Ice sheets may melt rapidly in response to distant volcanoes

Posted: October 25, 2017 by oldbrew in Ice ages, research, volcanos
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This is the finding from a new research paper entitled ‘Enhanced ice sheet melting driven by volcanic eruptions during the last deglaciation.’

Another very recently published paper (‘Very large release of mostly volcanic carbon during the Palaeocene–Eocene Thermal Maximum’) says something similar:
‘The Palaeocene–Eocene Thermal Maximum [PETM], was a global warming event that occurred about 56 million years ago, and is commonly thought to have been driven primarily by the destabilization of carbon from surface sedimentary reservoirs such as methane hydrates. However, it remains controversial whether such reservoirs were indeed the source of the carbon that drove the warming…[We] identify volcanism associated with the North Atlantic Igneous Province rather than carbon from a surface reservoir, as the main driver of the PETM. This finding implies that climate-driven amplification of organic carbon feedbacks probably played only a minor part in driving the event.’

So two papers saying volcanic ash on the ice, not carbon dioxide in the air, was the main player in PETM deglaciation.
– – –
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, says Phys.org.

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.

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.

Continued here.

Comments
  1. oldmanK says:

    An early 1st today; too tempting.

    Quote: “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.”

    The time is critical; at the ‘trip point of a glacial’. More likely the eruptions and ice melting are two concurrent effects of same cause. Melting an ice-sheet requires a lot of thermal input for a phase change; more than warming water or air by a couple of degrees.

  2. ivan says:

    Hear, Hear.

    oldmanK that was my first thought on reading this.

    It looks as if too many of the modern so called ‘scientists’ are so brainwashed that they automatically assume a necessary plant food is the cause of all the problems rather than looking at what caused the volcanism and did it also cause the melting. Unfortunately that type of research requires work and doesn’t get grant money.

  3. oldbrew says:

    “We know that if you have darker ice, you decrease the reflectance and it melts more quickly. It’s basic science,” says Muschitiello.
    – – –
    In the polar regions it’s going to be dark for half the year i.e. nothing to reflect, making albedo irrelevant 50% of the time. That’s also basic science.

  4. p.g.sharrow says:

    have they bothered to consider the increase in energy and density that volcanic activity adds to the atmosphere?…pg

  5. Bitter&twisted says:

    Who would have thought?
    Paint it black and the sun warms it more.

  6. oldmanK says:

    But my take on that is different. But first ask: what condition created great ice caps at both poles? Not today’s, because they are melting – and have been doing so for the last few millennia.

    Put the earth upright to the ecliptic and a great thermal engine will move great amounts of water to the poles where it will stay. No summer melting because of no summer all year. But that is an unstable dynamic so it will eventually tip. Then the initial melting is fast, but it is also very cataclysmic.

  7. oldmanK says:

    A good read here: https://www.academia.edu/34926783/Human_responses_and_non-responses_to_climatic_variations_during_the_last_Glacial-Interglacial_transition_in_the_eastern_Mediterranean?auto=download&campaign=weekly_digest

    Quote from conclusion: “Some of those environmental changes were of a speed and amplitude unprecedented in the last 20,000years. Periods of rapid warming and wetting-up of the climate followed by climatic reversals prompted a range of human adaptive responses, including some that-with hindsight- we might view as evolutionary false starts and dead ends, but others that eventually led to domestication of selected plants and animals ”

    No Milankovitch effects here.

  8. oldbrew says:

    Yellowstone spawned twin super-eruptions that altered global climate
    October 26, 2017

    “We discovered here that there are two ash-forming super-eruptions 170 years apart and each cooled the ocean by about 3 degrees Celsius,” said U.C. Santa Barbara geologist Jim Kennett
    . . .
    Kennett and colleagues discovered that the onset of the global cooling events was abrupt and coincided precisely with the timing of the supervolcanic eruptions, the first such observation of its kind.

    But each time, the cooling lasted longer than it should have, according to simple climate models, he said. “We see planetary cooling of sufficient magnitude and duration that there had to be other feedbacks involved.” These feedbacks might include increased sunlight-reflecting sea ice and snow cover or a change in ocean circulation that would cool the planet for a longer time. [bold added]

    Read more at: http://phys.org/news/2017-10-yellowstone-spawned-twin-super-eruptions-global.html

    See link for context.

  9. ewing.caldwell says:

    There is an alternative explanation for the PETM which does not require CO2 spurts, CH4 bursts and other Magic. It does involve the position of the Solar System [SS] in its orbit about the galactic centre and a dearth of cosmic rays to create cloud cover.

    It’s hinted at in Shaviv’s ice-ages research and is covered indirectly in Svensmark’s and Calder’s book The Chilling Stars. Chapt 5: The Dinosaur’s Guide to the Galaxy.”

    If I have read everything clearly, then the Late Cretacious and Paleogene up to the arrival of the Dinosaur Destroyer [DD] 65MYA, were pretty warm. The climate returned to that warmth after the detritus of the Big Bang cleared. The SS at the time was chasing the Sagittarius-Carina spiral arm. A spiral arm is a shock wave and if it’s anything like a terrestrial weather front (very dodgy analogy here!) then it’s rear side or trailing edge could be fairly calm with all the action happening at the front side or leading edge. Cosmic rays are well embedded as streams in the Spiral Arms, and probably particularly so at the leading edge.

    So the warmth of the PETM could have come from the lack of Cosmic Rays to generate cloud cover as the SS approached the trailing edge of the Sagittarius-Carina arm. Things changed as progress was made into the spiral arm and Cosmic Ray concentrations began to increase. Crossing the arm may have taken about 30-33MY, the SS orbital speed being higher than the spiral arm’s. The Big Freeze occurred when the SS emerged at the leading edge of the spiral arm and headed for the Orion spur.

    Gould’s Belt was created about 33MYA in the Orion arm. The Belt is a region of intense Cosmic Rays (relatively speaking) from both star formation and death. There’s no shortage of cloud now. It’s why we’re in an Ice Age, the Quaternary Ice Age. The SS sailed straight into the Cosmic Ray storm of these star deaths as it entered the belt a few million years ago

    There’s no need for CO2 to explain the PETM. Shaviv’s Ice Age paper and the Dinosaur’s Guide to the Galaxy in The Chilling Stars are enough.

  10. oldmanK says:

    ewing.caldwell says: October 26, 2017 at 11:30 am

    Quote: ” It’s why we’re in an Ice Age, the Quaternary Ice Age. The SS sailed straight into the Cosmic Ray storm of these star deaths as it entered the belt a few million years ago”.

    The question here is the abrupt warming that followed the YD, some 13ky ago. But also remember that abrupt warming happened five times in the last 450ky. See fig 1 in this WUWT link: https://wattsupwiththat.com/2017/08/04/paleoclimate-cycles-are-key-analogs-for-present-day-holocene-warm-period/