Solar Science

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Hathaway: “Sun’s contribution is small compared to volcanoes, El Nino and greenhouse gases”

with 9 comments

I’ve no objection at all and much praise when scientists actually make falsifiable predictions based on their understanding of the science. Thus when David Hathaway predicts that Solar Cycle 24 will be as large or larger than Solar Cycle 23, I applaud that boldness.

In this article on, several aspects to the current solar minimum are discussed:

The sun’s surface has been fairly blank for the last couple of years, and that has some worried that it may be entering another Maunder minimum, the sun’s 50-year abstinence from sunspots, which some scientists have linked to the Little Ice Age of the 17th century.

Could a new sunspot drought plunge us into another decades-long cold spell?

It’s not very likely, says David Hathaway a solar physicist at NASA’s Marshall Space Flight Center in Huntsville, Ala.

Fair enough. Perhaps if I used IPCC-speak, we’d give that a 10-20% probability?

Hathaway continues to make bold observations and predictions:

The sun’s energy drives all climate and weather on Earth. And Hathaway does agree there are good indications that fluctuations in solar output related to sunspot cycles influence the Earth’s climate. And the Maunder minimum isn’t the only evidence — scientists have linked two smaller sunspot minimums (periods of time with very few sunspots) in the early 19th century to cold spells, as well as periods before the Maunder minimum deduced from tree ring records, he said.

But the sun isn’t the only thing that influences our climate: volcanic eruptions, large-scale phenomena such as El Nino, and, more recently, the accumulation of greenhouse gases in the atmosphere also affect the global climate.

Prior to the industrial revolution, the sun probably accounted for about 10 to 30 percent of climate variability, Hathaway told, but now that greenhouse gases have started to build up, “the sun’s contribution is getting smaller and smaller,” he added.

So the pre-industrial climate change on Earth was only 10-30% driven by solar variability. I wonder what the other 70-90% were.

Hathaway hints that volcanic eruptions have an effect, but as far as I am aware such eruptions only cool for perhaps 2 or 3 years, hardly causing a blip in a climate trend [unless we’re talking about supervolcanic events which can cause climate cooling for decades, but we haven’t had one of those for 70,000 years with the Toba explosion]. Is the rest caused by the ENSO cycle?

What of the current solar minimum and the sputtering start to Solar Cycle 24?

Signs of the current, new solar cycle (which actually overlaps with the last cycle) showed up in November 2006, and its first sunspots were seen in January of this year, and again in April, Hathaway said. So already that rules out another Maunder minimum, Hathaway says, since this solar cycle has already begun producing spots, even if there haven’t been many of them yet.

This cycle is just simply “off to a slow start,” Hathaway said.

The last three solar cycles were also what Hathaway calls “big cycles,” meaning they had more than the average number of sunspots (the average is around 110 to 120 sunspots on any given day during the cycle’s maximum). It’s not unusual for such a spate of prolific cycles to be followed my more muted solar cycles (such as the cycle that preceded the last three biggies).

Hathaway says that solar physicists are divided on their predictions of this new solar cycle — some say it will be small, others say it will be another doozy. Predictions have ranged anywhere from 75 to 150 maximum spots during its peak. “There really are two camps,” Hathaway said. Whatever the number ends up being, though, “it’s not zero,” he added.

That depends on whether the Maunder Minimum was really devoid of sunspots or had sporadic “Tiny Tim” spot groups which were not seen because of the technology used at the time.

It’s doubtful that it was really zero during that time.

Here’s the clincher:

Why the sun is so fickle in its sunspot production is still something of a quandary. “We still don’t fully understand how the sun does this,” Hathaway noted.

Now that statement I regard as the most important of the article. It might not be a popular statement with people on either side of the argument, but as far as solar cycle prediction is concerned, nobody knows for sure what will happen with the Solar Cycle next week, never mind next year or five or ten years hence.

The science of the variation of the Sun’s solar cycle is in its vary early stages. No-one, not even David Hathaway, knows what will happen next. That’s why he’s checking the Sun every day.

As Kenneth Tapping has already reported (and I blogged his observation) long solar cycles are not that unusual historically and are not in themselves indicative of how powerful are the succeeding cycles. Tapping noted that the long and weak Solar Cycle 20, (which occurred during a global cool period on Earth), was succeeded by Solar Cycles 21, 22 and 23 all of which were relatively powerful (and coincided by chance with a global warming on Earth).

Little Ice Age

But on the point of whether even a Maunder Minimum style collapse would cool the Earth, Hathaway admirably sticks with the IPCC-derived consensus:

One idea springs from the fact that the sun emits much more ultraviolet radiation when it is covered in sunspots, which can affect the chemistry of Earth’s atmosphere. The other is that when the sun is active, it produces tangled magnetic fields that keep out galactic cosmic rays. Some scientists have proposed that a lack of sunspots means these cosmic rays are bombarding Earth and creating clouds, which can help cool the planet’s surface.

But these ideas aren’t yet proven, and anyway, the sun’s contribution is small compared to volcanoes, El Nino and greenhouse gases, Hathaway notes.

Even if there were another Maunder minimum, he says, we would still suffer the effects of greenhouse gases and the Earth’s climate would remain warm. “It doesn’t overpower them at all,” Hathaway said.

So according to Hathaway, greenhouse gases are warming the Earth to such an extent that solar variation becomes unimportant. Never mind whether I agree with him (and who am I to disagree with an expert?), I applaud David Hathaway for making such scientifically falsifiable statements.

I hope he’s right about the warming. So far, during the current warming, we’ve had the major deserts contract, the tropics expand and possibly a general reduction in hurricane frequency globally during the 20th Century.

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Written by John A

June 12, 2008 at 1:38 am

9 Responses

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  1. After reading this article I did a little checking on Wiki.

    Since the Dalton Cold Spell was not caused by industry or the sun (Hathaway), I researched volcanos. Laki in Iceland erupted from 1783-85 and, according to Wiki, played hell with Europe. As far as El Nino at that time, I didn’t get much info as the Wiki ref. wan’t money for the paper.

    But yeah, it’s a little surprising that Hathaway stuck his neck out (and hats off to him being a scientist instead of a …. ).

    If the sun stays quiet, we shall see if CO2 (MM or not), overwhelms the lack of solar activity. So far it’s not looking all that swell for Dr. H. , as the global temps aren’t cooperating.

    I hope Hansen, Gore, and all the watermellons get on this bus.

    Tom in Texas

    June 12, 2008 at 3:44 am

  2. …(Hathaway), so I

    …hats off

    …lack of
    …global temps

    Tom in Texas

    June 12, 2008 at 3:49 am

  3. …hats off = …hats off to
    wan’t = wanted

    always good to proofread before hitting “submit”.

    And what’s with the data adjustment on the right margin?

    Additional thought: What we don’t need is VEI 6 (or more) volcano (Laki) to ruin the experiment.

    Tom in Texas

    June 12, 2008 at 3:58 am

  4. Tom

    Even A VEI 6 explosion wouldn’t cause much more than a temporary dip in the “climate trend”.

    I think its appropriate to encourage scientists to make falsifiable statements so that, at the very least, we may know when they are right or wrong.

    With people like Gavin Schmidt, pinning them down to ANY falsifiable prediction is like nailing jello to the ceiling.

    At least Hathaway has the guts to say what he thinks in a way that cannot be disputed. My onlu hope is that we don’t have a disproof by way of a global cooling down, even on the scale of the Dalton Minimum.

    John A

    June 12, 2008 at 6:30 am

  5. I laud Hathaway for making a solid statement that can be checked against reality while most all of us will still be alive. Ought to take less than a decade to see how SC24 develops and, if it turns out to be a dud, how its effects combined with a PDO in its cold phase affect the climate.

    Leon Brozyna

    June 13, 2008 at 4:59 pm

  6. But these ideas aren’t yet proven, and anyway, the sun’s contribution is small compared to volcanoes, El Nino and greenhouse gases, Hathaway notes.

    Interesting comment coming from a person who is supposed to not back himself in the corner by drawing lines in the sand. He is also engaging in a logical fallacy, claiming you don’t understand something and then discounting it’s possible effect like claiming a tree falling in the forest doesn’t make a sound because no human was around to hear it.

    Dr. Hathaway admits he doesn’t know what influences sunspot numbers (which is his specialty) and then yet claims the sun isn’t the cause of natural climate variation? Illogical! We simply don’t know all the ways in which energy is transferred to the earth, TSI (combination of UV, IR, Visible light, Microwave and Xray) is just one of those means, we don’t know the degree of magnetic induction occurs between the earth and the sun. We don’t know how much cosmic rays affect the atmosphere. The fact is, we don’t know how much we really don’t know. No one can realistically make the statement Dr. Hathaway made, his was an article of faith in the pronouncements of the IPCC. He needs to stick to solar science (which he still doesn’t understand) and not reflexively extend professional courtesy to another field’s theory that maybe affected by his own without fully knowing the implications.


    June 14, 2008 at 12:57 am

  7. Both David Hathaway and Leif Svaalgard seem too eager to place their faith in the IPCC/Hansen/Gore hypothesis. I suppose it makes a difference who signs your paycheck.

    Al Fin

    June 15, 2008 at 8:08 pm

  8. I absolutely agree that paradigms and their theories without corresponding predictions to correct or discard them are not science.

    Hathaway’s cycle 24 prediction used the Geomagnetic peak 9 months following the cycle 23 sunspot max to predict the subsequent SS max. Thank you for participating, Dave.

    “some say it will be small, others say it will be another doozy. Predictions have ranged anywhere from 75 to 150 maximum spots during its peak”

    I would say <50 would be small. He is obviously talking in the echo chamber of professional comity. The lateness, and thereafter, slowness, cannot be otherwise interpreted than to doom predictions above 90, even Svalgaard’s 75(+/-8), seems in jeopardy.

    “the [variablility in the] sun’s contribution is small compared to volcanoes, El Nino and greenhouse gases”

    The edit is John’s understanding and I would agree must be credited to Dave. Still, apart from self-promotion, just how did Dave get his job? His grasp seems awfully feeble.

    Gary Gulrud

    June 19, 2008 at 6:56 pm

  9. The latest statement released by Mr. Hathaway:

    My favorite line: “The sun is now near the low point of its 11-year activity cycle,” says Hathaway.

    I love how the 11 year mark passed by in May ’07, making May ’08 the start of year 12, but that’s not mentioned in the statement. Nor is the fact that we’re now in our 55th month since the first spotless day of SC23. Mr. Hathaway can jump, shout, and try to distract us from the fact that SC24 is taking its own sweet time, but when he says things like this all it does is make him look silly. I expect better.


    July 11, 2008 at 11:33 pm

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