Study: Ice sheets may melt rapidly in response to soot from distant volcanoes

Study of ancient eruptions shows modern ice sheets could be vulnerable

From THE EARTH INSTITUTE AT COLUMBIA UNIVERSITY and the “dirty ice” melts faster department

Volcanic eruptions have been known to cool the global climate, but they can also exacerbate the melting of ice sheets, according to a paper published today in Nature Communications.

Researchers who analyzed ice cores and meltwater deposits found that ancient eruptions caused immediate and significant melting of the ice sheet that covered much of northern Europe at the end of the last ice age, some 12,000 to 13,000 years ago.

“Over a time span of 1,000 years, we found that volcanic eruptions generally correspond with enhanced ice sheet melting within a year or so,” says lead author Francesco Muschitiello, who completed the research as a postdoctoral fellow at Columbia University’s Lamont-Doherty Earth Observatory.

These weren’t volcanoes erupting on or near the ice sheet, but located a thousand miles away in some cases. The eruptions heaved huge clouds of ash into the sky, and when the ash fell on the ice sheet, its darker color made the ice absorb more solar heat than usual.

“We know that if you have darker ice, you decrease the reflectance and it melts more quickly. It’s basic science,” says Muschitiello. “But no one so far has been able to demonstrate this direct link between volcanism and ice melting when it comes to ancient climates.”

The discovery comes from the cross-sections of deposits, called glacial varves, most of which had been collected in the 1980s and 1990s. Varves are the layered sediments that form when meltwater below an ice sheet routes large amounts of debris into lakes near the sheet’s edge. Like the rings of a tree, the layers of a glacial varve tell the story of each year’s conditions; a thicker layer indicates more melting, since there would have been a higher volume of water to carry the sediment.

Sediments deposited by ice sheet meltwater provide clues about ancient climates, as well as the future effects of global warming. CREDIT Francesco Muschitiello

The team also compared the varves to cores from the Greenland ice sheet, whose layers contain a record of ancient atmospheric conditions. Testing of those layers for sulfates revealed which years experienced explosive volcanic eruptions, which tend to release large amounts of ash. Matching up the ice layers with varve layers from the same time periods, the team found that years with explosive volcanic activity corresponded to thicker varve layers, indicating more melting of the northern European ice sheet.

Muschitiello and his colleagues studied a period ranging from 13,200 to 12,000 years ago, when the last ice age was transitioning into today’s warm climate. They focused specifically on volcanic eruptions in the northern high latitudes–events similar to the 2010 eruptions of Iceland’s Eyjafjallajökull volcano. Although that eruption was relatively minor, its large ash cloud shut down air traffic across most of Europe for about a week.

How much melting could an eruption like that cause? “It’s difficult to put an exact number to it,” says glaciologist and coauthor James Lea from the University of Liverpool. “It depends on many factors.” Running thousands of model simulations, the team found that the amount of melting depends on the individual eruption, which season it occurs in, the snowpack conditions at the time, and the elevation of the ice sheet. “Change any one of these and you would get different amounts of melt,” says Lea. In the worst scenarios, the model predicted that ash deposition would remove between 20 centimeters and almost one meter of ice from the surface of the highest parts of the ice sheet.

The model results should be taken with a pinch of salt, Muschitiello cautions, due to uncertainties about past conditions. However, because the team simulated a very broad range of potential conditions, he’s confident that the ice sheet’s real response lies somewhere within their range.

Michael Sigl, a paleoclimatologist from the Paul Scherrer Institute in Switzerland who wasn’t involved in the new study, says the hypothesis that ash particles might counteract the cooling effects of volcanic eruptions is intriguing. But, he said, “coincidences in the timing of rapid ice-sheet melting events and eruption dates do not automatically imply causation, and there may be other scenarios that could be consistent with the presented data.” Sigl’s own work has found a link between eruption-induced ozone depletion and deglaciation in the Southern Hemisphere. Nevertheless, he says, the new study shows that more work is needed to understand the effects of aerosol emissions from volcanic eruptions.

The preliminary results suggest that “present day ice sheets are potentially very vulnerable to volcanic eruptions,” says Muschitiello. They also point to a possible hole in the climate models that scientists use to make predictions about the future: Models currently don’t simulate the ice sheets’ response to changes in particulate deposition from the atmosphere in an interactive way.

Another intriguing implication is that previous research has suggested that melting ice sheets and glaciers could increase the frequency of volcanic eruptions in glaciated areas by lightening loads on earth’s crust, allowing underlying magma to rise. If the link between volcanism and ice sheet melting is confirmed, it could indicate the presence of a so-called “positive feedback loop” in which eruptions exacerbate melting, and more melting causes more eruptions, and so on.

Muschitiello says the study “can give us hints about the mechanisms at play when you’re expecting rapid climate change.”


The paper, “Enhanced ice sheet melting driven by volcanic eruptions during the last deglaciation,” is available from the authors or After it is published, it will appear online at

76 thoughts on “Study: Ice sheets may melt rapidly in response to soot from distant volcanoes

  1. They may melt, as they have no doubt done in the past, but would they re-freeze to the same extent ? It appears that the loss of ice is due to a lack of re-freezing than actual melting. The end result is the same, but such a process would have a marked effect on volcanic processes such as this.

    • Why sit in front of their computers playing computer games/simulations when this could be an ideal subject for experiment in the field?
      You could seed 10metre square plots of ice with varying quantities and types of volcanic ash and see what happens when the sun shines instead of speculating.
      As we keep being told the sunshine is free and it would do everyone good to be out in the open air doing some real science!
      In agriculture most experiments are done on real live crops. At Rothamsted research station they have had a fertiliser experiment going in Broadbalk Field for over 150 years.

      • You can seed the ice with volcanic ash and by the next morning it will be hidden by a layer of frost. Ice sheets form for a reason. They don’t sit there waiting for something to come along and melt them.

        I love their conclusion that ash deposition coincides with warming except when it doesn’t.

      • Key Words, Geologist, Pizza, Beer
        Yea, StephenP you are right, go into the field and set up an experiment. This paper is again about explosive volcanism, whereas its the quiet type you might see registering a greater effect. I was in Panamint Valley, the first valley west of Death Valley and stopped by the shack of a hermit and asked him if we could bring anything from town. He said two frozen pizzas and two six packs of beer. We did so and when we stopped back by his shack he said give me one of the pizzas and open three beers one for each of us. He then went over to a large black basalt border, think Deccan Traps, Siberia, Columbia River Basalts, etc, but this from a local source. He opened the pizza and dropped it on the large boulder and it immediately began sizzling. By the time the beer was half empty the pizza was cooked. You can not do that with explosive volcanism, or limestone, or any other rock. The large flood basalt events need more respect that the showey explosive types. Think of this pizza boulder times an extremely large surface area and the effect continues for many decades before weathering produces soil profiles and whatever vegetation.

      • Because going into the field might mean you would have to face the trials and tribulations of real weather. In other words you might get really cold or fall into a crevasse. You can’t go to the local bar then home each night and probably have to camp out in a tent while wet and cold. Many scientists tried field work and decided they hated. Sitting in front of a computer and going to meetings is more their style. This assessment from a field biologists that spent 20 years in the field. I saw more than one marine scientist deathly sea sick, complained about the cold and generally wishing the trip was over. If they were recording data we double checked.

    • Just part of the NATURAL AMO cycle.

      1979 was an EXTREME level of sea ice in the Arctic.

      Even now after a slight RECOVERY (downwards) from that extreme, the level is STILL above what it has been for 90-95% of the last 10,000 years.

    • After melting, the surface water runs off to lower levels though moulins; and escapes along the bedrock, where temperatures are higher. There is a constant stream running under most glaciers.

      • Except when there isn’t. Moulins only exist in marginal areas of temperate ice-sheets. Try finding one in Antarctica or central Greenland for that matter.

    • They are conveniently leaving out the volcanic ash winters that would follow a series of large ash-releasing eruptions. We are talking more ice not less and then melting. Clearly the ash layer would be mostly buried in a year or two by the next winter’s snow. Five years and its buried. That much melt water would also tend to wash the ash away from the areas that are melting. A number of features here appear to be ignored in their thinking.

    • Yup, Gareth.

      The reason these ice sheets exist is because they get a LOT of snowfall. Even a very thin layer of fresh snow or frost would instantly negate the effect of ash deposited below. Sure, then there will still be more deposits of ash until the ash cloud disappears,intermingled with lots of fresh snow. More ash and particulares in the air also results in, guess, what, more precipitation, in the form of snow.

  2. “Like the rings of a tree, the layers of a glacial varve tell the story of each year’s conditions; a thicker layer indicates more melting.”
    I love this – “Like the rings of a tree” which Mannites believe can be an accurate proxy for paleo-temperatures.
    Except that tree rings and lacustrine varves can be thicker or thinner for several reasons, none of which might accurately imply paleo-temperature, or indeed volcanic emission variations. The tree ring-temperature link is palpable nonsense. I suspect that this sediment thickness-volcano link may not be far behind.

    • Ian Magness

      It’s like anything else in ‘commercialised’ science. A conclusion must be reached to justify the funding therefore one of innumerable possibilities must be shown to be true.

      What we don’t see are the failed experiments, of which, there should be far more than successes. After all, scientists are more often wrong than right else there would be no need for experiments.

  3. That study sounds like science was being done, but what on earth does this gibberish mean: ‘the study “can give us hints about the mechanisms at play when you’re expecting rapid climate change.”’? Is it just ill-fitting de rigueur boiler-plate that some editor insisted on? Has someone tried to hijack the paper to make it more 97%-ish?

  4. The usual final sentence:
    “Muschitiello says the study “can give us hints about the mechanisms at play when you’re expecting rapid climate change.””
    I’m not expecting rapid climate change.

  5. lled “positive feedback loop” in which eruptions exacerbate melting, and more melting causes more eruptions, and so on.

    and that (my supposition) is why we are her now discussing this – and why have the time & resources available to waste playing with computers.
    Earth has been inside 2 major snowballs (at least) and is presently in a succession of minor ones – ice ages & interglacials.

    Without ‘something’ to ‘break the ice’ we’d remain stuck there forever.
    Whatever breaks the ice usually brings a planet-load of new plant food and it is The Plants, via their control of water, that creates the balmy climate we have come to expect.
    When the plants run out of food, they die, fill the sky with CO2 & dust and place freezes.
    If you’re unlucky, like Planet Mars, the frozen water simply sublimates away into space

    Dis anyone watch the rabid warmists over at Wunderground while Ophelia strutted her stuff?
    They nearly choked trying to explain a cold sea and a hurricane – finally muttering an admission that some perishingly cold air above the ocean powered up the storm.
    A monster thing called the polar vortex, starts at minus 50degC and gets colder and so close we can nearly stand on tippy-toes and touch it. And we’re concerned about getting too warm!!!!!!!! Madness.
    Is cold what lifted Harvey and Irma out of the water? Our man ‘ren’ seemed to think so with all the graphics (s)he posted

    And see what weather the UK got with Ophelia?
    Dust filled sky, strong wind blowing, a faint red coloured sun that produced totally zero output from the nation’s solar panels that day.
    Yes the air temp was high, but why, what with the GHGE supposedly warming the surface, did my datalogger under 12″ of dirt not even register OIphelia’s presence? It saw 14degC and falling, the twin logger 5ft off the ground above it saw 21degC, peak.
    Warm Saharan air we were told but deserts are cold places, there is very little energy in them.

    Just like the Martians had to put up with.
    But when they got to named dust-storm Zebedee 97, on Valentine’s Day, they packed up and left.

  6. “can give us hints about the mechanisms at play when you’re expecting rapid climate change.”

    We should remember that the climate change is a stick with two ends (warm and cold)
    This is not the Mann’s hockey stick
    It is climate change carrot stick
    While the warming was going on, the carrots became plentiful in number of ways, more efficient food production, longer growing seasons, less winter heating fuel used, greening of the planet, etc..
    Notice that on the cold end there are no carrots for anyone, just bitter misery for millions or even billions of the poorer sections of the planet’s population.

  7. Sediment thickness is controlled by many things including the nature of the delta of deposition and where channels are bringing in sediment. The particle size varies with the velocity of the water related to distance from land. It takes longer for the same amount of fine sediment to accumulate. So a large population of a delta area would have to be sampled to see if the cores even remotely correlate. Probably not.

    • DK,
      I believe the varves are very fine-grained. Rock flour from the Summer melt, and a predominance of algal and diatom detritus during the Winter die-off. These accumulate in the lakes, not the distributary plain immediately below the glacial terminus.

    • Agreed!

      I always thought faster water carried and deposited more sediment as it slows down.
      Water obstacles that slow water velocity remove the larger particles before the meltwater enters a melt pond.

      Water events could include heavy rainstorms that briefly increase sediment loads.

      Even slow moving sediment carrying rivers drop much of their sediment load when encountering a dam.

      Leaving a lot of gross assumptions regarding varves.

  8. That’s what alarmists need, an exacerbated feedback loop to go with their Fruit Loop catastrophism.

    Believe it or not, when ash falls on snow thousands of miles away, snow falls on top of the ash and hides it with a perfectly white thin blanket of crystals.

    It seems ash fall causes melting except in those places where it doesn’t. Pardon me while I reflect on that.

  9. Volcanic ash falls on glaciers, which on the uppermost surface is uncompressed snow. It would seem to me that this uppermost snow level is going to turn to ice quicker with the ash in it and be buried under more snow negating the albedo until it is exposed again in a denser medium of ice. The new ice is much denser and more resistant to melting for given sunny heat days, hence it stays ice longer than perhaps melting quicker or sublimating away if it had just stayed snow. The chaos of the timing of the volcanic eruption itself will make every eruption site specific as regards to the season of the year. An eruption in spring/summer would have a quicker and different effect than an eruption in fall/winter being buried under further snowfall.

      • No. Dirty ice melts from the top and much faster than clean ice. But only when there is sunlight that can be absorbed by the dirt.

  10. “These weren’t volcanoes erupting on or near the ice sheet, but located a thousand miles away in some cases. The eruptions heaved huge clouds of ash into the sky, and when the ash fell on the ice sheet, its darker color made the ice absorb more solar heat than usual.” — This is not true always

    — Winter six months no solar energy — cloud cover
    — Summer six months with cloud cover
    — advective energy [warmer or cooler] do not act like solar energy
    — general circulation pattern and wind flow/jet streams patterns, etc

    Dr. S. Jeevananda Reddy

    • It is indeed complicated. If soot caused the Arctic ice pack to thin then the overlaying air would be warmed. link In other words, the process of losing heat to outer space would be accelerated.

      If the ice were darker it would absorb more heat when the sun shines. Would it not also radiate more heat after dark?

      When the sun shines for 24 hours a day, unless you’re right on the North Pole, the sun is significantly higher at noon than it is at midnight. Under those conditions it seems reasonable to expect that at midnight, when the sun is just grazing the horizon, the ice pack is radiating more than absorbing. Darkening the ice pack with soot should exacerbate the situation.

      • “Would it not also radiate more heat after dark?”

        Oddly enough no. Ice has an emissivity of 0.98. I don’t have a figure for volcanic ash, but almost no minerals have emissivities above 0.9.

    • Giant ice banks are formed on the shore of Lake Superior every year by wave action, these banks are completely infused with beach sand. Most winter nights gets really cold, especially if the sky is clear, certainly the sand-infused ice can drop to 0F or less on the surface, and there might not be much sun the next day to warm it up to melt. My experience is that sand-infused ice isn’t much different than regular clean ice on the nearby river until maybe late March. Then the longer sunny days can work on melting the sand-infused ice. The sand infused ice can disappear real fast under the right conditions.

      If these banks got dusted by volcanic ash early in the season, I highly doubt they would get “darker”. The ice is a mishmash of entrained air and snow and such, basically white in color and not clear, and any such dirt would quickly be obscured by whiteness. From what I’ve seen of arctic ice it’s kind of the same, not a sheet it’s a broken jumbled mess.

  11. I recall reading that the International Ice Patrol tried to accelerate iceberg melting by covering the surfaces of some with carbon black, soot, charcoal, etc., in attempts to melt the icebergs deliberately. (Bombs were also tried). They gave up. Ice is apparently not so easy to melt – all that thermal mass to deal with. (After all, whether iceberg or glacier, only the top surface is exposed to the atmosphere.)

  12. Muschitiello says the study “can give us hints about the mechanisms at play when you’re expecting rapid climate change.”

    Good thing we aren’t expecting rapid climate change.

  13. Perfect example of pseudoscience, and it is in the service of Warmism. What they want is fudge factors – “wild cards”, which can be used in their schmodels to “explain” whatever needs explaining.

  14. I understood that the catastrophic melting of north american ice fields around 11,000 years BC (not BP) was as the result of a meteor strike. I also understood that the release of pressure on the earth’s crust from 2km thick ice melting abruptly resulted in some volcanic eruptions.

    Isostatic rebound and consequential falling is still underway and seems to confuse – or be very convenient for – sea level rise ‘experts’ and activists.

    Makes me wonder why this study seems to have ignored the evidence of it being a meteor strike ? Or perhaps I have misunderstood some of the papers I have read.

    • I thought that the north american ice fields started to melt 20,000 years ago and that was natural and part of a cycle named Millankovic, or something like that.

  15. Let’s do a full-Earth-scale test to eliminate scale-up uncertainties:

    Century-scale volcanoes like El Chichon in 1982 and Pinatubo in 1991 cause global cooling of about 0.5C, which then dissipated over several years. That global cooling was the NET EFFECT of ALL factors, including the reduced transparency of the atmospheric due to airborne volcanic aerosols and particulates (the dominant factor) and lesser impacts such as ash darkening of ice sheets that caused some melting.

    In summary, the NET EFFECT of large-scale volcanoes is temporary global cooling – there is no evidence of any runaway warming effects from volcanoes.

    Regards, Allan


    Unlike the deeply flawed computer climate models cited by the IPCC, Bill Illis has created a temperature model that actually works in the short-term (multi-decades). It shows global temperatures correlate primarily with NIno3.4 area temperatures – an area of the Pacific Ocean that is about 1% of global surface area. There are only four input parameters, with Nino3.4 being the most influential. CO2 has almost no influence. So what drives the Nino3.4 temperatures? Short term, the ENSO. Longer term, probably the integral of solar activity – see Dan Pangburn’s work.

    Bill’s post is here.

    Bill’s equation is:
    Tropics Troposphere Temp = 0.288 * Nino 3.4 Index (of 3 months previous) + 0.499 * AMO Index + -3.22 * Aerosol Optical Depth volcano Index + 0.07 Constant + 0.4395*Ln(CO2) – 2.59 CO2 constant

    Bill’s graph is here – since 1958, not a whole lotta global warming goin’ on!

    My simpler equation using only the Nino3.4 Index Anomaly is:
    UAHLTcalc Global (Anom. in degC, ~four months later) = 0.20*Nino3.4IndexAnom + 0.15
    Data: Nino3.4IndexAnom is at:

    It shows that much or all of the apparent warming since ~1982 is a natural recovery from the cooling impact of two major volcanoes – El Chichon and Pinatubo.

    Here is the plot of my equation:

    I added the Sato Global Mean Optical Depth Index (h/t Bill Illis) to compensate for the cooling impact of major volcanoes, so the equation changes to:
    UAHLTcalc Global (Anom. in degC) = 0.20*Nino3.4IndexAnom (four months earlier) + 0.15 – 8*SatoGlobalMeanOpticalDepthIndex

    The “Sato Index” is factored by about -8 and here is the result – the Orange calculated global temperature line follows the Red actual UAH global LT temperature line reasonably well, with one brief deviation at the time of the Pinatubo eruption.

    Here is the plot of my new equation, with the “Sato” index:

    I agree with Bill’s conclusion that

    Regards, Allan

  16. The word “may” is powerfull. Have you ever counted how often it is used in papers about something with climate?

  17. Isn’t some of this thinking a bit contradictory? If large amounts of soot or ash are ejected into the atmosphere, especially the high atmosphere, we know conditions get colder. Presumably before any melting starts, lots of the soot gets covered by increased snowfall, which is one of the reasons we can identify episodes of major eruptions linked to cold conditions in the ice sheet records. So the more ash or soot, the more prolonged the cold period that follows should be, with more time for newly triggered snowfalls to cover or wash away the soot.
    Also, as the Earth is gradually losing its core heat (unless this is being replenished by radioactive decay heating) over time we should see fewer and less energetic eruptions. So less ash and soot over the long run.
    Their claims seem to me to have a few flaws and claim more than we know or can fully account for.

  18. I like these “scientific” studies. Touring Iceland, we were shown a glacier that retreated 2 km in just a few years possibly due to global warming. It was a dirty looking glacier and, indeed, there was a volcano upwind. I found later that it became active “a few years ago.” That melting will probably accelerate as the ash and dirt concentration increases. Undisputed impact of accelerated global warming.

  19. The ice melt response would depend on the stage of the glacial period – deep glacial little effect, glacial ending bigger effect. But even in the latter period, it would be minor. The cooling effect of the aerosols would result in frost and likely some snow which would quickly whiten the surface again. There could be some ponding on surface in some places that would simply refreeze.

    But this is not the main thing wrong with their thesis. Almost all the melt water generating the varves comes from under the ice. There is no sediment in most of the km or so of ice above the bottom.

    • Even at glacial maximum the accumulation and ablation zones of an ice-sheet will be in approximate balance.

      “Almost all the melt water generating the varves comes from under the ice. There is no sediment in most of the km or so of ice above the bottom.”

      You don’t have much practical experience of glaciers, right? Supraglacial river in Greenland:

      • I haven’t noticed you as a snarky type, tty. You could be a more experienced glaciologist than I, but I have been a student of continental glaciation at the University of Manitoba that sits on the floor of the late Lake Agassiz and its world famous varves and have been subjected to field trips to deltas and multiple shorelines from its draining out when the ice had receded, all now sitting there, out of place, like post disaster memoirs. Are you saying the continental glaciers are sandy and silty from top to bottom. Well they are not. Glacial maximum continental glaciers I was talking about. The grinding takes place at the base and and water is present even during the maximum. There isn’t “turbulence” mixing of the top layers of relatively clean ice. When the edges of the glacier are melting in the much advanced stage of deterioration as in your photo (not the 12,000 – 13,000 years ago of this article by contrast) – its probably 15C above in your picture. Maybe this will help to show you how sediment moves when a continental glacier is melting:

  20. if there is enough ash in the air to travel thousands of miles and deposit on the ice then there is enough ash in the air to diminish the heat from the sun (reflected back into space) so while you may have dirty ice it will get less sunlight to warm it up … could easily offset each other …

  21. Are the varves thicker because there is more water to carry the sediment, or because there is more sediment for the water to carry?

  22. Doesn’t this reinforce the idea that soot (actual carbon) has a greater impact on in glacier retreat than “greenhouse gases” (carbon dioxide)?

  23. There isn’t any “may melt rapidly”. There is no doubt that a soot covered ice or snow pack will absorb the heat from the Sun and melt whatever is below (snow/ ice). Every winter I put my ashes from my pellet stoves on the snow covering my south walkway and the Sun does the rest- melts it so I don’t have to shovel it.

    • Joe, your ashes go directly to your south walkway, without making a trip into the atmosphere. Your ashes do not have a chance to reduce sunlight the way a volcanic eruption would.


      • True but the soot on the snow stays long after the soot in the atmosphere is gone. But yes if the Sun doesn’t reach the dirty snow then it will not effect it.

  24. “Keep in mind this latest October 12 event is not associated with obvious earthquake swarms and proven volcanic eruptions as was the case during the 1999 – 2007 event. This earlier event was powerful but not obvious to those who did not understand its true nature. Even though it was associated with an extensive low intensity earthquake swarm, a huge methane release, and a significant series of volcanic eruptions along the Gakkel Ridge it was, and still is dismissed as insignificant by most climate scientists advocating the theory of man-made global warming”

  25. Another research study based on predispositions regarding theories. i.e. “Confirmation Bias”

    “events similar to the 2010 eruptions of Iceland’s Eyjafjallajökull volcano. Although that eruption was relatively minor, its large ash cloud shut down air traffic across most of Europe for about a week.”

    • And the ash fall on ice sheet study results are?
    • Not studied or inconvenient results.

    “How much melting could an eruption like that cause? “It’s difficult to put an exact number to it,” says glaciologist and coauthor James Lea from the University of Liverpool. “It depends on many factors.”

    Running thousands of model simulations, the team found that the amount of melting depends on the individual eruption, which season it occurs in, the snowpack conditions at the time, and the elevation of the ice sheet.”

    The researchers Ignore actual ash falls and prefer to run computer models until the results desired are produce.

    • Zero ability to replicate.
    • Verification or validation is near impossible.
    • Model runs that depend on a host of assumptions; happily provided as input by the authors.

    When dumping sand or ash, or even kitty litter on sidewalks to prevent slipping and hopefully melt some of the snow; one quickly discovers negative results.
    • A) Dark grit requires sunlight to work. Cloudy weather, no melt.
    • B) Thick layers of grist and especially ash insulate snow/ice from melting. Ash is a terrible conductor and layers of ash prevent convection.
    • C) Ice piles covered with thick layers of grit and ash last long into very warm spring weather.
    • D) Any additional snow/ice accumulation covers the grit/ash negating all benefits.

    Only the outer ash layer changes the albedo. Without conductive properties, covered ice/snow will not melt. Since the far North and South have greater periods of diurnal cold; freezing and refreezing ice dominates melting.

    One does wonder where the alleged researchers included ash thickness insulating properties in their “models”.

    • Observational evidence:

      Here in Colorado* we’d get say 18″ of snow. Then.
      Snow removal crews create 9-12′ snow mounds just COVERED with asphalt, dirt, oil stains, trash.
      After a month or more of 70°F+ days, still there. Dying away. But still there.

      *Colorado snow doesn’t stick around long. The high altitude and just about the most cloudless / sunshine days over any other state just eliminates snow.

      The snow in those parking lots disappear much faster (~week) when not plowed.

      I don’t really accept ‘soot’ melts glaciers. And it does appear intuitive to make that claim. But, yeah. Until observations.

  26. Compare advance and retreat of the polar ice coverage and the glaciers with the list of volcanic eruption V4, V5 & V6 since 1900.

    V4 (0.1 km3 to 1km3 DRE)*
    Nabro 2011
    Puyehue-Cordón Caulle 2011
    Grimsvötn 2011
    Merapi 2010
    Eyjafjallajökull 2010
    Sarychev Peak 2010
    Kasatochi 2008
    Chaiten 2008
    Reventator 2002
    Ulawun 2000
    Lascar 1993
    Mt. Spurr 1992
    Kelud 1990
    Kiluchevkoi 1987
    Chikurachki 1986
    Mount Augustine 1986
    Colo 1983
    Galunggung 1982
    Pagan 1981
    Alaid 1981
    Mount Augustine 1976
    Tolbachik 1975
    Volcan de Fuego 1974
    Tiatia 1973
    Fernandina 1968
    Mount Awu 1966
    Kelud 1966
    Taal 1965
    Shiveluch 1964
    Carran-Los Venados 1955
    Mount Spurr 1953
    Bagana 1952
    Kelud 1951
    Mount Lamington 1951
    Ambrym 1950
    Hekla 1947
    Sarychev Paek 1946
    Avachinsky 1945
    Paricutin 1943–1952
    Suoh 1933
    Volcan De Fuego 1932
    Mont Aniakchak 1931
    Kliucheskoi 1931
    Komagatake 1931
    Komagatake 1929
    Avachinsky 1926
    Raikoko 1924
    Manam 1919
    Kelud 1919
    Agrhan 1917
    Tungurahua 1916
    Sakurajima 1914
    Mount Lolobau 1911
    Grimsvötn 1903
    Monut Pelee 1902

    V5 (1 km3 to 10 km3 DRE)*
    Mt. Hudson 1991
     El Chichon 1982
    Mt. St. Helens 1980
     Agung 1963
    Bezymianny 1956
     Kharimkotan 1933
    Cerro Azul 1932
     Katla 1918
     Colima 1913
    Ksudach 1907

    V6 (10 km3 to 100 km3 DRE)*
    Pinatubo 1991
    Katmai/Novarupta 1912
    St. Maria 1902

    * Volume of tephra as ‘Dense Rock Equivalent’

  27. The misdirection in the article is in the photo. No matter where you look there are new layers on old. If catastrophic melting were a problem there would be a very thick darkened layer that all subsequent layers would have melted down to. That isn’t happening. The ice core is nothing but evidence of ice staying ahead of the soot.

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