Dronning Maud Meets the Little Ice Age

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.


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 Eschenbachweschenbach

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April 13, 2012 3:28 am

Um … well … they are being most expansive with their claim that the 1435 peak and the eruption “correspond”. The volcano is well after the eruption. How do they explain this?
Typo: The volcano is well after the eruption?
[Reply] Thanks, fixed. -w.]

April 13, 2012 3:34 am

Could it have been this eruption in China @ 1200?

Ed Fix
April 13, 2012 3:56 am

In otherwords, they present two ice growth spurts that don’t quite line up with volcanic events, and they invent two ad hoc explanations to shoehorn the data into their hypothesis. Unconvincing at best.

April 13, 2012 3:59 am

Excellent as usual, Willis.

Mike Jowsey
April 13, 2012 4:05 am

Hi Willis – thanks for another logical evisceration of dodgy science. I noted a few typos – hate to be the pedant, but here goes…
And while you would expect an immediate increase in the rate of ice cap expansion, the increase doesn’t begin until about 1670.
The date 1670 should be 1270?
The volcano is well after the eruption.
The peak is well after the eruption?
The peak ice cap expansion occurs in 1435, a full two decades before the eruption in 1655.
1655 s/b 1455?

April 13, 2012 4:09 am

What are these references to the 1600s? Perhaps you need a proofreader.

April 13, 2012 4:18 am

Couldn’t possibly have been the sun—with the Wolf minimum from 1280 to1350, the Sporer Minimum from 1460 to 1550 and the Maunder Minimum from 1645 to 1715. The sun may have taken 2 sunspot cycles to slide into the minimum much as it seems to be doing at present, which could explain the early rise in sea ice.
Seems a better fit than volcanoes. The geo-chemical record should show the GCR flux by-products.
Although what happened with the ice during the Maunder minimum? History records European mountain glacier growth with several rapid increases during those times right up to 1730.

April 13, 2012 4:23 am

Outstanding. Assuming the dating of the QML ice cores is reliable, this paper is thoroughly debunked. Surely the reviewers should have caught this? Have you sent your critique to the authors?

Allan MacRae
April 13, 2012 4:28 am

Thank you Willis.
But why use real data when you can assume fabricated data?
You can “prove” anything you want with fabricated data, and never have a failed hypothesis, and always get published in the “top” journals, in this brave new world of science.
The warmist approach could also apply to engineering: “Assume a bridge. Now drive over it.”
OK – this is nonsense – but it’s already being done in Western Europe and Ontario, where subsidized wind and solar power are damaging electrical grid security and supply.
It really IS that absurd.
“Stupid is as stupid does.”
– Forrest Gump

Jim Melton
April 13, 2012 4:28 am

Well spotted Willis,
It’s all (post)normal;
Coincidence = Causation
Cherry picked data = Global truth
Agenda driven science = Anything to prop-up ‘the cause’
ps I think you have a couple of typos of dates under the last graph.

Paul Mackey
April 13, 2012 4:42 am

There are a few numerical typo in here, eg
“occurs in 1435, a full two decades before the eruption in 1655”

Bob Shapiro
April 13, 2012 4:47 am

And, why was it that the eruption just after 1800 didn’t cause ice eruption?

Bob Shapiro
April 13, 2012 4:48 am

I mean ice expansion.

April 13, 2012 4:50 am

Brilliant again! Thankyou.
Sadly, I think we can expect much more of such trash as Rio+20 nears. Two such papers this week and many more to come (sigh).

April 13, 2012 4:51 am

Out of interest – since I don’t know – would the fact that the sulphate records are from the antarctic and the paper is based upon the arctic be of any relevance. I wonder about the movement of sulphates between the two hemispheres – rate and uniformity

D Nash
April 13, 2012 4:56 am

Hey Willis,
Had the same thoughts myself. Couple of typos:
The peak ice cap expansion occurs in 1435, a full two decades before the eruption in 1655 (should be 1455).
The volcano is well after the eruption – assuming that the eruption is well after the peak.

Gail Combs
April 13, 2012 5:01 am

The Mysterious Missing Eruption of 1258 A.D. by Erik Klemetti, assistant professor of Geosciences at Denison University.
A closer look at that missing eruption.

April 13, 2012 5:01 am

Willis…I am really glad that you make time for this kind of detailed critical review…I fear no one of those scientists who publish in the literature will do so (there is little motivation when most will readily accept it – otherwise they have to look more closely at the natural warming and cooling events). The pity is that there is then no record of criticism in the published literature and this bad science is all that students will have to refer to…unless science institutions embrace blogging realities! If you had time for a little note to the journal….

John S
April 13, 2012 5:03 am

“The peak ice cap expansion occurs in 1435, a full two decades before the eruption in 1655.”

April 13, 2012 5:08 am

In para after figure 4 “the increase doesn’t begin until about 1670.” Imagine should read 1270. Similarly next para “1435, a full two decades before the eruption in 1655” must be 1255.

Bill Marsh
April 13, 2012 5:09 am

It seems to me that there is a trend emerging with the last few papers is to attempt to disregard or downplay the use of Antarctic ice cores as a temperature proxy and/or atmospheric content measure. I’m not sure, but I suspect, that is because the ice cores aren’t telling the story ‘The team’ wants to hear. I find that more disturbing than selective omission of data because it is inconvenient to your proposed findings.

April 13, 2012 5:22 am

This would not have passed a fifth grade peer review. Slight correlation now proves causation?

April 13, 2012 5:30 am

I am shocked that no-one can see how ice causes volcanoes from this data.

April 13, 2012 5:35 am

People gave me money to do a study to prove something. My study failed utterly. I would never receive money to do anything again any time soon, therefore I wrote up a paper anyway. The new science.

April 13, 2012 5:35 am

I looked at this last night and wasn’t convinced
but than I am biased, since for period where there are the actual data available and not based on proxies I have different idea why the Northern Hemisphere came out of the Little Ice Age and the subsequent warming
and therefore it is possible to speculate that reason for going into the LIA is reversed, and it is not the volcanic sulfate.

April 13, 2012 5:36 am

nice discussion of the missing eruption here
it even quotes a Mannian paper (2012)

April 13, 2012 5:36 am

I noticed that as well. Cause has to precede effect, not that such pesky details seem to bother climate science.
One issue here is, how good a proxy for the climate effects of volcanoes is SO2? An SO2 spike in the core is a sure sign a volcanic eruption occured but the climate effect is largely extrapolation from 2 recent eruptions (Pinatuba and El Chico) or if you prefer guesswork. We really don’t know if climate effect is proportional to SO2 content.

ferd berple
April 13, 2012 5:57 am

If anything, the data shows that ice causes volcanoes.
It has been observed that volcanoes and earthquakes increase at times of planetary alignment. Clearly the earth’s climate regulates the orbit of the planets.

ferd berple
April 13, 2012 6:03 am

Why should cause and effect be a problem in climate science? Gore didn’t let the lag between temperature and CO2 influence his results. He and the IPCC got the Nobel for proving that temperature causes CO2.

Rob Crawford
April 13, 2012 6:07 am

When did science overturn causality?

April 13, 2012 6:09 am

Typos… 1655 and 1670…. Should be 1455 and 1470.
[Fixed. Thank you, and the others who helped proof this. Robt]

David in Georgia
April 13, 2012 6:10 am

Wait a minute! How many times has a Climate Scientist (TM) or a Global Warming advocate told us that the Little Ice Age was purely a regional thing and did not reflet a global change in temperature? Now that they have a partial explanation for it volcanoes caused measurable ice cap expansion affecting at least half of the globe?
If volcanoes caused a decrease in temperature enough to cause dozens of decades of ice growth, then it would follow that before that ice growth (and before the volcanoes) the temperature had to be higher that after the volcanoes. Therefore, the temperature during the LIA was cooler than the previous temperatures, enough to cause rapid growth of ice.
So, once the effects of that cooling have subsided enough, melting of that ice is natural, and not due to CO2. If this paper has any validity at all, it can be used to show that our current warming is not only natural, but merely a return to pre-LIA temperatures.

ferd berple
April 13, 2012 6:17 am

It has been observed that volcanic hotspots often occur in antipodal pairs, suggesting that oceanic meteor impacts are one possible cause. A novel mechanism by which orbital mechanics influences climate?

ferd berple
April 13, 2012 6:25 am

Rob Crawford says:
April 13, 2012 at 6:07 am
When did science overturn causality?
When it conflicts with Political Correctness. Science that shows politically incorrect conclusions is heavily censored and de-funded.

Colin Porter
April 13, 2012 6:31 am

I know that we have crossed swords in the past Willis, but I too am very much with you on this one and likewise I am trying to control my blood pressure.
Your analysis concentrated mainly on the first part of the argument regarding correlation of LIA to volcanism. As with other areas of climate science, they seem to require a heavy dose of positive feedback in order to justify their theories. In this case, volcanic activity by itself can only perturb the climate for a small number of years and to justify extending it for the duration of the LIA, which incidentally did not exist anyway because I know a Mann who says so, the concept of a large positive feedback must be invoked via increased albido from more extensive sea ice cover. But is this really possible? After all, this sea ice albido is patently incapable of supporting the existing sea ice through the summer months as it looses 50% or more of its area/extent in summer. And if the sea ice does extend initially due to volcanic aerosol activity, then the increased sea ice is going to be moderated by virtue of the fact that the lower latitudinal ice will be much more susceptible to disappearing from a higher insolation of the sun and from warmer oceans at that latitude. i.e. yet again negative feedback moderating climate.
Perhaps you may like to find time in the future to lay the ghost of the overstated influence of high latitude ice on albedo.

April 13, 2012 6:32 am

Nice refutation and falsification of their paper Willis. Keep up with your explosive slicing and dicing. You’re the paper shredder! [;)]

April 13, 2012 6:53 am

Erm… that PDF thingy… it seems to be labeled “KILL RATE (arbitrary units)” in very similar graph in Roger Pielke’s Sr.’s post from a few days ago. And it is connected somehow to land ice extent, measuring how much of vegetation died at that period. And there’s another graph showing sea ice (with another arbitrary units) which has very different peaks, which somehow seem to follow both eruptions quite nicely with a little delay.
Now, vegetation death rate changes may have many reasons, and speed of land ice growth may be just one of them. Personally I wouldn’t take either of the two peaks as too important as it’s the area below the curve which tells us total amount of deaths and here the area between the two peaks is much more important than the peaks themselves. And after the second peak, the death rate likely diminished because there was too little to die left.
The graph basically tells us that at about 1280 the land ice started to grow until about 1435 when all of the examined land was already covered by ice. The temperature graph corresponds to that, too.

John Blake
April 13, 2012 6:57 am

Anyone citing “models” –the more, the faster, and the worse– is ipso facto guilty of circular reasoning, false pleading via argumentum ad verecundiam.
Refutation at length and in detail is good to put on-record, but
let’s face it: Whater their mutual-admiration credentialism, such ad hoc vs. empirical exegeses are not just academically misleading but worthless on their face.
Better to simply construct a checklist of standard fallacies and rate these endlessly repetitive exercises in grant-esque futility on a 10-point scale accordingly.

April 13, 2012 7:01 am

Willis: thanks, another tight grouping in the ten-ring. In light of your analysis, their argument reads like a “just so” bedtime tale.

Pamela Gray
April 13, 2012 7:07 am

They make the same mistake all wriggle matchers do. No plausable mechanism regardless of what came first, the chicken or the egg. I swear, if I really worked at it and got me some of that algore funding, I could convince learn-ed Ph.D. types of folk that my never-fail rising at 5:00 AM MUST be the cause of day. Won’t go into the cause of night.

April 13, 2012 7:10 am

Folks: may I offer a suggestion as to one reason why the warmist arguments have so much power? The Mercator projection combined with sparse sampling in high (especially northern) latitudes combined further with fancy interpolation. The result is that a few “hot” numbers from 85 degrees north becomes a proxy for the whole Arctic, and then shown in blazing red on a graphic which assigns far too much psychological weight to the vanishingly-small regions of the globe. We are wired to pay attention to that color and that visual overemphasis. And these people keep playing us with it. Can we try to correct for that, with different projections? With a 90 degree rotation of the lat/long grid just to show the viewer what that does to all the red versus green and blue on the fright maps?

April 13, 2012 7:27 am

“Abrupt onset of volcanism triggered by the Little Ice Age.”
There, I fixed it.

Bill Illis
April 13, 2012 7:41 am

The GISP2 Greenland ice core volcanic sulfates goes back 110,000 years so we can check to see if big volcanoes always result in Little Ice Ages.
The Holocene and the transition out of the last Ice Age had many very large volcanoes. Many are twice as large as the 1258 event or four times Tambora. Not much of an impact against the trends.

April 13, 2012 7:41 am

Did these researchers use Mr. Peabody’s Way-Back machine to “precisely” date the records of ice cap growth?
Jay Davis

April 13, 2012 7:46 am

Thanks Willis, good article.

Doug Proctor
April 13, 2012 7:59 am

Is it possible that the internet, blogging and, for the first time, a large number of non-academic, but technically proficient readers, are revealing how much shoddy scientific work has always been published?
I’m suspicious that the pressure to publish (justification for grants in our policy-pertinent period) is just making obvious what few knew all along.

April 13, 2012 8:08 am

Typo. Talking about the rate of ice cap expansion around the 1258 eruption Willis writes: “And while you would expect an immediate increase in the rate of ice cap expansion, the increase doesn’t begin until about [1470].”
Seems that should be 1270.

April 13, 2012 8:13 am

You can’t “precisely date” ice cores. Tree rings are annual rings, ice core rings are not. It snows all year round in the Arctic and Antarctic.

April 13, 2012 8:13 am

Willis, this was excellent. You can’t claim causality if the cooling precedes the volcano.
One thing though, about strength of volcanos. The last half of the 20th C, if my calculations are correct, was pretty low, relative to the 13th and 15th C, in terms of Tg of sulfur emitted. I calculate that Pinatubo released about 9 Tg of sulfur (20 million tons of SO2). On Fig. 1 above, Krakatoa looks to be around 20 Tg of sulfur (1883), about twice Pinatubo in the same graphic, and the earlier, larger Tambora (1815) looks to have emitted about 120 Tg of sulfur. Tambora is the volcano that created the Year without a Summer in New England, which caused the migration from New England to the Ohio valley. The Year without a Summer also caused considerable starvation in Europe. Pinatubo appears to be the largest emitter of sulfur in the 20th C, so the 20th C is pretty low in vulcanism, using SO2 (sulfur) as the metric of measurement, relative to most centuries in the millenium.
The 1280 volcano emitted 258 Tg of sulfur, over ten times what Krakatoa emitted, and just over double what Tambora emitted. Just that one volcano appears to make the 13th C more volcanic than any of the other centuries on the chart. The 1435 volcano emitted about 150 Tg of sulfur, but that one volcano doesn’t seem to be enough to make the 15th C more volcanic than the 19th, but it is still quite large by historical standards, about 15 times more SO2 emissions than Pinatubo.
What does this mean? I like the interpretation found in the Wikipedia entry for the Year without a Summer. Causality for the crop-killing freezing temps in both Europe and New England is jointly attributed to both very low solar activity (Daulton minimum) and the cooling effects of Tambora.
Similarly, didn’t we also have a cooling sun after circa 1300, leading down to the Maunder Minimum? It seems to me that volcanism of this magnitude (258 and 150 Tg sulfur, vs. about 9 for Pinatubo) could add to a cooling process already underway, as Tambora appears to have done.
In other words, the actual story (as posited herein) was that natural forces were already producing cooling, and volcanism added to that. But this story wasn’t good enough, you had to get rid of natural forces producing cooling (just as David Deming relates that an IPCC person in the mid 1990s told he that they had to get rid of the Medieval Warm period.) So the authors morphed interesting science (really big volcanos enhanced cooling process already underway) to a more politically correct but scientifically wrong story, e.g. that volcanos CAUSED the cooling. Once again, science is twisted to serve politics.
At least they’ll get their grants the next few years!

Arno Arrak
April 13, 2012 8:28 am

If this proves anything it is that volcanic eruptions just don’t measure up to their reputation. I have come to the conclusion that volcanic cooling that is supposed to follow an eruption and have an influence on climate simply does not exist. Part of it is due to ignorance of the fact that all climate graphs at all times are full of El Nino peaks and La Nina valleys in between. Those are the spikes they try to eliminate by their running averages. It so happens that when a volcano erupts when an El Nino has just peaked and a La Nina valley is beginning to form that La Nina valley is recruited as an example of volcanic cooling happening. Two examples of this are Mount Pinatubo and Gunung Agung. On the other hand, when the eruption takes place when the La Nina has bottomed out and the next El Nino is just beginning the expected cooling is simply absent and nobody has any idea where it went. El Chichon in Mexico is an example of that. Whether a cooling can be observed after any particular eruption thus depends upon the timing of the eruption with respect to the location of neighboring El Nino and LacNina phases of ENSO. This of course is contrary to claims that volcanic cooling can ovecome El Nino warming as so-called “experts” have been telling us. For more info read pages 17-21 in “What Warming?”

April 13, 2012 8:41 am

“First, the expansion of the ice cap started in 1215, about 45 years before the eruption in 1258. ”
err no. the PDF starts to change in 1215. entirely different thing than you describe.
The ice expansion does not start in 1215. The PDF, the probability, starts to change in 1215.

April 13, 2012 8:51 am

This refutation is pretty weak. The paper undoubtedly has problems, but Willis is being a bit lazy with this write up.
“but what started and maintained the cold summers from 900 to 1000?”
This is an interesting question, the answer to which may support or refute their assertions, but merely asking the question does nothing. They don’t seem to be saying ice cap expansion can only be caused by volcanoes, merely that the two in question were. Yes finding what caused the earlier expansion might reveal the cause for the later two, or it might not. Willis’ comment does nothing to answer this question.
“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.”
Again, the writers asserted that the time periods were two among other active periods. NOT the two most but two of the most. I would think that of the 24 half centuries (chronologically) having 2 of the top 4 or 5 most active would make this a valid statement. I don’t know if both periods are in the top 4 or 5, but Willis offers no evidence to the contrary. He merely says he doesn’t like it because of two periods that are more active than one of the authors.
Willis’ other points are a little better, though with the typo’s it is not clear to me if he is clear on the original paper.
I didn’t read the original paper, but I do know that nothing in this article is particularly damning of it. Very weak tea indeed.

April 13, 2012 8:56 am

Steven Mosher says:
April 13, 2012 at 8:41 am
““First, the expansion of the ice cap started in 1215, about 45 years before the eruption in 1258. ”
err no. the PDF starts to change in 1215. entirely different thing than you describe.
The ice expansion does not start in 1215. The PDF, the probability, starts to change in 1215.”
Nice catch, Steve. The paper is therefore unfalsifiable, and therefore unscientific.

Gail Combs
April 13, 2012 9:06 am

Doug Proctor says:
April 13, 2012 at 7:59 am
Is it possible that the internet, blogging and, for the first time, a large number of non-academic, but technically proficient readers, are revealing how much shoddy scientific work has always been published?….
You might want to read some of Dr. Scott Armstrong’s Papers:
“Bafflegab Pays,” 1980: http://marketing.wharton.upenn.edu/ideas/pdf/armstrong2/bafflegab.pdf
This is my favorite one on experts. “Incomprehensible, You Say? Brilliant!” 1980 http://marketing.wharton.upenn.edu/ideas/pdf/Armstrong/Mass%20Media/Bulletin%201980.pdf
“Forecasting: Of Suckers and Seers” 1985: http://marketing.wharton.upenn.edu/ideas/pdf/Armstrong/Mass%20Media/The%20Press%201985.pdf
He has a whole bunch of interesting papers on research and peer review: (see bottom of page) http://marketing.wharton.upenn.edu/people/faculty/Armstrong/Mass_Media.cfm#knowledge

Gail Combs
April 13, 2012 9:17 am

elmer says:
April 13, 2012 at 8:13 am
You can’t “precisely date” ice cores. Tree rings are annual rings, ice core rings are not. It snows all year round in the Arctic and Antarctic.
They use O18 to date ice core and other proxies This is why Pat Franks article was so fiercely contested http://wattsupwiththat.com/2012/04/03/proxy-science-and-proxy-pseudo-science/
The ice core dating looks reasonably accurate for ice cores… maybe. That is if there was snowfall and it did not sublimate. http://www.iceandclimate.nbi.ku.dk/research/strat_dating/annual_layer_count/ice_core_dating/
In the interior of Antarctica precipitation is as low as 50 mm per year, while in coastal regions it can be as high as 250 mm per year. It is also very windy. That is why I say “maybe”

Henry Clark
April 13, 2012 9:23 am

Good article. As I was just noting elsewhere, Bond et al. 2001 note, regarding cold events like the Little Ice Age:
Our correlations are evidence, therefore, that over the last 12,000 years virtually every centennial time scale increase in drift ice documented in our North Atlantic records was tied to a distinct interval of variable and, overall, reduced solar output.
The alarmist side has tried to get rid of the Medieval Warm Period and to pretend the Little Ice Age was caused by anything other than solar variation primarily. In fact, the wikipedia article on the LIA suggests human activity affecting CO2 levels as a plausible cause, which would be comedy except some people actually fall for that; CO2 levels meanwhile varied by only a handful of ppm like this illustrates:
Their tactics break down extra much when one considers more than the past millenium but also the rest of the Holocene, where correlation with solar activity (not as the sole influence but often a predominant one along with cosmic rays affected by it) occurs time and time again.

Bill Marsh
April 13, 2012 9:23 am

The more I think about this paper, the more it appears to be similar to the convoluted logic and date manipulation used by Immanuel Velikovsky in his seminal work, “Worlds in Collision”. In it he freely changed dates of various catastrophes around the world to support his contention that the ‘exodus’ events were the result of a comet colliding with the earth. Their reasoning bears striking similarities to the tortured logic of Velikovsky.

April 13, 2012 9:26 am

Pamela Gray, I get up early to fire up my wood stove too.

April 13, 2012 9:36 am

The chronology of volcanic and climatic events in this paper is based on 14C dating of tundra vegetation, yet the authors are talking about accuracies of only a few years. There is no way you can get that kind of accuracy from radiocarbon dates. Radiocarbon ages are expressed in radiocarbon years before present. A radiocarbon year is not the same as a calendar year because of variation in the production rate of 14C in the atmosphere caused by variation in the neutron flux that creates 14C from nitrogen. So any radiocarbon date has to be adjusted by means of a calibration curve to convert radiocarbon years to calendar years. The problem is that the calibration curve to make this conversion is not a straight line–it’s a wiggly line with more than one possible intercept corresponding to sevedral possible dates, (i.e., a 14C date might correspond to anywhere from 1-3 or more calendar dates, rather than one date). So I pulled up the standard 14C calibration curve to see what kind of accuracy one could claim for ages in the past 1200 years. For example, if the measured 14C age was 600 radiocarbon years (i.e, around 1400 AD), the calibrated calendar age intercept could be any of three ages, 640, 590, or 560 calendar years (or between the calendar years of 1372 to 1452). . For a 14C age of 350 radiocarebon years, the possible calendar year intercepts vary from 450 to 300 calendar years (or 1562 t0 1712 AD). Yet the authors of this paper are attempting to make correlations between volcanic and climatic events within a matter of only a few years. The bottom line here is that 14C dates cannot possibly provide the accuracy claimed in this paper.

April 13, 2012 9:38 am

In the 21 year period 1990-2010 inclusive, while Arctic Ice was steadily declining in the nearby Kamchatka peninsula and the Kurile Islands there were on average about 2.5 volcanic eruptions annually.
Kamchatka Volcanoes
Bezymianny: 2010, 2009, 2008, 2007, 2000-05, 1998, 1997, 1996-97, 1994-95, 1993-94, 1992, 1991, 1990
Klyuchevskoy: 2010, 2009, 2007, 2005, 2002-04, 2000, 1998, 1996-97, 1994-95, 1993, 1992, 1991
Sheveluch: 2000-10, 1998, 1997, 1993-94, 1991, 1990
Avachinsky: 2001, 1991
Karymsky: 1996-2009
Koryaksky: 2009, 2008
Mutnovsky: 2000
Kurile Islands Volcanoes
2010, 2x 2009, 2008, 2007, 2×2005, 2003, 2002, 1999, 1997, 1996,1991
These eruptions caused some of the ‘Sudden Stratospheric Warming’ ( http://hal.archives-ouvertes.fr/docs/00/56/34/77/PDF/SSW.pdf ) in the winter months, but an AGW advocate would solemnly testify that it is the CO2 which has saved the Northern Hemisphere from the onset of another Little Ice Age

April 13, 2012 9:51 am

If there was causation – “volcanos cause ice increase”, then there should have been SOME ice growth around the double erruptions recorded about 1825. Zero, zip, nada. Theory falsified.

April 13, 2012 10:04 am

As well as this paper we have had Booth et al claiming that most unforced variation in the measured temperature record was due to aerosols. Is there a movement with the climate science community to use aerosols to explain what they cannot otherwise explain. Perhaps it is time for paper claiming that the Yellowstone Erruption of 2015 caused the levelling off of temperature in the early 21st centruy.

April 13, 2012 10:45 am

Don Easterbrook says:
April 13, 2012 at 9:36 am
Absolutely agree.
(Willis Eschenbach says: April 13, 2012 at 10:28 am)
Arctic ice 14C dating is prone to significant errors, radioactive deposition are subject to atmospheric conditions as well as diffusion process within the ice.
Here is graphic illustration how a NASA’s scientist may have made errors in dating the solar activity during the Dalton Minimum 1800-1820.
Steve Mosher: data is available, no code required.

April 13, 2012 11:12 am

Putting PDF (Probability Density Function) on the Y-axis is pure balderdash.
It is to imply some significance with high values with meaningful events above the noise.
A PDF is a function with many Ys for many Xs (or Ts)/ So exactly what are they plotting vs time? Max value Y at it’s X? So we see as visually important high precision of insignificant events and as unimportant where there is wide uncertainty of significant events. Backwards! We should also visualize that every event in the data results in a PDF and the the events must superimpose at each and every point in time. Finally, we are to believe that the uncertainties contributing to each PDF’s event timing are independent of each other, when in fact each event is most certainly shares common elements of uncertainty; if one event has +/- 10 years of uncertainty, I’d bet the neighboring event in time has the same, and linked, uncertainty.
Far better to plot the aerosol loading on Y and express timing PDF as a 90% confidence error bar in the X direction.

kadaka (KD Knoebel)
April 13, 2012 11:25 am

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).
That would be times 1000 to change 0.40 (40%) to 400.
Y-axis label says “…PDF (percent * 10)”
Resuming reading…

April 13, 2012 11:26 am

Re: Willis 10:41am
I didn’t mean criticism of your article as criticism of you personally. I chose “lazy” over ham-handed or clumsy, but perhaps you prefer those descriptors. If you’re going to go to the trouble of doing something, you might as well do it properly.
I didn’t read the article in question. I did read your article. Yours was unpersuasive from a logical point of view. I make no representation about the validity of the original piece. Don Easterbrook has an illuminating comment upthread that seemed to pretty well sh%t-can the piece for the carbon dating error margins.
You make no reply to my substantive criticisms of your piece. Do you take them as granted?
There were enough apparent typo’s to suggest that the article was not proofread. If not, doing so in the future may help clarify presentation and formulation.
My favorite post of yours over the years was on the Fair Weather Gale; well written, entertaining and informative. Many other posts have been incisive and penetrating. This one is not. Sorry if that bums you out.

Septic Matthew/Matthew R Marler
April 13, 2012 12:12 pm

Ice peaks without eruptions, ice peaks with eruptions, eruptions without icepeaks. Not a strong covariation between ice peaks and eruptions.
Willis, thanks again.

Dave Wendt
April 13, 2012 12:40 pm

Anopheles says:
April 13, 2012 at 5:30 am
I am shocked that no-one can see how ice causes volcanoes from this data.
That was my thought when I first encountered this back in January. The “data” they have assembled more strongly implies that increasing isostacy from expanding ice triggers significant volcanism, but even at that it wouldn’t be much better than a vague suggestion, but still better than the chicken before the egg analysis they present.

April 13, 2012 12:48 pm

It seems like I remember reading letters to the editor to journals from old publications that read like this. IOW someone would write a paper, someone would evicserate it, and then folks would either also eviciserate the original paper or they would savage the critics methodology. When did the journals start sidelining the critical responses and forcing folks to find sites like this one to get both sides of a story? Anybody can be guilty of expectational bias, but there should be an expectation that you might get ridiculed if you fell into that trap.

April 13, 2012 12:57 pm

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

April 13, 2012 2:16 pm

The paper under study here has been already extensively discussed in this post
The problems that Willis is noticing was already noted by me in many times. For example
A figure similar to Willis’ Figure 1 has been prepared by Geoff Sharp after my request:
The Little Ice Age was driven by the sun as also my last paper shows
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]

April 13, 2012 2:59 pm

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

Dr. Nicola Scafetta
Not anywhere as good as these graphics shows how we got out of it.
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..

April 13, 2012 3:24 pm

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.

Gail Combs
April 13, 2012 3:57 pm

Excellent Willis, I don’t know how you find the time to do all the in-depth digging you do for WUWT.

April 13, 2012 5:28 pm

Sera says:
April 13, 2012 at 3:34 am
Could it have been this eruption in China @ 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:

April 13, 2012 5:36 pm

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.

Chuck Nolan
April 13, 2012 5:55 pm

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!

April 13, 2012 6:45 pm

Re: Willis @ 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.

April 14, 2012 12:01 am

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.

April 14, 2012 2:07 am

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.

Lars P.
April 14, 2012 2:18 am

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.

Ed Zuiderwijk
April 14, 2012 2:43 am

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).

Ed Zuiderwijk
April 14, 2012 2:57 am

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?

Peter Miller
April 14, 2012 3:07 am

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.

April 14, 2012 3:11 am

Willis: “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“ …”

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.

April 14, 2012 7:20 am

Blade says:
April 14, 2012 at 3:11 am
You can see effect of some volcanic eruptions on the CET here:

April 14, 2012 1:05 pm

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
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
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.

April 14, 2012 1:59 pm

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!

April 14, 2012 1:59 pm

…geology major at SacU.

April 14, 2012 4:35 pm

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).”
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.

April 14, 2012 6:35 pm

Great stuff, Willis. Thanks.

Jose Mayo
April 16, 2012 7:51 am

Perdón, pero no hablo inglés;
Tengo una pequeña duda: Una molécula de CO², o cualquier outro gás de “efecto invernadero”, ¿es un “reflector”, o un “difusor”? O sea, si recibe un rayo infra-rojo, ¿lo “devuelve”, o lo difunde en todas las direcciones?
Gracias por la atención.

Jose Mayo
April 16, 2012 11:39 am

Muchas gracias, Mr. Willis, pero… Si esa molecula primero se calienta con un rayo directo (los demás supongo que sean en gran parte reflectidos, cómo en cualquier cuerpo esferico), y después de calentarse emite en todas las direcciones, ¿qué cantidad del calor que recibe, efectivamente, podria “devolver” en dirección al suelo? ¿Se tiene ésto en cuenta, al calcular el “efecto invernadero”?
Gracias otra vez.

April 18, 2012 10:48 pm

I assume it might be fair to ask if there is some underlying driver that causes increased volcanic activity at times and reduced activity at others. I do not know if anyone has tried to evaluate the climatic impacts of super-volcano eruptions. It would seem that these would have a much greater effect than the Little Ice Age if that were caused by volcanic activity.

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