Trigger for Little Ice Age – a half century of volcanism?

Winter landscape with iceskaters, c. 1608, Hen...

Winter landscape with iceskaters, c. 1608, Hendrick Avercamp (Photo credit: Wikipedia)

Dr. Roger Pielke Sr. writes on his blog today:

Every once in a while. a nugget of new research insight appears that adds to our understanding of the climate system, and its complexity. One article of this type has appeared.

Miller, G. H., et al. (2012), Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks, Geophys. Res. Lett.,39,L02708,doi:10.1029/2011GL050168

The Miller et al article is also at Physics Today, and is paywalled, but with an interesting title:

The triggering and persistence of the Little Ice Age with this even more interesting subtitle:

“A mere half century of volcanism seems to have initiated a chill lasting half a millennium”.

The key points from GRL are:

  • Little Ice Age began abruptly in two steps
  • Decadally paced explosive volcanism can explain the onset
  • A sea-ice/ocean feedback can sustain the abrupt cooling

Abstract:

Northern Hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes. However, the causes of superposed century-scale cold summer anomalies, of which the Little Ice Age (LIA) is the most extreme, remain debated, largely because the natural forcings are either weak or, in the case of volcanism, short lived. 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. A transient climate model simulation shows that explosive volcanism produces abrupt summer cooling at these times, and that cold summers can be maintained by sea-ice/ocean feedbacks long after volcanic aerosols are removed.

Our results suggest that the onset of the LIA can be linked to an unusual 50-year-long episode with four large sulfur-rich explosive eruptions, each with global sulfate loading >60 Tg. The persistence of cold summers is best explained by consequent sea-ice/ocean feedbacks during a hemispheric summer insolation minimum; large changes in solar irradiance are not required.

Here’s one of the figures via GRL:

h/t to Bill Yarber

99 thoughts on “Trigger for Little Ice Age – a half century of volcanism?

  1. I somehow do not believe that changes in snow/ice cover make such strong feedbacks. There was record snow cover in recent winters in Northern hemisphere and what. Until ENSO is somehow affected, it is only something happening up there.

  2. I bet at the time vulcanism and the resulting weather changes were explained by the sins of man, and people were offered to repent, change their ways and give generously to the church/shaman.
    What has changed? Humans really would do with evolving further.

  3. Miller got the dates from radio carbon dating dead plant material from beneath receding ice margins on Baffin Island in the Canadian Arctic. The kill dates were clustered between 1275 and 1300 with a second cluster at about 1450 indicating that this region at least was ice free between 550 and 700 years ago.
    At the very least this shows that the retreating ice in that part of the artic is nothing new.

  4. Does that mean the Maunder and the Dalton minimum didn’t happen. Surface tension blocks heat and is the key to the climate on this planet. The only energy that goes into the ocean goes in via the sun’s rays. The ocean ignores the second law of thermodynamics.

  5. I don’t understand the histograms, and would welcome an explanation or interpretation of what the data is saying. Because it does seem to be of interest …

  6. @TerryS

    Good points. The existence of ice-free regions is confirmed by the Iceland, Greenland and Newfoundland settlements of the time. The implications for the ‘permafrost’ are also large as it means those frozen bogs are not permanent, and contain large amounts of relatively recent vegetation. You might have noticed the consistent avoidance of recognition in alarmist comments about retreating ice and permafrost: that obviously biomass regrowth will commence immediately it is warm enough to do so. Emphasis has instead concentrated on ‘carbon emissions’ from rotting vegetation in the ground with not even a nod to the obvious: that it got there by itself, literally.

  7. But I thought the scientific alarmist hierarchy told us that we humans are responsible for ‘climate change’ and everything bad that has / is / will ever happen.
    Obviously some human skeptic jokers must have been stoking the volcanoes.

    On a serious note, the theory sounds plausible (unlike CAGW).
    Is this a well founded study and conclusion?

  8. No, no, no. He’s got it all wrong. There *must* have been a sudden decrease in CO2 to cause it, because the science is settled and only CO2 drives the climate.

  9. Interesting. So the grand solar minimum across that time frame was irrelevant. Or did it perhaps trigger volcanism?

    rgb

  10. Wow, no mention at all of solar influences. The Maunder Minimum coincides very well with the grand solar minimum at the time, with a similar correlation with the Dalton Minimum.

    Those worthless models again—they still do not include solar cycles and the solar/cosmic wind connection.

    robert barclay says: April 12, 2012 at 8:49 am
    “Surface tension blocks heat and is the key to the climate on this planet. The only energy that goes into the ocean goes in via the sun’s rays. The ocean ignores the second law of thermodynamics.”

    Robert, this makes no sense, particularly the last statement.

  11. No no. Don’t you guys read anything? Little Ice Age was caused by Columbus finding Americas and causing millions of natives to die from smallpox! Less people = less CO2 = cold.

    I read it from a study that was peer reviewed so it must be true.

  12. Does anyone know the reasoning behind postulating the four large erruptions? Was it that erruptions were recorded or do they just make the model work?

  13. The article triggers a feeling of “deja vu”. I took Reid Bryson’s class on climatic history in the late seventies, and he was already then talking about there being periods when volcanoes are exceptionally active, and how these active periods are a significant factor in global temperature changes. Didn’t think much of Reid’s argument then, but the more I have been reading on historical climate, the more it begins to look like he was onto something. (Bryson’s view of human-caused global warming: “hogwash”.)

  14. Can’t be true: according to the alarmists man made global weirding causes vulcanism, earthquakes etc./sarc

  15. @Tony: the histograms are (from the paper, top to bottom):

    (a) Relative kill rates of moss by expanding local icecaps on Baffin Island, determined by carbon-14 dating. (b) Global mass of volcanic sulfate aerosol in the stratosphere, estimated from sulfates in ice cores. (c) Temperature anomalies in southern Greenland (relative to the 1880–1980 mean), determined from borehole measurements. (d) Concentration of ice-loving microplankton in sediment cores from the shelf off Iceland’s north coast, a proxy for sea-ice accumulation there

  16. “The CLOUD results show that a few kilometres up in the atmosphere sulphuric acid and water vapour can rapidly form clusters, and that cosmic rays enhance the formation rate by up to ten-fold or more”

    -From CERN’s CLOUD press release

    “Our results suggest that the onset of the LIA can be linked to an unusual 50-year-long episode with four large sulfur-rich explosive eruptions, each with global sulfate loading >60 Tg.”

    -Abstract

    Interesting…

  17. Gaaah cancel above. Wrong diagram. The (partially) right labels are:
    A – don’t know
    B – Global mass of volcanic sulfate aerosol in the stratosphere, estimated from sulfates in ice cores
    C – Relative kill rates of moss by expanding local icecaps on Baffin Island, determined by carbon-14 dating
    D – not sure
    E – Concentration of ice-loving microplankton in sediment cores from the shelf off Iceland’s north coast, a proxy for sea-ice accumulation there
    F – Temperature anomalies in southern Greenland (relative to the 1880–1980 mean), determined from borehole measurements.

  18. I guess it must be a coincidence that solar minimums and colder weather happen at the same time. Why can’t it be that both solar and volcanic contributed to the situation? And what was the source for the volcanic eruption data? And the solar data? 600 to 700 years ago?

  19. So their computer says white ice, reflecting light, is more important than there being less light or more cosmic rays. Nice computer. Nice imaginary world.

    Using some skepticism on the LIA sunspot observations, however… Taking their volcanic activity at face value, might there have been enough stuff in the atmosphere to affect the observations of sun spots? I rather doubt that, as observing the sun deals with so much excess illumination that the sun spot counts are probably still correct.

  20. The LIA happened when and if it can be explained away. It takes powerful editorial forcings to keep that balance in place.

  21. Next they’ll explain that supervolcano eruptions are clustered every 1,000 years.
    (Minoan warm time, Roman, Medieval…)

    Maybe they’re even stupid enough to believe it themselves.

  22. A general question: TerryS mentioned carbon dating. That looks at Carbon 14 and its ratio to “normal” Carbon from atmospheric CO2 being incorporated into living things. We know that CO2 levels have fluctuated throughout history. Does carbon dating take these fluctuations into account?

  23. “I guess it must be a coincidence that solar minimums and colder weather happen at the same time.”

    Powerful enough volcano could influence the sun, right?

  24. Don’t forget, regulars here, you need to not believe this, because you already “know” that the LIA was caused by solar forcing.

  25. robert barclay says: April 12, 2012 at 8:49 am
    “Surface tension blocks heat and is the key to the climate on this planet. The only energy that goes into the ocean goes in via the sun’s rays. The ocean ignores the second law of thermodynamics.”
    ___________________________________
    HUH?

    Are you talking about this graph: http://lasp.colorado.edu/sorce/images/instruments/sim/fig01.gif

    It shows the wavelengths that penetrate to 10 meters below the ocean surface.

  26. The problem with volcanic eruptions as also the paper states is that the aerosol forcing is relative short lived. It could of course create some triggering mechanism, theoretically.
    Another factor which I guess the paper didn’t mention is that the cooling of the early 14 century happened to coincide with what is called the Wolf solar minimum.
    Hey could the sun have something to so with it?
    No, not according to the prevailing wisdom of today’s climate science, which seem to believe that climate forcing during the Holocene can only be explained by changes in the composition of the atmosphere, aerosols and nothing else.

  27. Sitting here reading this in the UK, from where I have also seen recent mention that Katla is showing signs of life in Iceland … hmmm.

    Resourceguy says: (10:00 am) … powerful editorial forcings …
    I like that! :-)

  28. I will add this other study to the discussion. Study of Dust in Ice Cores Shows Volcanic Eruptions Interfere with the Effect of Sunspots on Global Climate

    Seems Sunspots DO correlate with climate…. Unless volcanic action interferes according to this study of dust in Greenland ice cores, sunspots, and volcanoes. Combining the studies you end up with the Sun (solar insolation + magnetic field), Ocean and Volcanoes influencing the climate just as Joe Bastardi and many of the rest of us have been saying all along.

    The research, published in a paper in the May 15 [2002] issue of Geophysical Research Letters, provides striking evidence that sunspots — blemishes on the sun’s surface indicating strong solar activity — do influence global climate change, but that explosive volcanic eruptions on Earth can completely reverse those influences.

    It is the first time that volcanic eruptions have been identified as the atmospheric event responsible for the sudden and baffling reversals that scientists have seen in correlations between sunspots and climate…

    “By carefully studying the timing of other volcanic eruptions, we found that they coincided with all of the correlation reversals between sunspots and climate,” said Ram.

    A chart in the paper shows how six major volcanic eruptions between 1800 and 1962 occurred during precisely the same years when there were reversals in the correlation between sunspot activity and climate….

    According to Donarummo, it long has been known that volcanoes add more dust and more sulfates to the atmosphere.

    The UB team discovered that these additional sulfates cause cosmic rays to have a more pronounced effect on Earth by spurring the formation of small droplets in the atmosphere that, in turn, cause the formation of a type of cloud that does not produce rain.

    “During these times of high volcanic activity, the sunspot/climate correlation reverses and dust levels rise, even in the absence of high sunspots,” explained Stolz.

  29. I carried out a very detailed reconstruction of temperature from 1538 and in doing so compared the reconstrctions of Dr Mann and Hubert Lamb

    http://judithcurry.com/2011/12/01/the-long-slow-thaw/

    This covered a large period of the Little Ice Age. The name is a misnomer as although it might have included some extended cold periods there were many warm years also. Many of the summers were notably warm, it was the cold winters that often brought the averages down.

    Volcanos could well have had a sporadic and significant effect, combined no doubt with changes in the position of the jet stream and for some reason the weather patterrns often became ‘stuck’. (long periods of winter easterlies in the UK)

    However volcanos are only going to be one of a number of causes of the LIA periods and at times likely had little effect during the half millenium cited as the time scale of this event
    tonyb

  30. rgb @ duke

    I saw a graph of volcanic / earthquake activity, I think it might have been Landscheidt, but I can’t remember where.

    Anyway, it showed regular marked increases of activity during solar minimums. The two seem to go together, a double whammy for climate.

  31. I don’t buy it. We’ve seen the effect on climate from large volcanic eruptions. Remember Mount St. Helens, Mt. Pinatubo. The climatic effect from these were only 1-2 years. This is just another attempt at negating the effect of solar output on climate. There has been an ongoing effort in this area for about a year now. In a few months you’ll see a new paper from “The Team” pointing to this paper as proof that solar irradiance has no effect on climate.

  32. Interesting data, screwed up interpretation. That Miller et al. have been able to date expansions of the ice cap is a significant advance, but notice that the dates of these advances match neatly with sharp declines in solar-magnetic activity:

    LIA summer cold and ice growth began abruptly between 1275 and 1300 AD, followed by a substantial intensification 1430–1455 AD.

    Below is a graph of solar proxies from Usoskin 2003. It shows solar activity levels halving from 1200 to 1250, with an uptick before continuing to plummet after 1300, and it shows solar activity bottoming out around 1450:

    Yet Miller et al. pretend that their findings militate against a solar explanation, arguing that, thanks to their volcanic-amplification theory, “large changes in solar irradiance are not required.” This is just what the CO2 alarmists say about their CO2 driven models today. By adjusting a hundred parameters they can tweak their CO2 driven model to very roughly fit a hundred and fifty years of temperature data, so why should they bother to look at the evidence for other explanations when they are “not required”?

    Miller claims that “natural forcings are either weak or, in the case of volcanism, short lived.” But this depends on the unstated assumption that the only natural solar forcing is solar irradiance, when he has actually provided substantial evidence that solar activity has a stronger effect than can be accounted for by solar irradiance alone.

    Yes, it COULD be that volcanism induces feedback effects that amplify its cooling effects, and it could be that there is an amplification mechanism for solar effects, as Svensmark’s GCR-cloud theory predicts. Miller has actually provided substantial evidence in support of Svensmark’s theory, yet he refuses to note it, and actually presents his paper as an argument against a solar explanation. Another example of how every piece of data has to be twisted to favor the “consensus” anti-CO2 narrative and against the competing solar theory.

  33. Mad Scotsman says:
    April 12, 2012 at 9:08 am
    So the LIA did happen. Someone should tell Mann & Jones fast.
    ———————————————————-
    And what is the name of what happened before the LIA

  34. They seem anxious to avoid looking at the Wolf and Spoerer grand solar minima, which occured at the same time as their cooling initiation events.

  35. Looks like the html for showing the Usoskin figure does not work in the comments. You can view the graph here:

  36. A transient climate model simulation shows that explosive volcanism produces abrupt summer cooling at these times, and that cold summers can be maintained by sea-ice/ocean feedbacks long after volcanic aerosols are removed.

    Oh, good. Some more model results. And this model has proven accuracy? And references to these proofs of accuracy?

  37. robert barclay says:
    April 12, 2012 at 8:49 am
    Surface tension blocks heat and is the key to the climate on this planet. The only energy that goes into the ocean goes in via the sun’s rays. The ocean ignores the second law of thermodynamics.
    **************************************

    This garbage again? Why do people keep repeating this?

  38. The other fun part of connecting massive / multiple volcanic eruptions with cold snaps is mapping their frequency against solar cycles. There are a few who suggest periods of low solar activity have more eruptions. Pushback against this notion has been significant, as corellation does not suggest causation. Worse still, eruptions are not all that easy to find or date as you go back into the past. For example, the cause of the 535 AD event cooling down into the Dark Ages is unknown. There is an ongoing argument between advocates of a Krakatau eruption around then and advocates of a cometary impact somewhere. All in all, a fascinating mystery to unravel; one in which more data, more observations is always better than less. Cheers -

  39. Willis Eschenbach says:
    April 12, 2012 at 11:07 am
    Original paper available here …
    w.

    Thanks, what I’d really like to see is the SI, can you or Lief make that available? Thanks

  40. Wow, there have been 4 or 5 ‘new’ findings in the last few months that have put the kabosh on some of what skeptics have been saying such as this one, and the paper that shows CO2 leading temp.

    How nice that these are released just before Rio+20.

  41. Willis Eschenbach, thank you for the link to the original.

    The authors’ last sentence seems sufficiently modest: The
    coincidence of repeated explosive volcanism with centuries
    of lower-than-modern solar irradiance (Figure 2a) [Schmidt
    et al., 2011] indicates that volcanic impacts were likely
    reinforced by external forcing [Mann et al., 2009], but that
    an explanation of the LIA does not require a solar trigger.

    A belief in their result requires a belief in the accuracy of their model. But their paper highlights the fact that disentangling solar and volcanic “forcings” will not be easy, and multiple models (with conflicting interpretations) will likely be found to be equally accurate for the last 1,000 years’ temperature history.

    “Does not require” is complementary to the AGW proponents’ claim that any accurate model for the 20th century does require CO2. But multiple models have been produced that are as accurate as the IPCC models without “requiring” CO2. I think a fair assessment at this time is that the effects of the “forcings” can not be disentangled by complex modeling of the historical records because the forcings are “coincident”; and the anthropogenic CO2 effect is not very strong, at best, in the recent historical record.

    The paper adds valuable empirical evidence.

  42. What this is telling me is two fold

    1) That there is no longer any contradiction in the small changes in solar forcing and the relatively large change in the LIA. Good for the consensus view.

    2) The extended impact of these volcanic forcings suggests a major role for ocean circulation (natural variability) in translating external forcings into climate change. Good for the skeptic view.

    So something for everybody. Hoorah!

  43. The problems with the Miller et al paper are
    (i) it’s model-based
    (ii) it assumes that variation in the sunspot cycle only modulates solar irradiance, neglecting eg the solar cycle modulation of galactic cosmic rays reaching Earth’s atmosphere
    (iii) it doesn’t identify by location or date the specific volcanic eruptions

  44. I had a look at the SO4 measurements from the Greenland and Antarctica ice cores.

    They both show a really large eruption in 1258 AD (twice as large as Tambora) and then again in 1285 (Tambora size). Antarctica has two other Tambora sized eruptions around the time in 1269 and 1277 but these are not evident in Greenland. Antartica has one other very large eruption in 1455 AD.

    Interestingly they both have very large spikes for the 1971 Feugo eruption.

  45. The idea of one major eruption VEI6+ as a causative factor for the LIA may appear attractive, but what if there were several VEI2-4 level eruptions within a fairly short time frame? Surely those might have a greater cumulative effect on airborne aerosols than just one massive eruption.

  46. Schroder says: @ April 12, 2012 at 10:28 am

    The (btw very good) Eruptions blog has this to say about the last study about this subject…
    __________________________________
    Your buddy (Erik Klemetti, an assistant professor of Geosciences at Denison University) over at Wired have also taken a look at this study.

    Volcanoes and the Little Ice Age: Not the Smoking Gun?

    ….I wanted to try to identify the volcanoes in questions – likely eruptions that were at least VEI5-6 to allow for a large plume and maximum dispersal of volcanic aerosols like sulfur dioxide. However, some eruptions do release more sulfur dioxide than their size might imply – so we need to keep that in mind.

    Potential culprits for 4 large explosive eruptions between 1275-1300 AD:
    Quilotoa, Ecuador (VEI 6 in 1280)

    And that’s it. So, unless Gao et al. (2008) or Miller et al. (2010) know something we don’t, there are a number of mystery eruptions in that period….

    He goes on to discuss whether there is any supporting data on volcanoes for this theory.

  47. “Northern Hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes.”

    Can somebody explain that, because it doesn’t make sense to me. If the earth wobbles like a top, with one complete wobble every 26,000 years, then if it is summer now in the NH when the earth is on this side of the sun, then in 13000 years, it will be summer in the NH when the earth is on the other side of the sun.

    But the same amount of heat will be received by the NH from the sun in summer, whether the earth is on one side of the sun or another. And it will be the same for the other seasons and for the SH.

    If the amount of earth’s axial tilt were to change, that would make for a different amount of heat being received during the NH’s summer, but that is not what happens during the wobbling.

  48. kramer says:
    April 12, 2012 at 11:58 am

    Wow, there have been 4 or 5 ‘new’ findings in the last few months that have put the kabosh on some of what skeptics have been saying such as this one, and the paper that shows CO2 leading temp.

    How nice that these are released just before Rio+20.
    ______________________________________
    And all of them are PAL- reviewed by HONEST upstanding scientists like Peter Gleick. Too bad the public is no longer buying the propaganda, only the Regulating Class is still on board the bus. Of course the Regulating Class are the ones with all the political power.

  49. “robert barclay says: April 12, 2012 at 8:49 am
    Does that mean the Maunder and the Dalton minimum didn’t happen. Surface tension blocks heat and is the key to the climate on this planet. The only energy that goes into the ocean goes in via the sun’s rays. The ocean ignores the second law of thermodynamics.”

    There are also about 5,000 ocean floor volcanoes that can put heat into the oceans. Now I have no idea if active volcanoes on land release stress in the crust enough to quiet down the ocean floor volcanoes or if there is some other mechanism (ie. Piers Corbyn’s ideas) as to how solar can influence volcanoes.

  50. Is there not evidence of increased volcanic activity coinciding with lower solar output ?. A combination of both over a period is not beyond the boundaries of possibility.

  51. A beautiful painting by Avercamp, although it’s worth noting that Bruegel the Elder painted similar painting 40 years before in 1565:

    Bruegel set this style of painting which influenced Avercamp. He was also the first landscape painter. It has been argued that the harsh winters forced this change of style away from paintings where landscapes were stylised, Italianate and idyllic backdrops to more realistic scenes peopled with ordinary people. The harsh conditions may well have precipitated the Reformation.
    I thought the climate had been benign and stable until recently. However, Bruegel and Avercamp are just painters so what would they know? (/satire)

  52. Here’s some related things I’d like to see examined and discussed.

    http://www.sciencenews.org/view/generic/id/332612/title/Small_volcanoes_add_up_to_ cooler_climate

    Small volcanoes add up to cooler climate

    Airborne particles help explain why temperatures rose less last decade

    By Alexandra Witze August 13th, 2011; Vol.180 #4 (p. 5)

    Along with sulfur emitted by coal-burning power plants, volcanic particles spewed high in the atmosphere reduced the amount of global warming otherwise expected during the 2000s, a new study finds…

    Volcanoes affect upwelling and ocean currents as static heat sources

    NPG – Abstract – The effect of a localized geothermal heat source on deep water formation

    http://www.nonlin-processes-geophys.net/18/841/2011/npg-18-841-2011.html

    Explosive volcanic eruptions triggered by cosmic rays: Volcano as a bubble chamber 10.1016/j.gr.2010.11.004 : Gondwana Research | ScienceDirect.com

    http://www.sciencedirect.com/science/article/pii/S1342937X10001966

    http://www.deepdyve.com/lp/elsevier/explosive-volcanic-eruptions-triggered-by-cosmic-rays-volcano-as-a-3p053jxP0S

  53. You see, I don’t think the timing matches historical (anecdotal) reality. The LIA in Europe really didn’t hit until 1314/5 and in fact the years immediately preceding were supposed to be quite warm, an Indian Summer of the MWP, even.
    What would the time lag be, if you had some mega eruption in South America, how long would it take to affect the weather in Europe and how long would this effect last ? If Katla blew her top, would Europe south of Scotland really be affected ? Wouldn’t the winds blow the clouds over Scandinavia and Russia ?
    This volcano stuff sounds seductive, but a single eruption ( or 4 ) isn’t going to screw the weather for 50 years or so, feedbacks notwithstanding. The LIA eased off a bit in the 16thC and then really swung between baking summers and freezing winters in the 17thC, so what else caused this “second wind” in the LIA ?

  54. I think there have been too many other volcanoes at other times for the volcanic theory to work.

    Cosmic Rays on the other hand.

    “Close similarities are evident between the temperature and GCR records, showing an association of high GCR flux with a cooler climate, and low GCR flux with a warmer climate. This pattern has been extended over the last two millennia by a reconstruction of Alpine temperatures with a speleothem from Spannagel Cave in Austria (Fig. 3) [40]. Temperature maxima in this region of central Europe during the Medieval Warm Period were about 1.7C higher than the minima in the Little Ice Age, and similar to present-day values. The high correlation of the temperature variations to the 14C record (Fig. 3) suggests that solar/cosmic ray forcing was a major driver of climate over this period.”

    http://arxiv.org/pdf/0804.1938.pdf$$yFulltext

    Surveys in Geophysics 28, 333–375, doi: 10.1007/s10712-008-9030-6 (2007).

  55. It is also worth noting that the worst Plague to hit Europe (and the World) was during this cold period, reducing Europes population by 50%. Before that It seems the cold that followed the end of the MWP brought smaller harvests followed by death and disease:

    http://en.wikipedia.org/wiki/Black_Death

    “In Europe, the Medieval Warm Period ended some time towards the end of the 13th century, bringing the “Little Ice Age” and harsher winters with reduced harvests. In northern Europe, new technological innovations such as the heavy plough and the three-field system were not as effective in clearing new fields for harvest as they were in the Mediterranean because the north had poor clay soil. Food shortages and rapidly inflating prices were a fact of life for as much as a century before the plague. Wheat, oats, hay and consequently livestock were all in short supply. Their scarcity resulted in malnutrition, which increases susceptibility to infections due to weakened immunity. Consistently high fertility rates, at five or more children per woman throughout Europe, resulted in high population growth rates and contributed to food shortages. In the autumn of 1314, heavy rains began to fall, followed by several years of cold and wet winters. The already weak harvests of the north suffered and the seven-year famine ensued. In the years 1315 to 1317 a catastrophic famine, known as the Great Famine, struck much of northwest Europe. It was arguably the worst in European history, reducing the population by perhaps more than 10 percent.”

    So which is worse, warming or cooling?

  56. The paper seems to point the finger at decreased solar insolation as the direct cause of the LIA, but as noted above, the LIA was characterized by frequently warmer summers but colder winters, which indicates decreased cloud cover, which would result in increased insolation.

    Which suggests to me the cause was volcanoes plus something else. That something else could well be anthropogenic as post 1300 there were large human population declines, from famine, the Black Death and wars. I don’t find persistent sea ice convincing. Sea ice is a negative feedback to cooling as it acts as an ocean insulator.

  57. Small volcanoes add up to cooler climate
    Airborne particles help explain why temperatures rose less last decade

    The climate models over-estimate volcanic aerosol cooling by a factor of 2 or 3. They are one of the main ways the models fiddle the fact their GHG warming predictions are nowhere near reality. Note there no actual measurements in that study, just models.

    There hasn’t been a large volcanic eruption since 1991. Yet the climate has cooled, when the models say it should be rapidly warming.

  58. Brian R says
    I don’t buy it. We’ve seen the effect on climate from large volcanic eruptions. Remember Mount St. Helens, Mt. Pinatubo.
    ————
    These 2 eruptions were babies. So you saw very little effect. A repeat of Tambora you would definitely notice.

  59. higley7 says
    Those worthless models again—they still do not include solar cycles and the solar/cosmic wind connection.
    ———–
    I bet the models do include solar cycles.

  60. Yes this paper was disccused on WUWT last January and as “Schroder” points out via his link http://www.wired.com/wiredscience/2012/01/volcanoes-and-the-little-ice-age-not-the-smoking-gun/
    Miller et al have cooked the books in what amounts to a pathetic display of pal review by the so called reviewers.

    This paper should be exposed as a sham supporting AWG and not a reliable scientific document. Miller has used the world sulfur dioxide record instead of the northern hemisphere record to support his views. If the southern hemisphere volcanoes do not show up in the northern hemishere record how can they affect moss growth?? When looking at the northern hemisphere record in isolation the Miller et al claims look very weak.

    Why wasnt this picked up in peer review?

    OT…is anyone else using modzilla and XP having trouble with the comment window in wordpress blogs? I have to press enter to display the full size text box and the spell checker has gone.

  61. rgb.
    Robert, a few conversations I had with the late Jan Pompe centred around the possibility that there might be a correlation between low Solar activity and volcanism. We never reached a conclusion unfortunately.

    Sea Ice. Jan and I also discussed this. I posited here a few years back that a reduction in sea ice would be a negative feedback. My posit then and now is that due to the low incidence at minimum, the albedo change would be minimal. The loss of energy from open water would be huge.

    Now a rant obout terminology. People talk about precession when what they really mean is nutation. Do your gyroscopic physics folks!
    Incidentally. When nutation becomes too large, A gyro will topple, wonder if that has ever happened before!

    DaveE.

  62. OT…is anyone else using modzilla and XP having trouble with the comment window in wordpress blogs? I have to press enter to display the full size text box and the spell checker has gone.

    ^^^ Yes, but it seems fine with Moz+Ubuntu. Weird.

  63. Joe Zarg says:
    April 12, 2012 at 1:01 pm

    “Northern Hemisphere summer temperatures over the past 8000 years have been paced by the slow decrease in summer insolation resulting from the precession of the equinoxes.”

    Can somebody explain that, because it doesn’t make sense to me…..
    _______________________________
    Try this website with good animation illustrating Obliquity, Eccentricity, and Precession: http://www.sciencecourseware.org/eec/GlobalWarming/Tutorials/Milankovitch/

    or this for a written explanation: http://www.indiana.edu/~geol105/images/gaia_chapter_4/milankovitch.htm

    Further reading: (New info) http://motls.blogspot.com/2010/07/in-defense-of-milankovitch-by-gerard.html

  64. John M says:
    April 12, 2012 at 6:28 pm

    Aha! I knew the Earth’s temperature was self-regulating, since we now know (hey I read it in The Telegraph) that climate change causes volcanoes to erupts.

    http://www.telegraph.co.uk/earth/environment/climatechange/7604188/Volcanic-ash-cloud-Global-warming-may-trigger-more-volcanoes.html

    See? Warming = volcanoes = cooling…now we just have to wait.
    _____________________________________
    But maybe not for long….

    Another Icelandic Volcano Is Rumbling

    Katla, yet another huge Icelandic volcano, is showing signs that it may soon erupt and cause chaos to world air transport.

    Al Jazeera reports that earth tremors around the immense volcano are leading to concerns that an eruption could have both profound effects on Iceland’s landscape, as well as disrupting travel worldwide….

    However it has been quiet recently: http://en.vedur.is/earthquakes-and-volcanism/earthquakes/

  65. The Little Ice Age did indeed begin suddenly, but it had multiple phases (at least 5). All of these phases seem to be related to the same causal mechanism and correlate exactly with solar events (Sporer Minimum, Maunder Minimum, Dalton Minimum, 1880-1915 Minimum, 1945-1977 minimum). One episode of volcanism doesn’t prove anything–explosive volcanic eruptions are common occurences and most are associated with only a year or two of cooling. Hence, volcanic eruptions are not likely suspects for prolonged or repeated cooling. All 5 of the cold phases of the Little Ice Age are not related to unusual volcanic activity. Correlating some volcanic eruptions with cooling doesn’t prove the cooling was caused by the volcanic activity. If you like correlations, the excellent correlation of cooling with solar events is a much better match. Sorry–volcanism won’t do the job.

  66. Obvious question, I suppose, but are the 4 eruptions identified in the paper & are they independently confirmed by other studies ???

  67. Don Easterbrook cites real world empirical data to support a robust explanation of the cause of the LIA. In contrast, Pielke Snr cites a study that uses a model that proposes a different causal explanation – one that Don points-out actually doesn’t fit with historical pattern of the LIA.

    This might be an opportunity for readers to self-assess whether they might be prone to inexplicable outbursts of politically-motivated alarmism.

    Q. Which of the following do you consider is likely to provide a better causal explanation of an observed phenomenon in the real physical world:

    a) a model of reality which doesn’t correspond with the observed pattern of the phenomenon in question?
    or
    b) data from the real physical world which does correlate with the observed pattern of the phenomenon in question?

  68. Don Easterbrook (April 12, 2012 at 7:17 pm) concisely asserted:
    “Sorry–volcanism won’t do the job.”

    Agree (but the baseball bat will convince many to “see” otherwise).

  69. robert barclay says:
    April 12, 2012 at 8:49 am

    The ocean ignores the second law of thermodynamics.

    Don’t be silly.

  70. The key thing with snow-ice cover will be how long it lasts into the summer. The albedo effect can only be strong for as long as the snow-ice remains.

    If big volcanoes produce ‘summers without summers’ (1816 apparently did), then the argument is logical.

    Does scientific archaelogy yet have the ability to identify cooler summers without necessarily having colder winters? That might be a key thing to investigate…….

  71. Jeff L says:
    April 12, 2012 at 8:16 pm

    Obvious question, I suppose, but are the 4 eruptions identified in the paper & are they independently confirmed by other studies ???
    ___________________________________
    An Article about this paper discusses that issue. Volcanoes and the Little Ice Age: Not the Smoking Gun? by EriK Klemetti.

    “Erik Klemetti is an assistant professor of Geosciences at Denison University. His passion in geology is volcanoes, and he has studied them all over the world.”

  72. The most powerful physical process which controls global climate is overturning ocean circulation, because it works like heat pump cooling the ocean and heating atmosphere. And intensity of this circulation is critically controlled by sinking of warm salty waters at the rim of marine ice near Greenland. Forming of near-bottom return current depends on details of sea bottom topography at sinking site, so the position of this rim is of primary importance for intensity of overturning circulation and heat balance between ocean and atmosphere. This establishes a positive feedback loop: slowing down of overturning circulation cools Arctic basin first and leads to sea ice expansion which slows down the circulation even more. All other forcings – cloud cover, orbital wobbling, snow-ice cover or volcanism – work only through this amplification mechanism, which, being based on positive feedback, provides also natural oscillatory behavior at different time scales, that is, auto-oscillations which can be phase-locked with external periodical forcings. Many different forcing mechanisms can be involved, but it always necessary to remember that they apply to a system which is inherently unstable and can powerfully amplify their effects by natural predilection for oscillations.

  73. Geoff Sharp (April 12, 2012 at 5:14 pm) asked:
    “Why wasnt this picked up in peer review?”
    ___________________
    Paul Vaughan says: @ April 12, 2012 at 10:10 pm
    You have faith in peer review?
    By nature it’s socially corrupt.

    When no one’s qualified to supervise:

    http://en.wikipedia.org/wiki/Peter_Principle

    _____________________________
    Here is an even better example of the problem.
    An Article on scientist falsifying data in Scientific American declaring there is no real problem acording to a “study” done by the vice provost of Caltech.

    …The reason that it is so rare (compared with, say, corruption in politics) is that science is designed to detect deception (of one’s self and others) through colleague collaboration, graduate student mentoring, peer review, experimental corroboration and results replication. The general environment of openness and honesty, though mythic in its idealized form, nonetheless exists and in the long run weeds out the cheats and exposes frauds and hoaxes, as history has demonstrated…. http://www.scientificamerican.com/article.cfm?id=when-scientists-sin&page=2

    So how does this hand wavy “Study” published in Scientific American stack up against actual surveys?

    How Many Scientists Fabricate and Falsify Research? A Systematic Review and Meta-Analysis of Survey Data

    Abstract

    The frequency with which scientists fabricate and falsify data, or commit other forms of scientific misconduct is a matter of controversy…. This is the first meta-analysis of these surveys.

    To standardize outcomes, the number of respondents who recalled at least one incident of misconduct was calculated for each question, and the analysis was limited to behaviours that distort scientific knowledge: fabrication, falsification, “cooking” of data, etc… Survey questions on plagiarism and other forms of professional misconduct were excluded. The final sample consisted of 21 surveys that were included in the systematic review, and 18 in the meta-analysis….

    A pooled weighted average of 1.97% (N = 7, 95%CI: 0.86–4.45) of scientists admitted to have fabricated, falsified or modified data or results at least once –a serious form of misconduct by any standard– and up to 33.7% admitted other questionable research practices. In surveys asking about the behaviour of colleagues, admission rates were 14.12% (N = 12, 95% CI: 9.91–19.72) for falsification, and up to 72% for other questionable research practices.

    Considering that these surveys ask sensitive questions and have other limitations, it appears likely that this is a conservative estimate of the true prevalence of scientific misconduct…

    Of course the Climategate e-mails and the experiences of scientists show journals now run according to “Pal-Review”

    EXAMPLES:
    2003: Michael Mann on what “the community” should do to punish a journal that dared to print dissenting views on the climate hoax and
    2007 Mann email to Phil Jones: “I have a top lawyer already representing me…Wei Chyung needs to sue them, or at the least threaten a lawsuit…The threat of a lawsuit alone my prevent them from publishing this paper, so time is of the essence” There is lots more interesting stuff at Over 250 noteworthy Climategate 2.0 emails

  74. It is not a case of either/or. Solar forcings do exist, and sulfates in the atmosphere (or lack of them) can be effected by the solar forcings.

    We need to think about both sunbeams and volcanoes, and likely other factors as well, including the small influence of CO2.

    Furthermore, we need to play about with the simple fact each action creates a reaction. Think of it in terms of water sloshing in a bathtub. As a small child, I could irritate my parents by timing the movement of my butt in such a manner as to generate a super-slosh. In the same manner, two large volcanoes five years apart might have a very different effect from two volcanoes of the exact same size seven years apart.

    Great science is done in bathtubs, you know.

  75. Dr. Iben Browning wrote and lectured on volcanoes and climate for decades. He made the Little Ice Age connection years ago. His daughter now has a newletter on the subject. He gave very interesting lectures. His book is called “Climate and the Affairs of Men.”

  76. @Sergey (April 13, 2012 at 1:52 am)

    Wind’s more primal.
    It’s role in evaporation and mixing can’t be ignored.
    It’s driven by temperature _gradients_.

    Sensible climate narratives must be consistent with Earth Orientation Parameter (EOP) records.


    Climatologists NEED to VERY CAREFULLY learn how to use EOP to trim by orders of magnitude the set of permissible model states.

  77. robert barclay says: April 12, 2012 at 8:49 am
    “Surface tension blocks heat and is the key to the climate on this planet. The only energy that goes into the ocean goes in via the sun’s rays. The ocean ignores the second law of thermodynamics.”

    Robert, this makes no sense, particularly the last statement.

    Yeah, I already pointed this out in another thread — it almost looks like he’s cut and pasting a paragraph from a third place. The ocean, like everything else, obeys all of the laws of thermodynamics and surface tension has virtually no effect on heat transmission and is utterly irrelevant to the Earth’s climate. It is true that most of the heat that goes into the upper ocean goes in via the Sun’s rays, although I’m certain that there is a steady outflow from the Earth’s interior at the bottom that is low in intensity (power per unit area) but high in aggregate power and at least a moderate amount of heat exchange at the surface from conduction and infalling latent heat, e.g. a warm rain on a colder sea.

    But asserting that anything violates the second law just makes it instantly clear that the speaker or writer is a nut. It gives climate skeptics in general a bad name, even though most of us are actually sane and know better.

    rgb

  78. Try this website with good animation illustrating Obliquity, Eccentricity, and Precession: http://www.sciencecourseware.org/eec/GlobalWarming/Tutorials/Milankovitch/

    Although I’m already familiar with the idea, I visited this to see if something had changed. It hadn’t. To be honest, the correlation of any subset of precession, obliquity, and orbital resonance with climate sucks. The best that can be said of it is that orbital resonance kind of works for the last 600,000 years (but utterly fails for earlier periods) and some combination of obliquity and precession sort of works before that for a while (but utterly fails now or still earlier) and that before that, there isn’t any correlation at all between these cycles and either the general depression of the global mean temperature that started some 5 million years ago or the “fluctuation noise” around this mean temperature.

    Yes, there are probably some resonant amplifications in the fourier spectrum of the noise associated with the period. No, they do not appear to make a particularly good explanation of why the Earth was 2 K warmer 5 million years ago than it is in the present, why that temperature at first gradually, then much more rapidly decreased by some 8 K, then stabilized some 6K cooler than the present but with geologically brief excursions up 6 K (to the present warm interglacial temperatures) and nearly catastrophically deadly and equally brief excursions down by up to 4K (to where atmospheric CO_2 comes very close to reaching the lower boundary of sustaining plant life outside of the ocean).

    At least I have yet to see it. Personally, I think this explanation sucks. The best it can do is suggest that Milankovitch is capable of acting as a resonant trigger between states that are stabilized by something else, with the mean temperature in the cold phase in particular having nothing to do with orbital resonances, precessions, or obliquity per se.

    rgb

  79. Caleb says:
    April 13, 2012 at 3:27 am
    science … bathtubs…

    So, are you going to change your tag to “Archimedes”?
    ;)
    /9-p

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