Nuccitelli: Grand Solar Minimum Would Barely Dent Global Warming

August 14, 2013

One of the enduring standards of climate denialism: We’re going into a new solar minimum, the earth is going to get colder, we’ll have a new “little ice age”.

I handled it some time ago in the video above. There’s been a minor revival due to a recent article in a right wind Danish newspaper. Dana Nuccitelli explains in The Guardian:

Recent articles in the Danish newspaper Jyllands-Posten (translation available here) and in the Irish Times both ran headlines claiming that another grand solar minimum could potentially trigger an “ice age” or “mini ice age” this century. These articles actually refer to the Little Ice Age (LIA) – a period about 500 to 150 years ago when global surface temperatures were approximately 1°C colder than they are today. This is quite different from an ice age, which are more like 5°C colder than today. The LIA was not actually very cold on a global scale.

So, in order to trigger another LIA, a new grand solar minimum would have to cause about 1°C cooling, plus it would have to offset the continued human-caused global warming of 1 to 5°C by 2100, depending on how our greenhouse gas emissions change over the next century.

In the Jyllands-Posten article, Henrik Svensmark (the main scientist behind the hypothesis that the sun has a significant indirect impact on global climate via galactic cosmic rays) was a bit more measured, suggesting,

“I can imagine that it will become 0.2°C colder. I would be surprised if it became 1–2°C”

So these two articles are suggesting that a grand solar minimum could have a net cooling effect in the ballpark of 1 to 6°C, depending on how human greenhouse gas emissions change over the next century. Is it plausible that a grand solar minimum could make that happen?

The short answer is, ‘No.’

Fortunately, Solar Output is Stable

We’re fortunate that the amount of solar radiation reaching the Earth’s surface is very stable. Climate contrarians will often ask if we’d prefer if the planet were warming or cooling, suggesting that global warming is a good thing because at least the planet isn’t getting colder. This is a false dichotomy – an ideal climate is a stable one.

The relatively stable climate over the past 10,000 years has allowed establishment of human civilization, by making it possible to create large stationary agricultural farms because we could rely on stable weather patterns. During that time, net global surface temperatures changes haven’t exceeded 1°C from the coldest to the hottest climates, though we’re now approaching that degree of change, with 1°C warming since the LIA, 0.8°C of that over the past century, with much more to come.

What difference would a grand solar minimum make in the amount of solar energy reaching Earth? Two examples are the Maunder Minimum, a period of very low solar activity between 1645 and 1715, and theDalton Minimum, a period of low (but not as low as the Maunder Minimum) solar activity between 1790 and 1830.

Relative to current levels, the Dalton Minimum represents a 0.08% decrease in the amount of solar radiation reaching the Earth’s surface, and the Maunder Minimum represents a 0.25% decline. That’s how stable solar activity is. That’s also why we’re playing with fire by increasing the greenhouse effect so much and so quickly. We’re threatening the stability of the climate that has been so favorable to our development.

Peer-Reviewed Research Says Global Warming will Continue

There have been several studies in recent years investigating what impact another grand solar minimum would have on global surface temperatures, since solar research suggests it’s possible we could be due for another extended solar minimum. Generally these studies will run climate model simulations under a given greenhouse gas emissions scenario with stable solar activity, then run the same scenario with the sun going into a grand minimum, and look at the difference in resulting global surface temperature changes.

Using this approach, Feulner & Rahmstorf (2010) (PDF available here) estimated that another solar minimum equivalent to the Dalton and Maunder minima would cause 0.09°C and 0.26°C cooling, respectively.

The global mean temperature difference is shown for the time period 1900 to 2100 for the IPCC A2 emissions scenario. The red line shows predicted temperature change for the current level of solar activity, the blue line shows predicted temperature change for solar activity at the much lower level of the Maunder Minimum, and the black line shows observed temperatures through 2010. Adapted from Feulner & Rahmstorf (2010) by SkepticalScience.com

Jones et al. (2012) (PDF available here) arrived at a nearly identical result, with cooling from another Dalton and Maunder minimum at 0.09°C and 0.26°C, respectively. Similarly, a new paper by Anet et al. (2013) found that a grand solar minimum will cause no more than 0.3°C cooling over the 21st century.

Consistent with these previous studies, Meehl et al. (2013) (PDF available here) estimate a Maunder Minimum would cause about 0.26°C cooling, but as soon as solar activity began to rise again, that cooling would be offset by solar warming. This is a key point, because a grand solar minimum would not be a permanent change. These solar minima last for a few decades, but eventually solar activity rises once again. Thus any cooling caused by a solar minimum would only be temporary.

The cooling effect of a grand solar minimum can also be estimated very easily without the aid of climate models, because the change in the amount of solar radiation reaching the Earth’s surface is directly proportional to the temperature change it causes. Performing this calculation yields the same result as the model-based research: approximately 0.3°C cooling from another Maunder-type grand solar minimum. Click here to see the details behind the calculation.

The Heating of the Deep Oceans

In the Jyllands-Posten article, Svensmark also disputes the data showing the accelerated accumulation of heat in the deep oceans.

“How can the ocean below 700 meters be heated up, without the upper ocean warming up accordingly?”

This is an increasingly common argument made by climate contrarians, and a bit of a strange one. The data are what they are - we’ve measured the deep ocean warming, including with reliable instruments on Argo buoys for close to a decade now. Even if we couldn’t explain how the heat got there, it’s there.

But let’s address the question anyway – do we expect to have seen some obvious indication of heat being transferred from the shallow to deep ocean layers?

It’s certainly not clear that we should. Consider the analogy of a bathtub. Water from the faucet represents heat entering the shallow ocean layer. Water exiting the drain represents heat leaving the shallow oceans and entering the deep oceans. The water level in the bathtub represents the heat in the shallow ocean layer (which is what we measure).

If the amount of water entering the tub from the faucet is the same as the amount of water draining out of the tub, the water level in the tub won’t change. Yet the water still flows down the drain. Climate scientist Gavin Schmidt has discussed this point, summarized here.

In short, we wouldn’t necessarily see the heat being transferred through the shallow to the deep oceans. However, there has been plenty of warming of the shallow oceans that could have been transferred to the deeper oceans. In our case, the water is flowing into the tub faster than it’s draining out – the shallow oceans are warming fast, as the figure above illustrates.

Svensmark Gets Ocean Warming Wrong

Unfortunately Svensmark appears to be unfamiliar with this ocean heating data, saying,

“The thousands of buoys that we have deployed after 2003 to measure the ocean temperature, have not registered any temperature rise.”

This is just totally wrong, even if we ignore the rapid warming of the deep oceans (as is clear from a simple examination of the figure above). The ocean heat content data can be downloaded from the National Oceanographic Data Center here. The heating trend since 2003 in the upper 700 meters of oceans is equivalent to nearly 1 Hiroshima atomic bomb detonation per second (plus another 3 per second in the deep oceans). Both the shallow and deep oceans are accumulating a whole lot of heat, with no signs of slowing whatsoever. If anything, the heating of the oceans and the planet as a whole is accelerating.

Human Influence on Climate Change is Bigger than the Sun’s

The bottom line is that the sun and the amount of solar radiation reaching Earth are very stable. Even during the Maunder and Dalton grand solar minima, global cooling was relatively small – smaller than the amount of global warming caused by human greenhouse gas emissions over the past century.

A new grand solar minimum would not trigger another LIA; in fact, the maximum 0.3°C cooling would barely make a dent in the human-caused global warming over the next century. While it would be enough to offset to about a decade’s worth of human-caused warming, it’s also important to bear in mind that any solar cooling would only be temporary, until the end of the solar minimum.

The science is quite clear that the human influence on climate change has become bigger than the sun’s. At this point, speculation about another mini ice age is pure fantasy.

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29 Responses to “Nuccitelli: Grand Solar Minimum Would Barely Dent Global Warming”

  1. omnologos Says:

    Nutticelli is a running joke – if you’ve got something to say I recommend going to the sources and not his predigested rubbish

    • dana1981 Says:

      Yay for ad hominems!

      • omnologos Says:

        on the topics where AR5 will disagree with SkS, who’ll be debunking whom?

        • heijdensejan Says:

          We will see when we get there…..

        • MorinMoss Says:

          Can’t we count on your panoptical perspective to ferret out the truth?

          • omnologos Says:

            of course not -like Fermi I understand I’m mostly good at spotting faults :)

          • MorinMoss Says:

            A useful skill but I was taught that if all you look for are faults, that’s all you’ll ever find.

          • omnologos Says:

            who’s this Dana anyway? Why would we trust him to report on the current relevant literature? What makes him more qualified to do that than you, or Peter? Or the IPCC?

            We can only answer these questions by critically analyzing his writings. That starts with trying to find any faults in the reasoning. I say, if even I can find faults, his writing must be of a very poor quality. Etc etc.

          • MorinMoss Says:

            Dana’s credentials are easy enough to find – http://www.skepticalscience.com/team.php

            I’m sure you knew them already.

            I’m curious as to what faults you’ve found in the arguments and analyses of people on both sides of the AGW issue.

          • omnologos Says:

            MorinMoss – as I said the only way is to go to the sources. You haven’t listed a single reason why one should believe Dana’s summaries of the science more than anyone else’s: because there is no such a reason. What are the SkS amateurs to make them substitute the scientists?

            Dana will report according to his bias, like everybody else. The difference is that those whom the ipcc will destroy, it first made them mad with the absurd, silly, stupid notion that they could actually write themselves a thoughtful, comprehensive, solid report on the state of the science.

            And don’t you worry, I’ve been having periodic spats with the Slayers too.

    • ahaveland Says:

      You can jump off a cliff and flap your arms, and maybe even convince yourself and others that you are flying, but you’ll still make a mess on the rocks while we laugh at you from our scientific parachutes.

  2. pinroot Says:

    The nice thing is, even if a solar minimum does cause a mini-iceage, the state-of-the-art data homogenization techniques currently in use will show each year warmer than the last.

  3. Nick Carter Says:

    Wait a minute. I thought the standard explanation for our irrefutable increased warming over the past 30 years was due to INCREASED solar activity. At least that’s what Willy Soon tells us. Also, according to David Evans, a computer model shows a “thermal hot spot” but balloon data don’t show the same. Besides, we can’t rely on models to forecast data…oh, wait. And what about the temperature record? We can’t possibly know about our changing climate with only 150 years of thermometric data, but we do know that the earth’s atmosphere has stopped warming over the past 15 years, so we know global warming is over…oh, wait. Besides, the paleo climate record shows that it’s warmed and cooled before…(that’s 11,000+ years of data). But we can’t rely on old fossil data to tell us what happened way back when. It’s not reliable…oh, wait. The only reliable source I get my climate information is Lord Christopher Monckton, the Third Viscount of Brenchley. He was Margaret Thatcher’s science advisor in the late 70s, and early 80s. Just ask George Guise, her science advisor!…oh, wait. You say she made a speech on the dangers of Global Warming in 1980? Of course she did. Monckton pumped her with this fake information to break a coal miner strike so that she could make nuclear power popular in the UK. I remember reading about this at a rally in West Virginia where Monckton was speaking to a bunch of union coal minors. He led the chant “Global Warming is B.S.”…oh, wait… But he’s still a Lord, even though Parliament sent him a Cease and Desist letter telling him to stop calling himself a lord. I’m okay with him using it as an honorary title. After all, one of the greatest modern American heroes of the American Midwest was Colonel Sanders. ;)

    • andrewfez Says:

      Soon’s model fails to track reality (i.e. the satellite TSI being measured since 1978), grossly overestimating it by more than 5W*m^-2 and its variability by a factor of more than five. But the model is used in lieu of the true TSI in that Oregon Petition scheme, on several of the arguments in the accompanying ‘review’, made to look like a scientific article. It’s disinformation backing disinformation.

      • Nick Carter Says:

        Thanks for the helpful info, Andrew. I put some details in a post below.

        • andrewfez Says:

          No problem Nick. Soon’s inability to replicate the actual TSI with his model is the most probable reason it wasn’t chosen for use with the IPCC in the AR4 stuff.

          Let me know if you want a PDF copy of Bill Allan’s critique of Soon’s model. Bill Allan is an expert on solar irradiance and on the earth’s magnetosphere. It’s hard to find just doing internet searches, and last time i tried to replicate my search for it on the net, i failed. But i do have it on my hard drive.

          Soon is either out of date, incompetent, or trying to reverse engineer his model (using wildly speculative proxys) to make it say what Exxon wanted it to say.

  4. Nick Carter Says:

    coal miners. Minor error :P

  5. petermogensen Says:

    Svensmark recently did a radio interview with a rightwing Danish youth-politician hell-bend on denying climate change.
    Though he was careful not to say anything which explicitly would reveal his un-scientific bias it showed very clearly that he suffers from the same ideological motivations as most deniers.
    He even (basically) repeated some of the classic talking-points like “CO2 is plant food”.

    Audio (in Danish):
    http://arkiv.radio24syv.dk/video/8401489/mikrofonholder-uge-27-2013

    Honerstly… I’m beginning to loose patience with this irrational ideological behaviour. It’s plain stupid. Just because they haven’t got the imagination to think of solutions which they don’t think would please the socialist, then the problem must not exist.
    I’m “liberal” (which in european terms mean kinda right-wing/libetarian) like the guy doing the interview. But I’m not stupid, and I don’t think denying a problem makes it go away.
    So when there is an easy effective free-market solution like James Hansen, Bob Inglis and Art Laffer proposes, then why not DO IT ?!
    Why have more meetings with the Flat Earth Society ?

  6. Nick Carter Says:

    On a serious note, thank you andrewfez on Soon’s insolation misinformation. I wondered what he did since he’s very careful to self source his calculations. I’ll put that in my toolbox. Dana, I tried to find out this information on Soon but couldn’t find it on SKS. Wondering if they could put a category in on his “work”….call it “Too Soon”. You’re welcome ;). Peter-I’m off today so having an internet “field trip” and enjoying life. I’d love to pm you sometime and tell you what’s new here, if it’s okay with you. Have a great day, all.


  7. This solar minimum is not particularly strong and the next looks to very week. Had we had a purely natural level of CO2, then perhaps the next decade or two would have been a cooling cycle. If we intended to protect ourselves against a little ice age then we have rather over done it (to steal a quote).


  8. I also talked about something similar over two years ago.

    At the time it was in the context of an announcement by the Solar Physics Division of the American Astronomical Society that the sun could be entering a period of low activity. Which was then instantly used to claim that it would cause another Little Ice Age.

    But this ignores that the effect of such a period is small compared to the temperature increase caused by co2 emissions.

    It just amazes me that these arguments come back all the time.

    • MorinMoss Says:

      Here’s last week AGU’s report on the current & upcoming solar cycle.

      At ~31:00, a question was asked was the possible temp which the answer was this it’s not likely to be a significant forcing since the lower output is only a few milliwatts per sq. meter and even the change in TSI isn’t enough to be either a strong +ve or -ve forcing.


  9. ..no rise in Global Average Temperature since 1998 but with a gigantic rise in CO2 emissions after all 16 years ago India and China were barely producing anything! CO2 is not a factor as its ability to keep in heat declines logarithmically in proportion to saturation and has done its work.

    Records that were once derided as impossible, like 5 years of constant rain show that the LIA was a disaster yet if it was to happen today then multiply that by 7 billion.

    ..if the USA should fall……

    • MorinMoss Says:

      You’re a bit behind on the latest climate news. The supposed lull | hiatus | slowed warming | cooling event | deep freeze | whatever is now believed to be a symptom of inadequate numbers of permanent temp stations in the Arctic.

      Of course, this is a well-known weakness of the HadCRUT data set. Let’s all hope that we can get more reliable temp measurements from the Arctic soon.


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