OK, I’m going to talk about global cooling: cue, derisive laughter from Climate Scepticism’s troll-like AGW-convinced readers. I’m also – wait for it – going to talk specifically about global cooling due to a Maunder Minimum type decline in solar activity: cue almost insane high-pitched babbling from the ‘it’s not the sun, stupid’ ranks of the ‘Believers in the Pre-Eminence of His/Her Radiatively Forced Royal Highness, the One, the Magnificent, the All-Powerful, CO2’ (aka the Scientifically Naive, aka the Climatologically Challenged).

AGW alarmists have been pooh-poohing the idea of global cooling for years now, scoffing at the various hit and miss predictions and projections which have appeared on sceptic blogs throughout the years, gleefully declaring that warming is still happening in spite of declining solar activity, therefore solar variability must have very little influence on the climate and the actual variation in Total Solar Irradiance is so miniscule that the radiative forcing from solar variability is tiny in comparison to that from CO2, blah, blah, blah. That stance is becoming ever more difficult to justify. Firstly, they were wrong about the former – mechanisms have been identified whereby solar variability can significantly affect the climate – and if it turns out that they are wrong about the latter and climate sensitivity due to CO2 is on the low side, as recent observational estimates suggest, whilst at the same time, the influence of a significant decline in solar activity has been underestimated, then society may have a problem.

Meehl et al, 2013, estimated the reduction in global warming which would be caused by an upcoming grand solar minimum (GSM) to be “several tenths of a degree Celsius” between 2020 and 2070. For this they used a climate model with a high climate sensitivity of 3.2C – which is the CMIP5 multi-model mean. They concluded that the modest cooling would not reverse the warming trend, just slow it down somewhat, and by 2070, we’d be back on track for full-on Thermageddon. Other studies have shown similar. What seems highly unlikely is that Meehl et al accounted for large uncertainties in multi-decadal internal (ocean) variability forcing – expected to exert a cooling influence in the coming decades. Also, whilst their estimate assumes strong near-future GHG warming, it also fails to adequately quantify the extreme decline in solar UV which is expected during a GSM, as we shall see.

A new study has been published which looks at the expected decrease in UV solar output resulting from the sun proceeding into a grand solar minimum. Media reports (plus here) and one of the authors of the study basically confirm that, even though it will cool the earth, it will still be no big deal, quoting Meehl et al above, saying what the authors of that earlier study said, that global warming will soon outpace any modest global cooling.

A team of scientists led by research physicist Dan Lubin at Scripps Institution of Oceanography at the University of California San Diego has created for the first time an estimate of how much dimmer the Sun should be when the next minimum takes place.

Lubin and other scientists predict a significant probability of a near-future grand minimum because the downward sunspot pattern in recent solar cycles resembles the run-ups to past grand minimum events.

Despite how much the Maunder Minimum might have affected Earth the last time, Lubin said that an upcoming event would not stop the current trend of planetary warming but might slow it somewhat. The cooling effect of a grand minimum is only a fraction of the warming effect caused by the increasing concentration of carbon dioxide in the atmosphere. After hundreds of thousands of years of CO2 levels never exceeding 300 parts per million in air, the concentration of the greenhouse gas is now over 400 parts per million, continuing a rise that began with the Industrial Revolution. Other researchers have used computer models to estimate what an event similar to a Maunder Minimum, if it were to occur in coming decades, might mean for our current climate, which is now rapidly warming.

One such study looked at the climate consequences of a future Maunder Minimum-type grand solar minimum, assuming a total solar irradiance reduced by 0.25 percent over a 50-year period from 2020 to 2070. The study found that after the initial decrease of solar radiation in 2020, globally averaged surface air temperature cooled by up to several tenths of a degree Celsius. By the end of the simulated grand solar minimum, however, the warming in the model with the simulated Maunder Minimum had nearly caught up to the reference simulation. Thus, a main conclusion of the study is that “a future grand solar minimum could slow down but not stop global warming.”

Makes you wonder why Lubin and co. bothered looking into it in the first place, if all they were going to say is, ‘well, yes, it will put a small dent in global warming, but that’s all’. Are they right about this though? Is Lubin’s opinion justified by the science he presents?

The world has warmed somewhere between 0.8C and 1.0C in the last 170 years. According to climate scientists, this is a big deal. Since 1976 or thereabouts, it’s warmed about 0.6C – which in itself is not unprecedented (it warmed by as much from 1910 to 1945). Apparently though, this latter warming is an even bigger deal because the IPCC is 95% certain that all of it is due to fossil fuel emissions. 0.6C actual warming in 42 years. Contrast this with say 0.3C global cooling in maybe as little as 30 years – not unrealistic according to the above referenced study. Then consider that some Northern Hemisphere regions may experience winter cooling at least double this – 0.6C in as little as three decades. These are conservative estimates. Other studies indicate larger declines occurring during the Maunder Minimum. Then consider that every 0.1C cooling, pound for pound, is a lot more damaging to human society, to agriculture, to health, than the equivalent warming, which may even be beneficial in many circumstances. Then consider that renewables have trebled the price of electricity in some parts of the developed world – ironically, with the supposed intention of reducing global warming – resulting in a dangerous reliance upon intermittent, unreliable and expensive wind power, to meet demand. This is not a scenario that the developed nations have planned for, having been convinced by climate scientists that the only climate change threat is from GHG warming.

Global warming obsessed scientists and the media are still dismissive of the threat posed by possible decreasing temperatures; they still push the dubious notion that it is increasing global temperatures which threaten us, not ‘slight cooling’ from a dimmer, less active Sun. Literally, they are gambling with the lives of many, many thousands of people. It would be supremely ironic if, after years of alarmists telling us ‘it’s worse than we thought’ and it actually turning out to be rather better than we thought, that they now tell us global cooling will be no big deal when in fact it turns out to be pretty disastrous. Because what they conveniently forget is that future warming projections are based upon climate models which, until the latest ‘spurt’ in global mean temperature caused by Pacific warming and a powerful El Nino, were looking pretty useless. They’re going to look useless again if a GSM/internal variability offsets global warming in the next 10 years or (horror!) the world cools. It’s all very well introducing ad hoc reasons why warming won’t be quite as rapid as predicted, but the fact is, the current generation of CMIP5 climate models don’t adequately account for solar forcing or internal variability due to ocean cycles.

Lubin, for his part, makes it clear that the cooling due to a GSM is as a result of a top-down interaction of the stratosphere with the lower troposphere, precipitated by a decrease in solar UV causing a thinning of the ozone layer:

“Now we have a benchmark from which we can perform better climate model simulations,” Lubin said. “We can therefore have a better idea of how changes in solar UV radiation affect climate change.”

The reduced energy from the Sun sets into motion a sequence of events on Earth beginning with a thinning of the stratospheric ozone layer. That thinning in turn changes the temperature structure of the stratosphere, which then changes the dynamics of the lower atmosphere, especially wind and weather patterns. The cooling is not uniform. While areas of Europe chilled during the Maunder Minimum, other areas such as Alaska and southern Greenland warmed correspondingly.

Thus it would appear that the cooling effect of any possible future grand solar minimum is critically dependent upon the reduction in solar UV intensity and not merely a function of the more modest decline in TSI. Lubin and his team estimated a UV reduction during a future GSM of 6.9% below the UV intensity during the solar cycle 22 (1986-96) minimum.

Reconstructions for UV irradiance from the historical MM to the present-day vary widely. Krivova et al. (2010) estimate a difference between the MM and recent solar minima of 5.1% in the Schumann–Runge continuum (1300–1750 Å) and 1.9% in the Schumann–Runge bands (1750–2000 Å). Lean (2000) reconstructs a difference between MM and mean present-day solar spectral irradiance of ∼15% increasing to ∼30% as wavelength decreases from ∼1900 Å to ∼1300 Å. Our estimate for the interval 1250–1910 Å is 16.3% between quiet Sun and solar maximum, 11.1% between quiet Sun and median present day solar activity, and 6.9% between quiet Sun and cycle 22 minimum. Our solar analog estimate therefore appears to be intermediate between the Lean (2000) and Krivova et al. (2010) reconstructions.

Meehl et al, which Lubin references to justify his assertion that the upcoming GSM will only put a small dent in global warming, estimate the decline in spectral UV irradiance during a GSM thus:

The grand solar minimum is computed as the average of the 1976, 1986 and 1996 solar minima multiplied by (1-0.0025) across all spectral irradiances. In the prescribed SSI changes for these twentieth century minima, larger reductions (1-8%) occur in the ultraviolet range than other parts of the spectrum and this is therefore also reflected in the grand solar minima.

This is a curiously opaque way of saying they took the average of the minimum UV intensity of three consecutive solar cycle minima from 1976 to 1996 and assumed that, at the next GSM, the ‘quiet sun’ solar UV intensity would be 0.25% lower than this. As is evident, this is an order of magnitude less than Lubin’s estimate of 6.9% lower than the single minimum UV which occurred in 1986 (or 1996, depending on whether they took minimum at the beginning or end of the cycle). So it would appear that Lubin is contradicting the findings of his own research and that the expected cooling from a future GSM will be significantly in excess of what Meehl et al estimated in 2013. I guess that’s what you call being a ‘reluctant scientist’! Unfortunately, being a reluctant scientist might mean that the world is not adequately informed of the very real dangers of a possible fast approaching Grand Solar Minimum. It may even cost lives.


  1. Legend for the image:
    The Earth’s North magnetic pole has been wandering at 10-year intervals from 1970 to 2020, as seen in this animation from the National Centers for Environmental Information.


  2. A grand solar minimum will result in a trend of more negative NAO phases, especially during winter. Northern Europe is about to get a timely reminder of what this will mean.

    Liked by 1 person

  3. We know that models indicate more cooling in the northern hemisphere, more over land than water and more at higher latitudes. Europe is land, at high latitudes, in the northern hemisphere. Other studies have shown that Europe could see 2-3°C cooling in the winter. That would be painful.

    Based on history, Japan could be in for some pain as well. Records of cherry blossom time have been kept for 11 centuries. Aono and Kazui used the data to reconstruct springtime temperatures. They found cool periods that corresponded to the Wolf, Spoerer, Maunder, and Dalton minima. Estimated March mean temperature was about 3-4 °C lower than the present normal temperature.

    Liked by 2 people

  4. Not a big fan of the solar hypothesis in any of its flavors, for several reasons. But the Wyatt/Curry stadium wave paper also predicts northern hemisphere cooling into the mid 2030s on compelling observational grounds. Being right and being right for the wrong reasons are different things.



    Curry & Wyatt’s stadium wave hypothesis is a way of looking at natural internal variability over multi-decadal time scales. As far as I can see, they predict a continuation of the hiatus in global warming into the 2030s, as natural cooling offsets projected GHG global warming. This is not the same as centennial scale external forcing of the climate due to variations in solar irradiance – though I suspect strongly that natural internal variability is modulated to some degree by external forcing. Curry and Wyatt makes the distinction here:

    “The stadium wave holds promise in putting into perspective numerous observations of climate behavior, such as regional patterns of decadal variability in drought and hurricane activity, the researchers say, but a complete understanding of past climate variability and projections of future climate change requires integrating the stadium-wave signal with external climate forcing from the sun, volcanoes and anthropogenic forcing.

    “How external forcing projects onto the stadium wave, and whether it influences signal tempo or affects timing or magnitude of regime shifts, is unknown and requires further investigation,” Wyatt said. “While the results of this study appear to have implications regarding the hiatus in warming, the stadium wave signal does not support or refute anthropogenic global warming. The stadium wave hypothesis seeks to explain the natural multi-decadal component of climate variability.”


  6. At some point the so-called ‘hiatus’ is no longer the interruption of a trend, but IS the trend. Whether that’s 17, 20 or some another number of years, and what the supposed start date was, becomes more academic as time goes by with no significant additional warming.


  7. Antarctica hasn’t warmed in at least the last 38 years per MSU RSS:

    The southern hemisphere (which has a higher thermal inertia due to having less land and more water) has cooled since 1979 per Purich et. al.:

    North Atlantic SST and subsurface temperatures have been in a rapid down-trend per Smeed et. al:

    Southern hemisphere SST has been in an accelerating downtrend since 1979:

    The “global warming” (per the IPCC and other politicized climate agencies) is so spotty and regional that they’ve had to come up with the explanation of “warming holes” to hand-wave explain away the cooling trend over large regions of the northern hemisphere from 1990-2015:

    Given that ~1/3 of the northern hemisphere has experienced a temperature down-trend (and large swaths of the rest have experienced no trend), and given that the southern hemisphere (being comprised of more water and more ice) has experienced a temperature down-trend… the planet cannot be accumulating heat.

    Global warming exists solely in the failed and useless computer models and the manipulated data of the IPCC and other politicized climate agencies. This is why they’ve become so shrill of late… they’re trapped by their own lies having run headlong into the brick wall of reality, and they really have no other recourse but to ramp up their alarmist blather in hopes their momentum will carry them through the coming decades of brutal cold. It won’t work.

    Government efforts are just now underway to defund all climate fraudsters and prosecute them for their wide-ranging and economically destructive fraud.

    And with that now being made public, we can expect the left to squeal all the louder. Music to our ears, to be honest.

    Liked by 1 person

  8. Reflecting on the question that is the title of this interesting essay, it might be good to ponder the answer of “neither”.
    Global “climate” has wandered around a very narrow range of weather manifestations and stats iver the last ~120 years or so.
    None of the excursions of warming, cooling, storm frequency etc. have extended very far in any direction.

    Liked by 1 person

  9. Hunter,

    Global climate aka global average surface temperature, has never been a very satisfactory metric of or practical way of examining the impact of changing climate. Regional changes in climate have far more immediate and direct impact upon people and the environment and it is these changes – far more complex than a mere thermometer based record of daily temperature – which we should be studying, particularly in terms of what drives such change. If a grand solar minimum does indeed occur, I strongly suspect that global warming obsessed scientists are going to learn a hard lesson that they should have focused much more on regional climates rather than fretting so much about a supposed global energy imbalance manifested as tiny changes in GMST and even tinier changes in sea surface temperatures from 0-3000m.


  10. The UK did just get a timely reminder of the sort of severe winter/early spring weather we can expect if a grand solar minimum turns out to be a reality. Guess what? An additional estimated 2300 people died recently solely due to the ‘Beast from the East’ – this is on top of the people the government normally expects to die from the cold during winter. Why did these 2300 people die? Because their underlying health problems were exacerbated by living in inadequately heated housing. I wonder why these poor people didn’t just turn up the heating to keep warm? All that clean, green, lovely energy just waiting to burn a hole in their wallet or bank balance and they didn’t avail themselves of it. I can’t understand it.



  11. Manic,

    The vested interests industry have been very successful in snuffing out serious debate on the urgency and effectiveness of global warming mitigation policies and questions on the quality of the ‘science’ which supposedly underpins those policies. This is because, by and large, the planet has consistently warmed since the late 1970s. Even when it didn’t warm much – from 1998 onwards – the data fiddlers were able to wring out an acceptable upward trend, their task made easier by the large El Nino in 2015/16. But if winters do get colder, in North America, Europe and Asia, in South America and in Australia, and people keep dying because they can’t afford to pay their bills, the climate change industrial complex is going to have a very tough task keeping a lid on public dissent. The longer they achieve this feat, the more monumental will be the eventual backlash.


  12. You may have a point in that the climate is more sensitive to changes in UV than in total solar irradiance (as Maycock et al explain in reference to stratospheric circulation). However, in the last paragraph you suggest a contradiction between Lubin et al (2017) and Meehl et al (2013) that is not as evident as you say. Meehl et al recognises UV reductions of 1-8%, but chooses a decline in TSI of only 0.25% below an ‘ordinary’ solar minimum, because all UV (below 400nm) is only about 8% of solar output. Hence that figure is an order of magnitude less.

    Meehl et al is far from the only study suggesting a grand solar minimum would only slightly (and of course temporarily) slow global warming. You might also be interested in Wang, Lean & Sheeley (2005), ‘Modeling the Sun’s Magnetic Field and Irradiance since 1713’, Astrophys J 625:522-538, suggesting UV increase since the Maunder minimum is less than 1%. Tau Ceti may not be a good analogue.

    Liked by 1 person

  13. Cedric,

    Meehl et al’s figure of 1-8% is with reference to the decline in solar UV COMPARED TO THE DECLINE IN THE VISIBLE PART OF THE SPECTRUM FROM SOLAR MAX TO SOLAR MIN OVER ANY GIVEN CYCLE. This has little to do with the decline in UV irradiance predicted to occur during a GSM, taking as reference points the spectral UV irradiance occurring at the minimums of cycles when solar activity is high and the expected spectral UV irradiance at cycle minimums during a GSM. Meehl et al make it very clear that they apply the reduction of 0.25% across all spectral irradiances; thus this should be compared with Lubin et al who calculate a much bigger reduction in UV irradiance of 6.9%.


  14. Jaime – are you sure you’re reading Meehl et al correctly? This is it again:

    “In the prescribed SSI changes for these 20th century minima, larger reductions (1–8%) occur in the ultraviolet range than other parts of the spectrum and this is therefore also reflected in the grand solar minima. Some studies argue for an even greater reduction in the UV during the Maunder Minimum [e.g., Krivova and Solanki, 2005] but given the debate regarding SSI variations in the most recent solar minima [Haigh et al., 2010; Lean and DeLand, 2012], we chose to apply the percentage‐wise reduction equally across all spectral irradiances.”

    It’s not 1-8% of the variation in a solar cycle (that is 1-8% of a variation 1-8%), but of total UV. Possibly confusingly UV is about 8% of TSI. A grand minimum is really the absence of solar cycle maxima, plus admittedly some effect of which Lubin17 represents one estimate (I’m sceptical because we’re not exactly orbiting a variable star, and it conflicts with Wang, Lean & Sheeley). Haigh says less UV may be compensated by increased visible.

    Anyway, have you read Maycock et al (2015)?
    That may strengthen your case: it varies UV by -0.85% below mean and TSI by -0.12%, so obviously less warming from ozone, and finds a relative cooling of 0.1 K. Now if you (naively) assumed the cooling were related solely to the UV component, 6.9/(0.85-0.35)*0.1 K is about 1.4 K, which would certainly make a big, if temporary, dent in 21st Century warming.

    I hope you agree that it would be interesting to re-run Maycock et al with the Lubin et al figures. But do you know what figure Lubin17 finds for total irradiance? That is what can legitimately be compared with Meehl13’s 0.25%.


  15. Cedric, you missed out the sentence just before your quote which is:

    “The grand solar minimum is computed as the average of the 1976, 1986 and 1996 solar minima multiplied by (1-0.0025) across all spectral irradiances.”

    You can’t misinterpret this; they are saying they assume all spectral irradiances decline equally by 0.25% when comparing the minima during normal activity to the expected minima during a GSM. The confusing sentence is this:

    “In the prescribed SSI changes for these 20th century minima, larger reductions (1–8%) occur in the ultraviolet range than other parts of the spectrum and this is therefore also reflected in the grand solar minima.”

    The 1-8% figure for UV SSI is clearly referring to the reduction in UV compared to the ‘other parts of the spectrum’. As they’ve already stated that it is assumed only a 0.25% reduction in UV SSI occurs going from normal activity to GSM, then 1-8% can only mean the observed decline in UV going from solar max to solar min in any given cycle and thus the authors use this fact to suggest that the greater decline in UV going from normal sun to GSM is somehow accounted for! Very odd.

    I’ll take a look at Maycock et al.

    Lubin et al do not appear to calculate an estimate for the decline in TSI.


  16. The reason climate scientists are wrong is that they discounted any solar influence in late 20th. century warming, and attributed it all to AGW. Solar activity was very high during most of the century, and must have contributed to warming. If so, then a Maunder type minimum will have maybe double the effect that they estimate, and the world will cool.

    Liked by 1 person

  17. Thanks for providing that link Stephen. Basically, your hypothesis is that a more active sun induces greater ozone over the equator and less over the poles, and vice versa. Joanna Haigh’s work appears to show that declining UV also initiates a layered response in stratospheric ozone. It’s certainly not settled science and research is ongoing, but what seems to be certain is that declining UV does have a significant effect upon climate, globally, but especially regionally. Teasing out the exact mechanisms of that interaction is going to take more work, but I’ve no doubt that we will understand the processes involved a lot better in the coming decades and I’m willing to bet that the main impetus for such ongoing research will be observations of the real effects of declining solar activity upon the climate.


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