Carbon cycle conundrums: cave deposits show surprising shift in permafrost over the last 400,000 years

Posted: April 29, 2021 by oldbrew in climate, History, research
Tags: ,

speleothems

Six most common speleothems [image credit: Dave Bunnell / Under Earth Images @ Wikipedia]

The MIT research article this report is based on includes the phrase ‘carbon cycle conundrums’ in its title. In the discussion section we find this: ‘However, atmospheric CO2 and CH4 concentrations did not exceed Holocene levels during MIS 11, seemingly indicating that widespread ground thaw did not initiate a permafrost carbon feedback where increased atmospheric greenhouse gases and subsequent warming thaw permafrost that releases more greenhouse gases.’ If no ‘carbon feedback’, what does that say about the theories behind current climate paranoia?
– – –
Nearly one quarter of the land in the Northern Hemisphere, amounting to some 9 million square miles, is layered with permafrost—soil, sediment, and rocks that are frozen solid for years at a time, says Phys.org.

Vast stretches of permafrost can be found in Alaska, Siberia, and the Canadian Arctic, where persistently freezing temperatures have kept carbon, in the form of decayed bits of plants and animals, locked in the ground.

Scientists estimate that more than 1,400 gigatons of carbon is trapped in the Earth’s permafrost.

As global temperatures climb, and permafrost thaws, this frozen reservoir could potentially escape into the atmosphere as carbon dioxide and methane, significantly amplifying climate change [Talkshop comment: according to certain disputed theories]. However, little is known about permafrost’s stability, today or in the past.

Now geologists at MIT, Boston College, and elsewhere have reconstructed permafrost’s history over the last 1.5 million years. The researchers analyzed cave deposits in locations across western Canada and found evidence that, between 1.5 million and 400,000 years ago, permafrost was prone to thawing, even in high Arctic latitudes. Since then, however, permafrost thaw has been limited to sub-Arctic regions.

The results, published in Science Advances, suggest that the planet’s permafrost shifted to a more stable state in the last 400,000 years, and has been less susceptible to thawing since then.

In this more stable state, permafrost likely has retained much of the carbon that it has built up during this time, having little opportunity to gradually release it.

“The stability of the last 400,000 years may actually work against us, in that it has allowed carbon to steadily accumulate in permafrost over this time. Melting now might lead to substantially greater releases of carbon to the atmosphere than in the past,” says study co-author David McGee, associate professor in MIT’s Department of Earth, Atmospheric, and Planetary Sciences.

Full article here.

Research article: Increasing Pleistocene permafrost persistence and carbon cycle conundrums inferred from Canadian speleothems [Science Advances, 28 Apr 2021]

Comments
  1. saighdear says:

    Yes, well, and as per a long discussion with a local weather watcher, t’other day, … ” If there is a Climate Emergency, then why don’t the counter AGW crowd get together with the government and EDUCATE THEM….” Surely a 3-hour Lab session off facts is sufficient: considerin that our leaders reckon they are not dimwits, they should be able to understand basic acts within a 3- hour stint.

  2. JB says:

    “Scientists estimate that more than 1,400 gigatons of carbon is trapped in the Earth’s permafrost.”

    Just how much carbon is locked up in living tissue? Do any of them know of a surety how much carbon exists on this planet?

    “found evidence that, between 1.5 million and 400,000 years ago”

    I’m skeptical of anything dated past 10Kya as the error increases with age. This is a long known problem with ice core dating.

    “reconstructed permafrost’s history”

    That is truly some feat, when verbiage as “suggest”, “may”, “estimate”, and “little is known” are used. Just where in all this “research” are falsifiable tests being done?

    Seems to me the very idea of “carbon feedback” is suspect when there is no such thing as a GREENHOUSE gas. Just ordinary atmospheric gases.

  3. DB says:

    In addition to the new paleo data we have field experiments.
    https://www.sciencenews.org/article/warming-may-not-release-arctic-carbon
    The Arctic’s stockpile of carbon may be more secure than scientists thought. In a 20-year experiment that warmed patches of chilly ground, tundra soil kept its stored carbon, researchers report….

    In 1989, ecologists set up greenhouses on plots of tundra in northern Alaska. Air temperature inside the greenhouses was on average 2 degrees Celsius warmer than outside….

    Overall, though, there was no difference in total soil carbon in the greenhouse plots compared with plots that had no greenhouses.

  4. oldbrew says:

    Conundrums due to expectations based on greenhouse-type theories not being met?

    Research article: More broadly, the general similarity of atmospheric CO2 and CH4 concentrations during warm interglacials of, respectively, the past ~1500 ka (37, 38) and ~800 ka (31, 32), despite differences in the spatial extent of deep permafrost thaw that we infer for the last 1500 ka, suggests that greenhouse gas concentrations during these interglacials were relatively insensitive to permafrost thaw (Fig. 3, D and E). [bold added]

    Nothing there for alarmists.

    However, atmospheric CO2 and CH4 concentrations did not exceed Holocene levels during MIS 11 (31, 32) (Fig. 3, D and E), seemingly indicating that widespread ground thaw did not initiate a permafrost carbon feedback where increased atmospheric greenhouse gases and subsequent warming thaw permafrost that releases more greenhouse gases.

    Nothing there for them either. What invisible greenhouse are they talking about? ‘Fictitious’ springs to mind.

  5. pochas94 says:

    saighdear wrote:

    “why don’t the counter AGW crowd get together with the government and EDUCATE THEM….”

    These are people who don’t know what they are talking about, who get their “facts” from others who don’t know what they are talking about. Their aim is financial security and, above all, political power. For them education is as water on a duck’s back.

  6. oldbrew says:

    NASA Knew
    Posted on April 26, 2021 by tonyheller

    Fifty years ago, NASA’s leading climatologists knew that a runaway greenhouse effect was not possible.
    https://realclimatescience.com/2021/04/nasa-knew-2/

  7. saighdear says:

    in reply to pochas94, Yes indeed POWER …. and one of the Mantras? – Education & Save the NHS ……. so it is Education, just for the sake of it. …. Easy to go off- topic here about Education and who got what job ot of it …..

  8. oldbrew says:

    Gumnut’s guide…

    The Working Class Guide to Climate Change:

    Decarbonising the economy = Removing your job.
    Carbon Capture = Capturing your savings.
    Net Zero = How much you’ll have in your pocket after decarbonisation and carbon capture.
    The Great Reset = Replacing Make America Great Again with Make AOC a Greater Pain.
    Climate Summit = An opportunity for peak hypocrisy.
    Renewables = Power generation infrastructure that often needs to be renewed (replaced) before it has generated more power than was used in manufacturing and installing it.

    https://climatechangedispatch.com/climate-change-carbon-and-a-science-lesson-for-boris-johnson/#comment-48681

  9. ivan says:

    All this shows just how little they actually know about the earth, its atmosphere and how it all works in conjunction with the sun.

  10. Phoenix44 says:

    “Prone to thawing”?

    Is that a truly pathetic attempt to say without saying that it was warmer then than now?

  11. oldbrew says:

    Phoenix – yes.

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