar grand cycle forcing.

November 25, 2021 10:48 am

1. An alternative to anthropogenic global warming theory

The observed seasonal heating and cooling of high latitude ocean is shown below:

Reply to  Girma
November 25, 2021 10:51 am

Because the heat capacity of the atmosphere is much smaller than the mixed ocean layer, the atmosphere is seasonally heated to a higher temperature and cooled to a lower temperature than the mixed ocean layer. As a result, during the seasonal solar heating from March to August, heat flows from the warmer atmosphere to the relatively colder mixed ocean layer, resulting in the observed seasonal global sea level rise. During the seasonal cooling from August to March, heat flows from the relatively warmer mixed ocean layer to the colder atmosphere and to space, resulting in the observed seasonal global sea level fall.

From the above figure, solar energy is absorbed by the ocean during spring and summer and this absorbed energy is released to the atmosphere and to space during autumn and winter. However, the absorbed and released heat energy are not equal because of heat flow from the warmer mixed ocean layer to the colder deeper ocean in order to satisfy the second principle of thermodynamics that heat must flow downhill on the temperature scale. As a result, we have the energy balance equation for the ocean given by

ΔQstored = ΔQheating –  ΔQcooling

This asymmetry in the seasonal heating and cooling rates explains the observed asymmetry in the climate variables (atmospheric CO2, GMT and sea level). The fact that the sea level rises annually indicates energy is being stored in the ocean. This energy that is locked as sea level rise is released only when the sea level falls, which is when the atmosphere cools relative to the ocean mixed layer (at night, during autumn, winter and ice ages).

2. Anthropogenic Global Warming theory

IPCC 1990 (SPM):
“Short-wave solar radiation can pass through the clear atmosphere relatively unimpeded. But long-wave terrestrial radiation emitted by the warm surface of the Earth is partially absorbed and then re-emitted by a number of trace gases in the cooler atmosphere above. Since, on average, the outgoing long wave radiation balances the incoming solar radiation both the atmosphere and the surface will be warmer than they would be without the greenhouse gases.”

Houghton (2004):
“The basic principle of Global warming can be understood by considering the radiation energy from the Sun that warms the Earth’s surface and the Thermal radiation from the Earth and the Atmosphere that is radiated out to space. On average these two radiation streams must balance. If the balance is disturbed (for instance by an increase in atmospheric Carbon dioxide) it can be restored by an increase in the Earth’s surface temperature.”

A simplified diagram for the ”greenhouse effect” is shown below:

Reply to  Girma
November 25, 2021 10:54 am


As shown in the above figure, the greenhouse warming theory assumes that heat is trapped by greenhouse gases and that warms the surface. This is inconsistent with the observation that the earth surface warms ONLY during spring and summer and the absorbed heat is released in autumn and winter. This is repeated each and every year. The ocean absorbs heat during spring and summer because the atmosphere that has a much lower heat capacity than the mixed ocean layer is heated to a much higher temperature so heat flows from the warmer atmosphere to the relatively colder mixed ocean layer. In autumn and spring, the above heat flow reverses because the atmosphere is cooled to a much lower temperature than the mixed layer so heat flows from the relatively warmer mixed ocean layer to the colder atmosphere. The schematic diagram for the greenhouse effect shown above is inconsistent with these observations.

The greenhouse theory also assumes that the radiation energy from the Sun and the thermal radiation from the earth surface must balance. This assumption is inconsistent with storage of heat energy in the ocean as described by Hoeffert (1980):

Rossby[1959], for example, in discussing the response of the  climate system to imbalances between absorbed solar energy flux and outgoing longwave radiative flux to space considered the possible significance of ocean water below the main thermocline as a secular heat reservoir. He concluded firstly  that in all probability a global radiation balance in general does not exist, even if periods of several decades are taken into account; and secondly that anomalies of heat may be stored for long periods isolated in the deep ocean. After several decades to centuries these anomalies return to the upper ocean where they again participate in atmospheric climatic processes.”

November 26, 2021 7:54 pm

TSI fluctuations during active/inactive sunspot cycles can’t be the primary cause of warming/cooling during Grand Solar Minima/Maxima cycles because a 1 watt differential is too small to substantially affect global temperatures.

it most likely the Svensmark Effect that causes cooling during weak sunspot activity, but that hypothesis has yet to be confirmed.

it is interesting to note that the Little Ice Age (1280~1850) corresponds almost perfectly to the Wolf, Sporer, Maunder and Dalton Grand Solar Minima events which occurred during over the LIA, and the 1933~1996 Grand Solar Maximum (the strongest sunspot activity in 11,400 years) corresponds to the Modern Warming Period, especially since the 1996~2015 Hiatus started at the same time the Grand Solar Maximum ended, despite 30% of of CO2 emissins since 1750 occurring during the Hiatus, which only ended following the 2025/16 Super El Niño event.

One most always try to avoid the pitfalls of the logical fallacy of post hoc ergo proctor hoc, but there does seem to be a compelling correlation between sunspot activity and global warming/cooling trends.

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