Guest Post by Willis Eschenbach
I have to learn to keep my blood pressure down … this new paper, “Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks“, hereinafter M2012, has me shaking my head. It has gotten favorable reports in the scientific blogs … I don’t see it at all. Anthony provides an overview of the paper here.
First, the authors say:
Here we present precisely dated records of ice-cap growth from Arctic Canada and Iceland showing that LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 1430– 1455 AD. Intervals of sudden ice growth coincide with two of the most volcanically perturbed half centuries of the past millennium.
OK, precisely dated records show that big volcanoes equals Little Ice Ages. Peaks in ice growth coincide with volcanoes. Got it. Then in the paper they discuss the later interval of “sudden ice growth”. They start by saying …
The PDF peak [in ice growth] between 1430 and 1455 AD corresponds with a large eruption in 1452 AD …
What’s the problem with these claims? Figure 1, which is from their study with a couple of my annotations, shows the problem …
Figure 1. Original Caption Figure 2. … (b) Global stratospheric sulfate aerosol loadings [Gao et al., 2008]. (c) Ice cap expansion dates based on a composite of 94 Arctic Canada calibrated 14C PDFs (probability distribution functions). I added the vertical red line down from the top of the “D” panel that shows the full size of the sulfates from the eruption in 1258 (258 teragrams [megatonnes]). The vertical blue line, also added, indicates the timing of the following large eruption in 1455.
I get nervous when people cut off important data in a graph, it’s a bad sign regarding their transparency … but I digress …
I always look for alternative ways to verify what the authors are showing. In this case, the GAO et al 2008 aerosol loadings shown in figure 1(B) are calculated loadings using a record of the volcanoes and a climate model. Me, I always prefer actual data. Fortunately, we have very accurate data thanks to the ice core record from a place with the lovely name of Dronning Maud Land. You may not recognize it by its Norwegian name, but when I say “Queen Maud Land”, everyone knows where that is … well, everyone but me, I had to look it up …
Figure 2. Location of Dronning Maud Land, home of ice. And ice cores.
Ice cores record how much sulfate has fallen on the ice during past years. Sulfate comes from volcanoes, and is ejected high into the stratosphere. From there it is mixed worldwide, and eventually it settles out on the ice. The sulfate record from two different ice cores in Dronning Maud Land agree to within a couple of years, so we can have confidence that they are accurate.
Next, before I go further, what is the “probability density function (PDF)” that the paper uses? It is a function that gives the probability of an event occurring in a certain year. For example, carbon-14 dating of some dead moss might give the date it died as say 1135. Are we sure it died in exactly 1135? No way, that’s just the most probable value. It might have died in 1134, or 1136. It might also have died in 1130 or 1140, but the probability of it being either of those years is much lower than the probability that the date is actually 1135. The probability density function is the function that gives us the probability of the event actually occurring in each years. Typically it looks like the famous “bell curve” or Gaussian curve, peaked in the middle and fading to zero on either side. It may be asymmetrical, with different probabilities that the event is before or after the most probable date. It is a good way to aggregate data
With that as prologue, here is the overview of the two records. One is the ice expansion record from the M2012 paper. The other is the volcanic sulfate record from the Maud Dronning Land ice cores.
Figure 3. Volcanic sulfate records from Maud Dronning Land (blue and green) and the ice cap expansion records from Baffin Island (purple line). The PDF values are the probability percentages multiplied by 100, so for example if the scale reads “400” that means 40% (0.40).
Right away you can see some curious things. There is a large expansion of the ice cap (increasing purple line) in the century from 900 to 1000, but nary a volcano in sight. They say in the paper that “cold summers can be maintained by sea-ice/ocean feedbacks long after volcanic aerosols are removed …”, but what started and maintained the cold summers from 900 to 1000?
Then there’s the claim that the intervals of sudden ice growth in 1280 and 1435 occur during “two of the most volcanically perturbed half centuries of the past millennium” … I’ll buy that for the year 1280, but 1435? One lousy volcano in the half century around 1435, it wasn’t even as “volcanically perturbed” as the last half of the 20th century or the first half of the 19th century.
Intrigued by these problems with their claims, I looked closer. Figure 4 shows a closeup of the time in question:
Figure 4. As in Figure 3, volcanic sulfate records from Maud Dronning Land (blue and green) and the ice cap expansion records from Baffin Island (purple line).
More oddities. First, the expansion of the ice cap started in 1215, about 45 years before the eruption in 1258. Then in 1250, the rate of ice cap expansion increased, almost a decade before the eruption. And while you would expect an immediate increase in the rate of ice cap expansion, the increase doesn’t begin until about [1470].
But that’s nothing compared to the other end of the period. The peak ice cap expansion occurs in 1435, a full two decades before the eruption in [1455]. Nor does the eruption speed up the ice cap expansion. In fact, the expansion slows markedly after the 1455 eruption.
Now, you may recall that I quoted the start of a sentence above, which said:
The PDF peak between 1430 and 1455 AD corresponds with a large eruption in 1452 AD …
Um … well … they are being most expansive with their claim that the 1435 peak and the eruption “correspond”. The volcano is well after the expansion in ice area. How do they explain this?
Well, the sentence goes on to say:
… although the ages of the three largest 5-year bins appear to precede the eruption date. In contrast to the earlier 13th Century peak, the second PDF peak occurs at the end of a 150-year interval of variable but falling snowline (Figure 2c), raising the possibility that the PDF peak plausibly reflects a brief natural episode of summer cold that preceded the large 1452 AD eruption. Alternatively, the apparent lead of kill dates with respect to the 1452 eruption may be a consequence of combined measurement and calibration uncertainties.
To me, that’s special pleading. Not only that, but it destroys their entire case. Here’s why:
If the 1435 peak “plausibly reflects a brief natural episode”, then why should we believe the much smaller 1280 peak is not just another “brief natural episode”?
Alternatively, if the timing of their “precisely dated” 1435 record is really off by twenty years due to “combined measurement and calibration uncertainties”, then why on earth should we believe the timing of the “precisely dated” 1280 peak?
I’m sorry, but I just don’t see the evidence that volcanoes had anything to do with the changes in the Baffin Island ice cap. And their whole sea/ice feedback claim? I note that the claim is supported by … well … I fear all it is supported by is models all the way down.
w.
PS—An oddity. The 1258 volcanic eruption was the largest in the last 2,000 years … and as far as I can determine, nobody knows where it occurred.
DATA: All data used in this post is available here as a comma-separated (CSV) file.
Willis Eschenbach says on April 13, 2012 at 10:41 am:
Bill says: “I didn’t read the original paper, but I do know that nothing in this article is particularly damning of it.”
=======
That’s “a small but good one” Willis. – Not much is getting past your “goal-posts” this season. – Well
done!
The paper under study here has been already extensively discussed in this post
http://wattsupwiththat.com/2012/01/30/new-paper-speculates-on-volcanoes-during-the-little-ice-age/
The problems that Willis is noticing was already noted by me in many times. For example
http://wattsupwiththat.com/2012/01/30/new-paper-speculates-on-volcanoes-during-the-little-ice-age/#comment-880310
http://wattsupwiththat.com/2012/01/30/new-paper-speculates-on-volcanoes-during-the-little-ice-age/#comment-880320
A figure similar to Willis’ Figure 1 has been prepared by Geoff Sharp after my request:
http://wattsupwiththat.com/2012/01/30/new-paper-speculates-on-volcanoes-during-the-little-ice-age/#comment-880423
http://www.landscheidt.info/images/miller.png
The Little Ice Age was driven by the sun as also my last paper shows
http://wattsupwiththat.files.wordpress.com/2012/03/scafetta_fig7.png
The only intersting point that Willis and Anthony should note is that [SNIP: Dr. Scafetta, you may be right, but somehow I don’t see this ending well and would prefer that it didn’t get started at all. Sorry. -REP]
Bill says:
April 13, 2012 at 11:26 am
That’s total BS. An article can’t be “lazy”, “ham-handed”, or “clumsy”, those are human attributes. So you couldn’t have been criticizing the article. You were attacking me for being “lazy” … and now you are trying to defend your actions by asking if I prefer to be called “ham-handed” rather than “lazy”. You probably don’t even realize how offensive you are being.
The way to falsify scientific ideas is to quote them so we know what you are on about, and then point out exactly where and why they are wrong. What you are doing is attacking me, not my ideas.
That’s airy-fairy hand-waving. You can’t be bothered to read the paper we are discussing, but you want to tell me my logic is unpersuasive?
Quote exactly what I said, and tell us where the big logic fail is …
Substantive? I didn’t see anything substantive in your post to reply to. Please point out for me what you think are “substantive criticisms”.
My substantive criticisms of the paper are that their claims about the cold spells being related to vulcanism are nonsense, because the cold spells happened before the volcanoes that were supposed to cause them, and because we know of similar cold spells without volcanoes.
If you have a problem with that, spell it out.
w.
Nicola Scafetta says:
April 13, 2012 at 2:16 pm
The Little Ice Age was driven by the sun as also my last paper shows
http://wattsupwiththat.files.wordpress.com/2012/03/scafetta_fig7.png
Dr. Nicola Scafetta
Not anywhere as good as these graphics shows how we got out of it.
http://www.vukcevic.talktalk.net/GTCa.htm
Since there are no direct data to show how we got into the LIA, that side of business is just a speculation, whomever it comes from..
Nicola Scafetta says:
April 13, 2012 at 2:16 pm
Congratulations, Nicola. I hadn’t read your comments or seen Geoff’s graph, well done both.
Not sure what your point is in bringing it up here, however. Neither of you bothered to go to the original sulfate data instead of depending on the Gao climate model results. Neither of you took the time to get the values used by the M2012 authors for the PDF of the ice cap expansion, so that you could examine the exact timing.
w.
Thanks very much Willis for pointing out my error.
I will try refrain from snap judgements… I subsequently read the paper a few times. I applaud the attempt.
I’m not happy with the number of data points – 13 out of 41 samples produced 90% of one peak, hmm, 13 samples of vegetation is not much. A few goats could change that, or a lot of other things. I was not comfortable with their comparisons to selected parts of other proxies.
Their explanation of the causes of the varve thickness had me wondering if they were having it both ways. If I understand them right, a hot (or wet!) summer makes lots of sediment for that year, but long term a big cold glacier produces even more sediment (more grinding perhaps).
So I wonder how much more long term precipitation changes make a difference compared to temperature changes.
I thought your analysis was very good. Thanks.
BTW, there is a lot for everyone to learn so there is no point in others personal attacks.
Excellent Willis, I don’t know how you find the time to do all the in-depth digging you do for WUWT.
Sera says:
April 13, 2012 at 3:34 am
Could it have been this eruption in China @ur momisugly 1200?
……..
Probably not , it’s both to far off in time , and to small , the mysterious 1258 eruption is belived to have resulted in a dose somewhere between 300 and 600 extra megatonnes of H2SO4 (sulpuric acid) forming in the athmosphere from it. The the H2SO4 estimate for the eruption discussed in the paper you link to is “only” around 35 megatonnes.
more info here:
http://www.wired.com/wiredscience/2012/02/the-mysterious-missing-eruption-of-1258-a-d/
Ooos , sorry I was to quick on the send buttoon in my former comment, when reading on from seras comment I saw that several others had already posted the link i put in it , prior to my posting.
Anopheles says:
April 13, 2012 at 5:30 am
I am shocked that no-one can see how ice causes volcanoes from this data.
—————-
I thought it was co2 that caused volcanoes… it’s worse than I thought!
Re: Willis @ur momisugly 2:49pm
While true that those things are all human attributes, I thought it was clear from my comments that I was impugning your efforts in the specific instance of this post. To make it explicit: Based on numerous previous postings from you that indicate a generally comprehensive grasp of issues and clear elucidation of principles, this post does not measure up. I found the effort in this instance to be substandard. The writing is clumsy. It seems hastily dashed together. There were (presumably) typographical errors indicative of a lack of proofreading or editing. Taken as a whole, that adds up to a bit of laziness. In this instance. I do not know you personally at all and have no basis for making any assertions about your general character. But you already know this, so spare me the crocodile tears.
In truth, you are the one doing the hand waving, trying to distract from the actual criticism I raised with the personal insult bogey-man. In my original comment, I quoted two sections of your post and listed exactly what I thought was wrong with them. To reiterate and expand:
“Right away you can see some curious things. There is a large expansion of the ice cap (increasing purple line) in the century from 900 to 1000, but nary a volcano in sight. They say in the paper that “cold summers can be maintained by sea-ice/ocean feedbacks long after volcanic aerosols are removed …”, but what started and maintained the cold summers from 900 to 1000?”
You raise the perfectly reasonable question of what caused cold summers from 900-1000, however, this says nothing about their premise as you quote in the paragraph. In your quote of the source article, there is no mention or even implication of exclusivity. I don’t see any indication they feel that cold summers can only be caused by volcanic aerosols. Your implication seems to be that their failure to explain the earlier cooling undermines their explanation for the later coolings. This does not logically follow from the premises you present.
As I mentioned in my orignal comment, the answer to your perfectly reasonable question may well undermine their argument. Or it may support it or be irrelevant. But simply asking the question is no refutation of their claim.
Next I quoted this section from your post:
“Then there’s the claim that the intervals of sudden ice growth in 1280 and 1435 occur during “two of the most volcanically perturbed half centuries of the past millennium” … I’ll buy that for the year 1280, but 1435? One lousy volcano in the half century around 1435, it wasn’t even as “volcanically perturbed” as the last half of the 20th century or the first half of the 19th century.”
Your quote of the source article says “two of the most” not “the two most”. Based on your last sentence mentioning the last half of 20th and first half of 19th centuries, I conclude that like me, you are taking half centuries to mean 900-950, 951-1000…. 1951-2000 etc, rather than on a rolling basis. You acknowldege that the 1280 growth occurs during one of the most active half centuries. Then you suggest the 1435 growth does not fit that category because you can name two periods that are more active. I stated that out of the 24 half century periods on the chart, being in the 4 or 5 most active would suffice to make their claim true.
The above two quotes look to me to be the first two criticisms you leveled against the original piece. I find your reasoning lacking and these failures tend to undermine the rest of your article. When combined with the typos it creates the impression of a hastily composed piece.
As for reading the original article and commenting on that, in this case, my critique is of your article, so quite reasonably, I am sending it to you. This shouldn’t be particularly surprising or unwelcome.
Bill
Bill says:
April 13, 2012 at 6:45 pm
I find it astonishing that you haven’t read the original study. That would be the first thing I’d do. I don’t follow that one, you sound almost proud about not reading the paper that is the subject of discussion.
In any case, you say:
My point was simple. There is no need to invoke volcanoes. We know ice cap expansion happens without volcanoes because of the evidence from the earlier period. We also know it happens without volcanoes from the 1435 peak, which was NOT preceded by a volcano. I see you don’t like that point, because it raises the bar. If the only time expansion happened was when volcanos went off, that would be much stronger evidence. So the cold summers from in the volcano-free time from 900-1000 AD are indeed relevant.
You also say:
Fine. Let us agree that the 1435 growth was in the top five half centuries, and we can move on to any significant criticisms you might have.
Well, escuuuse me … see, Bill, I have a day job. I pound nails for a living. I drive my truck to the supplier and load it with big pieces of wood and take them to the job site and cut them into smaller pieces and then assemble the small pieces into a house. I’m not some scientist who can work all day and into the evening on his beloved project. In addition, I do extensive original climate research and investigation, and that is my real love. So I write for the blog where and when I can, often into the late hours. So yes, typos happen. To me what is important is to get the ideas out there.
The problem is that I’m presented with a constant flood of poorly conceived and executed scientific papers claiming improbable things. I wouldn’t mind if the purveyors of those ideas didn’t want to use those studies to justify restructuring the global economy and taxing the very energy the poor depend on. Inexpensive energy is the greatest friend of the poor.
So yes, I feel a certain sense of urgency. It is necessary to counter these studies in the public mind, not six months from now in some journal ariticle, but now, today, while people are talking about it. I want to have an effect on the ongoing topics of discussion.
So I regret that there are typos, and that it may be broader than it is deep, but it’s that old bugaboo, T-I-M-E. I’m doing it to stimulate ideas and to promote discussion, so I’ll roll with it.
Let me close by asking the relevant questions again.
If the 1435 peak “plausibly reflects a brief natural episode” as they sy, then why should we believe the much smaller 1280 peak is not just another “brief natural episode”, like the earlier 900-1000 period of ice expansion?
Alternatively, if the timing of their “precisely dated” 1435 record is really off by twenty or thirty years due to “combined measurement and calibration uncertainties”, then why on earth should we believe the timing of their “precisely dated” 1280 peak? If that kind of error is possible, then the earlier ice expansion peak may have preceded the 1258 eruption.
w.
Some eruptions do not have an SO2 signal, like the recent Grímsvötn plume, which hit the stratosphere hard with ash, minus anything to be oxidized into sulfate aerosols. SO2 only showed when the eruption was died down and ending. But the volume of ash was actually larger than the recent Eyafjallajökull eruptions. Fine ash can stay aloft for a longer time than more coarse ash. Just as some SO2 is so rich it makes crystals too large to stay aloft for longevity.
Willis, if I understand the generality of your effort it is sort of like this. There is too much “science” lately that involves someone generating a thesis, collecting data and doing analyses that fail to support the thesis, and then writing a story that pretends the thesis has been proved. There has been a lot of that lately revealed by you and others on WUWT. I don’t know if this bad science is a recent trend or if it is just that blogs have recently highlighted it.
I was taught many decades ago to be especially suspicious and critical of my analyses that supported my initial thesis. If your criticism can help some younger scientists learn that lesson you will have done an important service.
I hope the trolls don’t distract you from the really important work of actually building something of value.
Thank you Willis, excellent refutation. Feeling sorry for the paper but I see it throughout trashed.
With the new post-modern science I wonder if there will not be somebody who will regurgitate later the idea, make some “small adjustments” to the data and voila, everything appears in the right sequence, all running as it should, first volcano then frozen land …
But I digress, who would change data to fit it to theory in the scientific community… this cannot happen.
Just as an aside. If you even visit Switzerland take the mountain train to the top of the Jungfrau mountain (near Interlaken). Well worth the money. Most of the track is in a tunnel inside the mountain winding upwards to the station inside at 3400 m altitude (over 10000 feet). Then you walk through the “ice palace” to get onto the gletcher itself for some sunbathing (bring your swimming suit!). But inside you can see many meters into the ice and you clearly see the thin layers of vulcanic dust suspended in the ice of varying thickness and density. A complete record of thousands of years of vulcanic activity right in front of your eyes.
(btw. I’m not Swiss, just that you know).
Where was the eruption in 12-whatever?
Let’s make an educated guess. There are no records anywhere of it. Most likely reason: it occured far from any populated areas. It’s the highest peak in the Maud record. Possibly because it was relative near to that place.
There’s a whopper of a vulcano which perfectly fits these two assumed criteria: Mount Erebus. About as remote as you can have it. Nobody knew of its existence in the 13-th century and it’s pretty much next door to Chez Maud’s.
This raises another interesting question: to what extend does the distance of the sampling place from the eruption bias the measurement, or to put it differently, how representative is the magnitude of the aerosol peak for the effect globally?
Putting my ‘climate science’ hat on, can I suggest: a) one eruption was the wrong type of sulphates, and/or b) the data for the eruption and/or ice expansion dates needs to be adjusted or manipulated.
I am confident that one of these tactics will provide a solution to your problem – also, you can be assured it is sound ‘climate science’, as typically practiced in the world today.
I know the feeling Willis. It sure looks like the common denominator of all CAGW propaganda is that anything and everything is on the table EXCEPT for natural climate variation and that big ball of thermonuclear fusion in the sky.
While I am aware of the vast effects of volcanoes, I personally doubt any of them (except perhaps the most gigantic super-volcanoes like Yellowstone or the Siberian Traps) would result in a sustained climate shift.
For the authors of that paper the inconvenient fact that the two most recent large eruptions Tambora (April 1815) and Krakatoa (August 1883) occurred at the tail end of the Little Ice Age can not sit well. I don’t know how they can spin it either, unless they suggest the LIA was running out of steam and Tambora extended it by a few decades. As another poster mentioned upthread, ‘The Year Without A Summer’ and other evidence shows the real global effects of such a large blast, although it’s doubtful anything was still directly attributable to Tambora after say 10 years. When I was young (who knows if they adjusted the Science books since) Krakatoa was blamed for the harsh winters for several years after 1883 right up to the big blizzard in NYC in 1888. Five years of effects for that one, at most.
So we’re back to cause and effect again. Did these two blasts (1) end the Little Ice Age somehow, (2) extend the Little Ice Age longer, or (3) not effect the long term climate in the least? What a pickle. I do not think we have a clue at all yet.
Blade says:
April 14, 2012 at 3:11 am
…………..
You can see effect of some volcanic eruptions on the CET here:
http://www.vukcevic.talktalk.net/CET-D1.htm
vukcevic says:
April 14, 2012 at 7:20 am
Not sure if that was supposed to be satire, vukcevic but I see no effect at all on the CET. The three largest volcanoes in that time period (Tambora, Krakatoa, and Pinatubo) do absolutely nothing to the CET.
w.
Willis Eschenbach says: April 14, 2012 at 9:38 am
…………..
Hi Willis
The CET is only reliable record we have at the time of Mayon and Tambora, and extending to Krakatoa and Pinatubo
http://www.vukcevic.talktalk.net/CET-D1.htm
The Mayon and Tambora eruptions coincided with the Dalton Minimum so it is impossible to disentangle two. Impact of the of the Krakatoa eruption ‘appear’ to be more definitive with about 7 years of low temperatures at the time. This is version with actual temperature values
http://www.vukcevic.talktalk.net/CET-D.htm
but haven’t had time yet to mark major volcanic eruptions.
It is a matter of interpretation what you can see and conclude, I didn’t say the effect was large or small, for those three volcanoes or any other in particular, just offered a facility where one visually can observe what the effect may or may not be, but to exclude any effect of the above mentioned volcanic eruptions I wouldn’t agree with.
I, Papa Giorgio, posted a link to this story on a friends FB (who is a geology major — specialising in volcanic “stuff” … I don’t know!), here is his response:
I think i found the problem. Your author is using antarctic ice core data to refute a study done on northern hemisphere data. Though volcanic eruptions can be known to deposit some materials world wide, distance plays quite a factor. I wouldn’t expect a sulfur rich vulcinian eruption from say Etna, to deposit with the same density in antarctica than say finalnd. That’s pretty obvious, especially considering wind patterns in the northern hemisphere. […] The data shows a correlation between times of vulcanism (in the northern hemisphere) and some periods of glacier growth. It’s not claiming that all periods of glaciation are caused by volcanoes, but asserting that volcanoes may be a factor considering that the ash they emit blocks out solar rays.
Like any study, there is variability in the data (as your author points out), so i’m not surprised that the dates don’t line up exactly. I don’t see the same issues with the study that this author did, but i am glad there are people out there questioning the findings.
A compliment? Again, I don’t know!
…geology major at SacU.
Perhaps the 1258 eruption was El Chichon in Mexico. Also there was a volcanic eruption in the 15th Century in Hawaii, not recorded in ice cores:
“The ‘Aila`au eruption, as it is called, took place from a vent area just east of Kilauea Iki….The eruption probably lasted about 50 years, from about 1420 to 1470…Such a long eruption naturally produced a large volume of lava, estimated to be about 5.2 cubic kilometres (1.25 cubic miles) after accounting for the bubbles in the lava…This large volume of lava covered a huge area, about 430 square kilometres (166 square miles).”
http://hvo.wr.usgs.gov/volcanowatch/archive/2000/00_02_03.html
It doesn’t seem to have been an explosive eruption and therefore deposited no volcanic material in the polar regions. With no material reaching the stratosphere it perhaps only slightly exacerbated the Spörer Minimum locally.
Your carefully detailed and precise comparison of ice expansion and volcanic sulphates demonstrates very clearly that Miller et al. shows no relationship between volcanoes and ice cap expansion.
As a layman I would guess that the effect a volcanic eruption would have on climate would be limited to an area the size of which would relate to the force of the eruption. But this effect must be somewhat limited, given that a very large eruption such as Kuwae in 1452, in the Southern Hemisphere, deposited a considerable amount of volcanic material in Antarctica and Greenland but still had no effect on the polar ice caps.
Willis, I saw the comments concerning Mann and Nature and was appalled. You really are to be commended for the careful and time consuming work you have done on Shakun and Miller. This blog is perhaps well ahead of its time in pointing the way to a new and far better peer review process than a journal sending a paper to the usual suspects. And perhaps in the future may become established as a source of reliable new scientific papers.