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Wed, Apr. 26th, 2006, 07:51 pm
level_head: Solar Variance and Wikipedia Bias

Wikipedia has an article on Solar Variance -- how much the sun's output changes over time. This is largely in the context of downplaying the Sun's role in global warming:
Total solar output is now measured to vary (over the last two 11-year sunspot cycles) by less than 0.1%[2][3] or about 1 W/m² peak-to-trough of the 11 year sunspot cycle.
The above quote ignores that, since 1850, solar output is up several times that.

For a long time -- in fact, up until late in the 20th century -- it was thought that more sunspots (which are cooler than the rest of the Sun) meant less total output. We now know that solar faculae -- bright areas associated with sunspots -- mean that the sun's net output increases when there are more sunspots. Even Wikipedia, if you follow the links, ultimately admits this -- just not on the same page:
Faculae are produced by concentrations of magnetic field lines, and are most commonly found in the vicinity of sunspots; this is why the Sun is actually brighter when sunspots are more numerous.
If you'd restricted yourself to the main page on Solar Variance, all you would learn is:
The Sun's surface is also the most active when there are more sunspots, although the luminosity does not change much due to an increase in bright spots (faculae). (Emphasis added -- LH)
Who defines "much"? Under some definitions, the Sun does not change much, ever. But despite reinforcing further down that "the variation during recent cycles has been 0.1%", it does let slip that "Since the Maunder Minimum, over the past 300 years there probably has been an increase of 0.1 to 0.6%, with climate models often using a 0.25% increase."

I have seen no papers supporting the 0.1% number for that period, and others report as much as 1.25%. However, even the 0.6% number has mostly happened in the last half-century or so, as we will see.

Wikipedia's main article includes this handy graphic, showing 11,000 years of sunspot activity:

Note that for the last two millennia, the trend has been downward -- less sunspots, thus less total energy from the Sun reaching the Earth. When you look at this chart, you can immediately discard the notion of the Sun being involved in any recent warming trends.

The text nearby, though, tells you that something doesn't jive:
The level of solar activity during the past 70 years is exceptional - the last period of similar magnitude occurred over 8,000 years ago. The Sun was at a similarly high level of magnetic activity for only ~10% of the past 11,400 years, and almost all of the earlier high-activity periods were shorter than the present episode.
Why doesn't the graph look like that? Because the graph was constructed by a Wikipedia member, who apparently did not want to use the scarier graph built by NOAA. Here's the NOAA data that he used, if you want to plug it in yourself.. The data supplied by NOAA stops at 1899, though you have to read carefully to realize this. (The "55" in the data means "the decade centered 55 years before 1950.)

I added data to 1995 from this source, and produced the chart below. The overlap from 1645 to 1895 is good -- but NOW you can see how dramatic the last few decades have been. Note the data in red, making the chart rather different from the cut-down Wikipedia version above.
Solar activity to 1995
An update of the chart in Wikipedia, which cuts off in 1895. That original "short" chart is at: http://en.wikipedia.org/wiki/Image:Sunspots_11000_years.jpg
My chart, the one you see here, is at:
http://pics.livejournal.com/level_head/pic/0006hx06/g73
Solar activity to 1995
What effect has the dramatic increase in solar activity had on Earth's air temperature? It's politically correct to say "very little" -- but I cannot see support for this position in the actual data.

(Edit: In the Y axis legend, I wrote "Average sunspots per decade" -- a better expression would have been "Average sunspots per year, averaged by decade." This is the same method that the Wikipedia chart used; my phrasing was imprecise.)

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Thu, Apr. 27th, 2006 04:54 am (UTC)
makovette

Facinating work LH.

Why not submit this as an update to the article citing sources &ct as you did above?

CYa!
Mako

Thu, Apr. 27th, 2006 05:34 am (UTC)
level_head

My position is in the minority -- though I'm using real data. It would be stomped upon and reverted.

For example, I just now looked at the revisions -- and a previous chart HAD been posted with more current data. (Amusingly, it also used red for the recent data.) It was replaced with the short-data chart now visible on that site.

The data above, going back 11,400 years, is a decadal average. The Sun's natural sunspot cycle is about 11 years. This produces a strange effect -- like talking the temperature at a site every eleven months starting in July. After several years, you are in the middle of winter, and after several more years in summer again.

This would make you think that the temperature runs on a very long cycle, but it's an artifact of how you took your measurements.

I'll redo the chart above using a three-decade moving average -- it should smooth out the bumps and make the pattern more obvious. Other charts on the Wikipedia page use that sort of average.

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Thu, Apr. 27th, 2006 10:56 pm (UTC)
chipuni

I agree with Makovette. You should add your information to Wikipedia, even if you fully admit that it is a minority view.

Fri, Apr. 28th, 2006 01:27 am (UTC)
level_head

I am reluctant to simply barge in and replace someone else's chart. It seemed ... rude.

So, I just posted a comment to the chart's author, suggesting an update.

If that gets no action, well, then all bets are off. ];-)

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Thu, Apr. 27th, 2006 05:34 am (UTC)
torakiyoshi

Mako makes a good point. The beauty of Wikipedia is the ability to fix it when errors are found.

My question takes a bit of a different tack:

How on earth are we able to tell how many sunspots there were 11,400 years ago, when the earliest confirmed writing was only 5500 (or 8300, depending on who you believe) years ago??

Have the best

-=TK

Thu, Apr. 27th, 2006 05:47 am (UTC)
level_head

The National Oceanographic and Atmospheric Agency -- NOAA -- reports the paper that is the source for this data:
Direct observations of sunspot numbers are available for the past four centuries, but longer time series are required, for example, for the identification of a possible solar influence on climate and for testing models of the solar dynamo. Here we report a reconstruction of the sunspot number covering the past 11,400 years, based on dendrochronologically dated radiocarbon concentrations.

We combine physics-based models for each of the processes connecting the radiocarbon concentration with sunspot number. According to our reconstruction, the level of solar activity during the past 70 years is exceptional, and the previous period of equally high activity occurred more than 8,000 years ago. We find that during the past 11,400 years the Sun spent only of the order of 10% of the time at a similarly high level of magnetic activity and almost all of the earlier high-activity periods were shorter than the present episode. Although the rarity of the current episode of high average sunspot numbers may indicate that the Sun has contributed to the unusual climate change during the twentieth century, we point out that solar variability is unlikely to have been the dominant cause of the strong warming during the past three decades.

The series of reconstructed 10-yr averaged sunspot numbers with their 68% uncertainty. Years are given BP (before present), i.e. the calendar AD year, Yad, is related to the BP year, Ybp, as Yc=1950-Ybp. The tabulated years correspond to centers of the corresponding 10-year intervals. Negative values are artifacts and are consistent with zero within the error limits.
The record for the past several hundred years matches the direct observations well, giving some confidence to earlier numbers.

Note the consistent pattern -- most discussions of solar variance contain a disclaimer of "it doesn't really mean anything" as I have placed in bold in the quote above. I'll address the "past three decades" data in another post -- but it is my opinion that the bolded statement above is simply a wrong.

That "matching actual observations" has NOT been working for reconstruction of temperatures -- a topic for another post.

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Thu, Apr. 27th, 2006 01:48 pm (UTC)
deckardcanine

That may be the first chart I've ever seen to show time progressing from right to left.

Thu, Apr. 27th, 2006 05:19 pm (UTC)
level_head

It's not uncommon to do it this way in research papers -- but my specific purpose here was to match, exactly, the chart in Wikipedia.

Then show the part left off.

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Thu, Apr. 27th, 2006 01:49 pm (UTC)
shockwave77598

I'm curious as to how they can reconstruct average number of sunspots as a historical record. They are a magnetic disturbance and we are quite shielded by the Earth's magnetosphere.

Also, are you aware of what's now being called "Global Dimming"? Seems the soot we've been putting out makes clouds more reflective which balances the increase of CO2. Now that we are cleaning up the soot, the equation is unbalanced.

Thu, Apr. 27th, 2006 05:50 pm (UTC)
level_head

I'm curious as to how they can reconstruct average number of sunspots as a historical record. They are a magnetic disturbance and we are quite shielded by the Earth's magnetosphere.

So shielded that the Sun's storms have no effect on communications and power lines? Clearly not.

Check above, I've linked the paper with the methods, which involved sun-triggered radioactive isotopes. It's not certain, of course, but agrees fairly well during the overlap where we have actual observations.

Amusingly, you can see that the graph above has some points of "less than zero" sunspots. Not a perfect model of reality, but still of some use.

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Thu, Apr. 27th, 2006 05:52 pm (UTC)
level_head

Also, are you aware of what's now being called "Global Dimming"?

*chuckle* Oh, yes.

Note that almost all discussions of "global dimming" -- now thought to be something that happened during the 50s to the 80s last century -- talk about less sunlight reaching the surface. Of course, sunlight absorbed by particles in the atmosphere still heat the atmosphere -- but they make it sound like global dimming has been cooling the planet, and ameliorating CO2. But it affects the local surface only.

Only an increase in albedo would have that total effect. And in fact, analyses of the dimming show that it was a local phenomenon, operating over populated areas, with a rate over cities about 2.6 times the rate over urban areas.

During the same period in question, the band of the Earth between 15 degrees north and south of the Equator brightened. So, the appellation "global" is hardly warranted.

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Thu, Apr. 27th, 2006 05:58 pm (UTC)
shockwave77598

*nods* Yeah, last week was the first I'd heard of it. I thought some of the data was a little... reaching.

Thu, Apr. 27th, 2006 05:58 pm (UTC)
level_head

Also, are you aware of what's now being called "Global Dimming"?

Note, also, that even the proponents of "global dimming" couch the measurements in the most tentative of terms -- it's "almost certainly a real effect" is as strong as they can get, and each study is fraught with its own opponents of the methods.

We cannot even get agreement on temperature measurements.

This deserves a post as well. But I should be able to find you a paper on the topic... ah. Here's one.

Note that this artifact of the last century is still being flogged by the media. Consider: Article headlines like "Goodbye Sunshine" make it seem like something scary happening now. That article starts out:
"Each year less light reaches the surface of the Earth. No one is sure what's causing 'global dimming' - or what it means for the future. In fact most scientists have never heard of it. By David Adam"
Do you think he is dishonest, or merely misinformed?

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Wed, Jun. 14th, 2006 11:17 pm (UTC)
penguin42

What effect has the dramatic increase in solar activity had on Earth's air temperature? It's politically correct to say "very little" -- but I cannot see support for this position in the actual data.

How is the data you've collected supposed to support or refute that contention? All you're doing is reporting solar activity ... you're not doing anything to link it to climate forcing on earth. Just because the sun increased its activity slightly in the last couple centuries doesn't mean that suddenly all global warming can be explained by it!

Here's what you need to do:
1) Collect sunspot data
2) Establish exactly how much change in solar output these changes in sunspots indicate
3) Establish exactly how changes in solar output affect Earth's climate.
4) Plug your data from 2) into the theory from 3) to get an estimate of solar climate forcing
5) Compare this data with how much Earth's climate has actually changed.
6) If 4 and 5 match then you can proclaim global warming dead. If they're very different then the "politically correct" view is strongly supported.

You have not done 2-6, therefore you can't make any conclusions about the validity of the "politically correct" view.


And for further reading, here's some links to more informed and thorough discussions about solar climate forcing.


... that said, I see no problem in including your updated chart in the article, as long as you don't string any of your malformed conclusions along with it.

Wed, Aug. 30th, 2006 09:55 pm (UTC)
level_head

I appreciate your input -- but I must note that no one has performed even your Step 2 as of yet. Correlations between solar variation and Earth climate effects are described in the most vague and hesitant of terms.

In any event, while almost everyone is quick to state that "solar variation is small" -- there is certainly good support for high degrees of influence of this "small" variation on the Earth's climate.

See, for example, this link: "Strong coherence between solar variability and the monsoon in Oman between 9 and 6 kyr ago"

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Wed, Dec. 14th, 2011 06:42 pm (UTC)
(Anonymous): Nice Catch

Very nicely done.

BTW, you have a pointer to a wiki chart that has now been deleted. Guess it wasn't enough to remove it from the article, they had to remove the evidence too...

"For example, I just now looked at the revisions -- and a previous chart HAD been posted with more current data. (Amusingly, it also used red for the recent data.) It was replaced with the short-data chart now visible on that site."

Now gives a 404 error if you hit the link....

Chiefio.wordpress.com AKA E.M.Smith